МОЛЕКУЛЫ АНТИ-APRIL АНТИТЕЛА И ИХ ПРИМЕНЕНИЕ

Abstract

Раскрыты молекулы антитела, которые специфически связываются с APRIL. Молекулы антитела можно использовать для лечения, профилактики и / или диагностики расстройств, таких как IgA-нефропатия.

Description

[0001] ANTIBODY MOLECULES TO APRIL AND USES THEREOF

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of U.S. Provisional Application Nos. 63 / 043,558, filed June 24, 2020; 63 / 091,002, filed October 13, 2020; 63 / 136,950, filed January 13, 2021; and 63 / 195,527, filed June 1, 2021. The contents of the aforementioned applications are hereby incorporated by reference in their entirety.

[0004] SEQUENCE LISTING

[0005] The instant application contains a Sequence Listing which has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on June 17, 2021, is named P2029-7037WO_SL.txt and is 259,172 bytes in size.

[0006] BACKGROUND

[0007] IgA nephropathy is one of the most prevalent, chronic glomerular diseases worldwide. Conservative epidemiological estimates cite a global incidence of approximately 5-50 cases / million (children) and 10-40 cases / million (adults). This incidence of disease presents a regional bias with a higher prevalence in Asia and the Americas, with a particularly higher disease burden in Japan and regions of China. Biopsy confirmed cases of IgA nephropathy in Japan are projected at approximately 350,000. In the US, this projection is approximately 100,000 — as such, it is the most frequently diagnosed 1° glomerular disease in adults. While a relatively indolent disease, IgA nephropathy leads to end stage renal disease (ESRD), i.e., renal failure in 20-50% of patients within a 20-30 year span. These numbers are likely grossly underreported given the need to confirm the disease by kidney biopsy, a protocol that is variably practiced in various clinical settings. The disease has a complex pathogenesis with genetic, epidemiological, and potentially environmental components to disease etiology, pathology, and progression. It likewise has a variable clinical presentation ranging from asymptomatic to end-stage renal failure (ESRD). IgA nephropathy is caused by the deposition of IgA, typically in the form of immune complexes in the mesangium of the kidney. There are currently no disease-specific treatments to address primary disease or progression.

[0008] There is a need for developing new approaches for treating, preventing and diagnosing IgA nephropathy and other disorders that share similar disease mechanisms. SUMMARY

[0009] Accordingly, in certain aspects, this disclosure provides a method for treating a disorder, the method comprising administering to a subject in need thereof an anti- APRIL antibody molecule described herein, wherein the antibody molecule is administered at a dose that reduces, or is likely to reduce, the level of aberrantly glycosylated IgA (a-g IgA), e.g. aberrantly glycosylated IgAl (a-g IgAl), by at least 40% in the subject, thereby treating the disorder. In an embodiment, the level of a-g IgA comprises, or is, the level of a-g IgAl.

[0010] In an embodiment, the level of a-g IgA is reduced by at least 40% about 4 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 8 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 12 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 16 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% for a predetermined period, e.g., at least one, two, three, or four weeks, or at least one, two, or three months. In an embodiment, the level of a-g IgA is reduced by at least 50%. In an embodiment, the level of a-g IgA is reduced by at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. In an embodiment, the antibody molecule is administered as a single dose. In an embodiment, the antibody molecule is administered as a repeated dose. In an embodiment, the antibody molecule is administered subcutaneously. In an embodiment, the antibody molecule is administered intravenously.

[0011] In an embodiment, the disorder is an APRIL-associated disorder. In an embodiment, the disorder is associated with an aberrant level of total IgA. In an embodiment, the disorder is a disorder associated with a-g IgA (e.g., a-g IgAl).

[0012] In an embodiment, the disorder is IgA nephropathy (IgAN). In an embodiment, the IgAN is a familial IgAN. In an embodiment, the IgA is an adult IgAN. In an embodiment, the IgAN is a post transplant IgAN, a pediatric IgAN, or a crescentic IgAN.

[0013] In an embodiment, the disorder is a chronic kidney disease (CKD) or a disorder associated with CKD. In an embodiment, the CKD is an advanced CKD, e.g., with an estimated glomerular filtration rate (eGFR) equal to or greater than about 30 or about 45.

[0014] In an embodiment, the disorder is Henoch-Schonlein purpura (HSP). In an embodiment, the disorder is cutaneous vasculitis or IgA vasculitis. In an embodiment, the disorder is IgA dermatitis, e.g., IgA bullous dermatosis. In an embodiment, the disorder is Waldenstrom macroglobulinemia (WM). In an embodiment, the disorder is lupus nephritis.

[0015] In an embodiment, the subject is a human. In an embodiment, the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has, or is identified as having, a genomic susceptible locus of the disorder, e.g., IgA nephropathy. In an embodiment, the method further comprises determining whether the subject has a genomic susceptible locus of the disorder, e.g., IgA nephropathy.

[0016] In an embodiment, the anti-APRIL antibody molecule is an anti-APRIL antibody molecule described herein. In an embodiment, the anti-APRIL antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419- 0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237. In an embodiment, the anti-APRIL antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419- 1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0017] In an embodiment, the level of a-g IgA is determined in a sample from the subject. In an embodiment, the method described herein further comprises determining the level of a-g IgA in a sample from the subject. In an embodiment, the method further comprises determining the level of total IgA in the sample. In an embodiment, the method further comprising determining the level of IgM and / or IgG in the sample. In an embodiment, the method further comprises obtaining a sample from the subject. In an embodiment, the sample is a blood or serum sample.

[0018] In an embodiment, the method further comprises administering a second therapeutic agent or modality to the subject. In an embodiment, the second therapeutic agent or modality is a small molecule. In an embodiment, the second therapeutic agent or modality is an antibody molecule.

[0019] In an embodiment, the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti-APRIL antibody molecule. In an embodiment, the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti-APRIL antibody molecule. In an embodiment, the subject receives the vaccine before, concurrent with, or after administration of the anti-APRIL antibody molecule. In an embodiment, administration of the anti-APRIL antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In an embodiment, administration of the anti-APRIL antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine. In an embodiment, the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after administration of the anti-APRIL antibody molecule.

[0020] In an embodiment, the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®). In an embodiment, the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after administration of the anti-APRIL antibody molecule.

[0021] In an aspect, the disclosure features a method of treating a disorder, the method comprising administering to a subject in need thereof an anti-APRIL antibody molecule, wherein the administration reduces the level of a-g IgA (e.g., a-g IgAl) by at least 40% in the subject, thereby treating the disorder. In an embodiment, the level of a-g IgA comprises, or is, the level of a-g IgAl.

[0022] In an embodiment, the level of a-g IgA is reduced by at least 40% about 4 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 8 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 12 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 16 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% for a predetermined period, e.g., at least one, two, three, or four weeks, or at least one, two, or three months. In an embodiment, the level of a-g IgA is reduced by at least 50%. In an embodiment, the level of a-g IgA is reduced by at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. In an embodiment, the antibody molecule is administered as a single dose. In an embodiment, the antibody molecule is administered as a repeated dose. In an embodiment, the antibody molecule is administered subcutaneously. In an embodiment, the antibody molecule is administered intravenously.

[0023] In an embodiment, the disorder is an APRIL-associated disorder. In an embodiment, the disorder is associated with an aberrant level of total IgA. In an embodiment, the disorder is a disorder associated with a-g IgA (e.g., a-g IgAl). In an embodiment, the disorder is IgA nephropathy (IgAN). In an embodiment, the IgAN is a familial IgAN. In an embodiment, the IgA is an adult IgAN. In an embodiment, the IgAN is a post transplant IgAN, a pediatric IgAN, or a crescentic IgAN.

[0024] In an embodiment, the disorder is a chronic kidney disease (CKD) or a disorder associated with CKD. In an embodiment, the CKD is an advanced CKD, e.g., with an estimated glomerular filtration rate (eGFR) equal to or greater than about 30 or about 45.

[0025] In an embodiment, the disorder is Henoch-Schonlein purpura (HSP). In an embodiment, the disorder is cutaneous vasculitis or IgA vasculitis. In an embodiment, the disorder is IgA dermatitis, e.g., IgA bullous dermatosis. In an embodiment, the disorder is Waldenstrom macroglobulinemia (WM). In an embodiment, the disorder is lupus nephritis.

[0026] In an embodiment, the subject is a human. In an embodiment, the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has, or is identified as having, a genomic susceptible locus of the disorder, e.g., IgA nephropathy. In an embodiment, the method described herein further comprises determining whether the subject has a genomic susceptible locus of the disorder, e.g., IgA nephropathy.

[0027] In an embodiment, the anti-APRIL antibody molecule is an anti-APRIL antibody molecule described herein. In an embodiment, the anti-APRIL antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419- 0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237. In an embodiment, the anti-APRIL antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419- 1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0028] In an embodiment, the level of a-g IgA is determined in a sample from the subject. In an embodiment, the method further comprises determining the level of a-g IgA in a sample from the subject. In an embodiment, the method further comprises determining the level of total IgA in the sample. In an embodiment, the method further comprising determining the level of IgM and / or IgG in the sample. In an embodiment, the method further comprises obtaining a sample from the subject. In an embodiment, the sample is a blood or serum sample.

[0029] In an embodiment, the method further comprises administering a second therapeutic agent or modality to the subject. In an embodiment, the second therapeutic agent or modality is a small molecule. In an embodiment, the second therapeutic agent or modality is an antibody molecule.

[0030] In an embodiment, the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti -APRIL antibody molecule. In an embodiment, the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti-APRIL antibody molecule. In an embodiment, the subject receives the vaccine before, concurrent with, or after administration of the anti-APRIL antibody molecule.

[0031] In an embodiment, administration of the anti-APRIL antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In an embodiment, administration of the anti-APRIL antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine. In an embodiment, the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after administration of the anti-APRIL antibody molecule.

[0032] In an embodiment, the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®). In an embodiment, the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after administration of the anti-APRIL antibody molecule.

[0033] In yet another aspect, the disclosure features a method of treating a disorder, the method comprising administering to a subject in need thereof an anti-APRIL antibody molecule, wherein the antibody molecule is administered at a dosage (e.g., dose and frequency) that reduces, or is likely to reduce, the level of a-g IgA (e.g., a-g IgAl) by at least 40% in the subject, thereby treating the disorder.

[0034] In an embodiment, the level of a-g IgA comprises, or is, the level of a-g IgAl.

[0035] In an embodiment, the level of a-g IgA is reduced by at least 40% about 4 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 8 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 12 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 16 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% for a predetermined period, e.g., at least one, two, three, or four weeks, or at least one, two, or three months. In an embodiment, the level of a-g IgA is reduced by at least 50%. In an embodiment, the level of a-g IgA is reduced by at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. In an embodiment, the antibody molecule is administered as a single dose. In an embodiment, the antibody molecule is administered as a repeated dose. In an embodiment, the antibody molecule is administered subcutaneously. In an embodiment, the antibody molecule is administered intravenously.

[0036] In an embodiment, the disorder is an APRIL-associated disorder. In an embodiment, the disorder is associated with an aberrant level of total IgA. In an embodiment, the disorder is a disorder associated with a-g IgA (e.g., a-g IgAl).

[0037] In an embodiment, the disorder is IgA nephropathy (IgAN). In an embodiment, the IgAN is a familial IgAN. In an embodiment, the IgA is an adult IgAN. In an embodiment, the IgAN is a post transplant IgAN, a pediatric IgAN, or a crescentic IgAN.

[0038] In an embodiment, the disorder is a chronic kidney disease (CKD) or a disorder associated with CKD. In an embodiment, the CKD is an advanced CKD, e.g., with an estimated glomerular filtration rate (eGFR) equal to or greater than about 30 or about 45.

[0039] In an embodiment, the disorder is Henoch-Schonlein purpura (HSP). In an embodiment, the disorder is cutaneous vasculitis or IgA vasculitis. In an embodiment, the disorder is IgA dermatitis, e.g., IgA bullous dermatosis. In an embodiment, the disorder is Waldenstrom macroglobulinemia (WM). In an embodiment, the disorder is lupus nephritis.

[0040] In an embodiment, the subject is a human. In an embodiment, the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has, or is identified as having, a genomic susceptible locus of the disorder, e.g., IgA nephropathy. In an embodiment, the method further comprises determining whether the subject has a genomic susceptible locus of the disorder, e.g., IgA nephropathy. In an embodiment, the anti-APRIL antibody molecule is an anti-APRIL antibody molecule described herein. In an embodiment, the anti-APRIL antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419- 0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237. In an embodiment, the anti-APRIL antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419- 1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0041] In an embodiment, the level of a-g IgA is determined in a sample from the subject. In an embodiment, the method further comprises determining the level of a-g IgA in a sample from the subject. In an embodiment, the method further comprises determining the level of total IgA in the sample. In an embodiment, the method further comprising determining the level of IgM and / or IgG in the sample. In an embodiment, the method further comprises obtaining a sample from the subject. In an embodiment, the sample is a blood or serum sample.

[0042] In an embodiment, the method further comprises administering a second therapeutic agent or modality to the subject. In an embodiment, the second therapeutic agent or modality is a small molecule. In an embodiment, the second therapeutic agent or modality is an antibody molecule.

[0043] In an embodiment, the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti-APRIL antibody molecule. In an embodiment, the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti-APRIL antibody molecule. In an embodiment, the subject receives the vaccine before, concurrent with, or after administration of the anti-APRIL antibody molecule.

[0044] In an embodiment, administration of the anti-APRIL antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In an embodiment, administration of the anti-APRIL antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine. In an embodiment, the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after administration of the anti-APRIL antibody molecule.

[0045] In an embodiment, the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®). In an embodiment, the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after administration of the anti-APRIL antibody molecule.

[0046] In another aspect, the disclosure features a method of treating a disorder, the method comprising selecting a dose or dosage (e.g., dose and frequency) for an anti-APRIL antibody molecule, wherein administration of the antibody molecule at the dose or dosage reduces, or is likely to reduce, the level of a-g IgA (e.g., a-g IgAl) by at least 40% in a subject in need thereof; and administering the antibody molecule to the subject at the selected dose or dosage, thereby treating the disorder. In an embodiment, the level of a-g IgA comprises, or is, the level of a-g IgAl.

[0047] In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 4 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 8 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 12 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 16 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% for a predetermined period, e.g., at least one, two, three, or four weeks, or at least one, two, or three months. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 50%. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. In an embodiment, the antibody molecule is administered as a single dose. In an embodiment, the antibody molecule is administered as a repeated dose. In an embodiment, the antibody molecule is administered subcutaneously. In an embodiment, the antibody molecule is administered intravenously.

[0048] In an embodiment, the disorder is an APRIL-associated disorder. In an embodiment, the disorder is associated with an aberrant level of total IgA. In an embodiment, the disorder is a disorder associated with a-g IgA (e.g., a-g IgAl).

[0049] In an embodiment, the disorder is IgA nephropathy (IgAN). In an embodiment, the IgAN is a familial IgAN. In an embodiment, the IgA is an adult IgAN. In an embodiment, the IgAN is a post transplant IgAN, a pediatric IgAN, or a crescentic IgAN. In an embodiment, the disorder is a chronic kidney disease (CKD) or a disorder associated with CKD. In an embodiment, the CKD is an advanced CKD, e.g., with an estimated glomerular filtration rate (eGFR) equal to or greater than about 30 or about 45.

[0050] In an embodiment, the disorder is Henoch-Schonlein purpura (HSP). In an embodiment, the disorder is cutaneous vasculitis or IgA vasculitis. In an embodiment, the disorder is IgA dermatitis, e.g., IgA bullous dermatosis. In an embodiment, the disorder is Waldenstrom macroglobulinemia (WM). In an embodiment, the disorder is lupus nephritis.

[0051] In an embodiment, the subject is a human. In an embodiment, the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has, or is identified as having, a genomic susceptible locus of the disorder, e.g., IgA nephropathy. In an embodiment, the method further comprises determining whether the subject has a genomic susceptible locus of the disorder, e.g., IgA nephropathy.

[0052] In an embodiment, the anti-APRIL antibody molecule is an anti-APRIL antibody molecule described herein. In an embodiment, the anti-APRIL antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419- 0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237. In an embodiment, the anti-APRIL antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419- 1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0053] In an embodiment, the level of a-g IgA is determined in a sample from the subject. In an embodiment, the method further comprises determining the level of a-g IgA in a sample from the subject. In an embodiment, the method further comprises determining the level of total IgA in the sample. In an embodiment, the method further comprising determining the level of IgM and / or IgG in the sample. In an embodiment, the method further comprises obtaining a sample from the subject. In an embodiment, the sample is a blood or serum sample. In an embodiment, the method further comprises administering a second therapeutic agent or modality to the subject. In an embodiment, the second therapeutic agent or modality is a small molecule. In an embodiment, the second therapeutic agent or modality is an antibody molecule.

[0054] In an embodiment, the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti -APRIL antibody molecule. In an embodiment, the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti-APRIL antibody molecule. In an embodiment, the subject receives the vaccine before, concurrent with, or after administration of the anti-APRIL antibody molecule.

[0055] In an embodiment, administration of the anti-APRIL antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In an embodiment, administration of the anti-APRIL antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine. In an embodiment, the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after administration of the anti-APRIL antibody molecule.

[0056] In an embodiment, the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®). In an embodiment, the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after administration of the anti-APRIL antibody molecule.

[0057] In an aspect, the disclosure features a method of treating a disorder, the method comprising responsive to a determination that administration of an anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA (e.g., a-g IgAl) by at least 40% in a subject in need thereof, administering to the subject an anti-APRIL antibody molecule, thereby treating the disorder. In an embodiment, the level of a-g IgA comprises, or is, the level of a-g IgAl.

[0058] In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 4 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 8 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 12 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 16 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% for a predetermined period, e.g., at least one, two, three, or four weeks, or at least one, two, or three months. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 50%. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. In an embodiment, the antibody molecule is administered as a single dose. In an embodiment, the antibody molecule is administered as a repeated dose. In an embodiment, the antibody molecule is administered subcutaneously. In an embodiment, the antibody molecule is administered intravenously.

[0059] In an embodiment, the disorder is an APRIL-associated disorder. In an embodiment, the disorder is associated with an aberrant level of total IgA. In an embodiment, the disorder is a disorder associated with a-g IgA (e.g., a-g IgAl).

[0060] In an embodiment, the disorder is IgA nephropathy (IgAN). In an embodiment, the IgAN is a familial IgAN. In an embodiment, the IgA is an adult IgAN. In an embodiment, the IgAN is a post transplant IgAN, a pediatric IgAN, or a crescentic IgAN.

[0061] In an embodiment, the disorder is a chronic kidney disease (CKD) or a disorder associated with CKD. In an embodiment, the CKD is an advanced CKD, e.g., with an estimated glomerular filtration rate (eGFR) equal to or greater than about 30 or about 45.

[0062] In an embodiment, the disorder is Henoch-Schonlein purpura (HSP). In an embodiment, the disorder is cutaneous vasculitis or IgA vasculitis. In an embodiment, the disorder is IgA dermatitis, e.g., IgA bullous dermatosis. In an embodiment, the disorder is Waldenstrom macroglobulinemia (WM). In an embodiment, the disorder is lupus nephritis.

[0063] In an embodiment, the subject is a human. In an embodiment, the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has, or is identified as having, a genomic susceptible locus of the disorder, e.g., IgA nephropathy. In an embodiment, the method further comprises determining whether the subject has a genomic susceptible locus of the disorder, e.g., IgA nephropathy. In an embodiment, the anti-APRIL antibody molecule is an anti-APRIL antibody molecule described herein. In an embodiment, the anti-APRIL antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419- 0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237. In an embodiment, the anti-APRIL antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419- 1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0064] In an embodiment, the level of a-g IgA is determined in a sample from the subject. In an embodiment, the method further comprises determining the level of a-g IgA in a sample from the subject. In an embodiment, the method further comprises determining the level of total IgA in the sample. In an embodiment, the method further comprising determining the level of IgM and / or IgG in the sample. In an embodiment, the method further comprises obtaining a sample from the subject. In an embodiment, the sample is a blood or serum sample.

[0065] In an embodiment, the method further comprises administering a second therapeutic agent or modality to the subject. In an embodiment, the second therapeutic agent or modality is a small molecule. In an embodiment, the second therapeutic agent or modality is an antibody molecule.

[0066] In an embodiment, the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti-APRIL antibody molecule. In an embodiment, the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti-APRIL antibody molecule. In an embodiment, the subject receives the vaccine before, concurrent with, or after administration of the anti-APRIL antibody molecule.

[0067] In an embodiment, administration of the anti-APRIL antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In an embodiment, administration of the anti-APRIL antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine. In an embodiment, the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after administration of the anti-APRIL antibody molecule.

[0068] In an embodiment, the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®). In an embodiment, the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 11 I / ml , in the blood), e.g., 1, 2, 3, 4,

[0069] 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after administration of the anti-APRIL antibody molecule.

[0070] In another aspect, the disclosure features a method of treating a disorder, the method comprising determining whether administration of an anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA (e.g., a-g IgAl) by at least 40% in a subject in need thereof, if the antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, administration of the antibody molecule is initiated, continued, or maintained. In an embodiment, the level of a-g IgA comprises, or is, the level of a-g IgAl.

[0071] In an embodiment, if the antibody molecule does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40%, administration of the antibody molecule is terminated, discontinued, or altered. In an embodiment, if the antibody molecule does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40%, a different therapeutic agent or modality is administered.

[0072] In an embodiment, the level of a-g IgA is reduced by at least 40% about 4 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 8 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 12 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 16 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% for a predetermined period, e.g., at least one, two, three, or four weeks, or at least one, two, or three months. In an embodiment, the level of a-g IgA is reduced by at least 50%. In an embodiment, the level of a-g IgA is reduced by at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. In an embodiment, the antibody molecule is administered as a single dose. In an embodiment, the antibody molecule is administered as a repeated dose. In an embodiment, the antibody molecule is administered subcutaneously. In an embodiment, the antibody molecule is administered intravenously.

[0073] In an embodiment, the disorder is an APRIL-associated disorder. In an embodiment, the disorder is associated with an aberrant level of total IgA. In an embodiment, the disorder is a disorder associated with a-g IgA (e.g., a-g IgAl).

[0074] In an embodiment, the disorder is IgA nephropathy (IgAN). In an embodiment, the IgAN is a familial IgAN. In an embodiment, the IgA is an adult IgAN. In an embodiment, the IgAN is a post transplant IgAN, a pediatric IgAN, or a crescentic IgAN. In an embodiment, the disorder is a chronic kidney disease (CKD) or a disorder associated with CKD. In an embodiment, the CKD is an advanced CKD, e.g., with an estimated glomerular filtration rate (eGFR) equal to or greater than about 30 or about 45.

[0075] In an embodiment, the disorder is Henoch-Schonlein purpura (HSP). In an embodiment, the disorder is cutaneous vasculitis or IgA vasculitis. In an embodiment, the disorder is IgA dermatitis, e.g., IgA bullous dermatosis. In an embodiment, the disorder is Waldenstrom macroglobulinemia (WM). In an embodiment, the disorder is lupus nephritis.

[0076] In an embodiment, the subject is a human. In an embodiment, the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has, or is identified as having, a genomic susceptible locus of the disorder, e.g., IgA nephropathy. In an embodiment, the method further comprises determining whether the subject has a genomic susceptible locus of the disorder, e.g., IgA nephropathy.

[0077] In an embodiment, the anti-APRIL antibody molecule is an anti-APRIL antibody molecule described herein. In an embodiment, the anti-APRIL antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419- 0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237. In an embodiment, the anti-APRIL antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419- 1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0078] In an embodiment, the level of a-g IgA is determined in a sample from the subject. In an embodiment, the method further comprises determining the level of a-g IgA in a sample from the subject. In an embodiment, the method further comprises determining the level of total IgA in the sample. In an embodiment, the method further comprising determining the level of IgM and / or IgG in the sample. In an embodiment, the method further comprises obtaining a sample from the subject. In an embodiment, the sample is a blood or serum sample. In an embodiment, the method further comprises administering a second therapeutic agent or modality to the subject. In an embodiment, the second therapeutic agent or modality is a small molecule. In an embodiment, the second therapeutic agent or modality is an antibody molecule.

[0079] In an embodiment, the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti -APRIL antibody molecule. In an embodiment, the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti-APRIL antibody molecule. In an embodiment, the subject receives the vaccine before, concurrent with, or after administration of the anti-APRIL antibody molecule.

[0080] In an embodiment, administration of the anti-APRIL antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In an embodiment, administration of the anti-APRIL antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine. In an embodiment, the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after administration of the anti-APRIL antibody molecule.

[0081] In an embodiment, the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®). In an embodiment, the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after administration of the anti-APRIL antibody molecule.

[0082] In yet another aspect, the disclosure features a method of treating a disorder, the method comprising determining whether administration of an anti-APRIL antibody molecule at a dose or dosage reduces, or is likely to reduce, the level of a-g IgAl (e.g., a-g IgAl) by at least 40% in a subject in need thereof, if the antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% at the dose or dosage, administration of the antibody molecule at the dose or dosage is initiated, continued, or maintained. In an embodiment, the level of a-g IgA comprises, or is, the level of a-g IgAl.

[0083] In an embodiment, if the antibody molecule does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40% at the dose or dosage, administration of the antibody molecule at the dose or dosage is terminated, discontinued, or altered.

[0084] In an embodiment, the level of a-g IgA is reduced by at least 40% about 4 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 8 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 12 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 16 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% for a predetermined period, e.g., at least one, two, three, or four weeks, or at least one, two, or three months. In an embodiment, the level of a-g IgA is reduced by at least 50%. In an embodiment, the level of a-g IgA is reduced by at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. In an embodiment, the antibody molecule is administered as a single dose. In an embodiment, the antibody molecule is administered as a repeated dose. In an embodiment, the antibody molecule is administered subcutaneously. In an embodiment, the antibody molecule is administered intravenously.

[0085] In an embodiment, the disorder is an APRIL-associated disorder. In an embodiment, the disorder is associated with an aberrant level of total IgA. In an embodiment, the disorder is a disorder associated with a-g IgA (e.g., a-g IgAl).

[0086] In an embodiment, the disorder is IgA nephropathy (IgAN). In an embodiment, the IgAN is a familial IgAN. In an embodiment, the IgA is an adult IgAN. In an embodiment, the IgAN is a post transplant IgAN, a pediatric IgAN, or a crescentic IgAN.

[0087] In an embodiment, the disorder is a chronic kidney disease (CKD) or a disorder associated with CKD. In an embodiment, the CKD is an advanced CKD, e.g., with an estimated glomerular filtration rate (eGFR) equal to or greater than about 30 or about 45.

[0088] In an embodiment, the disorder is Henoch-Schonlein purpura (HSP). In an embodiment, the disorder is cutaneous vasculitis or IgA vasculitis. In an embodiment, the disorder is IgA dermatitis, e.g., IgA bullous dermatosis. In an embodiment, the disorder is Waldenstrom macroglobulinemia (WM). In an embodiment, the disorder is lupus nephritis.

[0089] In an embodiment, the subject is a human. In an embodiment, the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has, or is identified as having, a genomic susceptible locus of the disorder, e.g., IgA nephropathy. In an embodiment, the method further comprises determining whether the subject has a genomic susceptible locus of the disorder, e.g., IgA nephropathy. In an embodiment, the anti-APRIL antibody molecule is an anti-APRIL antibody molecule described herein. In an embodiment, the anti-APRIL antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419- 0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237. In an embodiment, the anti-APRIL antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419- 1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0090] In an embodiment, the level of a-g IgA is determined in a sample from the subject. In an embodiment, the method further comprises determining the level of a-g IgA in a sample from the subject. In an embodiment, the method further comprises determining the level of total IgA in the sample. In an embodiment, the method further comprising determining the level of IgM and / or IgG in the sample. In an embodiment, the method further comprises obtaining a sample from the subject. In an embodiment, the sample is a blood or serum sample.

[0091] In an embodiment, the method further comprises administering a second therapeutic agent or modality to the subject. In an embodiment, the second therapeutic agent or modality is a small molecule. In an embodiment, the second therapeutic agent or modality is an antibody molecule.

[0092] In an embodiment, the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti-APRIL antibody molecule. In an embodiment, the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti-APRIL antibody molecule. In an embodiment, the subject receives the vaccine before, concurrent with, or after administration of the anti-APRIL antibody molecule.

[0093] In an embodiment, administration of the anti-APRIL antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In an embodiment, administration of the anti-APRIL antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine. In an embodiment, the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after administration of the anti-APRIL antibody molecule.

[0094] In an embodiment, the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®). In an embodiment, the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 11 I / ml , in the blood), e.g., 1, 2, 3, 4,

[0095] 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after administration of the anti-APRIL antibody molecule.

[0096] In an aspect, the disclosure features a method of treating a disorder, the method comprising determining whether administration of a therapeutic agent or modality other than an anti-APRIL antibody molecule described herein reduces, or is likely to reduce, the level of a-g IgA by at least 40% in a subject in need thereof, if the therapeutic agent or modality does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40%, administering an anti-APRIL antibody molecule described herein to the subject. In an embodiment, the antibody molecule is administered at a dose or dosage that reduces, or is likely to reduce, the level of a-g IgA by at least 40% in the subject. In an embodiment, the level of a-g IgA comprises, or is, the level of a-g IgAl.

[0097] In an embodiment, the therapeutic agent or modality reduces, or is likely to reduce, the level of a- g IgA by at least 40% about 4 weeks after the antibody molecule is administered. In an embodiment, the therapeutic agent or modality reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 8 weeks after the antibody molecule is administered. In an embodiment, the therapeutic agent or modality reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 12 weeks after the antibody molecule is administered. In an embodiment, the therapeutic agent or modality reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 16 weeks after the antibody molecule is administered.

[0098] In an embodiment, the therapeutic agent or modality reduces, or is likely to reduce, the level of a-g IgA by at least 40% for a predetermined period, e.g., at least one, two, three, or four weeks, or at least one, two, or three months. In an embodiment, the therapeutic agent or modality reduces, or is likely to reduce, the level of a-g IgA by at least 50%. In an embodiment, the therapeutic agent or modality reduces, or is likely to reduce, the level of a-g IgA by at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. In an embodiment, the therapeutic agent or modality is administered as a single dose. In an embodiment, the therapeutic agent or modality is administered as a repeated dose. In an embodiment, the antibody molecule is administered subcutaneously. In an embodiment, the antibody molecule is administered intravenously.

[0099] In an embodiment, the disorder is associated with an aberrant level of total IgA. In an embodiment, the disorder is a disorder associated with a-g IgA (e.g., a-g IgAl).

[0100] In an embodiment, the disorder is IgA nephropathy (IgAN). In an embodiment, the IgAN is a familial IgAN. In an embodiment, the IgA is an adult IgAN. In an embodiment, the IgAN is a post transplant IgAN, a pediatric IgAN, or a crescentic IgAN. In an embodiment, the disorder is a chronic kidney disease (CKD) or a disorder associated with CKD. In an embodiment, the CKD is an advanced CKD, e.g., with an estimated glomerular filtration rate (eGFR) equal to or greater than about 30 or about 45.

[0101] In an embodiment, the disorder is Henoch-Schonlein purpura (HSP). In an embodiment, the disorder is cutaneous vasculitis or IgA vasculitis. In an embodiment, the disorder is IgA dermatitis, e.g., IgA bullous dermatosis. In an embodiment, the disorder is Waldenstrom macroglobulinemia (WM). In an embodiment, the disorder is lupus nephritis.

[0102] In an embodiment, the subject is a human. In an embodiment, the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has, or is identified as having, a genomic susceptible locus of the disorder, e.g., IgA nephropathy. In an embodiment, the method further comprises determining whether the subject has a genomic susceptible locus of the disorder, e.g., IgA nephropathy.

[0103] In an embodiment, the anti- APRIL antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419- 0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237. In an embodiment, the anti-APRIL antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419- 0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0104] In an embodiment, the level of a-g IgA is determined in a sample from the subject. In an embodiment, the method further comprises determining the level of a-g IgA in a sample from the subject. In an embodiment, the method further comprises determining the level of total IgA in the sample. In an embodiment, the method further comprising determining the level of IgM and / or IgG in the sample. In an embodiment, the method further comprises obtaining a sample from the subject. In an embodiment, the sample is a blood or serum sample. In an embodiment, the method further comprises administering a second therapeutic agent or modality to the subject. In an embodiment, the second therapeutic agent or modality is a small molecule. In an embodiment, the second therapeutic agent or modality is an antibody molecule.

[0105] In an embodiment, the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti -APRIL antibody molecule. In an embodiment, the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti-APRIL antibody molecule. In an embodiment, the subject receives the vaccine before, concurrent with, or after administration of the anti-APRIL antibody molecule.

[0106] In an embodiment, administration of the anti-APRIL antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In an embodiment, administration of the anti-APRIL antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine. In an embodiment, the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after administration of the anti-APRIL antibody molecule.

[0107] In an embodiment, the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®). In an embodiment, the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after administration of the anti-APRIL antibody molecule.

[0108] In another aspect the disclosure features a method of reducing the level of a-g IgA (e.g., a-g IgAl) in subject, the method comprising administering an anti-APRIL antibody molecule to a subject in a need thereof, e.g., at a dose or dosage that reduces, or is likely to reduce, the level of a-g IgA by at least 40% in the subject, thereby reducing the level of a-g IgA. In an embodiment, the level of a-g IgA comprises, or is, the level of a-g IgAl.

[0109] In an embodiment, the level of a-g IgA is reduced by at least 40% about 4 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 8 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 12 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% about 16 weeks after the antibody molecule is administered. In an embodiment, the level of a-g IgA is reduced by at least 40% for a predetermined period, e.g., at least one, two, three, or four weeks, or at least one, two, or three months. In an embodiment, the level of a-g IgA is reduced by at least 50%. In an embodiment, the level of a-g IgA is reduced by at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. In an embodiment, the antibody molecule is administered as a single dose. In an embodiment, the antibody molecule is administered as a repeated dose. In an embodiment, the antibody molecule is administered subcutaneously. In an embodiment, the antibody molecule is administered intravenously.

[0110] In an embodiment, the subject is a human. In an embodiment, the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has, or is identified as having, a genomic susceptible locus of the disorder, e.g., IgA nephropathy. In an embodiment, the method further comprises determining whether the subject has a genomic susceptible locus of the disorder, e.g., IgA nephropathy.

[0111] In an embodiment, the subject has or is identified as having an APRIL-associated disorder. In an embodiment, the subject has or is identified as having a disorder associated with an aberrant level of total IgA. In an embodiment, the subject has or is identified as having a disorder associated with a-g IgA (e.g., a-g IgAl).

[0112] In an embodiment, the subject has or is identified as having an IgA nephropathy (IgAN). In an embodiment, the IgAN is a familial IgAN. In an embodiment, the IgA is an adult IgAN. In an embodiment, the IgAN is a post-transplant IgAN, a pediatric IgAN, or a crescentic IgAN.

[0113] In an embodiment, the subject has or is identified as having a chronic kidney disease (CKD) or a disorder associated with CKD. In an embodiment, the CKD is an advanced CKD, e.g., with an estimated glomerular filtration rate (eGFR) equal to or greater than about 30 or about 45.

[0114] In an embodiment, the subject has or is identified as having a Henoch-Schonlein purpura (HSP). In an embodiment, the subject has or is identified as having a cutaneous vasculitis or IgA vasculitis. In an embodiment, the subject has or is identified as having an IgA dermatitis, e.g., IgA bullous dermatosis. In an embodiment, the subject has or is identified as having a Waldenstrom macroglobulinemia (WM). In an embodiment, the subject has or is identified as having a lupus nephritis.

[0115] In an embodiment, the anti-APRIL antibody molecule is an anti-APRIL antibody molecule described herein. In an embodiment, the anti-APRIL antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419- 0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237. In an embodiment, the anti- APRIL antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419- 1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0116] In an embodiment, the level of a-g IgA is determined in a sample from the subject. In an embodiment, the method further comprises determining the level of a-g IgA in a sample from the subject. In an embodiment, the method further comprises determining the level of total IgA in the sample. In an embodiment, the method further comprising determining the level of IgM and / or IgG in the sample. In an embodiment, the method further comprises obtaining a sample from the subject. In an embodiment, the sample is a blood or serum sample.

[0117] In an embodiment, the method further comprises administering a second therapeutic agent or modality to the subject. In an embodiment, the second therapeutic agent or modality is a small molecule. In an embodiment, the second therapeutic agent or modality is an antibody molecule.

[0118] In an embodiment, the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti- APR TL antibody molecule. In an embodiment, the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti-APRIL antibody molecule. In an embodiment, the subject receives the vaccine before, concurrent with, or after administration of the anti-APRIL antibody molecule.

[0119] In an embodiment, administration of the anti-APRIL antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In an embodiment, administration of the anti-APRIL antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine. In an embodiment, the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after administration of the anti-APRIL antibody molecule.

[0120] In an embodiment, the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®). In an embodiment, the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after administration of the anti-APRIL antibody molecule. In yet another aspect, the disclosure features a method of selecting an anti- APRIL antibody molecule for treating a disorder, the method comprising determining whether administration of the anti- APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA (e.g., a-g IgAl) by at least 40% in a subject in need thereof, thereby selecting the anti-APRIL antibody molecule. In an embodiment, the level of a-g IgA comprises, or is, the level of a-g IgAl.

[0121] In an embodiment, the anti-APRIL antibody molecule is an anti-APRIL antibody molecule described herein. In an embodiment, the anti-APRIL antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419- 0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237. In an embodiment, the anti-APRIL antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419- 1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0122] In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 4 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 8 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 12 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 16 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% for a predetermined period, e.g., at least one, two, three, or four weeks, or at least one, two, or three months. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 50%. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. In an embodiment, the antibody molecule is administered as a single dose. In an embodiment, the antibody molecule is administered as a repeated dose. In an embodiment, the antibody molecule is administered subcutaneously. In an embodiment, the antibody molecule is administered intravenously.

[0123] In an embodiment, the subject is a human. In an embodiment, the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has, or is identified as having, a genomic susceptible locus of the disorder, e.g., IgA nephropathy. In an embodiment, the method further comprises determining whether the subject has a genomic susceptible locus of the disorder, e.g., IgA nephropathy.

[0124] In an embodiment, the subject has or is identified as having an APRIL-associated disorder. In an embodiment, the subject has or is identified as having a disorder associated with an aberrant level of total IgA. In an embodiment, the subject has or is identified as having a disorder associated with a-g IgA (e.g., a-g IgAl).

[0125] In an embodiment, the subject has or is identified as having an IgA nephropathy (IgAN). In an embodiment, the IgAN is a familial IgAN. In an embodiment, the IgA is an adult IgAN. In an embodiment, the IgAN is a post-transplant IgAN, a pediatric IgAN, or a crescentic IgAN.

[0126] In an embodiment, the subject has or is identified as having a chronic kidney disease (CKD) or a disorder associated with CKD. In an embodiment, the CKD is an advanced CKD, e.g., with an estimated glomerular filtration rate (eGFR) equal to or greater than about 30 or about 45.

[0127] In an embodiment, the subject has or is identified as having a Henoch-Schonlein purpura (HSP). In an embodiment, the subject has or is identified as having a cutaneous vasculitis or IgA vasculitis. In an embodiment, the subject has or is identified as having a IgA dermatitis, e.g., IgA bullous dermatosis. In an embodiment, the subject has or is identified as having a Waldenstrom macroglobulinemia (WM). In an embodiment, the subject has or is identified as having a lupus nephritis.

[0128] In an embodiment, the level of a-g IgA is determined in a sample from the subject. In an embodiment, the method further comprises determining the level of a-g IgA in a sample from the subject. In an embodiment, the method further comprises determining the level of total IgA in the sample. In an embodiment, the method further comprising determining the level of IgM and / or IgG in the sample. In an embodiment, the method further comprises obtaining a sample from the subject. In an embodiment, the sample is a blood or serum sample.

[0129] In an embodiment, the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti -APRIL antibody molecule. In an embodiment, the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti-APRIL antibody molecule. In an embodiment, the subject receives the vaccine before, concurrent with, or after administration of the anti-APRIL antibody molecule.

[0130] In an embodiment, administration of the anti-APRIL antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In an embodiment, administration of the anti-APRIL antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine. In an embodiment, the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after administration of the anti-APRIL antibody molecule.

[0131] In an embodiment, the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®). In an embodiment, the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after administration of the anti-APRIL antibody molecule.

[0132] In another aspect, the disclosure features a method of selecting a dose or dosage (e.g., dose and frequency) for an anti-APRIL antibody molecule for treating a disorder, the method comprising determining whether administration of the anti-APRIL antibody molecule at a dose or dosage reduces, or is likely to reduce, the level of a-g IgA (e.g., a-g IgAl) by at least 40% in a subject in need thereof, thereby selecting the dose or dosage. In an embodiment, the level of a-g IgA comprises, or is, the level of a-g IgAl.

[0133] In an embodiment, the anti-APRIL antibody molecule is an anti-APRIL antibody molecule described herein. In an embodiment, the anti-APRIL antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419- 0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237. In an embodiment, the anti-APRIL antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419- 1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0134] In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 4 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 8 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 12 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 16 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% for a predetermined period, e.g., at least one, two, three, or four weeks, or at least one, two, or three months. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 50%. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. In an embodiment, the antibody molecule is administered as a single dose. In an embodiment, the antibody molecule is administered as a repeated dose. In an embodiment, the antibody molecule is administered subcutaneously. In an embodiment, the antibody molecule is administered intravenously.

[0135] In an embodiment, the subject is a human. In an embodiment, the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has, or is identified as having, a genomic susceptible locus of the disorder, e.g., IgA nephropathy. In an embodiment, the method further comprises determining whether the subject has a genomic susceptible locus of the disorder, e.g., IgA nephropathy.

[0136] In an embodiment, the subject has or is identified as having an APRIL-associated disorder. In an embodiment, the subject has or is identified as having a disorder associated with an aberrant level of total IgA. In an embodiment, the subject has or is identified as having a disorder associated with a-g IgA (e.g., a-g IgAl).

[0137] In an embodiment, the subject has or is identified as having an IgA nephropathy (IgAN). In an embodiment, the IgAN is a familial IgAN. In an embodiment, the IgA is an adult IgAN. In an embodiment, the IgAN is a post-transplant IgAN, a pediatric IgAN, or a crescentic IgAN.

[0138] In an embodiment, the subject has or is identified as having a chronic kidney disease (CKD) or a disorder associated with CKD. In an embodiment, the CKD is an advanced CKD, e.g., with an estimated glomerular filtration rate (eGFR) equal to or greater than about 30 or about 45. In an embodiment, the subject has or is identified as having a Henoch-Schonlein purpura (HSP). In an embodiment, the subject has or is identified as having a cutaneous vasculitis or IgA vasculitis. In an embodiment, the subject has or is identified as having a IgA dermatitis, e.g., IgA bullous dermatosis. In an embodiment, the subject has or is identified as having a Waldenstrom macroglobulinemia (WM). In an embodiment, the subject has or is identified as having a lupus nephritis.

[0139] In an embodiment, the level of a-g IgA is determined in a sample from the subject. In an embodiment, the method further comprises determining the level of a-g IgA in a sample from the subject. In an embodiment, the method further comprises determining the level of total IgA in the sample. In an embodiment, the method further comprising determining the level of IgM and / or IgG in the sample. In an embodiment, the method further comprises obtaining a sample from the subject. In an embodiment, the sample is a blood or serum sample.

[0140] In an embodiment, the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti -APRIL antibody molecule. In an embodiment, the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti-APRIL antibody molecule. In an embodiment, the subject receives the vaccine before, concurrent with, or after administration of the anti-APRIL antibody molecule.

[0141] In an embodiment, administration of the anti-APRIL antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In an embodiment, administration of the anti-APRIL antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine. In an embodiment, the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after administration of the anti-APRIL antibody molecule.

[0142] In an embodiment, the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®). In an embodiment, the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after administration of the anti-APRIL antibody molecule.

[0143] In another aspect, the disclosure features a method of selecting a subject for treating a disorder, the method comprising determining whether administration of an anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA (e.g., a-g IgAl) by at least 40% in a subject in need thereof, thereby selecting the subject. In an embodiment, the level of a-g IgA comprises, or is, the level of a-g IgAl.

[0144] In an embodiment, the anti-APRIL antibody molecule is an anti-APRIL antibody molecule described herein. In an embodiment, the anti-APRIL antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419- 0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237. In an embodiment, the anti-APRIL antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419- 1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0145] In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 4 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 8 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 12 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% about 16 weeks after the antibody molecule is administered. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% for a predetermined period, e.g., at least one, two, three, or four weeks, or at least one, two, or three months. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 50%. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. In an embodiment, the antibody molecule is administered as a single dose. In an embodiment, the antibody molecule is administered as a repeated dose. In an embodiment, the antibody molecule is administered subcutaneously. In an embodiment, the antibody molecule is administered intravenously.

[0146] In an embodiment, the subject is a human. In an embodiment, the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has, or is identified as having, a genomic susceptible locus of the disorder, e.g., IgA nephropathy. In an embodiment, the method further comprises determining whether the subject has a genomic susceptible locus of the disorder, e.g., IgA nephropathy.

[0147] In an embodiment, the subject has or is identified as having an APRIL-associated disorder. In an embodiment, the subject has or is identified as having a disorder associated with an aberrant level of total IgA. In an embodiment, the subject has or is identified as having a disorder associated with a-g IgA (e.g., a-g IgAl).

[0148] In an embodiment, the subject has or is identified as having an IgA nephropathy (IgAN). In an embodiment, the IgAN is a familial IgAN. In an embodiment, the IgA is an adult IgAN. In an embodiment, the IgAN is a post-transplant IgAN, a pediatric IgAN, or a crescentic IgAN.

[0149] In an embodiment, the subject has or is identified as having a chronic kidney disease (CKD) or a disorder associated with CKD. In an embodiment, the CKD is an advanced CKD, e.g., with an estimated glomerular filtration rate (eGFR) equal to or greater than about 30 or about 45.

[0150] In an embodiment, the subject has or is identified as having a Henoch-Schonlein purpura (HSP). In an embodiment, the subject has or is identified as having a cutaneous vasculitis or IgA vasculitis. In an embodiment, the subject has or is identified as having an IgA dermatitis, e.g., IgA bullous dermatosis. In an embodiment, the subject has or is identified as having a Waldenstrom macroglobulinemia (WM). In an embodiment, the subject has or is identified as having a lupus nephritis.

[0151] In an embodiment, the level of a-g IgA is determined in a sample from the subject. In an embodiment, the method further comprises determining the level of a-g IgA in a sample from the subject. In an embodiment, the method further comprises determining the level of total IgA in the sample. In an embodiment, the method further comprising determining the level of IgM and / or IgG in the sample. In an embodiment, the method further comprises obtaining a sample from the subject. In an embodiment, the sample is a blood or serum sample.

[0152] In an embodiment, the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti- APR TL antibody molecule. In an embodiment, the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the anti-APRIL antibody molecule. In an embodiment, the subject receives the vaccine before, concurrent with, or after administration of the anti-APRIL antibody molecule.

[0153] In an embodiment, administration of the anti-APRIL antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In an embodiment, administration of the anti-APRIL antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine. In an embodiment, the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after administration of the anti-APRIL antibody molecule.

[0154] In an embodiment, the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®). In an embodiment, the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after administration of the anti-APRIL antibody molecule.

[0155] In another aspect, the disclosure features a method of treating IgA nephropathy, the method comprising administering to a subject in need thereof an effective amount of an anti-APRIL antibody molecule (e.g., an anti-APRIL antibody molecule described herein), wherein the subject has received, or is going to receive, a vaccine (e.g., a vaccine described herein) within 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 weeks of administration of the anti-APRIL antibody molecule, thereby treating IgA nephropathy.

[0156] In an embodiment, the method further comprising administering the vaccine to the subject before, concurrently with, or after administration of the anti-APRIL antibody molecule.

[0157] In another aspect, the disclosure features a method of vaccinating a subject, the method comprising administering to the subject an effective amount of a vaccine (e.g., a vaccine described herein), wherein the subject has received, or is going to receive, an anti-APRIL antibody molecule (e.g., an anti-APRIL antibody molecule described herein) within 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 weeks of administration of the vaccine, thereby vaccinating the subject.

[0158] In an embodiment, the method further comprising administering the anti-APRIL antibody molecule to the subject before, concurrent with, or after administration of the vaccine.

[0159] In yet another aspect, the disclosure features a method of treating a disorder, the method comprising administering an anti-APRIL antibody molecule to a subject in a need thereof, e.g., at a dose or dosage that reduces, or is likely to reduce, the level of IgM by at least a predetermined percentage in the subject, thereby treating the disorder.

[0160] In an embodiment, the anti-APRIL antibody molecule is an anti-APRIL antibody molecule described herein. In an embodiment, the anti-APRIL antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419- 0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237. In an embodiment, the anti- APRIL antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419- 1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0161] In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of IgM by at least 20%, 25%, 30%, 35%, 40%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. In an embodiment, the antibody molecule is administered as a single dose. In an embodiment, the antibody molecule is administered as a repeated dose. In an embodiment, the antibody molecule is administered subcutaneously. In an embodiment, the antibody molecule is administered intravenously.

[0162] In an embodiment, the subject is a human. In an embodiment, the subject has, or is identified as having, a level of IgM that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of IgM in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder.

[0163] In an embodiment, the disorder is associated an aberrant level of IgM. In an embodiment, the disorder is a chronic kidney disease (CKD) or kidney injury. In an embodiment, the disorder is a fibrosis. In an embodiment, the disorder is an IgM mediated neuropathy, e.g., anti-MAG neuropathy or a neuropathy associated with anti-GMl. In an embodiment, the disorder is systemic lupus erythematosus (SLE). In an embodiment, the administration does not reduce, or does not substantially reduce, the level of IgG in the subject. In an embodiment, the administration reduces the level of IgG by no more than a predetermined percentage in the subject. In an embodiment, the administration reduces the level of IgG by at least a predetermined percentage in the subject.

[0164] In an embodiment, the level of IgM is determined in a sample from the subject. In an embodiment, the method further comprises determining the level of IgM in a sample from the subject. In an embodiment, the method further comprises determining the level of total IgM in the sample. In an embodiment, the method further comprising determining the level of IgA (e.g., total IgA and / or a-g IgA) and / or IgG in the sample. In an embodiment, the level of a-g IgA comprises, or is, the level of a-g IgAl. In an embodiment, the method further comprises obtaining a sample from the subject. In an embodiment, the sample is a blood or serum sample. In an embodiment, the method further comprises administering a second therapeutic agent or modality to the subject. In an embodiment, the second therapeutic agent or modality is a small molecule. In an embodiment, the second therapeutic agent or modality is an antibody molecule.

[0165] In an embodiment, the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule. In an embodiment, the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule. In an embodiment, the subject receives the vaccine before, concurrent with, or after administration of the antibody molecule.

[0166] In an embodiment, administration of the antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In an embodiment, administration of the antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine. In an embodiment, the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after the antibody molecule is administered.

[0167] In an embodiment, the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®). In an embodiment, the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after the antibody molecule is administered.

[0168] In another aspect, the disclosure features a method of reducing the level of IgM in a subject, the method comprising administering an anti-APRIL antibody molecule to a subject in a need thereof, e.g., at a dose or dosage that reduces, or is likely to reduce, the level of IgM by at least a predetermined percentage in the subject, thereby reducing the level of IgM.

[0169] In an embodiment, the anti-APRIL antibody molecule is an anti-APRIL antibody molecule described herein. In an embodiment, the anti-APRIL antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419- 0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237. In an embodiment, the anti-APRIL antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419- 1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0170] In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of IgM by at least 20%, 25%, 30%, 35%, 40%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, e.g., over a predetermined period. In an embodiment, the antibody molecule is administered as a single dose. In an embodiment, the antibody molecule is administered as a repeated dose. In an embodiment, the antibody molecule is administered subcutaneously. In an embodiment, the antibody molecule is administered intravenously.

[0171] In an embodiment, the subject is a human. In an embodiment, the subject has, or is identified as having, a level of IgM that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of IgM in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder.

[0172] In an embodiment, the disorder is associated an aberrant level of IgM. In an embodiment, the disorder is a chronic kidney disease (CKD) or kidney injury. In an embodiment, the disorder is a fibrosis. In an embodiment, the disorder is an IgM mediated neuropathy, e.g., anti-MAG neuropathy or a neuropathy associated with anti-GMl. In an embodiment, the disorder is systemic lupus erythematosus (SLE). In an embodiment, the administration does not reduce, or does not substantially reduce, the level of IgG in the subject. In an embodiment, the administration reduces the level of IgG by no more than a predetermined percentage in the subject. In an embodiment, the administration reduces the level of IgG by at least a predetermined percentage in the subject.

[0173] In an embodiment, the level of IgM is determined in a sample from the subject. In an embodiment, the method further comprises determining the level of IgM in a sample from the subject. In an embodiment, the method further comprises determining the level of total IgM in the sample. In an embodiment, the method further comprising determining the level of IgA (e.g., total IgA and / or a-g IgA) and / or IgG in the sample. In an embodiment, the level of a-g IgA comprises, or is, the level of a-g IgAl. In an embodiment, the method further comprises obtaining a sample from the subject. In an embodiment, the sample is a blood or serum sample.

[0174] In an embodiment, the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule. In an embodiment, the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule. In an embodiment, the subject receives the vaccine before, concurrent with, or after administration of the antibody molecule.

[0175] In an embodiment, administration of the antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In an embodiment, administration of the antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine. In an embodiment, the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after the antibody molecule is administered.

[0176] In an embodiment, the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®). In an embodiment, the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after the antibody molecule is administered.

[0177] In another aspect, the disclosure features a method of treating a disorder, the method comprising administering an anti-APRIL antibody molecule to a subject in a need thereof, e.g., at a dose or dosage that reduces, or is likely to reduce, the levels of IgA and IgM by at least predetermined percentages in the subject, thereby treating the disorder.

[0178] In an embodiment, the level of IgA comprises, or is, the level of total IgA and / or a-g IgA. In an embodiment, the level of a-g IgA comprises, or is, the level of a-g IgAl.

[0179] In an embodiment, the anti-APRIL antibody molecule is an anti-APRIL antibody molecule described herein. In an embodiment, the anti-APRIL antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419- 0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237. In an embodiment, the anti-APRIL antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419- 1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0180] In an embodiment, the administration does not reduce or does not substantially reduce, the level of IgG in the subject. In an embodiment, the administration reduces the level of IgG by no more than a predetermined percentage in the subject. In an embodiment, the administration reduces the level of IgG by at least a predetermined percentage in the subject. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, e.g., over a predetermined period. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of total IgA by at least 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, e.g., over a predetermined period. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of IgM by at least 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, e.g., over a predetermined period. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of IgA (e.g., total and / or a-g IgA) by at least 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95% and the level of IgM by at least 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, e.g., over a predetermined period. In an embodiment, the antibody molecule is administered as a single dose. In an embodiment, the antibody molecule is administered as a repeated dose. In an embodiment, the antibody molecule is administered subcutaneously. In an embodiment, the antibody molecule is administered intravenously.

[0181] In an embodiment, the subject is a human. In an embodiment, the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of IgM that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgM in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder.

[0182] In an embodiment, the disorder is an APRIL-associated disorder. In an embodiment, the disorder is associated an aberrant level of IgA (e.g., total IgA and / or a-g IgA) and / or IgM, e.g., a disorder described herein. In an embodiment, the disorder is systemic lupus erythematosus (SLE). In an embodiment, the administration does not reduce, or does not substantially reduce, the level of IgG in the subject. In an embodiment, the administration reduces the level of IgG by no more than a predetermined percentage in the subject. In an embodiment, the administration reduces the level of IgG by at least a predetermined percentage in the subject. In an embodiment, the level of IgA and / or IgM (and optionally IgG) is determined in a sample from the subject. In an embodiment, the method further comprises determining the level of a-g IgA in a sample from the subject. In an embodiment, the method further comprises determining the level of total IgA in the sample. In an embodiment, the method further comprising determining the level of IgM in the sample. In an embodiment, the method further comprising determining the level of IgG in the sample. In an embodiment, the method further comprises obtaining a sample from the subject. In an embodiment, the sample is a blood or serum sample.

[0183] In an embodiment, the method further comprises administering a second therapeutic agent or modality to the subject. In an embodiment, the second therapeutic agent or modality is a small molecule. In an embodiment, the second therapeutic agent or modality is an antibody molecule.

[0184] In an embodiment, the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule. In an embodiment, the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule. In an embodiment, the subject receives the vaccine before, concurrent with, or after administration of the antibody molecule.

[0185] In an embodiment, administration of the antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In an embodiment, administration of the antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine. In an embodiment, the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after the antibody molecule is administered.

[0186] In an embodiment, the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®). In an embodiment, the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after the antibody molecule is administered.

[0187] In yet another aspect, the disclosure features a method of reducing the levels of IgA and IgM in subject, the method comprising administering an anti-APRIL antibody molecule to a subject in a need thereof, e.g., at a dose or dosage that reduces, or is likely to reduce, the levels of IgA and IgM by at least predetermined percentages in the subject, thereby reducing the levels of IgA and IgM.

[0188] In an embodiment, the level of IgA comprises, or is, the level of total IgA and / or a-g IgA. In an embodiment, the level of a-g IgA comprises, or is, the level of a-g IgAl.

[0189] In an embodiment, the anti-APRIL antibody molecule is an anti-APRIL antibody molecule described herein. In an embodiment, the anti-APRIL antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419- 0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237. In an embodiment, the anti- APRIL antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419- 1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0190] In an embodiment, the administration does not reduce or does not substantially reduce, the level of IgG in the subject. In an embodiment, the administration reduces the level of IgG by no more than a predetermined percentage in the subject. In an embodiment, the administration reduces the level of IgG by at least a predetermined percentage in the subject.

[0191] In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 20%, 25%, 30%, 35%, 40%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, e.g., over a predetermined period. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce the level of total IgA by at least 20%, 25%, 30%, 35%, 40%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, e.g., over a predetermined period. In an embodiment, the anti- APRIL antibody molecule reduces, or is likely to reduce, the level of IgM by at least 20%, 25%, 30%, 35%, 40%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, e.g., over a predetermined period. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of IgA (e.g., total and / or a-g IgA) by at least 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95% and the level of IgM by at least 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, e.g., over a predetermined period. In an embodiment, the antibody molecule is administered as a single dose. In an embodiment, the antibody molecule is administered as a repeated dose. In an embodiment, the antibody molecule is administered subcutaneously. In an embodiment, the antibody molecule is administered intravenously.

[0192] In an embodiment, the subject is a human. In an embodiment, the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of IgM that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgM in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder.

[0193] In an embodiment, the disorder is an APRIL-associated disorder. In an embodiment, the disorder is associated an aberrant level of IgA (e.g., total IgA and / or a-g IgA) and / or IgM, e.g., a disorder described herein. In an embodiment, the disorder is systemic lupus erythematosus (SLE). In an embodiment, the administration does not reduce, or does not substantially reduce, the level of IgG in the subject. In an embodiment, the administration reduces the level of IgG by no more than a predetermined percentage in the subject. In an embodiment, the administration reduces the level of IgG by at least a predetermined percentage in the subject. In an embodiment, the level of IgA and / or IgM (and optionally IgG) is determined in a sample from the subject. In an embodiment, the method further comprises determining the level of a-g IgA in a sample from the subject. In an embodiment, the method further comprises determining the level of total IgA in the sample. In an embodiment, the method further comprising determining the level of IgM in the sample. In an embodiment, the method further comprising determining the level of IgG in the sample. In an embodiment, the method further comprises obtaining a sample from the subject. In an embodiment, the sample is a blood or serum sample.

[0194] In an embodiment, the method further comprises administering a second therapeutic agent or modality to the subject. In an embodiment, the second therapeutic agent or modality is a small molecule. In an embodiment, the second therapeutic agent or modality is an antibody molecule.

[0195] In an embodiment, the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule. In an embodiment, the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule. In an embodiment, the subject receives the vaccine before, concurrent with, or after administration of the antibody molecule.

[0196] In an embodiment, administration of the antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In an embodiment, administration of the antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine. In an embodiment, the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after the antibody molecule is administered.

[0197] In an embodiment, the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®). In an embodiment, the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after the antibody molecule is administered.

[0198] In another aspect, the disclosure features a method of treating a disorder, the method comprising administering to a subject in need thereof an effective amount of an anti- APRIL antibody molecule, wherein the disorder is:

[0199] (a) an advanced chronic kidney disease (CKD) (e.g., with an eGFR equal to or greater than about 30 or 45);

[0200] (b) a post -transplant IgAN;

[0201] (c) a pediatric IgAN;

[0202] (d) Henoch-Schonlein purpura (HSP) or cutaneous vasculitis;

[0203] (e) IgAN with crescentic glomerulonephritis (GN);

[0204] (f) IgA vasculitis;

[0205] (g) IgA dermatitis;

[0206] (h) IgM mediated neuropathy (anti-MAG or anti-GMl);

[0207] (i) Waldenstrom macroglobulinemia (WM); or

[0208] (j) lupus nephritis.

[0209] In an embodiment, the anti-APRIL antibody molecule is an anti-APRIL antibody molecule described herein. In an embodiment, the anti-APRIL antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419- 0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237. In an embodiment, the anti-APRIL antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419- 1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0210] In an embodiment, the administration reduces, or is likely to reduce, the IgA in the subject. In an embodiment, the administration reduces, or is likely to reduce, the IgM in the subject. In an embodiment, the level of IgA comprises, or is, the level of total IgA and / or a-g IgA. In an embodiment, the level of a-g IgA comprises, or is, the level of a-g IgAl.

[0211] In an embodiment, the administration does not reduce or does not substantially reduce, the level of IgG in the subject. In an embodiment, the administration reduces the level of IgG by no more than a predetermined percentage in the subject. In an embodiment, the administration reduces the level of IgG by at least a predetermined percentage in the subject. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 20%, 25%, 30%, 35%, 40%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, e.g., over a predetermined period. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce the level of total IgA by at least 20%, 25%, 30%, 35%, 40%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, e.g., over a predetermined period. In an embodiment, the anti- APRIL antibody molecule reduces, or is likely to reduce, the level of IgM by at least 20%, 25%, 30%, 35%, 40%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, e.g., over a predetermined period. In an embodiment, the anti-APRIL antibody molecule reduces, or is likely to reduce, the level of IgA (e.g., total and / or a-g IgA) by at least 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95% and the level of IgM by at least 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, e.g., over a predetermined period. In an embodiment, the antibody molecule is administered as a single dose. In an embodiment, the antibody molecule is administered as a repeated dose. In an embodiment, the antibody molecule is administered subcutaneously. In an embodiment, the antibody molecule is administered intravenously.

[0212] In an embodiment, the subject is a human. In an embodiment, the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has, or is identified as having, a level of IgM that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgM in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. In an embodiment, the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder. In an embodiment, the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder.

[0213] In an embodiment, the disorder is an advanced chronic kidney disease (CKD) (e.g., with an eGFR equal to or greater than about 30 or 45). In an embodiment, the disorder is a post -transplant IgAN. In an embodiment, the disorder is a pediatric IgAN. In an embodiment, the disorder is Henoch-Schonlein purpura (HSP) or cutaneous vasculitis. In an embodiment, the disorder is IgAN with crescentic glomerulonephritis (GN). In an embodiment, the disorder is IgA vasculitis. In an embodiment, the disorder is IgA dermatitis. In an embodiment, the disorder is IgM mediated neuropathy (anti-MAG or anti-GMl). In an embodiment, the disorder is Waldenstrom macroglobulinemia (WM). In an embodiment, the disorder is lupus nephritis. In an embodiment, the method further comprises administering a second therapeutic agent or modality to the subject. In an embodiment, the second therapeutic agent or modality is a small molecule. In an embodiment, the second therapeutic agent or modality is an antibody molecule.

[0214] In an embodiment, the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule. In an embodiment, the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule. In an embodiment, the subject receives the vaccine before, concurrent with, or after administration of the antibody molecule.

[0215] In an embodiment, administration of the antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In an embodiment, administration of the antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine. In an embodiment, the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after the antibody molecule is administered.

[0216] In an embodiment, the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®). In an embodiment, the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after the antibody molecule is administered.

[0217] In another aspect, the disclosure features a method of treating a disorder associated with an autoantigen, the method comprising administering to a subject in need thereof an effective amount of a therapeutic agent or modality, wherein the administration reduces, or is likely to reduce, the level of autoantigen by at least a predetermined percentage in the subject.

[0218] In an embodiment, the subject is a human. In an embodiment, the subject has or is identified as having an APRIL-associated disorder.

[0219] In an embodiment, the level of the autoantigen is determined in a sample from the subject embodiment, the method further comprises obtaining a sample from the subject. In an embodiment, the sample is a blood or serum sample.

[0220] In an embodiment, the method further comprises administering a second therapeutic agent or modality to the subject. In an embodiment, the second therapeutic agent or modality is a small molecule. In an embodiment, the second therapeutic agent or modality is an antibody molecule. Enumerated Embodiments

[0221] 1. A method of treating a disorder, comprising: administering to a subject in need thereof an anti-APRIL antibody molecule described herein, wherein the antibody molecule is administered at a dose that reduces, or is likely to reduce, the level of aberrantly glycosylated IgA (a-g IgA) by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in the subject, thereby treating the disorder.

[0222] 2. A method of treating a disorder, comprising: administering to a subject in need thereof an anti-APRIL antibody molecule described herein, wherein the administration reduces the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in the subject, thereby treating the disorder.

[0223] 3. A method of treating a disorder, comprising: administering to a subject in need thereof an anti-APRIL antibody molecule described herein, wherein the antibody molecule is administered at a dosage (e.g., dose and frequency) that reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in the subject, thereby treating the disorder.

[0224] 4. A method of treating a disorder, comprising: selecting a dose or dosage (e.g., dose and frequency) for an anti-APRIL antibody molecule described herein, wherein administration of the antibody molecule at the dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in a subject in need thereof; and administering the antibody molecule to the subject at the selected dose or dosage, thereby treating the disorder.

[0225] 5. A method of treating a disorder, comprising: responsive to a determination that administration of an anti-APRIL antibody molecule described herein reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in a subject in need thereof, administering to the subject an anti-APRIL antibody molecule, thereby treating the disorder.

[0226] 6. A method of treating a disorder, comprising: determining whether administration of an anti-APRIL antibody molecule described herein reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in a subject in need thereof, if the antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, administration of the antibody molecule is initiated, continued, or maintained, optionally wherein if the antibody molecule does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40%, administration of the antibody molecule is terminated, discontinued, or altered, and / or a different therapeutic agent or modality is administered.

[0227] 7. A method of treating a disorder, comprising: determining whether administration of an anti-APRIL antibody molecule described herein at a dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in a subject in need thereof, if the antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% at the dose or dosage, administration of the antibody molecule at the dose or dosage is initiated, continued, or maintained, optionally wherein if the antibody molecule does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40% at the dose or dosage, administration of the antibody molecule at the dose or dosage is terminated, discontinued, or altered.

[0228] 8. A method of treating a disorder, comprising: determining whether administration of a therapeutic agent or modality other than an anti-APRIL antibody molecule described herein reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in a subject in need thereof, if the therapeutic agent or modality does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40%, administering an anti-APRIL antibody molecule described herein to the subject.

[0229] 9. A method of reducing the level of a-g IgA in subject, comprising: administering an anti-APRIL antibody molecule described herein to a subject in a need thereof, e.g., at a dose or dosage that reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in the subject, thereby reducing the level of a-g IgA.

[0230] 10. A method of selecting an anti-APRIL antibody molecule for treating a disorder, comprising: determining whether administration of an anti-APRIL antibody molecule described herein reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in a subject in need thereof, thereby selecting the anti-APRIL antibody molecule.

[0231] 11. A method of selecting a dose or dosage (e.g., dose and frequency) for an anti-APRIL antibody molecule for treating a disorder, comprising: determining whether administration of an anti-APRIL antibody molecule described herein at a dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in a subject in need thereof, thereby selecting the dose or dosage.

[0232] 12. A method of selecting a subject for treating a disorder, comprising: determining whether administration of an anti-APRIL antibody molecule described herein reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in a subject in need thereof, thereby selecting the subject, optionally wherein if the antibody molecule does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40%, administration of the antibody molecule is terminated, discontinued, or altered, or a different therapeutic agent or modality is administered.

[0233] 13. The method of any of embodiments 1-12, wherein the a-g IgA comprises or is a-g IgAl.

[0234] 14. The method of any of embodiments 1-13, wherein the level of a-g IgA is reduced by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) for a predetermined period, e.g., at least one, two, three, or four weeks, or at least one, two, or three months. 15. The method of any of embodiments 1-14, wherein the level of a-g IgA is reduced by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) about 4 weeks after the antibody molecule is administered.

[0235] 16. The method of any of embodiments 1-15, wherein the level of a-g IgA is reduced by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) about 8 weeks after the antibody molecule is administered.

[0236] 17. The method of any of embodiments 1-16, wherein the level of a-g IgA is reduced by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) about 12 weeks after the antibody molecule is administered.

[0237] 18. The method of any of embodiments 1-17, wherein the level of a-g IgA is reduced by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) about 16 weeks after the antibody molecule is administered.

[0238] 19. The method of any of embodiments 1-18, wherein the level of a-g IgA is reduced by at least

[0239] 50%.

[0240] 20. The method of any of embodiments 1-19, wherein the level of a-g IgA is reduced by at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%.

[0241] 21. The method of any of embodiments 1-20, wherein the antibody molecule is administered as a single dose.

[0242] 22. The method of any of embodiments 1-20, wherein the antibody molecule is administered as a repeated dose.

[0243] 23. The method of any of embodiments 1-22, wherein the antibody molecule is administered subcutaneously.

[0244] 24. The method of any of embodiments 1-22, wherein the antibody molecule is administered intravenously. 25. The method of any of embodiments 1-24, wherein the disorder is an APRIL-associated disorder.

[0245] 26. The method of any of embodiments 1-25, wherein the disorder is associated with an aberrant level of total IgA.

[0246] 27. The method of any of embodiments 1-26, wherein the disorder is a disorder associated with a- g lgA-

[0247] 28. The method of any of embodiments 1-27, wherein the disorder is IgA nephropathy (IgAN).

[0248] 29. The method of embodiment 28, wherein the IgAN is a familial IgAN.

[0249] 30. The method of embodiment 28, wherein the IgAN is an adult IgAN.

[0250] 31. The method of embodiment 28, wherein the IgAN is a post-transplant IgAN, a pediatric IgAN, or a crescentic IgAN.

[0251] 32. The method of any of embodiments 1-27, wherein the disorder is a chronic kidney disease (CKD) or a disorder associated with CKD.

[0252] 33. The method of embodiment 32, wherein the CKD is an advanced CKD, e.g., with an estimated glomerular filtration rate (eGFR) equal to or greater than about 30 or about 45.

[0253] 34. The method of any of embodiments 1-27, wherein the disorder is Henoch-Schonlein purpura

[0254] (HSP).

[0255] 35. The method of any of embodiments 1-27, wherein the disorder is cutaneous vasculitis or IgA vasculitis.

[0256] 36. The method of any of embodiments 1-27, wherein the disorder is IgA dermatitis, e.g., IgA bullous dermatosis.

[0257] 37. The method of any of embodiments 1-27, wherein the disorder is Waldenstrom macroglobulinemia (WM).

[0258] 38. The method of any of embodiments 1-27, wherein the disorder is lupus nephritis.

[0259] 39. The method of any of embodiments 1-38, wherein the subject is a human.

[0260] 40. The method of any of embodiments 1-39, wherein the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject.

[0261] 41. The method of any of embodiments 1-40, wherein the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject.

[0262] 42. The method of any of embodiments 1-41, wherein the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder.

[0263] 43. The method of any of embodiments 1-41, wherein the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder.

[0264] 44. The method of any of embodiments 1-43, wherein the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule.

[0265] 45. The method of any of embodiments 1-43, wherein the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule.

[0266] 46. The method of embodiment 44 or 45, wherein the subject receives the vaccine before, concurrent with, or after administration of the antibody molecule.

[0267] 47. The method of any of embodiments 44-46, wherein administration of the antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. 48. The method of any of embodiments 44-47, wherein admini tration of the antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine.

[0268] 49. The method of any of embodiments 44-48, wherein the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after administration of the antibody molecule.

[0269] 50. The method of any of embodiments 44-49, wherein the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®).

[0270] 51. The method of embodiment 50, wherein the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after administration of the antibody molecule.

[0271] 52. The method of any of embodiments 1-51, wherein the subject has, or is identified as having, a genomic susceptible locus of the disorder, e.g., IgA nephropathy.

[0272] 53. The method of any of embodiments 1-52, further comprising determining whether the subject has a genomic susceptible locus of the disorder, e.g., IgA nephropathy.

[0273] 54. The method of any of embodiments 1-53, wherein the antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419- 1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035- 062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0274] 55. The method of any of embodiments 1-54, wherein the antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419- 1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540- 063, 4540-033, 4439, or 4237. 56. The method of any of embodiments 1-55, wherein the level of a-g IgA is determined in a sample from the subject.

[0275] 57. The method of any of embodiments 1-56, further comprising determining the level of a-g IgA in a sample from the subject.

[0276] 58. The method of any of embodiments 1-57, further comprising determining the level of total IgA in the sample.

[0277] 59. The method of any of embodiments 1-58, further comprising determining the level of IgM and / or IgG in the sample.

[0278] 60. The method of any of embodiments 1-59, further comprising obtaining a sample from the subject.

[0279] 61. The method of embodiment 60, wherein the sample is a blood or serum sample.

[0280] 62. The method of any of embodiments 1-61, further comprising administering a second therapeutic agent or modality to the subject.

[0281] 63. The method of embodiment 62, wherein the second therapeutic agent or modality is a small molecule.

[0282] 64. The method of embodiment 62, wherein the second therapeutic agent or modality is an antibody molecule.

[0283] 65. A method of treating IgA nephropathy, comprising: administering to a subject in need thereof an effective amount of an anti- APRIL antibody molecule (e.g., an anti-APRIL antibody molecule described herein), wherein the subject has received, or is going to receive, a vaccine (e.g., a vaccine described herein) within 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 weeks of administration of the antibody molecule, thereby treating IgA nephropathy. 66. The method of embodiment 65, further comprising administering the vaccine to the subject before, concurrent with, or after administration of the antibody molecule.

[0284] 67. A method of vaccinating a subject, comprising: administering to the subject an effective amount of a vaccine (e.g., a vaccine described herein), wherein the subject has received, or is going to receive, an anti- APRIL antibody molecule (e.g., an anti -APRIL antibody molecule described herein) within 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 weeks of administration of the vaccine, thereby vaccinating the subject.

[0285] 68. The method of embodiment 67, further comprising administering the antibody molecule to the subject before, concurrent with, or after administration of the vaccine.

[0286] 69. The method of any of embodiments 44-68, wherein the vaccine is administered intramuscularly.

[0287] 70. A composition for use in treating IgA nephropathy in a subject, wherein the composition comprises an anti- APRIL antibody molecule (e.g., an anti-APRIL antibody molecule described herein) at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg, wherein the subject has received, or is going to receive, a vaccine (e.g., a vaccine described herein) within 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 weeks of administration of the antibody molecule.

[0288] 71. The composition for use of embodiment 70, further wherein the subject has been administered the vaccine before, concurrent with, or after administration of the antibody molecule.

[0289] 72. A composition for use in vaccinating a subject, the composition comprising an effective amount of a vaccine (e.g., a vaccine described herein), wherein the subject has received, or is going to receive, an anti-APRIL antibody molecule (e.g., an anti-APRIL antibody molecule described herein) within 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 weeks of administration of the vaccine, wherein the subject received, or is going to receive, the anti- APRIL antibody molecule at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg.

[0290] 73. The composition for use of embodiment 72, wherein the subject is administered the antibody molecule before, concurrent with, or after administration of the vaccine.

[0291] 74. A composition for use in treating a disorder in a subject, the composition comprising: an anti-APRIL antibody molecule described herein at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; and wherein the dosage reduces, or is likely to reduce, the level of aberrantly glycosylated IgA (a-g IgA) by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%,

[0292] 98%, 99%, or 100%) in the subject.

[0293] 75. A composition for use in treating a disorder in a subject, the composition comprising an anti- APRIL antibody molecule described herein at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg, wherein the dosage reduces the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in the subject.

[0294] 76. A composition for use in treating a disorder in a subject, the composition comprising an anti- APRIL antibody molecule described herein at a dosage (e.g., dose and frequency) that reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in the subject, wherein the dosage is about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg.

[0295] 77. A composition for use in treating a disorder in a subject, the composition comprising an anti- APRIL antibody molecule described herein to the subject at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; wherein the composition is formulated administered if administration of a therapeutic agent or modality other than an anti-APRIL antibody molecule described herein reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%,

[0296] 96%, 97%, 98%, 99%, or 100%) in the subject. 78. A composition for use in reducing the level of a-g IgA in a subject, the composition comprising an anti-APRIL antibody molecule described herein to a subject in a need thereof at a dose or dosage that reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in the subject, wherein the dose or dosage is about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg.

[0297] 79. A method of treating IgA nephropathy, comprising: administering to a subject in need thereof an anti-APRIL antibody molecule (e.g., an anti-APRIL antibody molecule described herein) at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg, wherein the subject has received, or is going to receive, a vaccine (e.g., a vaccine described herein) within 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 weeks of administration of the antibody molecule, thereby treating IgA nephropathy.

[0298] 80. The method of embodiment 79, further comprising administering the vaccine to the subject before, concurrent with, or after administration of the antibody molecule.

[0299] 81. A method of vaccinating a subject, comprising: administering to the subject an effective amount of a vaccine (e.g., a vaccine described herein), wherein the subject has received, or is going to receive, an anti-APRIL antibody molecule (e.g., an anti-APRIL antibody molecule described herein) within 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 weeks of administration of the vaccine, wherein the subject received, or is going to receive, the anti- APRIL antibody molecule at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; thereby vaccinating the subject.

[0300] 82. The method of embodiment 81, further comprising administering the antibody molecule to the subject before, concurrent with, or after administration of the vaccine.

[0301] 83. A method of treating a disorder, comprising: administering to a subject in need thereof an anti-APRIL antibody molecule described herein, wherein the antibody molecule is administered at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; and wherein the dosage administered to the subject reduces, or is likely to reduce, the level of aberrantly glycosylated IgA (a-g IgA) by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in the subject, thereby treating the disorder.

[0302] 84. A method of treating a disorder, comprising: administering to a subject in need thereof an anti-APRIL antibody molecule described herein at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg, wherein the administration reduces the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in the subject, thereby treating the disorder.

[0303] 85. A method of treating a disorder, comprising: administering to a subject in need thereof an anti-APRIL antibody molecule described herein, wherein the antibody molecule is administered at a dosage (e.g., dose and frequency) that reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in the subject, and wherein the dosage is about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; thereby treating the disorder.

[0304] 86. A method of treating a disorder, comprising: selecting a dose or dosage (e.g., dose and frequency) for an anti-APRIL antibody molecule described herein, wherein the dose or dosage is about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; and wherein administration of the antibody molecule at the dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in a subject in need thereof; and administering the antibody molecule to the subject at the selected dose or dosage, thereby treating the disorder.

[0305] 87. A method of treating a disorder, comprising: responsive to a determination that administration of an anti-APRIL antibody molecule described herein reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in a subject in need thereof, administering to the subject an anti-APRIL antibody molecule at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg, thereby treating the disorder.

[0306] 88. A method of treating a disorder, comprising: determining whether administration of an anti-APRIL antibody molecule described herein reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in a subject in need thereof, if the antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, administration of the antibody molecule at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg is initiated, continued, or maintained, optionally wherein if the antibody molecule does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40%, administration of the antibody molecule is terminated, discontinued, or altered, and / or a different therapeutic agent or modality is administered.

[0307] 89. A method of treating a disorder, comprising: determining whether administration of an anti-APRIL antibody molecule described herein at a dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in a subject in need thereof, if the antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40% at the dose or dosage, administration of the antibody molecule at the dose or dosage is initiated, continued, or maintained, wherein the dose or dosage is about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; optionally wherein if the antibody molecule does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40% at the dose or dosage, administration of the antibody molecule at the dose or dosage is terminated, discontinued, or altered.

[0308] 90. A method of treating a disorder, comprising: determining whether administration of a therapeutic agent or modality other than an anti- APRIL antibody molecule described herein reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in a subject in need thereof, if the therapeutic agent or modality does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40%, administering an anti-APRIL antibody molecule described herein to the subject at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg.

[0309] 91. A method of reducing the level of a-g IgA in subject, comprising: administering an anti-APRIL antibody molecule described herein to a subject in a need thereof at a dose or dosage that reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in the subject, wherein the dose or dosage is about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; thereby reducing the level of a-g IgA.

[0310] 92. A method of selecting an anti-APRIL antibody molecule for treating a disorder, comprising: determining whether administration of an anti-APRIL antibody molecule described herein at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in a subject in need thereof, thereby selecting the anti-APRIL antibody molecule.

[0311] 93. A method of selecting a dose or dosage (e.g., dose and frequency) for an anti-APRIL antibody molecule for treating a disorder, comprising: determining whether administration of an anti-APRIL antibody molecule described herein at a dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in a subject in need thereof, wherein the dose or dosage is about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; thereby selecting the dose or dosage.

[0312] 94. A method of selecting a subject for treating a disorder, comprising: determining whether administration of an anti-APRIL antibody molecule described herein at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg reduces, or is likely to reduce, the level of a-g IgA by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) in a subject in need thereof, thereby selecting the subject, optionally wherein if the antibody molecule does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40%, administration of the antibody molecule is terminated, discontinued, or altered, or a different therapeutic agent or modality is administered.

[0313] 95. The method of any of embodiments 79-94, wherein the a-g IgA comprises or is a-g IgAl.

[0314] 96. The method of any of embodiments 79-95, wherein the level of a-g IgA is reduced by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) for a predetermined period, e.g., at least one, two, three, or four weeks, or at least one, two, or three months.

[0315] 97. The method of any of embodiments 79-96, wherein the level of a-g IgA is reduced by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) about 4 weeks after the antibody molecule is administered.

[0316] 98. The method of any of embodiments 79-97, wherein the level of a-g IgA is reduced by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) about 8 weeks after the antibody molecule is administered.

[0317] 99. The method of any of embodiments 79-98, wherein the level of a-g IgA is reduced by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) about 12 weeks after the antibody molecule is administered. 100. The method of any of embodiments 79-99, wherein the level of a-g IgA is reduced by at least 40% (e.g., by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) about 16 weeks after the antibody molecule is administered.

[0318] 101. The method of any of embodiments 79-100, wherein the level of a-g IgA is reduced by at least 50%.

[0319] 102. The method of any of embodiments 79-101, wherein the level of a-g IgA is reduced by at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%.

[0320] 103. The method of any of embodiments 79-102, wherein the antibody molecule is administered as a single dose, e.g., in a period of at least 1, 2, 3, 4, 5, 6, 7, 8, 9. 10, 11, 12, 13, 14, 15, 16, 17, or 18 months.

[0321] 104. The method of any of embodiments 79-102, wherein the antibody molecule is administered as a repeated dose.

[0322] 105. The method of any of embodiments 79-104, wherein the antibody molecule is administered subcutaneously.

[0323] 106. The method of any of embodiments 79-104, wherein the antibody molecule is administered intravenously.

[0324] 107. The method of any of embodiments 79-106, wherein the disorder is an APRIL-associated disorder.

[0325] 108. The method of any of embodiments 79-107, wherein the disorder is associated with an aberrant level of total IgA.

[0326] 109. The method of any of embodiments 79-108, wherein the disorder is a disorder associated with a-g IgA.

[0327] 110. The method of any of embodiments 79-109, wherein the disorder is IgA nephropathy

[0328] (IgAN). 111. The method of embodiment 110, wherein the IgAN is a familial IgAN.

[0329] 112. The method of embodiment 110, wherein the IgAN is an adult IgAN.

[0330] 113. The method of embodiment 110, wherein the IgAN is a post-transplant IgAN, a pediatric IgAN, or a crescentic IgAN.

[0331] 114. The method of any of embodiments 79-108, wherein the disorder is a chronic kidney disease (CKD) or a disorder associated with CKD.

[0332] 115. The method of embodiment 114, wherein the CKD is an advanced CKD, e.g., with an estimated glomerular filtration rate (eGFR) equal to or greater than about 30 or about 45.

[0333] 116. The method of any of embodiments 79-108, wherein the disorder is Henoch-Schonlein purpura (HSP).

[0334] 117. The method of any of embodiments 79-108, wherein the disorder is cutaneous vasculitis or IgA vasculitis.

[0335] 118. The method of any of embodiments 79-108, wherein the disorder is IgA dermatitis, e.g., IgA bullous dermatosis.

[0336] 119. The method of any of embodiments 79-108, wherein the disorder is Waldenstrom macroglobulinemia (WM).

[0337] 120. The method of any of embodiments 79-108, wherein the disorder is lupus nephritis.

[0338] 121. The method of any of embodiments 79-120, wherein the subject is a human.

[0339] 122. The method of any of embodiments 79-121, wherein the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject. 123. The method of any of embodiments 79-122, wherein the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject.

[0340] 124. The method of any of embodiments 79-123, wherein the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder.

[0341] 125. The method of any of embodiments 79-123, wherein the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder.

[0342] 126. The method of any of embodiments 79-125, wherein the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule.

[0343] 127. The method of any of embodiments 79-125, wherein the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule.

[0344] 128. The method of embodiment 126 or 127, wherein the subject receives the vaccine before, concurrent with, or after administration of the antibody molecule.

[0345] 129. The method of any of embodiments 126-128, wherein administration of the antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%.

[0346] 130. The method of any of embodiments 126-129, wherein administration of the antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine.

[0347] 131. The method of any of embodiments 126-130, wherein the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after administration of the antibody molecule. 132. The method of any of embodiments 126-131, wherein the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®).

[0348] 133. The method of embodiment 132, wherein the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after administration of the antibody molecule.

[0349] 134. The method of any of embodiments 79-133, wherein the subject has, or is identified as having, a genomic susceptible locus of the disorder, e.g., IgA nephropathy.

[0350] 135. The method of any of embodiments 79-134, further comprising determining whether the subject has a genomic susceptible locus of the disorder, e.g., IgA nephropathy.

[0351] 136. The method of any of embodiments 79-135, wherein the antibody molecule comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419- 1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035- 062, 3934, 3833, 3631, 3732, 4338, 4540, 4540-063, 4540-033, 4439, or 4237.

[0352] 137. The method of any of embodiments 79-136, wherein the antibody molecule comprises the VH and VL of any of antibodies 2218, 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1205, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419- 1406, 2922, 3327, 3530, 3525, 3125, 2621, 4035, 4035-062, 3934, 3833, 3631, 3732, 4338, 4540, 4540- 063, 4540-033, 4439, or 4237.

[0353] 138. The method of any of embodiments 79-137, wherein the level of a-g IgA is determined in a sample from the subject.

[0354] 139. The method of any of embodiments 79-138, further comprising determining the level of a-g IgA in a sample from the subject.

[0355] 140. The method of any of embodiments 79-139, further comprising determining the level of total IgA in the sample.

[0356] 141. The method of any of embodiments 79-140, further comprising determining the level of IgM and / or IgG in the sample.

[0357] 142. The method of any of embodiments 79-141, further comprising obtaining a sample from the subject.

[0358] 143. The method of embodiment 142, wherein the sample is a blood or serum sample.

[0359] 144. The method of any of embodiments 79-143, further comprising administering a second therapeutic agent or modality to the subject.

[0360] 145. The method of embodiment 144, wherein the second therapeutic agent or modality is a small molecule.

[0361] 146. The method of embodiment 144, wherein the second therapeutic agent or modality is an antibody molecule.

[0362] 147. The method or composition for use of any of the preceding embodiments, wherein the subject is administered the anti -APRIL· antibody molecule at a concentration of about 100, 150, 175, 180, 190, 200, 210, 220, 225, 230, 240, 250, or 300 mg / mL.

[0363] 148. The method or composition for use of any of the preceding embodiments, wherein the subject is administered the anti-APRIL antibody molecule at a concentration of about 200 mg / mL.

[0364] 149. The method or composition for use of any of the preceding embodiments, wherein the subject is administered the anti-APRIL antibody molecule at a fixed dosage of about 200, 250, 300, 450, 400, 450, 500, 550, 600, 650, 700, 750, or 800 mg.

[0365] 150. The method or composition for use of any of the preceding embodiments, wherein the subject is administered the anti-APRIL antibody molecule at a fixed dosage of about 200 mg (e.g., at a volume of about 1 mL). 151. The method or composition for use of any of the preceding embodiments, wherein the subject is administered the anti-APRIL antibody molecule at a fixed dosage of about 400 mg (e.g., at a total volume of about 2 mL, e.g., as two administrations of 1 mL volumes or as one administration of a 2 mL volume).

[0366] 152. The method or composition for use of any of the preceding embodiments, wherein the subject is administered the anti-APRIL antibody molecule at a fixed dosage of at least 200 mg.

[0367] 153. The method or composition for use of any of the preceding embodiments, wherein the subject is administered the anti-APRIL antibody molecule at a fixed dosage of 800 mg or less.

[0368] 154. The method or composition for use of any of the preceding embodiments, wherein the subject is administered the anti-APRIL antibody molecule at a fixed dosage of about 600 mg (e.g., at a total volume of about 3 mL, e.g., as one administration of a 2 mL volume and one administration of a 1 mL volume).

[0369] 155. The method or composition for use of any of the preceding embodiments, wherein the subject is administered a single dose of the anti-APRIL antibody molecule.

[0370] 156. The method or composition for use of any of the preceding embodiments, wherein the subject is administered one or more additional dosages of the anti-APRIL antibody molecules (e.g., 24 hours, 48 hours, 72 hours, 4 days, 5 days, 6 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 1 month, 2 months, 3 months, 4 months, 5 months, or 6 months after the first administration).

[0371] 157. The method or composition for use of any of the preceding embodiments, wherein the subject is administered the anti-APRIL antibody molecule subcutaneously.

[0372] 158. The method or composition for use of any of the preceding embodiments, wherein the subject is administered the anti-APRIL antibody molecule intravenously.

[0373] 159. The method or composition for use of any of the preceding embodiments, wherein the anti- APRIL antibody molecule is administered as a liquid.

[0374] 160. An anti-APRIL antibody molecule, or a pharmaceutical composition comprising the anti- APRIL antibody molecule, for use in a method of treating a disorder in a human subject, wherein the antibody molecule is administered at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; wherein the administration reduces the level of aberrantly glycosylated IgA (a-g IgA) by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy.

[0375] 161. An anti- APRIL antibody molecule, or a pharmaceutical composition comprising the anti- APRIL antibody molecule, for use in a method of reducing the level of a-g IgA in a human subject, wherein the antibody molecule is administered at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; wherein the administration reduces the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the subject has, or is at risk of having, a disorder, e.g., IgA nephropathy.

[0376] 162. An anti- APRIL antibody molecule, or a pharmaceutical composition comprising the anti- APRIL antibody molecule, for use in a method of treating a disorder in a human subject, wherein the method comprises selecting a dose or dosage for the antibody molecule; wherein administration of the antibody molecule at the selected dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the antibody molecule is administered at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg, optionally wherein the disorder is IgA nephropathy.

[0377] 163. An anti-APRIL antibody molecule, or a pharmaceutical composition comprising the anti- APRIL antibody molecule, for use in a method of treating a disorder in a human subject, wherein the method comprises responsive to a determination that administration of the antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject, administering to the subject the antibody molecule at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy.

[0378] 164. An anti-APRIL antibody molecule, or a pharmaceutical composition comprising the anti- APRIL antibody molecule, for use in a method of treating a disorder in a human subject, wherein the method comprises determining whether administration of an anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject, if the antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%, administration of the antibody molecule at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg is initiated, continued, or maintained; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the antibody molecule is administered at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg, optionally wherein the disorder is IgA nephropathy, optionally wherein if the antibody molecule does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%, administration of the antibody molecule is terminated, discontinued, or altered, and / or a different therapeutic agent or modality is administered.

[0379] 165. An anti-APRIL antibody molecule, or a pharmaceutical composition comprising the anti- APRIL antibody molecule, for use in a method of treating a disorder in a human subject, wherein the method comprises determining whether administration of a therapeutic agent or modality other than the antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in a subject in need thereof, if the therapeutic agent or modality does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%, administering the antibody molecule to the subject at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy.

[0380] 166. An anti-APRIL antibody molecule, or a pharmaceutical composition comprising the anti- APRIL antibody molecule, for use in a method of treating a disorder in a human subject, wherein the antibody molecule is administered at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; and wherein the subject has received, or is going to receive, a vaccine within 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 weeks of administration of the antibody molecule, optionally wherein the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®), optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy, optionally wherein administration of the antibody molecule at the selected dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject.

[0381] 167. A method of treating a disorder, comprising: administering an anti- APRIL antibody molecule to a human subject in need thereof at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; wherein the administration reduces the level of aberrantly glycosylated IgA (a-g IgA) by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject; and wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), optionally wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy, thereby treating the disorder.

[0382] 168. A method of reducing the level of a-g IgA, comprising: administering an anti- APRIL antibody molecule to a human subject in need thereof, wherein the antibody molecule is administered at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; wherein the administration reduces the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the subject has, or is at risk of having, a disorder, e.g., IgA nephropathy, thereby reducing the level of a-g IgA.

[0383] 169. A method of treating a disorder, comprising: selecting a dose or dosage for an anti-APRIL antibody molecule; wherein administration of the antibody molecule at the selected dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the antibody molecule is administered at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg, optionally wherein the subject has, or is at risk of having, IgA nephropathy, thereby threating the disorder.

[0384] 170. A method of treating a disorder, comprising: responsive to a determination that administration of the antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject, administering to a human subject in need thereof an anti-APRIL antibody molecule at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy, thereby treating the disorder.

[0385] 171. A method of treating a disorder, comprising: determining whether administration of an anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject, if the antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%, administration of the antibody molecule at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg is initiated, continued, or maintained; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the antibody molecule is administered at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg, optionally wherein if the antibody molecule does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%, administration of the antibody molecule is terminated, discontinued, or altered, and / or a different therapeutic agent or modality is administered, optionally wherein the disorder is IgA nephropathy, thereby treating the disorder.

[0386] 172. A method of treating a disorder, comprising: determining whether administration of a therapeutic agent or modality other than an anti- APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in a subject in need thereof, if the therapeutic agent or modality does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%, administering the antibody molecule to a human subject at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy, thereby treating the disorder.

[0387] 173. A method of treating a disorder, comprising: administering an anti- APRIL antibody molecule to a human subject in need thereof at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; and wherein the subject has received, or is going to receive, a vaccine within 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 weeks of administration of the antibody molecule, optionally wherein the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®), optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy, optionally wherein administration of the antibody molecule at the selected dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject, thereby treating the disorder.

[0388] 174. A method of selecting an anti-APRIL antibody molecule for treating a disorder, comprising: determining whether administration of the antibody molecule at a dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in a human subject in need thereof, wherein the dose is about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg, optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy, thereby selecting the antibody molecule.

[0389] 175. A method of selecting a dose or dosage for an anti-APRIL antibody molecule for treating a disorder, comprising: determining whether administration of the antibody molecule at a dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in a human subject in need thereof, optionally wherein the dose is about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg, optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy, thereby selecting the dose or dosage.

[0390] 176. A method of selecting a human subject for treating a disorder, comprising: determining whether administration of an anti-APRIL antibody molecule at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject, optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy, thereby selecting the subject,

[0391] 177. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-176, wherein the a-g IgA comprises or is a-g IgAl.

[0392] 178. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-177, wherein the level of a-g IgA is reduced by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% for a predetermined period, e.g., at least one, two, three, or four weeks, or at least one, two, three, four, five, six, seven, eight, nine, ten, eleven, or twelve months.

[0393] 179. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-178, wherein the level of a-g IgA is reduced by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% about 4 weeks after the antibody molecule is administered.

[0394] 180. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-179, wherein the level of a-g IgA is reduced by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% about 8 weeks after the antibody molecule is administered.

[0395] 181. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-180, wherein the level of a-g IgA is reduced by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% about 12 weeks after the antibody molecule is administered.

[0396] 182. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-181, wherein the level of a-g IgA is reduced by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% about 16 weeks after the antibody molecule is administered. 183. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-182, wherein the level of a-g IgA is reduced by at least 50%.

[0397] 184. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-183, wherein the level of a-g IgA is reduced by at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%.

[0398] 185. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-184, e.g., in a period of at least 1, 2, 3, 4, 5, 6, 7, 8, 9. 10, 11, 12, 13, 14, 15, 16, 17, or 18 months.

[0399] 186. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-185, wherein the antibody molecule is administered as a repeated dose, e.g., in a period of at least 3, 6, 9. 12, 15, 18, 24, 30, or 36 months, optionally wherein the subject is administered one or more additional dosages of the anti-APRIL antibody molecules (e.g., 24 hours, 48 hours, 72 hours, 4 days, 5 days, 6 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 1 month, 2 months, 3 months, 4 months, 5 months, or 6 months after the first administration).

[0400] 187. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-186, wherein the antibody molecule is administered subcutaneously.

[0401] 188. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-186, wherein the antibody molecule is administered intravenously.

[0402] 189. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-188, wherein the disorder an APRIL-associated disorder.

[0403] 190. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-189, wherein the disorder is associated with an aberrant level of total IgA.

[0404] 191. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-190, wherein the disorder is a disorder associated with a-g IgA.

[0405] 192. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-191, wherein the disorder is IgA nephropathy (IgAN). 193. The antibody molecule, pharmaceutical composition, method for use of embodiment 192, wherein the IgAN is a familial IgAN.

[0406] 194. The antibody molecule, pharmaceutical composition, method for use of embodiment 192, wherein the IgAN is an adult IgAN.

[0407] 195. The antibody molecule, pharmaceutical composition, method for use of embodiment 192, wherein the IgAN is a post-transplant IgAN, a pediatric IgAN, or a crescentic IgAN.

[0408] 196. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-191, wherein the disorder is a chronic kidney disease (CKD) or a disorder associated with CKD.

[0409] 197. The antibody molecule, pharmaceutical composition, method for use of embodiment 196, wherein the CKD is an advanced CKD, e.g., with an estimated glomerular filtration rate (eGFR) equal to or greater than about 30 or about 45.

[0410] 198. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-191, wherein the disorder is Henoch-Schonlein purpura (HSP).

[0411] 199. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-191, wherein the disorder is cutaneous vasculitis or IgA vasculitis.

[0412] 200. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-191, wherein the disorder is IgA dermatitis, e.g., IgA bullous dermatosis.

[0413] 201. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-191, wherein the disorder is Waldenstrom macroglobulinemia (WM).

[0414] 202. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-191, wherein the disorder is lupus nephritis.

[0415] 203. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-202, wherein the subject is a human patient. 204. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-203, wherein the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject.

[0416] 205. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-204, wherein the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject.

[0417] 206. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-205, wherein the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder.

[0418] 207. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-206, wherein the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder.

[0419] 208. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-207, wherein the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule.

[0420] 209. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-208, wherein the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule.

[0421] 210. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 208 or 209, wherein the subject receives the vaccine before, concurrent with, or after administration of the antibody molecule.

[0422] 211. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-210, wherein administration of the antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%.

[0423] 212. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-211 , wherein administration of the antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine.

[0424] 213. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-212, wherein the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after administration of the antibody molecule.

[0425] 214. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-213, wherein the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®).

[0426] 215. The antibody molecule, pharmaceutical composition, method for use of embodiment 214, wherein the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after administration of the antibody molecule.

[0427] 216. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-215, wherein the subject has, or is identified as having, a genomic susceptible locus of the disorder, e.g., IgA nephropathy.

[0428] 217. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-216, further comprising determining whether the subject has a genomic susceptible locus of the disorder, e.g., IgA nephropathy.

[0429] 218. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-217, wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16.

[0430] 219. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-218, wherein the antibody molecule comprises a VH comprising the amino acid sequence of SEQ ID NO: 296, and a VL comprising the amino acid sequence of SEQ ID NO: 286, optionally wherein the antibody molecule is an IgG2.

[0431] 220. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-219, wherein the level of a-g IgA is determined in a sample from the subject.

[0432] 221. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-220, further comprising determining the level of a-g IgA in a sample from the subject.

[0433] 222. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-221, further comprising determining the level of total IgA in the sample.

[0434] 223. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-222, further comprising determining the level of IgM and / or IgG in the sample.

[0435] 224. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-223, further comprising obtaining a sample from the subject.

[0436] 225. The antibody molecule, pharmaceutical composition, method for use of embodiment 224, wherein the sample is a blood or serum sample.

[0437] 226. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-225, further comprising administering a second therapeutic agent or modality to the subject. 227. The antibody molecule, pharmaceutical composition, method for use of embodiment 226, wherein the second therapeutic agent or modality is a small molecule.

[0438] 228. The antibody molecule, pharmaceutical composition, method for use of embodiment 227, wherein the second therapeutic agent or modality is an antibody molecule.

[0439] 229. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-228, wherein the subject is administered the anti- APRIL antibody molecule at a concentration of about 100, 150, 175, 180, 190, 200, 210, 220, 225, 230, 240, 250, or 300 mg / mL.

[0440] 230. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-229, wherein the subject is administered the anti- APRIL antibody molecule at a concentration of about 200 mg / mL.

[0441] 231. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-230, wherein the subject is administered the anti- APRIL antibody molecule at a fixed dose of about 200, 250, 300, 450, 400, 450, 500, 550, 600, 650, 700, 750, or 800 mg.

[0442] 232. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-231, wherein the subject is administered the anti- APRIL antibody molecule at a fixed dose of about 200 mg (e.g., at a volume of about 1 mL).

[0443] 233. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-232, wherein the subject is administered the anti- APRIL antibody molecule at a fixed dose of about 400 mg (e.g., at a total volume of about 2 mL, e.g., as two administrations of 1 mL volumes or as one administration of a 2 mL volume).

[0444] 234. The antibody molecule, pharmaceutical composition, method for use of any of embodiments 160-233, wherein the subject is administered the anti-APRIL antibody molecule at a fixed dose of about 600 mg (e.g., at a total volume of about 3 mL, e.g., as one administration of a 2 mL volume and one administration of a 1 mL volume).

[0445] 235. The antibody molecule, pharmaceutical composition for use, or method of any of the preceding embodiments, wherein the subject is administered the anti-APRIL antibody molecule at a fixed dosage of at least 200 mg.

[0446] 236. The antibody molecule, pharmaceutical composition for use, or method of any of the preceding embodiments, wherein the subject is administered the anti- APRIL antibody molecule at a fixed dosage of 800 mg or less.

[0447] 237. The antibody molecule, pharmaceutical composition for use, or method of any of the preceding embodiments, wherein the anti- APRIL antibody molecule is administered as a liquid composition.

[0448] The disclosure contemplates all combinations of any one or more of the foregoing aspects and / or embodiments, as well as combinations with any one or more of the embodiments set forth in the detailed description and examples.

[0449] Other features, objects, and advantages of the compositions and methods herein will be apparent from the description and drawings, and from the claims.

[0450] BRIEF DESCRIPTION OF THE DRAWINGS

[0451] FIG. 1 depicts the mean percent change (± standard deviation) from baseline of aberrantly glycosylated immunoglobulin concentration over time by the indicated treatments (pooled placebo, antibody 2419-1406 at 0.5 mg / kg, antibody 2419-1406 at 2.0 mg / kg, antibody 2419-1406 at 6.0 mg / kg, antibody 2419-1406 at 12.0 mg / kg, placebo + vaccine, and antibody 2419-1406 at 6.0 mg / kg + vaccine) for all patients of any ethnicity (pharmacodynamic population).

[0452] FIG. 2 is a series of graphs showing mean percentage change from baseline in aberrantly glycosylated immunoglobulin A (a-g-IgAl; left panel) and immunoglobulin A (IgA; right panel), by treatment.

[0453] FIG. 3 is a graph showing tetanus immunoglobulin G (IgG) titer levels in the safety population.

[0454] FIG. 4 is a graph showing diphtheria immunoglobulin G (IgG) titer levels in the safety population.

[0455] FIG. 5 is a series of graphs showing IgA suppression by mAh 2419-1406 in healthy volunteers. Results are shown for subcutaneous (SC) administration (left panel) and for intravenous (IV) administration (right panel), as indicated. DETAILED DESCRIPTION

[0456] Disclosed herein are antibody molecules that bind to APRIL, e.g., human APRIL, mouse APRIL, or both, with high affinity and specificity. Advantageously, several of the antibody molecules describe herein have improved ability to reduce (e.g., inhibit, block, or neutralize) one or more biological activities of APRIL. Nucleic acid molecules encoding the antibody molecules, expression vectors, host cells, compositions (e.g., pharmaceutical compositions), kits, and methods for making the antibody molecules, are also provided. The antibody molecules and pharmaceutical compositions disclosed herein can be used (alone or in combination with other agents or therapeutic modalities) to treat, prevent and / or diagnose disorders and conditions, e.g., disorders and conditions associated with APRIL, e.g., IgA nephropathy (IgAN) or disorders associated with IgAN (e.g., an advanced chronic kidney disease (CKD), post transplant IgAN, pediatric IgAN, Henoch-Schonlein purpura (HSP) or cutaneous vasculitis, IgAN with crescentic glomerulonephritis (GN)), IgA vasculitis, IgA dermatitis (e.g., IgA dermatitis herpetiformis, IgA bullous dermatosis), IgM mediated neuropathy (e.g., anti-MAG peripheral neuropathy or IgM mediated neuropathy associated with anti-GMl antibodies), Waldenstrom’s macroglobulinemia (WM, also known as Waldenstrom macroglobulinemia), or lupus nephritis).

[0457] IgA nephropathy is one of the most prevalent, chronic glomerular diseases, with a global incidence of approximately 5-50 cases / million (children) and 10-40 cases / million (adults). While typically a relatively indolent disease, IgAN can progress to end-stage renal disease (e.g., kidney failure in 20%- 50% of patients within 20 to 30 years). IgA nephropathy patients with minor urine abnormalities, normal blood pressure and normal glomerular filtration rate (GFR) typically need periodic monitoring. For those with more advanced disease, the therapeutic options can include nonspecific treatment to reduce blood pressure and proteinuria by RAS blockade, as well as other general measures, such as lipid lowering, dietary restriction of sodium, smoking cessation and avoidance of NSAIDs and other nephrotoxins.

[0458] Without wishing to be bound by theory, it is believed that in some embodiments, the etiology of IgA nephropathy represents a two-hit phenomenon, wherein the first hit occurs in response to a mucosal infection, as production of polymeric IgAl, containing an aberrantly galactosylated hinge region (aberrantly glycosylated IgAl or a-g IgAl), presents as an autoantigen; and the second hit is the subsequent induction of autoantibodies that results in immune complex formation. These circulating immune complexes are then deposited in the kidney, where complement activation occurs, resulting in promotion of inflammatory pathways, mesangial hyperproliferation, glomerular damage, proteinuria, and progression of kidney disease leading to end-stage renal disease. Without wishing to be bound by theory, it is believed that in some embodiments, reduction of the autoantigen and / or autoantibody, and removal of the resulting immune complexes, and / or mitigation of complement activation can have a beneficial effect on progression of IgA nephropathy and other related diseases and disorders (e.g., an advanced chronic kidney disease (CKD), post-transplant IgAN, pediatric IgAN, Henoch-Schonlein purpura (HSP) or cutaneous vasculitis, IgAN with crescentic glomerulonephritis (GN), IgA vasculitis, IgA dermatitis (e.g., IgA dermatitis herpetiformis, IgA bullous dermatosis), IgM mediated neuropathy (e.g., anti-MAG peripheral neuropathy or IgM mediated neuropathy associated with anti-GMl antibodies), Waldenstrom’s Macroglobulinemia (WM), or lupus nephritis).

[0459] Without wishing to be bound by theory, it is believed that in some embodiments, the aberrant biosynthesis of polymeric IgA and antigenic a-g IgAl is correlated to both disease pathogenesis and progression. In an embodiment, the serum levels of a-g IgAl are correlated as a heritable trait with substantial heritability in a significant number of adult and pediatric familial IgA nephropathy cases. In an embodiment, a-g IgAl plays a role in disease pathogenesis, which can be determined, e.g., by ex vivo analysis of peripheral blood mononuclear cells (PBMCs) derived from patients. For example, a-g IgAl can be secreted in immortalized B cells from IgA nephropathy patients and IgAl production from patient lymphocytes can be correlated to serum levels of a-g IgAl. As another example, immune complexes derived in part from IgAl -producing cells that were then reconstituted in vitro using sera from IgA nephropathy patients can be pathogenic in mice following passive transfer. Without wishing to be bound by theory, it is believed that in some embodiments, serum levels of a-g IgAl can be predictive of disease outcomes and provide diagnostic utility as a biomarker for clinical evaluation of disease progression, treatment, and also stratification of patient populations. For example, a targeted reduction in IgA can be therapeutically advantageous and can effectively reduce immune deposits and kidney damage. In an embodiment, treatment with an antibody molecule described herein results in clinically relevant reduction of autoantigen levels, e.g., a-g IgA levels.

[0460] Without wishing to be bound by theory, it is believed that in some embodiments, the anti-APRIL antibody molecules described herein (e.g., single doses up to 12.0 mg / kg) are safe and well tolerated in healthy adults. In an embodiment, a single dose of the anti-APRIL antibody molecule can suppress free serum APRIL to the lower level of quantification. In an embodiment, serum a-g IgAl decreases in parallel with total serum IgA and recovers in a dose-dependent manner following detection of free APRIL in serum.

[0461] Without wishing to be bound by theory, it is believed that in some embodiments, the anti-APRIL antibody molecules described herein do not interfere with subjects’ ability to mount an antigen-specific serum IgG or IgA boost response to vaccination (e.g., tetanus and diphtheria toxoid vaccination), indicating that qualitative T-cell dependent antibody responses are preserved during APRIL suppression. Definitions

[0462] As used herein, the articles “a” and “an” refer to one or to more than one (e.g., to at least one) of the grammatical object of the article.

[0463] The term “or” is used herein to mean, and is used interchangeably with, the term “and / or”, unless context clearly indicates otherwise.

[0464] “About” and “approximately” shall generally mean an acceptable degree of error for the quantity measured given the nature or precision of the measurements. Exemplary degrees of error are within 20 percent (%), typically, within 10%, and more typically, within 5% of a given value or range of values.

[0465] The compositions and methods disclosed herein encompass polypeptides and nucleic acids having the sequences specified, or sequences substantially identical or similar thereto, e.g., sequences at least 85%, 90%, 95% identical or higher to the sequence specified.

[0466] In the context of an amino acid sequence, the term “substantially identical” is used herein to refer to a first amino acid that contains a sufficient or minimum number of amino acid residues that are i) identical to, or ii) conservative substitutions of aligned amino acid residues in a second amino acid sequence such that the first and second amino acid sequences can have a common structural domain and / or common functional activity. For example, amino acid sequences that contain a common structural domain having at least about 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity to a reference sequence, e.g., a sequence provided herein.

[0467] In the context of nucleotide sequence, the term “substantially identical” is used herein to refer to a first nucleic acid sequence that contains a sufficient or minimum number of nucleotides that are identical to aligned nucleotides in a second nucleic acid sequence such that the first and second nucleotide sequences encode a polypeptide having common functional activity, or encode a common structural polypeptide domain or a common functional polypeptide activity. For example, nucleotide sequences having at least about 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity to a reference sequence, e.g., a sequence provided herein.

[0468] The term “functional variant” refers polypeptides that have a substantially identical amino acid sequence to the naturally-occurring sequence, or are encoded by a substantially identical nucleotide sequence, and are capable of having one or more activities of the naturally-occurring sequence.

[0469] Calculations of homology or sequence identity between sequences (the terms are used interchangeably herein) are performed as follows.

[0470] To determine the percent identity of two amino acid sequences, or of two nucleic acid sequences, the sequences are aligned for optimal comparison purposes (e.g., gaps can be introduced in one or both of a first and a second amino acid or nucleic acid sequence for optimal alignment and non-homologous sequences can be disregarded for comparison purposes). In a typical embodiment, the length of a reference sequence aligned for comparison purposes is at least 30%, e.g., at least 40%, 50%, 60%, e.g., at least 70%, 80%, 90%, 100% of the length of the reference sequence. The amino acid residues or nucleotides at corresponding amino acid positions or nucleotide positions are then compared. When a position in the first sequence is occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, then the molecules are identical at that position.

[0471] The percent identity between the two sequences is a function of the number of identical positions shared by the sequences, taking into account the number of gaps, and the length of each gap, which need to be introduced for optimal alignment of the two sequences.

[0472] The comparison of sequences and determination of percent identity between two sequences can be accomplished using a mathematical algorithm. In some embodiments, the percent identity between two amino acid sequences is determined using the Needleman and Wunsch ((1970) J. Mol. Biol. 48:444- 453) algorithm which has been incorporated into the GAP program in the GCG software package (available at gcg.com), using either a Blossum 62 matrix or a PAM250 matrix, and a gap weight of 16,

[0473] 14, 12, 10, 8, 6, or 4 and a length weight of 1, 2, 3, 4, 5, or 6. In certain embodiments, the percent identity between two nucleotide sequences is determined using the GAP program in the GCG software package (available at gcg.com), using a NWSgapdna.CMP matrix and a gap weight of 40, 50, 60, 70, or 80 and a length weight of 1, 2, 3, 4, 5, or 6. One suitable set of parameters (and the one that should be used unless otherwise specified) are a Blossum 62 scoring matrix with a gap penalty of 12, a gap extend penalty of 4, and a frameshift gap penalty of 5.

[0474] The percent identity between two amino acid or nucleotide sequences can be determined using the algorithm of E. Meyers and W. Miller ((1989) CABIOS, 4: 11-17) which has been incorporated into the ALIGN program (version 2.0), using a PAM120 weight residue table, a gap length penalty of 12 and a gap penalty of 4.

[0475] The nucleic acid and protein sequences described herein can be used as a “query sequence” to perform a search against public databases to, for example, identify other family members or related sequences. Such searches can be performed using the NBLAST and XBLAST programs (version 2.0) of Altschul, et al. (1990) J. Mol. Biol. 215:403-10. BLAST nucleotide searches can be performed with the NBLAST program, score = 100, wordlength = 12 to obtain nucleotide sequences homologous to a nucleic acid as described herein. BLAST protein searches can be performed with the XBLAST program, score = 50, wordlength = 3 to obtain amino acid sequences homologous to protein molecules described herein.

[0476] To obtain gapped alignments for comparison purposes, Gapped BLAST can be utilized as described in Altschul et al, (1997) Nucleic Acids Res. 25:3389-3402. When utilizing BLAST and gapped BLAST programs, the default parameters of the respective programs (e.g., XBLAST and NBLAST) can be used. See ncbi.nlm.nih.gov. As used herein, the term “hybridizes under low stringency, medium stringency, high stringency, or very high stringency conditions” describes conditions for hybridization and washing. Guidance for performing hybridization reactions can be found in Current Protocols in Molecular Biology, John Wiley & Sons, N.Y. (1989), 6.3.1-6.3.6, which is incorporated by reference. Aqueous and nonaqueous methods are described in that reference and either can be used. Specific hybridization conditions referred to herein are as follows: 1) low stringency hybridization conditions in 6X sodium chloride / sodium citrate (SSC) at about 45°C, followed by two washes in 0.2X SSC, 0.1% SDS at least at 50°C (the temperature of the washes can be increased to 55°C for low stringency conditions); 2) medium stringency hybridization conditions in 6X SSC at about 45°C, followed by one or more washes in 0.2X SSC, 0.1% SDS at 60°C;

[0477] 3) high stringency hybridization conditions in 6X SSC at about 45 °C, followed by one or more washes in 0.2X SSC, 0.1% SDS at 65°C; and preferably 4) very high stringency hybridization conditions are 0.5M sodium phosphate, 7% SDS at 65°C, followed by one or more washes at 0.2X SSC, 1% SDS at 65°C. Very high stringency conditions 4) are suitable conditions and the ones that should be used unless otherwise specified.

[0478] It is understood that the molecules described herein may have additional conservative or non- essential amino acid substitutions, which do not have a substantial effect on their functions.

[0479] The term “amino acid” is intended to embrace all molecules, whether natural or synthetic, which include both an amino functionality and an acid functionality and capable of being included in a polymer of naturally-occurring amino acids. Exemplary amino acids include naturally-occurring amino acids; analogs, derivatives and congeners thereof; amino acid analogs having variant side chains; and all stereoisomers of any of any of the foregoing. As used herein the term “amino acid” includes both the D- or L- optical isomers and peptidomimetics.

[0480] A “conservative amino acid substitution” is one in which the amino acid residue is replaced with an amino acid residue having a similar side chain. Families of amino acid residues having similar side chains have been defined in the art. These families include amino acids with basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan), beta-branched side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine).

[0481] The terms “polypeptide,” “peptide” and “protein” (if single chain) are used interchangeably herein to refer to polymers of amino acids of any length. The polymer may be linear or branched, it may comprise modified amino acids, and it may be interrupted by non-amino acids. The terms also encompass an amino acid polymer that has been modified; for example, disulfide bond formation, glycosylation, lipidation, acetylation, phosphorylation, or any other manipulation, such as conjugation with a labeling component. The polypeptide can be isolated from natural sources, can be a produced by recombinant techniques from a eukaryotic or prokaryotic host, or can be a product of synthetic procedures.

[0482] The terms “nucleic acid,” “nucleic acid sequence,” “nucleotide sequence,” or “polynucleotide sequence,” and “polynucleotide” are used interchangeably. They refer to a polymeric form of nucleotides of any length, either deoxyribonucleotides or ribonucleotides, or analogs thereof. The polynucleotide may be either single-stranded or double-stranded, and if single-stranded may be the coding strand or non coding (antisense) strand. A polynucleotide may comprise modified nucleotides, such as methylated nucleotides and nucleotide analogs. The sequence of nucleotides may be interrupted by non-nucleotide components. A polynucleotide may be further modified after polymerization, such as by conjugation with a labeling component. The nucleic acid may be a recombinant polynucleotide, or a polynucleotide of genomic, cDNA, semisynthetic, or synthetic origin which either does not occur in nature or is linked to another polynucleotide in a non-natural arrangement.

[0483] The term “isolated,” as used herein, refers to material that is removed from its original or native environment (e.g., the natural environment if it is naturally occurring). For example, a naturally- occurring polynucleotide or polypeptide present in a living animal is not isolated, but the same polynucleotide or polypeptide, separated by human intervention from some or all of the co-existing materials in the natural system, is isolated. Such polynucleotides could be part of a vector and / or such polynucleotides or polypeptides could be part of a composition, and still be isolated in that such vector or composition is not part of the environment in which it is found in nature.

[0484] As used herein, the term “treat,” e.g., IgA nephropathy, means that a subject (e.g., a human) who has a disorder, e.g., IgA nephropathy, and / or experiences a symptom of a disorder, e.g., IgA nephropathy, will, in an embodiment, suffer less a severe symptom and / or recover faster when an antibody molecule is administered than if the antibody molecule were never administered. In an embodiment, when IgA nephropathy is treated, a kidney biopsy will show less or no IgA deposits, e.g., in the form of immune complexes in the mesangium of the kidney, after effective treatment for IgA nephropathy. For example, a diagnostic assay using immunofluorescence or electron microscopy will detect less no IgA deposits in a biological sample of a subject after administration of an antibody molecule described herein for the effective treatment of IgA nephropathy. Other assays, urine tests, blood tests, iothalamate clearance tests, or kidney imaging (e.g., ultrasound, X-rays, or cystoscopy), can also be used to monitor treatment in a patient, or to detect the presence, e.g., decreased presence (or absence), of a symptom of IgA nephropathy, after treatment of IgA nephropathy in the subject. Treatment can, e.g., partially or completely, alleviate, ameliorate, relieve, inhibit, or reduce the severity of, and / or reduce incidence, and optionally, delay onset of, one or more manifestations of the effects or symptoms, features, and / or causes of a disorder, e.g., IgA nephropathy. In an embodiment, treatment is of a subject who does not exhibit certain signs of a disorder, e.g., IgA nephropathy, and / or of a subject who exhibits only early signs of a disorder, e.g., nephropathy. In an embodiment, treatment is of a subject who exhibits one or more established signs of a disorder, e.g., IgA nephropathy. In an embodiment, treatment is of a subject diagnosed as suffering from a disorder, e.g., IgA nephropathy.

[0485] As used herein, the term “prevent,” a disorder, e.g., IgA nephropathy, means that a subject (e.g., a human) is less likely to have the disorder, e.g., IgA nephropathy, if the subject receives the antibody molecule.

[0486] Various aspects of the compositions and methods herein are described in further detail below. Additional definitions are set out throughout the specification.

[0487] APRIL

[0488] APRIL (A PRoliferation Inducing Ligand), also known as CD256, TNF- and APOL-related Leukocyte Expressed Ligand 2 (T ALL-2), or TNF-related Death Ligand 1 (TRDL-1), is a TNF family cytokine encoded by the Tumor Necrosis Factor Ligand Superfamily Member 13 TNFSF13 ) gene (also known as APRIL, TALL2, or ZTNF2). APRIL plays a role in a number of biological processes such as signal transduction, regulation of cell proliferation, and IgA class switching (Hahne et al. (1998) J. Exp. Med. 188:1185-1190 (1998); Castigli et al. Proc. Natl. Acad. Sci. U.S.A. 101:3903-3908 (2004)).

[0489] APRIL is both functionally and structurally related to BAFF (B Cell Activating Factor F13B) also known as BLyS (B lymphocyte stimulator). Both cytokines are involved in regulating keys aspects of innate and adaptive immune functions. Both APRIL and BAFF bind the lymphocyte receptors TACI (transmembrane activator and CAML interactor) and BCMA (B cell maturation antigen). APRIL and BAFF appear to heterologously interact with each other through protein-protein interactions. While both APRIL and BAFF share biochemical (receptor binding), immunological and even some structural overlap (e.g., as it relates to the three-dimensional topology of their respective receptor binding domains), the two cytokines, nevertheless, are both structurally and functionally distinct. APRIL binds to biologically relevant heparan sulfate (present in the extracellular matrices of cells as heparan sulfate proteoglycans); BAFF does not. This interaction plays a critical biological function with respect to promoting the oligomerization state of APRIL in concert with its localized interaction with TACI, which likewise requires HSPGS for full activity. Unlike BAFF which acts as a potent activator of B cells inclusive of both proliferation and differentiation, APRIL would appear to function more particularly with respect to the modulation of B cell phenotype, e.g., as it relates to IgA production and the differentiation / survival of IgA positive plasma cells. As such, a targeted disruption in APRIL-receptor signaling is expected to have less perturbative effects on B cell homeostasis and overall immune function in comparison to other immune related therapeutics that target BAFF (e.g., belimumab) or anti CD20 therapies (e.g., rituximab) that largely target pre and early B cells. APRIL has also been shown to be expressed at high levels on other myeloid related cells and lymphoid tissues, as well as hematological cancers (e.g., myeloma, chronic lymphocytic leukemia (CLL)) and solid tumors (e.g., colon, thyroid, and breast).

[0490] Exemplary amino acid and nucleotide sequences of human APRIL are described, e.g., in Hahne et al. J. Exp. Med. 188:1185-1190 (1998); Shu et al. J. Leukoc. Biol. 65:680-683 (1999); Kelly et al. Cancer Res. 60:1021-1027(2000); and Pradet-Balade et al. EMBO J. 21:5711-5720 (2002).

[0491] The amino acid sequence of human APRIL (isoform alpha, also referred to as the “canonical” sequence (SEQ ID NO: 85)) is provided as follows.

[0492] >huAPRIL

[0493] MPASSPFLLAPKGPPGNMGGPVREPALSVALWLSWGAALGAVACAMALLTQQTELQSLRREVSRLQGTGG PSQNGEGYPWQSLPEQSSDALEAWENGERSRKRRAVLTQKQKKQHSVLHLVPINATSKDDSDVTEVMWQP ALRRGRGLQAQGYGVRIQDAGVYLLYSQVLFQDVTFTMGQW SREGQGRQETLFRCIRSMPSHPDRAYNS CYSAGVFHLHQGDILSVIIPRARAKLNLSPHGTFLGFVKL

[0494] There are several isoforms of human APRIL produced by alternative splicing.

[0495] Isoform beta has the following amino acid sequence (SEQ ID NO: 86):

[0496] >sp1075888-2ITNF13_HUMAN Isoform Beta of Tumor necrosis factor ligand superfamily member 13 OS=Homo sapiens GN=TNFSF13

[0497] MPASSPFLLAPKGPPGNMGGPVREPALSVALWLSWGAALGAVACAMALLTQQTELQSLRREVSRLQGTGG PSQNGEGYPWQSLPEQSSDALEAWENGERSRKRRAVLTQKQKNDSDVTEVMWQPALRRGRGLQAQGYGVR IQDAGVYLLYSQVLFQDVTFTMGQW SREGQGRQETLFRCIRSMPSHPDRAYNSCYSAGVFHLHQGDILS VIIPRARAKLNLSPHGTFLGFVKL

[0498] The sequence of isoform beta differs from the canonical sequence as follows: amino acids 113-

[0499] 129 of SEQ ID NO: 85: KQHSVLHLVPINATSKD N

[0500] Isoform gamma has the following amino acid sequence (SEQ ID NO: 87):

[0501] >sp1075888-3ITNF13_HUMAN Isoform Gamma of Tumor necrosis factor ligand superfamily member 13 OS=Homo sapiens GN=TNFSF13

[0502] MPASSPFLLAPKGPPGNMGGPVREPALSVALWLSWGAALGAVACAMALLTQQTELQSLRREVSRLQGTGG PSQNGEGYPWQSLPEQSSDALEAWENGERSRKRRAVLTQKQKKQHSVLHLVPINATSKDDSDVTEVMWQP ALRRGRGLQAQGYGVRIQDAGVYLLYSQVLFQDVTFTMGQW SREGQGRQETLFRCIRSMPSHPDRAYNS CYSAGVFHLHQGDILSVIIPRARAKLNLSPHGTFLGL

[0503] The sequence of isoform gamma differs from the canonical sequence as follows: amino acids 247-249: Missing.

[0504] Isoform 4 has the following amino acid sequence (SEQ ID NO: 88):

[0505] >sp1075888-4ITNF13_HUMAN Isoform 4 of Tumor necrosis factor ligand superfamily member 13 OS=Homo sapiens GN=TNFSF13

[0506] MPASSPFLLAPKGPPGNMGGPVREPALSVALWLSWGAALGAVACAMALLTQQTELQSLRREVSRLQGTGG PSQNGEGYPWQSLPEQHSVLHLVPINATSKDDSDVTEVMWQPALRRGRGLQAQGYGVRIQDAGVYLLYSQ VLFQDVTFTMGQVVSREGQGRQETLFRCIRSMPSHPDRAYNSCYSAGVFHLHQGDILSVIIPRARAKLNL SPHGTFLGFVKL The sequence of isoform 4 differs from the canonical sequence as follows: amino acids 86-113: Missing.

[0507] Isoform TWE-PRIL has the following amino acid sequence (SEQ ID NO: 89):

[0508] >sp1043508-2ITNF12_HUMAN Isoform TWE-PRIL of Tumor necrosis factor ligand superfamily member 12 OS=Homo sapiens GN=TNFSF12

[0509] MAARRSQRRRGRRGEPGTALLVPLALGLGLALACLGLLLAW SLGSRASLSAQEPAQEELVAEEDQDPSE LNPQTEESQDPAPFLNRLVRPRRSAPKGRKTRARRAIAAHYEVHPRPGQDGAQAGVDGTVSGWEEARINS SSPLRYNRQIGEFIVTRAGLYYLYCQSSDALEAWENGERSRKRRAVLTQKQKKQHSVLHLVPINATSKDD SDVTEVMWQPALRRGRGLQAQGYGVRIQDAGVYLLYSQVLFQDVTFTMGQVVSREGQGRQETLFRCIRSM PSHPDRAYNSCYSAGVFHLHQGDILSVIIPRARAKLNLSPHGTFLGFVKL

[0510] Isoform 5 has the following amino acid sequence (SEQ ID NO: 90):

[0511] >sp1075888-5ITNF13_HUMAN Isoform 5 of Tumor necrosis factor ligand superfamily member 13 OS=Homo sapiens GN=TNFSF13

[0512] MGGPVREPALSVALWLSWGAALGAVACAMALLTQQTELQSLRREVSRLQGTGGPSQNGEGYPWQSLPEQH SVLHLVPINATSKDDSDVTEVMWQPALRRGRGLQAQGYGVRIQDAGVYLLYSQVLFQDVTFTMGQVVSRE GQGRQETLFRCIRSMPSHPDRAYNSCYSAGVFHLHQGDILSVIIPRARAKLNLSPHGTFLGFVKL

[0513] The sequence of isoform 5 differs from the canonical sequence as follows: amino acids 1-17: Missing; amino acids 87-114: Missing.

[0514] Other variant and alternative sequences of human APRIL are described, e.g., in The MGC Project Team, Genome Res. 14:2121-2127 (2004); Ota et al. Nat. Genet. 36:40-45 (2004); and Kelly et al.

[0515] Cancer Res. 60:1021-1027 (2000).

[0516] As used herein, when an anti-APRIL antibody molecule binds, or substantially binds, to human APRIL, it binds, or substantially binds, to one or more isoforms of human APRIL, e.g., one or more isoforms of human APRIL described herein. In an embodiment, the antibody molecule binds or substantially binds to human APRIL having the amino acid sequence of SEQ ID NO: 85. Exemplary amino acid and nucleotide sequences of mouse APRIL are described, e.g., in Yu et al.

[0517] Nat. Immunol. 1:252-256 (2000); Carninci et al. Science 309:1559-1563 (2005); The MGC Project Team, Genome Res. 14:2121-2127 (2004); and Bossen et al. J. Biol Chem. 281: 13964-13971 (2006).

[0518] The amino acid sequence of mouse APRIL isoform 1 (SEQ ID NO: 91) is provided as follows.

[0519] >muAPRIL MPASSPGHMGGSVREPALSVALWLSWGAVLGAVTCAVALLIQQTELQSLRREVSRLQRSGGPSQKQGERP WQSLWEQSPDVLEAWKDGAKSRRRRAVLTQKHKKKHSVLHLVPVNITSKADSDVTEVMWQPVLRRGRGLE AQGDIVRVWDTGIYLLYSQVLFHDVTFTMGQVVSREGQGRRETLFRCIRSMPSDPDRAYNSCYSAGVFHL HQGDIITVKIPRANAKLSLSPHGTFLGFVKL The amino acid sequence of mouse APRIL isoform 2 (SEQ ID NO: 92) is provided as follows. MPASSPGHMGGSVREPALSVALWLSWGAVLGAVTCAVALLIQQTELQSLRREVSRLQRSGGPSQKQGERP WQSLWEQSPDVLEAWKDGAKSRRRRAVLTQKHKKKHSVLHLVPVNITSKDSDVTEVMWQPVLRRGRGLEA QGDIVRVWDTGIYLLYSQVLFHDVTFTMGQW SREGQGRRETLFRCIRSMPSDPDRAYNSCYSAGVFHLH QGDIITVKIPRANAKLSLSPHGTFLGFVKL

[0520] As used herein, when an anti-APRIL antibody molecule binds, or substantially binds, to mouse APRIL, it binds, or substantially binds, to one or more isoforms of mouse APRIL, e.g., one or more isoforms of mouse APRIL described herein. In an embodiment, the antibody molecule binds or substantially binds to mouse APRIL having the amino acid sequence of SEQ ID NO: 91, SEQ ID NO: 92, or both.

[0521] As used herein, when an anti-APRIL antibody molecule does not bind, or does not substantially bind, to mouse APRIL, it does not bind, or does not substantially bind, to one or more isoforms of mouse APRIL, e.g., one or more isoforms of mouse APRIL described herein. In an embodiment, the antibody molecule does not bind, or does not substantially bind, to mouse APRIL having the amino acid sequence of SEQ ID NO: 91 or 92. In a typical embodiment, the antibody molecule does not bind, or does not substantially bind, to mouse APRIL having the amino acid sequence of SEQ ID NO: 91 and mouse APRIL having the amino acid sequence of SEQ ID NO: 92.

[0522] Sequence alignment of exemplary human and mouse APRIL proteins (SEQ ID NOS: 85 and 91, respectively) is shown in FIG. 13 of International Application Publication No. WO2017 / 091683, the contents of which are incorporated herein by reference in its entirety.

[0523] Epitope

[0524] The antibody molecule described herein can bind to an epitope on APRIL (e.g., human APRIL, mouse APRIL, or both). For example, an epitope bound by an antibody molecule described herein can include one or more epitope contact points described herein.

[0525] In an embodiment, the antibody molecule contacts (e.g., binds, or substantially binds, to) one or more residues, or one or more regions, as described in any of Tables 3-4 or 6, or Table 8 or any of FIGS. 14, 22, 23A-23B, 24A-24B, 25A-25B, or 38A-38B of International Application Publication No. WO2017 / 091683.

[0526] In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or more (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, or all) of the amino acid residues shown in Table 3. In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) all of the amino acid residues shown in Table 3. For example, the antibody molecules described herein can contact the amino acid residues shown in Table 3 in a manner that includes binding across two APRIL monomers (e.g., as depicted positionally in Table 3 as A vs. B). While not wishing to be bound by theory, it is believed that in an embodiment, at least some of the amino acid residues shown in Table 3 contribute to high affinity interactions between APRIL and the CDR2 domain of T ACI. In an embodiment, contacting one or more of the amino acid residues in Table 3 with an antibody molecule described herein inhibits, or substantially inhibits, binding of APRIL to TACI. Exemplary human APRIL amino acid residues that can bind to the anti-APRIL antibody molecules described herein are shown in Table 3. A structural representation of this epitope (e.g., defined both spatially and conformationally) is depicted in FIG. 14 of International Application Publication No. WO2017 / 091683.

[0527] Table 3. Exemplary Human APRIL Amino Acid Residues that Bind to Anti-APRIL Antibodies (amino acid numbering based on SEQ ID NO: 85)

[0528] In another embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or more (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, or all) of the amino acid residues shown in Table 4. In another embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) all of the amino acid residues shown in Table 4. In an embodiment, the antibody molecule binds, or substantially binds to, the C-D loop (e.g., the loop connecting b-sheets C and D), the G-H loop (e.g., the loop connecting b-sheets G and H), or both, on APRIL.

[0529] A structural (spatial) representation of this epitope (sometimes referred herein as “core region”) is depicted in FIG. 15 of International Application Publication No. WO2017 / 091683, which shows each APRIL protein molecule contains two packed antiparallel eight-stranded b-sheets (A to G), one inner and one outer, in a b-jelly roll topology. These B sheets are connected by loops that also define (based on secondary structure definitions) a desired epitope. While not wishing to be bound by theory, it is believed that as these positions / structures define a subset of key interactions with APRIL and the CRD2 domain of TACI, optimal inhibition of APRIL binding to TACI by such an antibody would be achieved.

[0530] Table 4. Exemplary Human APRIL Amino Acid Residues that Bind to Anti-APRIL Antibodies (amino acid numbering based on SEQ ID NO: 85)

[0531] In another embodiment, the antibody molecule does not bind to one, two, or all of Aspl29, Arg233, or HIS203, on human APRIL (e.g., SEQ ID NO: 85). For example, one or more mutations at these positions, e.g., Aspl29Ala, Arg233Asn, His203Asp, or any combination thereof, would not reduce, or substantially reduce, the binding affinity of the antibody molecule to human APRIL, or the inhibitory effect of the antibody molecule on a human APRIL activity (e.g., neutralization of APRIL binding to TACI).

[0532] In yet another embodiment, the antibody molecule binds, or substantially binds, to one or more (e.g., 2, 3, 4, 5, 6, 7, 8, 9, or all) residues of human APRIL (e.g., SEQ ID NO: 85) from positions 105-114 and / or one or more (e.g., 2, 3, 4, 5, 6, 7, 8, 9, or all) residues of mouse APRIL (e.g., SEQ ID NO: 91) from positions 96-105. In another embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or more (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or all) of the amino acid residues shown in Table 7. In another embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) all of the amino acid residues shown in Table 7.

[0533] Table 7. Exemplary Human APRIL Amino Acid Residues that Bind to Anti-APRIL Antibodies (amino acid numbering based on SEQ ID NO: 85)

[0534] In an embodiment, the antibody molecule, e.g., an anti-APRIL antibody molecule having one, two, three, four, five or six CDRs of any of monoclonal antibodies 2419, 2419-0105, 2419-0205, 2419- 0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1210, 2419-1305, 2419-1306, 2419-1310, or 2419-1406, binds to one or more amino acids described in Table 7. In another embodiment, the antibody molecule, e.g., a human-specific, anti-APRIL antibody molecule, e.g., having one, two, three, four, five or six CDRs of any of monoclonal antibodies 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419-0805, 2419-0806, 2419-1204, 2419-1210, 2419-1305, 2419-

[0535] 1306, 2419-1310, 2419-1406, binds to mouse APRIL when one or more (e.g., 2, 3, 4 or all) following positions within mouse APRIL (mouse APRIL numbering applies) are mutated, e.g., to the following: A120D, N224R, H163Q, K219I, or R181Q. In yet another embodiment, the antibody molecule, e.g., a human-specific, anti-APRIL antibody molecule, e.g., having one, two, three, four, five or six CDRs of any of monoclonal antibodies 2419, 2419-0105, 2419-0205, 2419-0206, 2419-0406, 2419-0605, 2419- 0805, 2419-0806, 2419-1204, 2419-1210, 2419-1305, 2419-1306, 2419-1310, 2419-1406, binds to mouse APRIL when the lysine at position 219 (mouse APRIL numbering applies) is mutated, e.g., to an isoleucine (i.e., K219I).

[0536] In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or more (e.g., 2, 3, l·, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,

[0537] 30, 31, 32, or all) of the amino acid residues of human APRIL shown in Table 6 of International Application Publication No. WO2017 / 091683. In an embodiment, the antibody molecule is an antibody molecule described herein, e.g., monoclonal antibody 2218, 2419, 2621, 2622, 3125, 3327, 3525, 3530, 4035, 3934, 3833, 3631, 3732, 4338, 4540, or 4237.

[0538] In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or more (e.g., 2, 3, 4, 5, 6, 7, 8, 9, or all) of the amino acid residues of human APRIL chosen from D132, V174, F176, V181, Q190, R195, R206, Y208, 1228, or N237. In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or more (e.g., 2, 3, 4, 5, or all) of the amino acid residues of human APRIL chosen from V 174, F176, Q190, R195, R206, or Y208. In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or more (e.g., 2, 3, or all) of the amino acid residues of human APRIL chosen from F176, V181, Q190, or 1228. In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or more (e.g., 2, or all) of the amino acid residues of human APRIL chosen from V 174, R206, or Y208.

[0539] In an embodiment, the antibody molecule does not contact (e.g., does not bind or does not substantially bind to) at least one (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) of the amino acid residues of human APRIL shown in Table 6 of International Application Publication No. WO2017 / 091683. In an embodiment, the antibody molecule is an antibody molecule described herein, e.g., monoclonal antibody 2218, 2419, 2621, 2622, 3125, 3327, 3525, 3530, 4035, 3934, 3833, 3631, 3732, 4338, 4540, or 4237.

[0540] In an embodiment, the antibody molecule does not contact (e.g., does not bind or does not substantially bind to) one or more (e.g., 2, 3, 4, 5, 6, or all) of the amino acid residues of human APRIL chosen from F176, V181, Q190, S226, 1228, Y208, or N237. In an embodiment, the antibody molecule does not contact (e.g., does not bind or does not substantially bind to) one or more (e.g., 2, 3, or all) of the amino acid residues of human APRIL chosen from V181, S226, 1228, or N237. In an embodiment, the antibody molecule does not contact (e.g., does not bind or does not substantially bind to) one or both of the amino acid residues of human APRIL chosen from Y208 or N237. In an embodiment, the antibody molecule does not contact (e.g., does not bind or does not substantially bind to) one or more (e.g., 2, 3, or all) of the amino acid residues of human APRIL chosen from F176, VI 81 , Q190, or N237.

[0541] In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or more (e.g., 2, 3, 4, 5, or all) of the amino acid residues of human APRIL chosen from V 174, F176, Q190, R195, R206, or Y208; and does not contact (e.g., does not bind or does not substantially bind to) one or more (e.g., 2, 3, or all) of the amino acid residues of human APRIL chosen from VI 81 , S226, 1228, or N237. In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or both of the amino acid residues of human APRIL chosen from V174 or R206; and does not contact (e.g., does not bind or does not substantially bind to) one or both of the amino acid residues of human APRIL chosen from VI 81 or N237 (and optionally S226). In an embodiment, the antibody molecule comprises one or more (e.g., two or three) heavy chain CDRs, one or more (e.g., two or three) light chain CDRs, or both of monoclonal antibody 4035. In an embodiment, the antibody molecule comprises a heavy chain region, a light chain variable region, or both, of monoclonal antibody 4035. In an embodiment, monoclonal antibody 4035 is a humanized antibody molecule.

[0542] In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or more (e.g., 2, 3, or all) of the amino acid residues of human APRIL chosen from F176, VI 81 , Q190, or 1228; and does not contact (e.g., does not bind or does not substantially bind to) one or both of the amino acid residues of human APRIL chosen from Y208 or N237. In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) amino acid residue 1228 of human APRIL; and does not contact (e.g., does not bind or does not substantially bind to) one or both of the amino acid residues of human APRIL chosen from Y208 or N237. In an embodiment, the antibody molecule comprises one or more (e.g., two or three) heavy chain CDRs, one or more (e.g., two or three) light chain CDRs, or both of monoclonal antibody 2419. In an embodiment, the antibody molecule comprises a heavy chain region, a light chain variable region, or both, of monoclonal antibody 2419. In an embodiment, monoclonal antibody 2419 is a humanized antibody molecule.

[0543] In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or more (e.g., 2, or ah) of the amino acid residues of human APRIL chosen from V 174, R206, or Y208; and does not contact (e.g., does not bind or does not substantially bind to) one or more (e.g., 2, 3, or ah) of the amino acid residues of human APRIL chosen from F176, V181, Q190, or N237. In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or both of the amino acid residues of human APRIL chosen from V 174 or R206; and does not contact (e.g., does not bind or does not substantially bind to) one or more (e.g., 2, 3, or ah) of the amino acid residues of human APRIL chosen from F176, V181, Q190, or N237. In an embodiment, the antibody molecule comprises one or more (e.g., two or three) heavy chain CDRs, one or more (e.g., two or three) light chain CDRs, or both of monoclonal antibody 3833. In an embodiment, the antibody molecule comprises a heavy chain region, a light chain variable region, or both, of monoclonal antibody 3833. In an embodiment, monoclonal antibody 3833 is a humanized antibody molecule.

[0544] In an embodiment, the epitope overlaps with a CRD2 receptor binding site. In an embodiment, the epitope is non-linear epitope, e.g., that spans across a monomer interface. In an embodiment, the epitope is in a region associated with both TACI and BCMA receptor blocking.

[0545] In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or more (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or ah) of the amino acid residues of human APRIL chosen from V133, V181, E185, Q187, G188, R189, Q190, E191, T192, R195, H218, L219, H220, S226, 1228, P230 (located in monomer A). In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or more (e.g., 2, 3, 4, 5, 6, 7, 8, 9, or ah) of the amino acid residues of human APRIL chosen from V121, 1123, Q139, P140, A141, L142, N237, S239, P240, or H241 (located in monomer B). In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or more (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, or ah) of the amino acid residues of human APRIL chosen from V133, V181, El 85, Q187, G188, R189, Q190, E191, T192, R195, H218, L219, H220, S226, 1228, P230 (located in monomer A); V121, 1123, Q139, P140, A141, L142, N237, S239, P240, or H241 (located in monomer B).

[0546] In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or more (e.g., 2, 3, or ah) of the amino acid residues of human APRIL chosen from VI 81 , Q190, T192, and 1228 (located in monomer A). In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or both of the amino acid residues of human APRIL chosen from A141 or H241 (located in monomer B). In an embodiment, the antibody molecule contacts (e.g., binds or substantially binds to) one or more (e.g., 2, 3, 4, 5, or ah) of the amino acid residues of human APRIL chosen from V181, Q190, T192, and 1228 (located in monomer A); A141 or H241 (located in monomer B).

[0547] In an embodiment, the antibody molecule comprises one or more (e.g., two or three) heavy chain CDRs, one or more (e.g., two or three) light chain CDRs, or both of monoclonal antibody 2419. In an embodiment, the antibody molecule comprises a heavy chain region, a light chain variable region, or both, of monoclonal antibody 2419. In an embodiment, monoclonal antibody 2419 is a humanized antibody molecule.

[0548] In an embodiment, the epitope comprise one or more (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, or ah) of the amino acid residues of human APRIL chosen from V133, V181, E185, Q187, G188, R189, Q190, E191, T192, R195, H218, L219, H220, S226, 1228, P230 (located in monomer A); V121, 1123, Q139, P140, A141, L142, N237, S239, P240, or H241 (located in monomer B). In an embodiment, the epitope comprises one or more (e.g., 2, 3, 4, 5, or all) of the amino acid residues of human APRIL chosen from V181, Q190, T192, and 1228 (located in monomer A); A141 or H241 (located in monomer B).

[0549] In an embodiment, a structural representation of this epitope is depicted in FIG. 38B of International Application Publication No. WO2017 / 091683. In an embodiment, the epitope comprises one or more (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, or all) of the amino acid residues shown in Table 8 of International Application Publication No. WO2017 / 091683.

[0550] In an embodiment, the antibody molecule contacts (e.g., binds, or substantially binds, to) all of the amino acid residues shown in any of Tables 3-4 or 7, or Table 8 of International Application Publication No. WO2017 / 091683. In an embodiment, the epitope comprises, or consists of, all of the amino acid residues shown in any of Tables 3-4 or 7, or Table 8 of International Application Publication No. WO2017 / 091683.

[0551] In an embodiment, the antibody molecule has one or more of the following properties described herein, e.g., one or more (e.g., two, three or all) of: (i) binds, or substantially binds, to human APRIL; (ii) binds, or substantially binds, to mouse APRIL; (iii) inhibits, or substantially inhibits, binding of APRIL (e.g., human APRIL, mouse APRIL, or both) to TACI (e.g., human TACI, mouse TACI, or both); or (iv) inhibits, or substantially inhibits, binding of APRIL (e.g., human APRIL, mouse APRIL, or both) to BCMA (e.g., human BCMA, mouse BCMA, or both). In an embodiment, the antibody molecule binds, or substantially binds, to mouse APRIL. In another embodiment, the antibody molecule does not bind, or binds with low affinity, to mouse APRIL.

[0552] Antibody Molecules

[0553] Disclosed herein are antibody molecules that bind to APRIL, e.g., an APRIL molecule described herein.

[0554] As used herein, the term “antibody molecule” refers to a protein, e.g., an immunoglobulin chain or a fragment thereof, comprising at least one immunoglobulin variable domain sequence. The term “antibody molecule” includes, for example, full-length, mature antibodies and antigen-binding fragments of an antibody. For example, an antibody molecule can include a heavy (H) chain variable domain sequence (abbreviated herein as VH), and a light (L) chain variable domain sequence (abbreviated herein as VL). In another example, an antibody molecule includes two heavy (H) chain variable domain sequences and two light (L) chain variable domain sequence, thereby forming two antigen binding sites, such as Fab, Fab’, F(ab’)2, Fc, Fd, Fd’, Fv, single chain antibodies (scFv for example), single variable domain antibodies, diabodies (Dab) (bivalent and bispecific), and chimeric (e.g., humanized) antibodies, which may be produced by the modification of whole antibodies or those synthesized de novo using recombinant DNA technologies. These functional antibody fragments retain the ability to selectively bind with their respective antigen or receptor. Antibodies and antibody fragments can be from any class of antibodies including, but not limited to, IgG, IgA, IgM, IgD, and IgE, and from any subclass (e.g., IgGl, IgG2, IgG3, and IgG4) of antibodies. The antibody molecules can be monoclonal or polyclonal. The antibody molecule can also be a human, humanized, CDR-grafted, or in vitro generated antibody. The antibody molecule can have a heavy chain constant region chosen from, e.g., IgGl, IgG2, IgG3, or IgG4. The antibody molecule can also have a light chain chosen from, e.g., kappa or lambda. The term “immunoglobulin” (Ig) is used interchangeably with the term “antibody” herein.

[0555] Examples of antigen-binding fragments include: (i) a Fab fragment, a monovalent fragment consisting of the VL, VH, CL and CHI domains; (ii) a F(ab')2 fragment, a bivalent fragment comprising two Fab fragments linked by a disulfide bridge at the hinge region; (iii) a Fd fragment consisting of the VH and CHI domains; (iv) a Fv fragment consisting of the VL and VH domains of a single arm of an antibody, (v) a diabody (dAb) fragment, which consists of a VH domain; (vi) a camelid or camelized variable domain; (vii) a single chain Fv (scFv), see e.g., Bird et al. (1988) Science 242:423-426; and Huston et al. (1988) Proc. Natl. Acad. Sci. USA 85:5879-5883); (viii) a single domain antibody. These antibody fragments may be obtained using any suitable method, including several conventional techniques known to those with skill in the art, and the fragments can be screened for utility in the same manner as are intact antibodies.

[0556] The term “antibody” includes intact molecules as well as functional fragments thereof. Constant regions of the antibodies can be altered, e.g., mutated, to modify the properties of the antibody (e.g., to increase or decrease one or more of: Fc receptor binding, antibody glycosylation, the number of cysteine residues, effector cell function, or complement function).

[0557] The antibody molecule can be a single chain antibody. A single-chain antibody (scFv) may be engineered (see, for example, Colcher, D. et al. (1999) Ann N Y Acad Sci 880:263-80; and Reiter, Y. (1996) Clin Cancer Res 2:245-52). The single chain antibody can be dimerized or multimerized to generate multivalent antibodies having specificities for different epitopes of the same target protein.

[0558] The antibody molecules disclosed herein can also be single domain antibodies. Single domain antibodies can include antibodies whose complementary determining regions are part of a single domain polypeptide. Examples include, but are not limited to, heavy chain antibodies, antibodies naturally devoid of light chains, single domain antibodies derived from conventional 4-chain antibodies, engineered antibodies and single domain scaffolds other than those derived from antibodies. Single domain antibodies may be any of the art, or any future single domain antibodies. Single domain antibodies may be derived from any species including, but not limited to mouse, human, camel, llama, fish, shark, goat, rabbit, and bovine. According to some aspects, a single domain antibody is a naturally occurring single domain antibody known as heavy chain antibody devoid of light chains. Such single domain antibodies are disclosed in WO 94 / 04678, for example. For clarity reasons, this variable domain derived from a heavy chain antibody naturally devoid of light chain is known herein as a VHH or nanobody to distinguish it from the conventional VH of four chain immunoglobulins. Such a VHH molecule can be derived from antibodies raised in Camelidae species, for example in camel, llama, dromedary, alpaca and guanaco. Other species besides Camelidae may produce heavy chain antibodies naturally devoid of light chain; such VHHs are also contemplated.

[0559] The VH and VL regions can be subdivided into regions of hypervariability, termed “complementarity determining regions” (CDR), interspersed with regions that are more conserved, termed “framework regions” (FR or FW). The terms “complementarity determining region,” and “CDR,” as used herein refer to the sequences of amino acids within antibody variable regions which confer antigen specificity and binding affinity. As used herein, the terms “framework,” “FW” and “FR” are used interchangeably.

[0560] The extent of the framework region and CDRs has been precisely defined by a number of methods (see, Rabat, E. A., et al. (1991) Sequences of Proteins of Immunological Interest, Fifth Edition, U.S. Department of Health and Human Services, NIH Publication No. 91-3242; Chothia, C. et al. (1987) J. Mol. Biol. 196:901-917; and the AbM definition used by Oxford Molecular’s AbM antibody modeling software. See, generally, e.g., Protein Sequence and Structure Analysis of Antibody Variable Domains.

[0561] In: Antibody Engineering Lab Manual (Ed.: Duebel, S. and Kontermann, R., Springer- Verlag, Heidelberg). In an embodiment, the following definitions are used: AbM definition of CDR1 of the heavy chain variable domain and Rabat definitions for the other CDRs. In an embodiment, Rabat definitions are used for all CDRs. In addition, embodiments described with respect to Rabat or AbM CDRs may also be implemented using Chothia hypervariable loops. Each VH and VL typically includes three CDRs and four FRs, arranged from amino-terminus to carboxy-terminus in the following order:

[0562] FR1, CDR1, FR2, CDR2, FR3, CDR3, and FR4.

[0563] As used herein, an “immunoglobulin variable domain sequence” refers to an amino acid sequence which can form the structure of an immunoglobulin variable domain. For example, the sequence may include all or part of the amino acid sequence of a naturally-occurring variable domain. For example, the sequence may or may not include one, two, or more N- or C-terminal amino acids, or may include other alterations that are compatible with formation of the protein structure.

[0564] The term “antigen-binding region” refers to the part of an antibody molecule that comprises determinants that form an interface that binds to an antigen, e.g., APRIL, or an epitope thereof. With respect to proteins (or protein mimetics), the antigen-binding region typically includes one or more loops (of at least, e.g., four amino acids or amino acid mimics) that form an interface that binds to the antigen, e.g., APRIL. Typically, the antigen-binding region of an antibody molecule includes at least one or two CDRs and / or hypervariable loops, or more typically at least three, four, five or six CDRs and / or hypervariable loops.

[0565] The terms “compete” or “cross-compete” are used interchangeably herein to refer to the ability of an antibody molecule to interfere with binding of an anti-APRIL antibody molecule, e.g., an anti-APRIL antibody molecule provided herein, to a target, e.g., APRIL. The interference with binding can be direct or indirect (e.g., through an allosteric modulation of the antibody molecule or the target). The extent to which an antibody molecule is able to interfere with the binding of another antibody molecule to the target, and therefore whether it can be said to compete, can be determined using a competition binding assay, for example, a FACS assay, an ELISA or BIACORE assay. In an embodiment, a competition binding assay is a quantitative competition assay. In an embodiment, a first anti-APRIL antibody molecule is said to compete for binding to the target with a second anti-APRIL antibody molecule when the binding of the first antibody molecule to the target is reduced by 10% or more, e.g., 20% or more,

[0566] 30% or more, 40% or more, 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, 95% or more, 98% or more, 99% or more in a competition binding assay (e.g., a competition assay described herein).

[0567] The terms “monoclonal antibody” or “monoclonal antibody composition” as used herein refer to a preparation of antibody molecules of single molecular composition. A monoclonal antibody composition displays a single binding specificity and affinity for a particular epitope. A monoclonal antibody can be made by hybridoma technology or by methods that do not use hybridoma technology (e.g., recombinant methods).

[0568] An “effectively human” protein is a protein that does not evoke a neutralizing antibody response, e.g., the human anti-murine antibody (HAMA) response. HAMA can be problematic in a number of circumstances, e.g., if the antibody molecule is administered repeatedly, e.g., in treatment of a chronic or recurrent disease condition. A HAMA response can make repeated antibody administration potentially ineffective because of an increased antibody clearance from the serum (see, e.g., Saleh et al, Cancer Immunol. Immunother., 32:180-190 (1990)) and also because of potential allergic reactions (see, e.g., LoBuglio et al., Hybridoma, 5:5117-5123 (1986)).

[0569] The antibody molecule can be a polyclonal or a monoclonal antibody. In some embodiments, the antibody can be recombinantly produced, e.g., produced by any suitable phage display or combinatorial methods. Various phage display and combinatorial methods for generating antibodies are known in the art (as described in, e.g., Ladner et al. U.S. Patent No. 5,223,409; Kang et al. International Publication No. WO 92 / 18619; Dower et al. International Publication No. WO 91 / 17271; Winter et al. International Publication WO 92 / 20791; Markland et al. International Publication No. WO 92 / 15679; Breitling et al. International Publication WO 93 / 01288; McCafferty et al. International Publication No. WO 92 / 01047; Garrard et al. International Publication No. WO 92 / 09690; Ladner et al. International Publication No.

[0570] WO 90 / 02809; Fuchs et al. (1991) Bio / Technology 9:1370-1372; Hay et al. (1992) Hum Antibod Hybridomas 3:81-85; Huse et al. (1989) Science 246:1275-1281; Griffths et al. (1993) EMBO J 12:725- 734; Hawkins et al. (1992) J Mol Biol 226:889-896; Clackson et al. (1991) Nature 352:624-628; Gram et al. (1992) PNAS 89:3576-3580; Garrad et al. (1991) Bio / Technology 9:1373-1377; Hoogenboom et al. (1991) Nuc Acid Res 19:4133-4137; and Barbas et al. (1991) PNAS 88:7978-7982, the contents of all of which are incorporated by reference herein).

[0571] In an embodiment, the antibody molecule is a fully human antibody (e.g., an antibody made in a mouse which has been genetically engineered to produce an antibody from a human immunoglobulin sequence), or a non-human antibody, e.g., a rodent (mouse or rat), goat, primate (e.g., monkey), camel antibody. In an embodiment, the non-human antibody is a rodent (mouse or rat antibody). Methods of producing rodent antibodies are known in the art.

[0572] Human monoclonal antibodies can be generated using transgenic mice carrying the human immunoglobulin genes rather than the mouse system. Splenocytes from these transgenic mice immunized with the antigen of interest are used to produce hybridomas that secrete human mAbs with specific affinities for epitopes from a human protein (see e.g., Wood et al. International Application WO 91 / 00906, Kucherlapati et al. PCT publication WO 91 / 10741; Lonberg et al. International Application WO 92 / 03918; Kay et al. International Application 92 / 03917; Lonberg, N. et al. 1994 Nature 368:856- 859; Green, L.L. et al. 1994 Nature Genet. 7:13-21; Morrison, S.L. et al. 1994 Proc. Natl. Acad. Sci. USA 81:6851-6855; Bruggeman et al. 1993 Year Immunol 7:33-40; Tuaillon et al. 1993 PNAS 90:3720-3724; Bruggeman et al. 1991 Eur J Immunol 21:1323-1326).

[0573] An antibody can be one in which the variable region, or a portion thereof, e.g., the CDRs, are generated in a non-human organism, e.g., a rat or mouse. Chimeric, CDR-grafted, and humanized antibodies are within the invention. Antibodies generated in a non-human organism, e.g., a rat or mouse, and then modified, e.g., in the variable framework or constant region, to decrease antigenicity in a human are within the invention.

[0574] Chimeric antibodies can be produced by any suitable recombinant DNA technique. Several are known in the art (see Robinson et al, International Patent Application Publication No. WO1987 / 002671; Akira, et al, European Patent Application Publication No. 184,187; Taniguchi, M., European Patent Application Publication No. 171,496; Morrison et al, European Patent Application Publication No. 173,494; Neuberger et al., International Patent Application Publication No. WO 86 / 01533; Cabilly et al. U.S. Patent No. 4,816,567; Cabilly et al, European Patent Application Publication No. 125,023; Better et al. (1988 Science 240:1041-1043); Liu et al. (1987) PNAS 84:3439-3443; Liu et al., 1987, J. Immunol. 139:3521-3526; Sun et al. (1987) PNAS 84:214-218; Nishimura et al., 1987, Cane. Res. 47:999-1005; Wood et al. (1985) Nature 314:446-449; and Shaw et al., 1988, J. Natl Cancer Inst. 80:1553-1559).

[0575] A humanized or CDR-grafted antibody will have at least one or two but generally all three recipient CDRs (of heavy and or light immunoglobulin chains) replaced with a donor CDR. The antibody may be replaced with at least a portion of a non-human CDR or only some of the CDRs may be replaced with non-human CDRs. It is only necessary to replace the number of CDRs required for binding of the humanized antibody to lipopolysaccharide. In an embodiment, the donor will be a rodent antibody, e.g., a rat or mouse antibody, and the recipient will be a human framework or a human consensus framework. Typically, the immunoglobulin providing the CDRs is called the “donor” and the immunoglobulin providing the framework is called the “acceptor.” In some embodiments, the donor immunoglobulin is a non-human (e.g., rodent). The acceptor framework is typically a naturally-occurring (e.g., a human) framework or a consensus framework, or a sequence about 85% or higher, e.g., 90%, 95%, 99% or higher identical thereto.

[0576] As used herein, the term “consensus sequence” refers to the sequence formed from the most frequently occurring amino acids (or nucleotides) in a family of related sequences (See e.g. , Winnaker, From Genes to Clones (Verlagsgesellschaft, Weinheim, Germany 1987). In a family of proteins, each position in the consensus sequence is occupied by the amino acid occurring most frequently at that position in the family. If two amino acids occur equally frequently, either can be included in the consensus sequence. A “consensus framework” refers to the framework region in the consensus immunoglobulin sequence.

[0577] An antibody can be humanized by any suitable method, and several such methods known in the art (see e.g., Morrison, S. L., 1985, Science 229:1202-1207, by Oi et al., 1986, BioTechniques 4:214, and by Queen et al. US 5,585,089, US 5,693,761 and US 5,693,762, the contents of ah of which are hereby incorporated by reference).

[0578] Humanized or CDR-grafted antibodies can be produced by CDR-grafting or CDR substitution, wherein one, two, or ah CDRs of an immunoglobulin chain can be replaced. See e.g., U.S. Patent 5,225,539; Jones et al. 1986 Nature 321:552-525; Verhoeyan et al. 1988 Science 239:1534; Beidler et al. 1988 J. Immunol. 141:4053-4060; Winter US 5,225,539, the contents of ah of which are hereby expressly incorporated by reference. Winter describes a CDR-grafting method which may be used to prepare humanized antibodies (UK Patent Application GB 2188638A, filed on March 26, 1987; Winter US 5,225,539), the contents of which is expressly incorporated by reference. Also provided are humanized antibodies in which specific amino acids have been substituted, deleted or added. Criteria for selecting amino acids from the donor are described in, e.g., US 5,585,089, e.g., columns 12-16 of US 5,585,089, the contents of which are hereby incorporated by reference. Other techniques for humanizing antibodies are described in Padlan et al. EP 519596 Al, published on December 23, 1992.

[0579] In an embodiment, the antibody molecule has a heavy chain constant region chosen from, e.g., the heavy chain constant regions of IgGl, IgG2 (e.g., IgG2a), IgG3, IgG4, IgM, IgAl, IgA2, IgD, and IgE; particularly, chosen from, e.g., the (e.g., human) heavy chain constant regions of IgGl, IgG2, IgG3, and IgG4. In another embodiment, the antibody molecule has a light chain constant region chosen from, e.g., the (e.g., human) light chain constant regions of kappa or lambda. The constant region can be altered, e.g., mutated, to modify the properties of the antibody molecule (e.g., to increase or decrease one or more of: Fc receptor binding, antibody glycosylation, the number of cysteine residues, effector cell function, and / or complement function). In an embodiment, the antibody molecule has effector function and can fix complement. In another embodiment, the antibody molecule does not recruit effector cells or fix complement. In certain embodiments, the antibody molecule has reduced or no ability to bind an Fc receptor. For example, it may be an isotype or subtype, fragment or other mutant, which does not support binding to an Fc receptor, e.g., it has a mutagenized or deleted Fc receptor binding region.

[0580] In an embodiment, a constant region of the antibody molecule is altered. Methods for altering an antibody constant region are known in the art. Antibody molecules s with altered function, e.g. altered affinity for an effector ligand, such as FcR on a cell, or the Cl component of complement can be produced by replacing at least one amino acid residue in the constant portion of the antibody with a different residue (see e.g., EP 388,151 Al, U.S. Pat. No. 5,624,821 and U.S. Pat. No. 5,648,260, the contents of all of which are hereby incorporated by reference). Amino acid mutations which stabilize antibody structure, such as S228P (EU nomenclature, S241P in Rabat nomenclature) in human IgG4 are also contemplated. Similar type of alterations could be described which if applied to the murine, or other species immunoglobulin would reduce or eliminate these functions.

[0581] In an embodiment, the antibody molecule comprises an Fc region that comprise one or more (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, or more) of mutations or combinations of mutations described in Table 6.

[0582] Table 6. Exemplary Fc mutations

[0583] In an embodiment, the Fc region comprises FcMutOOl. In an embodiment, the Fc region comprises FcMut002. In an embodiment, the Fc region comprises FcMut003. In an embodiment, the Fc region comprises FcMut004. In an embodiment, the Fc region comprises FcMut005. In an embodiment, the Fc region comprises FcMut006. In an embodiment, the Fc region comprises FcMut007. In an embodiment, the Fc region comprises FcMut008. In an embodiment, the Fc region comprises FcMut009. In an embodiment, the Fc region comprises FcMutOlO. In an embodiment, the Fc region comprises FcMutOl 1. In an embodiment, the Fc region comprises FcMut012. In an embodiment, the Fc region comprises FcMut013. In an embodiment, the Fc region comprises FcMut014. In an embodiment, the Fc region comprises FcMutOl 5. In an embodiment, the Fc region comprises FcMutOl 6. In an embodiment, the Fc region comprises FcMut017. In an embodiment, the Fc region comprises FcMutOl 8. In an embodiment, the Fc region comprises FcMut019. In an embodiment, the Fc region comprises FcMut020. In an embodiment, the Fc region comprises FcMut021. In an embodiment, the Fc region comprises FcMut022. In an embodiment, the Fc region comprises FcMut023. In an embodiment, the Fc region comprises FcMut024. In an embodiment, the Fc region comprises FcMut026. In an embodiment, the Fc region comprises FcMut027. In an embodiment, the Fc region comprises FcMut028. In an embodiment, the Fc region comprises FcMut029. In an embodiment, the Fc region comprises FcMut030. In an embodiment, the Fc region comprises FcMut031. In an embodiment, the Fc region comprises FcMut032. In an embodiment, the Fc region comprises FcMut033. In an embodiment, the Fc region comprises FcMut034. In an embodiment, the Fc region comprises FcMut035. In an embodiment, the Fc region comprises FcMut036. In an embodiment, the Fc region comprises FcMut037. In an embodiment, the Fc region comprises FcMut038. In an embodiment, the Fc region comprises FcMut039. In an embodiment, the Fc region comprises FcMut040. In an embodiment, the Fc region comprises FcMut041. In an embodiment, the Fc region comprises FcMut042. In an embodiment, the Fc region comprises FcMut043. In an embodiment, the Fc region comprises FcMut044. In an embodiment, the Fc region comprises FcMut045. In an embodiment, the Fc region comprises FcMut046. In an embodiment, the Fc region comprises FcMut047. In an embodiment, the Fc region comprises FcMut048. In an embodiment, the Fc region comprises FcMut049. In an embodiment, the Fc region comprises FcMut050. In an embodiment, the Fc region comprises FcMut051. In an embodiment, the Fc region comprises FcMut052. In an embodiment, the Fc region comprises FcMut053. In an embodiment, the Fc region comprises FcMut067. In an embodiment, the Fc region comprises FcMut068. In an embodiment, the Fc region comprises FcMut069. In an embodiment, the Fc region comprises FcMut070. In an embodiment, the Fc region comprises FcMut071. In an embodiment, the Fc region comprises FcMut072. In an embodiment, the Fc region comprises FcMut073. In an embodiment, the Fc region comprises FcMut074. In an embodiment, the Fc region comprises FcMut075. In an embodiment, the Fc region comprises FcMut076. In an embodiment, the Fc region comprises FcMut077. In an embodiment, the Fc region comprises FcMut078. In an embodiment, the Fc region comprises FcMut079. In an embodiment, the Fc region comprises FcMut080. In an embodiment, the Fc region comprises FcMut081. In an embodiment, the Fc region comprises FcMut082. In an embodiment, the Fc region comprises FcMut083. In an embodiment, the Fc region comprises FcMut084. In an embodiment, the Fc region comprises FcMut085. In an embodiment, the Fc region comprises FcMut086. In an embodiment, the Fc region comprises FcMut087. In an embodiment, the Fc region comprises FcMut088. In an embodiment, the Fc region comprises FcMut089. In an embodiment, the Fc region comprises FcMut090. In an embodiment, the Fc region comprises FcMut091. In an embodiment, the Fc region comprises FcMut093. In an embodiment, the Fc region comprises FcMut094. In an embodiment, the Fc region comprises FcMut095. In an embodiment, the Fc region comprises FcMut096. In an embodiment, the Fc region comprises FcMut097. In an embodiment, the Fc region comprises FcMut098. In an embodiment, the Fc region comprises FcMut099. In an embodiment, the Fc region comprises FcMutlOO. In an embodiment, the Fc region comprises FcMutlOl. In an embodiment, the Fc region comprises FcMutl02. In an embodiment, the Fc region comprises FcMutl03. In an embodiment, the Fc region comprises FcMutl04. In an embodiment, the Fc region comprises FcMutl05. In an embodiment, the Fc region comprises FcMutl06. In an embodiment, the Fc region comprises FcMutl07. In an embodiment, the Fc region comprises FcMutl08. In an embodiment, the Fc region comprises FcMutl09. In an embodiment, the Fc region comprises FcMutl 10. In an embodiment, the Fc region comprises FcMutl 11. In an embodiment, the Fc region comprises FcMutl 12. In an embodiment, the Fc region comprises FcMutl 13. In an embodiment, the Fc region comprises FcMutl 14. In an embodiment, the Fc region comprises FcMutl 15. In an embodiment, the Fc region comprises FcMutl 16. In an embodiment, the Fc region comprises FcMutl 17. In an embodiment, the Fc region comprises FcMutl 18. In an embodiment, the Fc region comprises FcMutl 19. In an embodiment, the Fc region comprises FcMutl 20. In an embodiment, the Fc region comprises FcMutl21. In an embodiment, the Fc region comprises FcMutl22. In an embodiment, the Fc region comprises FcMutl23. In an embodiment, the Fc region comprises FcMutl24. In an embodiment, the Fc region comprises FcMutl25. In an embodiment, the Fc region comprises FcMutl26. In an embodiment, the Fc region comprises FcMutl27. In an embodiment, the Fc region comprises FcMutl28. In an embodiment, the Fc region comprises FcMutl29. In an embodiment, the Fc region comprises FcMutl30. In an embodiment, the Fc region comprises FcMutl31. In an embodiment, the Fc region comprises FcMutl32. In an embodiment, the Fc region comprises FcMutl33. In an embodiment, the Fc region comprises FcMutl34. In an embodiment, the Fc region comprises FcMutl35. In an embodiment, the Fc region comprises FcMutl36. In an embodiment, the Fc region comprises FcMutl37. In an embodiment, the Fc region comprises FcMutl38. In an embodiment, the Fc region comprises FcMutl39. In an embodiment, the Fc region comprises FcMutl40. In an embodiment, the Fc region comprises FcMutl41. In an embodiment, the Fc region comprises FcMutl42. In an embodiment, the Fc region comprises FcMutl43. In an embodiment, the Fc region comprises FcMutl 44. In an embodiment, the Fc region comprises FcMutl 45. In an embodiment, the Fc region comprises FcMutl46. In an embodiment, the Fc region comprises FcMutl47. In an embodiment, the Fc region comprises FcMutl48. In an embodiment, the Fc region comprises FcMutl49. In an embodiment, the Fc region comprises FcMutl50. In an embodiment, the Fc region comprises FcMutl51. In an embodiment, the Fc region comprises FcMutl52. In an embodiment, the Fc region comprises FcMutl53. In an embodiment, the Fc region comprises FcMutl54. In an embodiment, the Fc region comprises FcMutl55. In an embodiment, the Fc region comprises FcMutl56. In an embodiment, the Fc region comprises FcMutl57. In an embodiment, the Fc region comprises FcMutl58. In an embodiment, the Fc region comprises FcMutl59. In an embodiment, the Fc region comprises FcMutl 60. In an embodiment, the Fc region comprises FcMutl61. In an embodiment, the Fc region comprises FcMutl62. In an embodiment, the Fc region comprises FcMutl63. In an embodiment, the Fc region comprises FcMutl 64. In an embodiment, the Fc region comprises FcMutl 65. In an embodiment, the Fc region comprises FcMutl66. In an embodiment, the Fc region comprises FcMutl67. In an embodiment, the Fc region comprises FcMutl68. In an embodiment, the Fc region comprises FcMutl69. In an embodiment, the Fc region comprises FcMutl70. In an embodiment, the Fc region comprises FcMutl71. In an embodiment, the Fc region comprises FcMutl72. In an embodiment, the Fc region comprises FcMutl73. In an embodiment, the Fc region comprises FcMutl74. In an embodiment, the Fc region comprises FcMutl75. In an embodiment, the Fc region comprises FcMutl76. In an embodiment, the Fc region comprises FcMutl77. In an embodiment, the Fc region comprises FcMutl78. In an embodiment, the Fc region comprises FcMutl79. In an embodiment, the Fc region comprises FcMutl80. In an embodiment, the Fc region comprises FcMutl81. In an embodiment, the Fc region comprises FcMutl82. In an embodiment, the Fc region comprises FcMutl83. In an embodiment, the Fc region comprises FcMutl84. In an embodiment, the Fc region comprises FcMutl85. In an embodiment, the Fc region comprises FcMutl86. In an embodiment, the Fc region comprises FcMutl87. In an embodiment, the Fc region comprises FcMutl88. In an embodiment, the Fc region comprises FcMutl89. In an embodiment, the Fc region comprises FcMutl90. In an embodiment, the Fc region comprises FcMutl91. In an embodiment, the Fc region comprises FcMutl92. In an embodiment, the Fc region comprises FcMutl93. In an embodiment, the Fc region comprises FcMutl94. In an embodiment, the Fc region comprises FcMutl95. In an embodiment, the Fc region comprises FcMutl96. In an embodiment, the Fc region comprises FcMutl97. In an embodiment, the Fc region comprises FcMutl98. In an embodiment, the Fc region comprises FcMutl99. In an embodiment, the Fc region comprises FcMut200. In an embodiment, the Fc region comprises FcMut201. In an embodiment, the Fc region comprises FcMut202. In an embodiment, the Fc region comprises FcMut203. In an embodiment, the Fc region comprises FcMut204. In an embodiment, the Fc region comprises FcMut205. In an embodiment, the Fc region comprises FcMut206. In an embodiment, the Fc region comprises FcMut207. In an embodiment, the Fc region comprises FcMut208. In an embodiment, the Fc region comprises FcMut209. In an embodiment, the Fc region comprises FcMut210. In an embodiment, the Fc region comprises FcMut211. In an embodiment, the Fc region comprises FcMut212. In an embodiment, the Fc region comprises FcMut213. In an embodiment, the Fc region comprises FcMut214. In an embodiment, the Fc region comprises FcMut215. In an embodiment, the Fc region comprises FcMut216. In an embodiment, the Fc region comprises FcMut217. In an embodiment, the Fc region comprises FcMut218. In an embodiment, the Fc region comprises FcMut219. In an embodiment, the Fc region comprises FcMut220. In an embodiment, the Fc region comprises FcMut221. In an embodiment, the Fc region comprises FcMut222. In an embodiment, the Fc region comprises FcMut223. In an embodiment, the Fc region comprises FcMut224. In an embodiment, the Fc region comprises FcMut225. In an embodiment, the Fc region comprises FcMut226. In an embodiment, the Fc region comprises FcMut227. In an embodiment, the Fc region comprises FcMut228. In an embodiment, the Fc region comprises FcMut229. In an embodiment, the Fc region comprises FcMut230. In an embodiment, the Fc region comprises FcMut231. In an embodiment, the Fc region comprises FcMut232. In an embodiment, the Fc region comprises FcMut233. In an embodiment, the Fc region comprises FcMut234. In an embodiment, the Fc region comprises FcMut242. In an embodiment, the Fc region comprises FcMut243. In an embodiment, the Fc region comprises FcMut244.

[0584] Other exemplary Fc mutations are described, e.g., in International...

Claims

What is claimed is:

1. An anti- APRIL antibody molecule, or a pharmaceutical composition comprising the anti- APRIL antibody molecule, for use in a method of treating a disorder in a human subject, wherein the antibody molecule is administered at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; wherein the administration reduces the level of aberrantly glycosylated IgA (a-g IgA) by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy.

2. An anti- APRIL antibody molecule, or a pharmaceutical composition comprising the anti- APRIL antibody molecule, for use in a method of reducing the level of a-g IgA in a human subject, wherein the antibody molecule is administered at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; wherein the administration reduces the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3),wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the subject has, or is at risk of having, a disorder, e.g., IgA nephropathy.

3. An anti- APRIL antibody molecule, or a pharmaceutical composition comprising the anti- APRIL antibody molecule, for use in a method of treating a disorder in a human subject, wherein the method comprises selecting a dose or dosage for the antibody molecule; wherein administration of the antibody molecule at the selected dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the antibody molecule is administered at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg,optionally wherein the disorder is IgA nephropathy.

4. An anti- APRIL antibody molecule, or a pharmaceutical composition comprising the anti- APRIL antibody molecule, for use in a method of treating a disorder in a human subject, wherein the method comprises responsive to a determination that administration of the antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject, administering to the subject the antibody molecule at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy.

5. An anti- APRIL antibody molecule, or a pharmaceutical composition comprising the anti- APRIL antibody molecule, for use in a method of treating a disorder in a human subject, wherein the method comprises determining whether administration of an anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject, if the antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%, administration of the antibody molecule at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg is initiated, continued, or maintained; andoptionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the antibody molecule is administered at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg, optionally wherein the disorder is IgA nephropathy, optionally wherein if the antibody molecule does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%, administration of the antibody molecule is terminated, discontinued, or altered, and / or a different therapeutic agent or modality is administered.

6. An anti- APRIL antibody molecule, or a pharmaceutical composition comprising the anti- APRIL antibody molecule, for use in a method of treating a disorder in a human subject, wherein the method comprises determining whether administration of a therapeutic agent or modality other than the antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in a subject in need thereof, if the therapeutic agent or modality does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%, administering the antibody molecule to the subject at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) anda light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy.

7. An anti- APRIL antibody molecule, or a pharmaceutical composition comprising the anti- APRIL antibody molecule, for use in a method of treating a disorder in a human subject, wherein the antibody molecule is administered at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; and wherein the subject has received, or is going to receive, a vaccine within 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 weeks of administration of the antibody molecule, optionally wherein the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®), optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy, optionally wherein administration of the antibody molecule at the selected dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject.

8. A method of treating a disorder, comprising: administering an anti- APRIL antibody molecule to a human subject in need thereof at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; wherein the administration reduces the level of aberrantly glycosylated IgA (a-g IgA) by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject; and wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), optionally wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy, thereby treating the disorder.

9. A method of reducing the level of a-g IgA, comprising: administering an anti- APRIL antibody molecule to a human subject in need thereof, wherein the antibody molecule is administered at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; wherein the administration reduces the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%,80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the subject has, or is at risk of having, a disorder, e.g., IgA nephropathy, thereby reducing the level of a-g IgA.

10. A method of treating a disorder, comprising: selecting a dose or dosage for an anti-APRIL antibody molecule; wherein administration of the antibody molecule at the selected dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the aminoacid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the antibody molecule is administered at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg, optionally wherein the subject has, or is at risk of having, IgA nephropathy, thereby threating the disorder.

11. A method of treating a disorder, comprising: responsive to a determination that administration of the antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject, administering to a human subject in need thereof an anti-APRIL antibody molecule at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy, thereby treating the disorder.

12. A method of treating a disorder, comprising: determining whether administration of an anti-APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%,99%, or 100% in the subject, if the antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%, administration of the antibody molecule at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg is initiated, continued, or maintained; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the antibody molecule is administered at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg, optionally wherein if the antibody molecule does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%, administration of the antibody molecule is terminated, discontinued, or altered, and / or a different therapeutic agent or modality is administered, optionally wherein the disorder is IgA nephropathy, thereby treating the disorder.

13. A method of treating a disorder, comprising: determining whether administration of a therapeutic agent or modality other than an anti- APRIL antibody molecule reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in a subject in need thereof, if the therapeutic agent or modality does not reduce, or is not likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%,administering the antibody molecule to a human subject at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; and optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy, thereby treating the disorder.

14. A method of treating a disorder, comprising: administering an anti- APRIL antibody molecule to a human subject in need thereof at a dose of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg; and wherein the subject has received, or is going to receive, a vaccine within 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 weeks of administration of the antibody molecule, optionally wherein the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®), optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy, optionally wherein administration of the antibody molecule at the selected dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject, thereby treating the disorder.

15. A method of selecting an anti-APRIL antibody molecule for treating a disorder, comprising: determining whether administration of the antibody molecule at a dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in a human subject in need thereof, wherein the dose is about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg, optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy, thereby selecting the antibody molecule.

16. A method of selecting a dose or dosage for an anti-APRIL antibody molecule for treating a disorder, comprising: determining whether administration of the antibody molecule at a dose or dosage reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in a human subject in need thereof, optionally wherein the dose is about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg, optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy, thereby selecting the dose or dosage.

17. A method of selecting a human subject for treating a disorder, comprising: determining whether administration of an anti-APRIL antibody molecule at a dosage of about 0.5 mg / kg, 2.0 mg / kg, 6 mg / kg, 9 mg / kg, 9.1 mg / kg, 12 mg / kg, or at a fixed dose of about 200 mg, 400 mg, 600 mg, or 800 mg reduces, or is likely to reduce, the level of a-g IgA by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% in the subject, optionally wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3),wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16, optionally wherein the disorder is IgA nephropathy, thereby selecting the subject,18. The antibody molecule or pharmaceutical composition for use of any of claims 1-7, or the method of any of claims 8-17, wherein the a-g IgA comprises or is a-g IgAl.

19. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18, or the method of any of claims 8-18, wherein the level of a-g IgA is reduced by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% for a predetermined period, e.g., at least one, two, three, or four weeks, or at least one, two, three, four, five, six, seven, eight, nine, ten, eleven, or twelve months.

20. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-19, or the method of any of claims 8-19, wherein the level of a-g IgA is reduced by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% about 4 weeks after the antibody molecule is administered.

21. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-20, or the method of any of claims 8-20, wherein the level of a-g IgA is reduced by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% about 8 weeks after the antibody molecule is administered.

22. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-21, or the method of any of claims 8-21, wherein the level of a-g IgA is reduced by at least 40%, 50%, 60%,70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% about 12 weeks after the antibody molecule is administered.

23. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-22, or the method of any of claims 8-22, wherein the level of a-g IgA is reduced by at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% about 16 weeks after the antibody molecule is administered.

24. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-23, or the method of any of claims 8-23, wherein the level of a-g IgA is reduced by at least 50%.

25. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-24, or the method of any of claims 8-24, wherein the level of a-g IgA is reduced by at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%.

26. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-25, or the method of any of claims 8-25, e.g., in a period of at least 1, 2, 3, 4, 5, 6, 7, 8, 9. 10, 11, 12, 13, 14, 15, 16, 17, or 18 months.

27. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-26, or the method of any of claims 8-26, wherein the antibody molecule is administered as a repeated dose, e.g., in a period of at least 3, 6, 9. 12, 15, 18, 24, 30, or 36 months, optionally wherein the subject is administered one or more additional dosages of the anti- APRIL antibody molecules (e.g., 24 hours, 48 hours, 72 hours, 4 days, 5 days, 6 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 1 month, 2 months, 3 months, 4 months, 5 months, or 6 months after the first administration).

28. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-27, or the method of any of claims 8-27, wherein the antibody molecule is administered subcutaneously.

29. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-27, or the method of any of claims 8-27, wherein the antibody molecule is administered intravenously.

30. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-29, or the method of any of claims 8-29, wherein the disorder an APRIL-associated disorder.

31. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-30, or the method of any of claims 8-30, wherein the disorder is associated with an aberrant level of total IgA.

32. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-31, or the method of any of claims 8-31, wherein the disorder is a disorder associated with a-g IgA.

33. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-32, or the method of any of claims 8-32, wherein the disorder is IgA nephropathy (IgAN).

34. The antibody molecule or pharmaceutical composition for use of claim 33, or the method of claim 33, wherein the IgAN is a familial IgAN.

35. The antibody molecule or pharmaceutical composition for use of claim 33, or the method of claim 33, wherein the IgAN is an adult IgAN.

36. The antibody molecule or pharmaceutical composition for use of claim 33, or the method of claim 33, wherein the IgAN is a post-transplant IgAN, a pediatric IgAN, or a crescentic IgAN.

37. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-32, or the method of any of claims 8-32, wherein the disorder is a chronic kidney disease (CKD) or a disorder associated with CKD.

38. The antibody molecule or pharmaceutical composition for use of claim 37, or the method of claim 37, wherein the CKD is an advanced CKD, e.g., with an estimated glomerular filtration rate (eGFR) equal to or greater than about 30 or about 45.

39. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-32, or the method of any of claims 8-32, wherein the disorder is Henoch-Schonlein purpura (HSP).

40. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-32, or the method of any of claims 8-32, wherein the disorder is cutaneous vasculitis or IgA vasculitis.

41. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-32,or the method of any of claims 8-32, wherein the disorder is IgA dermatitis, e.g., IgA bullous dermatosis.

42. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-32, or the method of any of claims 8-32, wherein the disorder is Waldenstrom macroglobulinemia (WM).

43. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-32, or the method of any of claims 8-32, wherein the disorder is lupus nephritis.

44. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-43, or the method of any of claims 8-43, wherein the subject is a human patient.

45. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-44, or the method of any of claims 8-44, wherein the subject has, or is identified as having, a level of a-g IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of a-g IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject.

46. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-45, or the method of any of claims 8-45, wherein the subject has, or is identified as having, a level of total IgA that is at least 1, 1.5, 2, 2.5, 3.5, 4, 4.5, or 5-fold higher than the level of total IgA in a reference subject, e.g., a subject who does not have the disorder, e.g., a healthy or normal subject.

47. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-46, or the method of any of claims 8-46, wherein the subject has received, or is receiving, a different therapeutic agent or modality for treating the disorder.

48. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-46, or the method of any of claims 8-46, wherein the subject has not received, or is not receiving, a different therapeutic agent or modality for treating the disorder.

49. The antibody molecule or pharmaceutical composition for use of any of claims 1-6 or 18-43, or the method of any of claims 8-13 or 15-43, wherein the subject has received, is receiving, or is going to receive, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule.

50. The antibody molecule or pharmaceutical composition for use of any of claims 1-6, 18-43 or 49, or the method of any of claims 8-13, 15-43 or 49, wherein the subject is, or is identified as being, in need of receiving, a vaccine, e.g., within 1, 2, 3, 4, 5, or 6 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks, of administration of the antibody molecule.

51. The antibody molecule or pharmaceutical composition for use of claim 49 or 50, or the method of claim 49 or 50, wherein the subject receives the vaccine before, concurrent with, or after administration of the antibody molecule.

52. The antibody molecule or pharmaceutical composition for use of any of claims 1-6, 18-43 or 49-51, or the method of any of claims 8-13, 15-43 or 49-51, wherein administration of the antibody molecule reduces the subject’s ability to have an effective antigen-specific serum IgG and / or IgA response to the vaccine by no more than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%.

53. The antibody molecule or pharmaceutical composition for use of any of claims 1-6, 18-43 or 49-52, or the method of any of claims 8-13, 15-43 or 49-52, wherein administration of the antibody molecule does not reduce, or does not substantially reduce, the subject’s ability to have an effective antigen- specific serum IgG and / or IgA response to the vaccine.

54. The antibody molecule or pharmaceutical composition for use of any of claims 1-6, 18-43 or 49-53, or the method of any of claims 8-13, 15-43 or 49-53, wherein the subject has or maintains an effective (e.g., protective) antigen-specific serum IgG and / or IgA response to the vaccine after administration of the antibody molecule.

55. The antibody molecule or pharmaceutical composition for use of any of claims 1-6, 18-43 or 49-54, or the method of any of claims 8-13, 15-43 or 49-54, wherein the vaccine comprises tetanus toxoid, diphtheria toxoid, or both (e.g., TENIVAC®).

56. The antibody molecule or pharmaceutical composition for use of claim 55, or the method of claim 55, wherein the subject has or maintains an effective (e.g., protective) level of tetanus and / or diphtheria anti-toxoid IgG (e.g., equal to or above 0.1 IU / mL in the blood), e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more weeks after administration of the antibody molecule.

57. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-56,or the method of any of claims 8-56, wherein the subject has, or is identified as having, a genomic susceptible locus of the disorder, e.g., IgA nephropathy.

58. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-57, or the method of any of claims 8-57, further comprising determining whether the subject has a genomic susceptible locus of the disorder, e.g., IgA nephropathy.

59. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-58, or the method of any of claims 8-58, wherein the antibody molecule comprises a heavy chain variable region (VH) comprising three heavy chain complementarity determining regions (HCDR1, HCDR2, and HCDR3) and a light chain variable region (VL) comprising three light chain complementarity determining regions (LCDR1, LCDR2, and LCDR3), wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 11 ; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 12, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16; or wherein the VH comprises an HCDR1 comprising the amino acid sequence of SEQ ID NO: 17; an HCDR2 comprising the amino acid sequence of SEQ ID NO: 282, and an HCDR3 comprising the amino acid sequence of SEQ ID NO: 13; and the VL comprises an LCDR1 comprising the amino acid sequence of SEQ ID NO: 280; an LCDR2 comprising the amino acid sequence of SEQ ID NO: 285, and an LCDR3 comprising the amino acid sequence of SEQ ID NO: 16.

60. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-59, or the method of any of claims 8-59, wherein the antibody molecule comprises a VH comprising the amino acid sequence of SEQ ID NO: 296, and a VL comprising the amino acid sequence of SEQ ID NO: 286, optionally wherein the antibody molecule is an IgG2.

61. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-60, or the method of any of claims 8-60, wherein the level of a-g IgA is determined in a sample from the subject.

62. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-61, or the method of any of claims 8-61, further comprising determining the level of a-g IgA in a sample from the subject.

63. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-62, or the method of any of claims 8-62, further comprising determining the level of total IgA in the sample.

64. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-63, or the method of any of claims 8-63, further comprising determining the level of IgM and / or IgG in the sample.

65. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-64, or the method of any of claims 8-64, further comprising obtaining a sample from the subject.

66. The antibody molecule or pharmaceutical composition for use of claim 65, or the method of claim 65, wherein the sample is a blood or serum sample.

67. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-66, or the method of any of claims 8-66, further comprising administering a second therapeutic agent or modality to the subject.

68. The antibody molecule or pharmaceutical composition for use of claim 67, or the method of claim 67, wherein the second therapeutic agent or modality is a small molecule.

69. The antibody molecule or pharmaceutical composition for use of claim 67, or the method of claim 67, wherein the second therapeutic agent or modality is an antibody molecule.

70. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-69, or the method of any of claims 8-69, wherein the subject is administered the anti- APRIL antibody molecule at a concentration of about 100, 150, 175, 180, 190, 200, 210, 220, 225, 230, 240, 250, or 300 mg / mL.

71. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-70, or the method of any of claims 8-70, wherein the subject is administered the anti- APRIL antibody molecule at a concentration of about 200 mg / mL.

72. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-71, or the method of any of claims 8-71, wherein the subject is administered the anti- APRIL antibody moleculeat a fixed dose of about 200, 250, 300, 450, 400, 450, 500, 550, 600, 650, 700, 750, or 800 mg.

73. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-72, or the method of any of claims 8-72, wherein the subject is administered the anti- APRIL antibody molecule at a fixed dose of about 200 mg (e.g., at a volume of about 1 mL).

74. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-72, or the method of any of claims 8-72, wherein the subject is administered the anti- APRIL antibody molecule at a fixed dose of about 400 mg (e.g., at a total volume of about 2 mL, e.g., as two administrations of 1 mL volumes or as one administration of a 2 mL volume).

75. The antibody molecule or pharmaceutical composition for use of any of claims 1-7 or 18-72, or the method of any of claims 8-72, wherein the subject is administered the anti- APRIL antibody molecule at a fixed dose of about 600 mg (e.g., at a total volume of about 3 mL, e.g., as one administration of a 2 mL volume and one administration of a 1 mL volume).