Compositions and Methods for Treating Lupus Nephritis

Abstract

The present disclosure generally relates to a method of treating lupus nephritis in a subject in need thereof. The method comprises determining that the subject has at least one of the following characteristics: an elevated C4x level, an elevated C4x / C4 ratio, a decreased C4 level, an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, or an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, wherein C4x is selected from C4a, C4b, and C4d, and administering an inhibitor of the classical complement pathway to the subject.

Description

Technical Field

[0001] Related Applications This patent application claims priority to U.S. Provisional Patent Application No. 63 / 341,835, filed on May 13, 2022, the entire disclosure of which is incorporated herein by reference.

Background Art

[0002] Systemic lupus erythematosus (SLE) is a biologically and clinically heterogeneous autoimmune disease characterized by a wide range of diverse clinical manifestations, particularly renal involvement. SLE is an autoimmune disease in which the body's immune system mistakenly attacks healthy tissues in many parts of the body. Symptoms vary from person to person and can range from mild to severe. Common symptoms include joint pain and swelling, fever, chest pain, hair loss, mouth ulcers, swollen lymph nodes, fatigue, and a rash that most commonly appears on the face. Often, there are periods of the disease called flares and periods of remission with few symptoms.

[0003] The cause of SLE is unknown. Genetics is thought to be involved along with environmental factors. There are several other types of lupus erythematosus, including discoid lupus erythematosus, neonatal lupus erythematosus, and subacute cutaneous lupus erythematosus. Renal involvement in SLE is called lupus nephritis (LN). LN occurs in up to 50% - 60% of SLE patients within the first 10 years of the disease and is a major cause of morbidity and mortality in these patients. To date, there is still no cure for lupus nephritis. There are only options to control symptoms, prevent relapses, and reduce organ damage. Therefore, there is a need in the art for new therapies for preventing and treating lupus nephritis.

Summary of the Invention

[0004] The present disclosure generally relates to a method of treating lupus nephritis in a subject in need thereof. The method comprises determining that the subject has at least one of the following characteristics: an elevated C4x level, an elevated C4x / C4 ratio, a decreased C4 level, an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, or an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level. C4x can be selected from the group consisting of C4a and C4d. The method further comprises administering to the subject an inhibitor of the classical complement pathway, for example, when the subject has an elevated C4x level, an elevated C4x / C4 ratio, a decreased C4 level, an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, or an elevated PACA1 and / or PACA3 level. A therapeutically effective amount of the inhibitor can be administered.

[0005] In some embodiments, the subject has at least two of the characteristics. For example, the characteristics can be selected from an elevated C4x level, an elevated C4x / C4 ratio, and a decreased C4 level, and / or the characteristics can be selected from the group consisting of an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, and a decreased C1s level. In some embodiments, the subject further has an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level. In some embodiments, the subject has at least one of the following additional characteristics: an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C3 level.

[0006] In some embodiments, the subject has an elevated C4x level. In some embodiments, the subject further has at least one of the following additional features: an elevated C4x / C4 ratio, a decreased C4 level, an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C3 level.

[0007] In some embodiments, the elevated C4x level is higher than the C4x level in a normal or healthy subject, higher than the C4x level in a normal or healthy subject of a similar age, or higher than a reference C4x level. The reference C4x level can be a value equal to or greater than the average or median of the C4x levels in samples from subjects with lupus nephritis, or a value equal to or greater than the average or median of the C4x levels in samples from subjects with lupus nephritis of a similar age. The reference C4x level can be a value at or above the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the C4x levels in samples from subjects with lupus nephritis. The reference C4x level can be a value at or above the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the C4x levels in samples from subjects with lupus nephritis of a similar age. The reference C4x level can be a value at or above the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the C4x levels in samples from normal or healthy subjects. The reference C4x level can be a value at or above the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the C4x levels in samples from normal or healthy subjects of a similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis.In some embodiments, the elevated C4x level is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% higher than the reference C4x level, or the elevated C4x level is at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% higher than the reference C4x level.

[0008] In some embodiments, the subject has an elevated C4x / C4 ratio. In some embodiments, the subject further has at least one of the following additional features: an elevated C4x level, a decreased C4 level, an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C3 level. In some embodiments, the elevated C4x / C4 ratio is greater than the C4x / C4 ratio in a normal or healthy subject, greater than the C4x / C4 ratio in a normal or healthy subject of similar age, or greater than a reference C4x / C4 ratio. The reference C4x / C4 ratio can be a value equal to or greater than the mean or median of the C4x / C4 ratio in samples from lupus nephritis subjects, or a value equal to or greater than the mean or median of the C4x / C4 ratio in samples from lupus nephritis subjects of similar age. The reference C4x / C4 ratio can be a value at the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile or greater of the C4x / C4 ratio in samples from lupus nephritis subjects. The reference C4x / C4 ratio can be a value at the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile or greater of the C4x / C4 ratio in samples from lupus nephritis subjects of similar age. The reference C4x / C4 ratio can be a value at the 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100th percentile or greater of the C4x / C4 ratio in samples from normal or healthy subjects. The reference C4x / C4 ratio can be a value at the 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100th percentile or greater of the C4x / C4 ratio in samples from normal or healthy subjects of similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis.In some embodiments, the elevated C4x / C4 ratio is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% greater than a reference C4x / C4 ratio, or at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% greater than the reference C4x / C4 ratio.

[0009] In some embodiments, the subject has a decreased C4 level. In some embodiments, the subject further has at least one of the following additional features: an increased C4x level, an increased C4x / C4 ratio, an increased C1sC1 inhibitor level, an increased C1sC1 inhibitor / C1s ratio, a decreased C1s level, an increased C2b level, an increased C2b / C2 ratio, a decreased C2 level, an increased pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an increased C3a level, an increased C3a / C3 ratio, or a decreased C3 level. In some embodiments, the decreased C4 level is less than the C4 level in a normal or healthy subject. The decreased C4 level can be less than the C4 level in a normal or healthy subject of the same age, less than a reference C4 level, or a value less than the average or median C4 level in a sample from a lupus nephritis subject. In some embodiments, the reference C4 level is a value less than the average or median C4 level in a sample from a lupus nephritis subject of the same age. The reference C4 level can be a value at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C4 levels in samples from lupus nephritis subjects of the same age. The reference C4 level can be a value at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C4 levels in samples from lupus nephritis subjects of the same age. The reference C4 level can be a value at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C4 levels in samples from normal or healthy subjects.The reference C4 level can be a value at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of C4 levels in samples derived from normal or healthy subjects of similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis. In some embodiments, the decreased C4 level is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% lower than the reference C4 level, or at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 50% lower than the reference C4 level.

[0010] In some embodiments, the subject has an elevated C1sC1 inhibitor level. In some embodiments, the subject has at least one of the following additional features: an elevated C4x level, an elevated C4x / C4 ratio, a decreased C4 level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C3 level. In some embodiments, the elevated C1sC1 inhibitor level is higher than the C1sC1 inhibitor level in a normal or healthy subject, higher than the C1sC1 inhibitor level in a normal or healthy subject of similar age, or higher than a reference C1sC1 inhibitor level. The reference C1sC1 inhibitor level can be a value that is equal to or greater than the mean or median of the C1sC1 inhibitor levels in samples from lupus nephritis subjects, or a value that is equal to or greater than the mean or median of the C1sC1 inhibitor levels in samples from lupus nephritis subjects of similar age. The reference C1sC1 inhibitor level can be a value that is equal to or greater than the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the C1sC1 inhibitor levels in samples from lupus nephritis subjects. The reference C1sC1 inhibitor level can be a value that is equal to or greater than the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the C1sC1 inhibitor levels in samples from lupus nephritis subjects of similar age. The reference C1sC1 inhibitor level can be a value that is equal to or greater than the 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100th percentile of the C1sC1 inhibitor levels in samples from normal or healthy subjects.The C1sC1 inhibitor level can be a value at or above the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the C1sC1 inhibitor level in a sample derived from a normal or healthy subject of the same age. In some embodiments, the normal or healthy subject does not have lupus nephritis. In some embodiments, the elevated C1sC1 inhibitor level is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% higher than the reference C1sC1 inhibitor level, or at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 50% higher than the reference C1sC1 inhibitor level.

[0011] In some embodiments, the subject has an elevated C1sC1 inhibitor / C1s ratio. In some embodiments, the subject has at least one of the following additional features: an elevated C4x level, a decreased C4 level, an elevated C4x / C4 ratio, an elevated C1sC1 inhibitor level, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C3 level. In some embodiments, the elevated C1sC1 inhibitor / C1s ratio is greater than the C1sC1 inhibitor / C1s ratio in a normal or healthy subject. In some embodiments, the elevated C1sC1 inhibitor / C1s ratio is greater than the C1sC1 inhibitor / C1s ratio in a normal or healthy subject of the same age. In some embodiments, the elevated C1sC1 inhibitor / C1s ratio is greater than a reference C1sC1 inhibitor / C1s ratio. In some embodiments, the reference C1sC1 inhibitor / C1s ratio is a value that is greater than or equal to the mean or median of the C1sC1 inhibitor / C1s ratio in samples derived from lupus nephritis subjects. In some embodiments, the reference C1sC1 inhibitor / C1s ratio is a value that is greater than or equal to the mean or median of the C1sC1 inhibitor / C1s ratio in samples derived from lupus nephritis subjects of the same age. In some embodiments, the reference C1sC1 inhibitor / C1s ratio is a value at or above the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C1sC1 inhibitor / C1s ratio in samples derived from lupus nephritis subjects. In some embodiments, the reference C1sC1 inhibitor / C1s ratio is a value at or above the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C1sC1 inhibitor / C1s ratio in samples derived from lupus nephritis subjects of the same age.In some embodiments, the reference C1s C1 inhibitor / C1s ratio is at or above the 50th percentile, 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C1s C1 inhibitor / C1s ratio in samples from normal or healthy subjects. In some embodiments, the reference C1s C1 inhibitor / C1s ratio is at or above the 50th percentile, 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C1s C1 inhibitor / C1s ratio in samples from normal or healthy subjects of similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis. In some embodiments, the elevated C1s C1 inhibitor / C1s ratio is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% greater than the reference C1s C1 inhibitor / C1s ratio. In some embodiments, the elevated C1s C1 inhibitor / C1s ratio is at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% greater than the reference C1s C1 inhibitor / C1s ratio.

[0012] In some embodiments, the subject has a decreased C1s level. In some embodiments, the subject has at least one of the following additional features: an increased C4x level, an increased C4x / C4 ratio, a decreased C4 level, an increased C1sC1 inhibitor / C1s ratio, a decreased C1sC1 inhibitor level, an increased C2b level, an increased C2b / C2 ratio, a decreased C2 level, an increased pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an increased C3a level, an increased C3a / C3 ratio, or a decreased C3 level. In some embodiments, the decreased C1s level is less than the C1s level in a normal or healthy subject. In some embodiments, the decreased C1s level is less than the C1s level in a normal or healthy subject of the same age. In some embodiments, the decreased C1s level is less than a reference C1s level. In some embodiments, the reference C1s level is a value that is less than the average or median of the C1s levels in samples from lupus nephritis subjects. In some embodiments, the reference C1s level is a value that is less than the average or median of the C1s levels in samples from lupus nephritis subjects of the same age. In some embodiments, the reference C1s level is a value that is less than or equal to the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C1s levels in samples from lupus nephritis subjects. In some embodiments, the reference C1s level is a value that is less than or equal to the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C1s levels in samples from lupus nephritis subjects of the same age.In some embodiments, the reference C1s level is a value at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C1s levels in samples from normal or healthy subjects. In some embodiments, the reference C1s level is a value at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C1s levels in samples from normal or healthy subjects of a similar age. In some embodiments, the normal or healthy subjects do not have lupus nephritis. In some embodiments, the decreased C1s level is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% lower than the reference C4 level. In some embodiments, the decreased C1s level is at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% lower than the reference C4 level.

[0013] In some embodiments, the subject has an elevated C2b level. In some embodiments, the subject has at least one of the following additional features: an elevated C4x level, an elevated C4x / C4 ratio, a decreased C4 level, an elevated C1sC1 inhibitor / C1s ratio, an elevated C1sC1 inhibitor level, a decreased C1s level, an elevated C2b / C2 ratio, a decreased C2 level, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C3 level. In some embodiments, the elevated C2b level is higher than the C2b level in a normal or healthy subject, or the elevated C2b level is higher than the C2b level in a normal or healthy subject of a similar age, or higher than a reference C2b level. The reference C2b level can be a value greater than or equal to the average or median of the C2b levels in samples from lupus nephritis subjects, or a value greater than or equal to the average or median of the C2b levels in samples from lupus nephritis subjects of a similar age. The reference C2b level can be a value at or above the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the C2b levels in samples from lupus nephritis subjects. The reference C2b level can be a value at or above the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the C2b levels in samples from lupus nephritis subjects of a similar age. The reference C2b level can be a value at or above the 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100th percentile of the C2b levels in samples from normal or healthy subjects. The reference C2b level can be a value at or above the 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100th percentile of the C2b levels in samples from normal or healthy subjects of a similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis.In some embodiments, the elevated C2b level is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% higher than the reference C2b level, or at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% higher than the reference C2b level.

[0014] In some embodiments, the subject has an elevated C2b / C2 ratio. In some embodiments, the subject has at least one of the following additional features: an elevated C4x level, an elevated C4x / C4 ratio, a decreased C4 level, an elevated C1sC1 inhibitor / C1s ratio, an elevated C1sC1 inhibitor level, a decreased C1s level, a decreased C2 level, an elevated C2b level, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C3 level. In some embodiments, the elevated C2b / C2 ratio is greater than the C2b / C2 ratio in a normal or healthy subject. In some embodiments, the elevated C2b / C2 ratio is greater than the C2b / C2 ratio in a normal or healthy subject of the same age. In some embodiments, the elevated C2b / C2 ratio is greater than a reference C2b / C2 ratio. In some embodiments, the reference C2b / C2 ratio is a value equal to or greater than the mean or median of the C2b / C2 ratio in samples from lupus nephritis subjects. In some embodiments, the reference C2b / C2 ratio is a value equal to or greater than the mean or median of the C2b / C2 ratio in samples from lupus nephritis subjects of the same age. In some embodiments, the reference C2b / C2 ratio is a value at or above the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C2b / C2 ratio in samples from lupus nephritis subjects. In some embodiments, the reference C2b / C2 ratio is a value at or above the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C2b / C2 ratio in samples from lupus nephritis subjects of the same age.In some embodiments, the reference C2b / C2 ratio is a value that is at or above the 50th percentile, 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C2b / C2 ratio in samples derived from normal or healthy subjects. In some embodiments, the reference C2b / C2 ratio is a value that is at or above the 50th percentile, 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C2b / C2 ratio in samples derived from normal or healthy subjects of a similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis. In some embodiments, the elevated C2b / C2 ratio is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% greater than the reference C2b / C2 ratio. In some embodiments, the elevated C2b / C2 ratio is at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% greater than the reference C2b / C2 ratio.

[0015] In some embodiments, the subject has a decreased C2 level. In some embodiments, the subject has at least one of the following additional features: an elevated C4x level, an elevated C4x / C4 ratio, a decreased C4 level, an elevated C1sC1 inhibitor / C1s ratio, an elevated C1sC1 inhibitor level, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C3 level. In some embodiments, the decreased C2 level is less than the C2 level in a normal or healthy subject, less than the C2 level in a normal or healthy subject of the same age, or less than a reference C2 level. The reference C2 level can be a value that is greater than or equal to the average or median of the C2 levels in samples from lupus nephritis subjects, or a value that is greater than or equal to the average or median of the C2 levels in samples from lupus nephritis subjects of the same age. The reference C2 level can be a value that is at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C2 levels in samples from lupus nephritis subjects. The reference C2 level can be a value that is at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C2 levels in samples from lupus nephritis subjects of the same age.The reference C2 level can be the value at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C2 level in samples from normal or healthy subjects, or can be the value at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C2 level in samples from normal or healthy subjects of similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis. In some embodiments, the decreased C2 level is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% lower than the reference C2 level, or is at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% lower than the reference C2 level.

[0016] In some embodiments, the subject has elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) levels. In some embodiments, the subject has at least one of the following additional features: elevated C4x level, elevated C4x / C4 ratio, decreased C4 level, elevated C1sC1 inhibitor / C1s ratio, elevated C1sC1 inhibitor level, decreased C1s level, elevated C2b level, elevated C2b / C2 ratio, decreased C2 level, elevated C3a level, elevated C3a / C3 ratio, or decreased C3 level.

[0017] In some embodiments, the elevated PACA1 and / or PACA3 levels are higher than the PACA1 and / or PACA3 levels in a normal or healthy subject, higher than the PACA1 and / or PACA3 levels in a normal or healthy subject of a similar age, or higher than a reference PACA1 and / or PACA3 level. The reference PACA1 and / or PACA3 level can be a value that is greater than or equal to the mean or median of the PACA1 and / or PACA3 levels in samples from lupus nephritis subjects, or a value that is greater than or equal to the mean or median of the PACA1 and / or PACA3 levels in samples from lupus nephritis subjects of a similar age. The reference PACA1 and / or PACA3 level can be a value at or above the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the PACA1 and / or PACA3 levels in samples from lupus nephritis subjects. The reference PACA1 and / or PACA3 level can be a value at or above the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the PACA1 and / or PACA3 levels in samples from lupus nephritis subjects of a similar age. The reference PACA1 and / or PACA3 level can be a value at or above the 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100th percentile of the PACA1 and / or PACA3 levels in samples from normal or healthy subjects, or a value at or above the 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100th percentile of the PACA1 and / or PACA3 levels in samples from normal or healthy subjects of a similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis.In some embodiments, the elevated PACA1 and / or PACA3 levels are at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% higher than the reference PACA1 and / or PACA3 levels, or at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% higher than the reference PACA1 and / or PACA3 levels.

[0018] In some embodiments, the subject has elevated C3a levels. In some embodiments, the subject has at least one of the following additional features: elevated C4x / C4 ratio, decreased C4 levels, elevated C1sC1 inhibitor levels, elevated C1sC1 inhibitor / C1s ratio, decreased C1s levels, elevated C2b levels, elevated C2b / C2 ratio, decreased C2 levels, elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) levels, elevated C4x levels, elevated C3a / C3 ratio, or decreased C3 levels. In some embodiments, the elevated C3a levels are higher than the C3a levels in a normal or healthy subject. In some embodiments, the elevated C3a levels are higher than the C3a levels in a normal or healthy subject of the same age. In some embodiments, the elevated C3a levels are higher than a reference C3a level. In some embodiments, the reference C3a level is a value equal to or greater than the mean or median of the C3a levels in samples from lupus nephritis subjects. In some embodiments, the reference C3a level is a value equal to or greater than the mean or median of the C3a levels in samples from lupus nephritis subjects of the same age. In some embodiments, the reference C3a level is a value at or above the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C3a levels in samples from lupus nephritis subjects. In some embodiments, the reference C3a level is a value at or above the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C3a levels in samples from lupus nephritis subjects of the same age.In some embodiments, the reference C3a level is a value at or above the 50th percentile, 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C3a levels in samples from normal or healthy subjects. In some embodiments, the reference C3a level is a value at or above the 50th percentile, 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C3a levels in samples from normal or healthy subjects of a similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis. In some embodiments, the decreased C3a level is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% higher than the reference C3a level. In some embodiments, the increased C3a level is at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% higher than the reference C3a level.

[0019] In some embodiments, the subject has an elevated C3a / C3 ratio. In some embodiments, the subject has at least one of the following additional features: an elevated C4x level, a decreased C4 level, an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C4x / C4 ratio, or a decreased C3 level. In some embodiments, the elevated C3a / C3 ratio is greater than the C3a / C3 ratio in a normal or healthy subject. In some embodiments, the elevated C3a / C3 ratio is greater than the C3a / C3 ratio in a normal or healthy subject of the same age. In some embodiments, the elevated C3a / C3 ratio is greater than a reference C3a / C3 ratio. In some embodiments, the reference C3a / C3 ratio is a value equal to or greater than the mean or median of the C3a / C3 ratio in samples from lupus nephritis subjects. In some embodiments, the reference C3a / C3 ratio is a value equal to or greater than the mean or median of the C3a / C3 ratio in samples from lupus nephritis subjects of the same age. In some embodiments, the reference C3a / C3 ratio is a value at or above the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C3a / C3 ratio in samples from lupus nephritis subjects. In some embodiments, the reference C3a / C3 ratio is a value at or above the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C3a / C3 ratio in samples from lupus nephritis subjects of the same age.In some embodiments, the reference C3a / C3 ratio is a value that is at or above the 50th percentile, 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C3a / C3 ratio in samples derived from normal or healthy subjects. In some embodiments, the reference C3a / C3 ratio is a value that is at or above the 50th percentile, 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C3a / C3 ratio in samples derived from normal or healthy subjects of a similar age. In some embodiments, the normal or healthy subjects do not have lupus nephritis. In some embodiments, the elevated C3a / C3 ratio is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% greater than the reference C3a / C3 ratio. In some embodiments, the elevated C3a / C3 ratio is at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% greater than the reference C3a / C3 ratio.

[0020] In some embodiments, the subject has a decreased C3 level. In some embodiments, the subject has at least one of the following additional features: an elevated C4x level, an elevated C4x / C4 ratio, an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C4 level. In some embodiments, the decreased C3 level is less than the C3 level in a normal or healthy subject. In some embodiments, the decreased C3 level is less than the C3 level in a normal or healthy subject of the same age. In some embodiments, the decreased C3 level is less than a reference C3 level. In some embodiments, the reference C3 level is a value that is less than the average or median C3 level in samples from lupus nephritis subjects. In some embodiments, the reference C3 level is a value that is less than the average or median C3 level in samples from lupus nephritis subjects of the same age. In some embodiments, the reference C3 level is a value that is less than or equal to the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C3 level in samples from lupus nephritis subjects. In some embodiments, the reference C3 level is a value that is less than or equal to the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C3 level in samples from lupus nephritis subjects of the same age.In some embodiments, the reference C3 level is a value that is at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C3 level in samples from normal or healthy subjects. In some embodiments, the reference C3 level is a value that is at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C3 level in samples from normal or healthy subjects of a similar age. In some embodiments, the normal or healthy subjects do not have lupus nephritis. In some embodiments, the decreased C3 level is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% lower than the reference C4 level. In some embodiments, the decreased C3 level is at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% lower than the reference C4 level.

[0021] In some embodiments, the C4x level, or the C4x / C4 ratio, or the C4 level, or the C1sC1 inhibitor level, or the C1sC1 inhibitor / C1s ratio, or the C1s level, or the C2b level, or the C2b / C2 ratio, or the C2 level, or the PACA1 and / or PACA3 level, or the C3a level, or the C3a / C3 ratio, or the C3 level, is measured in a biological sample. In some embodiments, the C4x level, or the C4x / C4 ratio, or the C4 level, or the C1sC1 inhibitor level, or the C1sC1 inhibitor / C1s ratio, or the C1s level, or the C2b level, or the C2b / C2 ratio, or the C2 level, or the PACA1 and / or PACA3 level, or the C3a level, or the C3a / C3 ratio, or the C3 level, is measured in plasma or urine. In some embodiments, the C4x level, or the C4x / C4 ratio, or the C4 level, or the C1sC1 inhibitor level, or the C1sC1 inhibitor / C1s ratio, or the C1s level, or the C2b level, or the C2b / C2 ratio, or the C2 level, or the PACA1 and / or PACA3 level, or the C3a level, or the C3a / C3 ratio, or the C3 level, is measured less than about 12 months prior to administration of a therapeutically effective amount of an inhibitor of the classical complement pathway. In some embodiments, the C4x level, or the C4x / C4 ratio, or the C4 level, or the C1sC1 inhibitor level, or the C1sC1 inhibitor / C1s ratio, or the C1s level, or the C2b level, or the C2b / C2 ratio, or the C2 level, or the PACA1 and / or PACA3 level, or the C3a level, or the C3a / C3 ratio, or the C3 level, is measured less than about 6 months prior to administration of the inhibitor. In some embodiments, the C4x level, or the C4x / C4 ratio, or the C4 level, or the C1sC1 inhibitor level, or the C1sC1 inhibitor / C1s ratio, or the C1s level, or the C2b level, or the C2b / C2 ratio, or the C2 level, or the PACA1 and / or PACA3 level, or the C3a level, or the C3a / C3 ratio, or the C3 level, is measured less than about 3 months prior to administration of the inhibitor.In some embodiments, the C4x level, or the C4x / C4 ratio, or the C4 level, or the C1sC1 inhibitor level, or the C1sC1 inhibitor / C1s ratio, or the C1s level, or the C2b level, or the C2b / C2 ratio, or the C2 level, or the PACA1 and / or PACA3 level, or the C3a level, or the C3a / C3 ratio, or the C3 level is measured less than about one month prior to administration of the inhibitor.

[0022] In some embodiments, the subject has an elevated urinary protein / creatinine ratio (UPCR) level. In some embodiments, the elevated UPCR level is higher than the UPCR level in a normal or healthy subject, higher than the UPCR level in a normal or healthy subject of similar age, or higher than a reference UPCR level. The reference UPCR level can be about 0.5 g / g, 1.0 g / g, 1.5 g / g, 2.0 g / g, 2.5 g / g, 3.0 g / g, 3.5 g / g, 4.0 g / g, 4.5 g / g, or 5.0 g / g or more. The elevated UPCR level can be at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 150%, 200%, 250%, 300%, 350%, 400%, 450%, 500%, 550%, 600%, 650%, 700%, 750%, 800%, 850%, 900%, 950%, 1000%, 2000%, 3000%, 4000%, or 5000% higher than the UPCR level in a normal or healthy subject or the reference UPCR level. The elevated UPCR level can be at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, 400% - 500%, 500% - 600%, 600% - 700%, 700% - 800%, 800% - 900%, 900% - 1000%, 1000% - 2000%, 2000% - 3000%, 3000% - 4000%, or 4000 - 5000% higher than the UPCR level in a normal or healthy subject or the reference UPCR level. In some embodiments, the UPCR level is measured in urine.

[0023] In some embodiments, the classical complement inhibitor is a C1 inhibitor, such as a small molecule, an antibody, an aptamer, an antisense nucleic acid, or a gene editing agent. In some embodiments, the antibody is a monoclonal antibody, a polyclonal antibody, a recombinant antibody, a humanized antibody, a human antibody, a chimeric antibody, a monovalent antibody, a multispecific antibody, or an antibody derivative thereof.

[0024] In some embodiments, the inhibitor of the classical complement pathway is a C1q inhibitor, such as a small molecule, an antibody, an aptamer, an antisense nucleic acid, or a gene editing agent. In some embodiments, the antibody is a monoclonal antibody, a polyclonal antibody, a recombinant antibody, a humanized antibody, a human antibody, a chimeric antibody, a monovalent antibody, a multispecific antibody, or an antibody derivative thereof. The antibody may be an anti-C1q antibody. In some embodiments, the antibody derivative is a single-arm antibody.

[0025] In some embodiments, the antibody is administered at a dose of at least 50 mg / kg, or at a dose of 50 mg / kg to 200 mg / kg. The antibody can be administered at a dose of 50 mg / kg, 55 mg / kg, 60 mg / kg, 65 mg / kg, 70 mg / kg, 75 mg / kg, 80 mg / kg, 85 mg / kg, 90 mg / kg, 95 mg / kg, 100 mg / kg, 105 mg / kg, 110 mg / kg, 115 mg / kg, 120 mg / kg, 125 mg / kg, 130 mg / kg, 135 mg / kg, 140 mg / kg, 145 mg / kg, 150 mg / kg, 155 mg / kg, 160 mg / kg, 165 mg / kg, 170 mg / kg, 175 mg / kg, 180 mg / kg, 185 mg / kg, 190 mg / kg, 195 mg / kg, or 200 mg / kg. In some embodiments, the antibody is administered up to a total of at least 50 mg. The antibody can be administered up to a total dose of 50 mg, 55 mg, 60 mg, 65 mg, 70 mg, 75 mg, 80 mg, 85 mg, 90 mg, 95 mg, 100 mg, 105 mg, 110 mg, 115 mg, 120 mg, 125 mg, 130 mg, 135 mg, 140 mg, 145 mg, 150 mg, 155 mg, 160 mg, 165 mg, 170 mg, 175 mg, 180 mg, 185 mg, 190 mg, 195 mg, or 200 mg. In some embodiments, the antibody is administered daily, once a week, once every two weeks, once a month, once every six weeks, or once every two months. In some embodiments, the antibody is administered for at least 3 months, 6 months, at least 7 months, at least 8 months, at least 9 months, at least 10 months, at least 11 months, or at least 12 months, preferably for at least 6 months. The antibody can be administered throughout the patient's life, or intermittently throughout the patient's life, for example, in response to a flare. In some embodiments, the antibody is administered at a dose of 75 mg / kg on days 1 and 5 or 6. In some embodiments, the antibody is further administered at a dose of 100 mg / kg every two weeks. In some embodiments, the antibody is administered intravenously.

[0026] In some embodiments, the antibody is an antibody fragment such as a Fab fragment, a Fab’ fragment, an F(ab’)2 fragment, an Fv fragment, a diabody, or a single-chain antibody molecule. In some embodiments, the antibody fragment is administered at a total dose of at least 250 mg, or up to a total dose of 250 mg to 1000 mg. In some embodiments, the antibody fragment is administered at a total dose of 250 mg, 275 mg, 300 mg, 325 mg, 350 mg, 375 mg, 400 mg, 425 mg, 450 mg, 475 mg, 500 mg, 525 mg, 550 mg, 575 mg, 600 mg, 625 mg, 650 mg, 675 mg, 700 mg, 725 mg, 750 mg, 775 mg, 800 mg, 825 mg, 850 mg, 875 mg, 900 mg, 925 mg, 950 mg, 975 mg, 1000 mg, 1250 mg, 1275 mg, 1300 mg, 1325 mg, 1350 mg, 1375 mg, 1400 mg, 1425 mg, 1450 mg, 1475 mg, 1500 mg, 1525 mg, 1550 mg, 1575 mg, 1600 mg, 1625 mg, 1650 mg, 1675 mg, 1700 mg, 1725 mg, 1750 mg, 1775 mg, 1800 mg, 1825 mg, 1850 mg, 1875 mg, 1900 mg, 1925 mg, 1950 mg, 1975 mg, 2000 mg, 2250 mg, 2275 mg, 2300 mg, 2325 mg, 2350 mg, 2375 mg, 2400 mg, 2425 mg, 2450 mg, 2475 mg, 2500 mg, 2525 mg, 2550 mg, 2575 mg, 2600 mg, 2625 mg, 2650 mg, 2675 mg, 2700 mg, 2725 mg, 2750 mg, 2775 mg, 2800 mg, 2825 mg, 2850 mg, 2875 mg, 2900 mg, 2925 mg, 2950 mg, 2975 mg, or up to a total dose of 3000 mg. In some embodiments, the antibody fragment is administered at a total dose of about 750 mg. In some embodiments, the antibody fragment is administered once daily, once every two days, once every three days, once every four days, once every five days, or once every six days, once a week, once every two weeks, or once a month. In some embodiments, the antibody fragment is administered three times a week.In some embodiments, the antibody fragment is administered for at least 3 months, 6 months, at least 7 months, at least 8 months, at least 9 months, at least 10 months, at least 11 months, or at least 12 months. The antibody fragment can be administered over the patient's lifetime or intermittently over the patient's lifetime, for example, in response to a flare. In some embodiments, the antibody fragment is administered subcutaneously.

[0027] In some embodiments, the anti-C1q antibody inhibits the interaction between C1q and the autoantibody or between C1q and C1r or between C1q and C1s, and / or promotes the clearance of C1q from the circulation or tissue. In some embodiments, the antibody comprises a light chain variable domain comprising HVR-L1 having the amino acid sequence of SEQ ID NO: 5, HVR-L2 having the amino acid of SEQ ID NO: 6, and HVR-L3 having the amino acid of SEQ ID NO: 7, and / or a heavy chain variable domain comprising HVR-H1 having the amino acid sequence of SEQ ID NO: 9, HVR-H2 having the amino acid of SEQ ID NO: 10, and HVR-H3 having the amino acid of SEQ ID NO: 11. In some embodiments, the antibody comprises a light chain variable domain comprising an amino acid sequence having at least about 95% homology with an amino acid sequence selected from SEQ ID NOs: 4 and 35-38, the light chain variable domain comprising HVR-L1 having the amino acid sequence of SEQ ID NO: 5, HVR-L2 having the amino acid of SEQ ID NO: 6, and HVR-L3 having the amino acid of SEQ ID NO: 7, preferably, the light chain variable domain comprises an amino acid sequence selected from SEQ ID NOs: 4 and 35-38. In some embodiments, the antibody comprises a light chain variable domain comprising an amino acid sequence having at least about 95% homology with an amino acid sequence selected from SEQ ID NOs: 8 and 31-34, the heavy chain variable domain comprising HVR-H1 having the amino acid sequence of SEQ ID NO: 9, HVR-H2 having the amino acid of SEQ ID NO: 10, and HVR-H3 having the amino acid of SEQ ID NO: 11, preferably, the heavy chain variable domain comprises an amino acid sequence selected from SEQ ID NOs: 8 and 31-34. In some embodiments, the antibody fragment comprises a heavy chain Fab fragment of SEQ ID NO: 39 and a light chain Fab fragment of SEQ ID NO: 40.

[0028] In some embodiments, an inhibitor of the classical complement pathway is a C1r inhibitor, such as a small molecule, antibody, aptamer, antisense nucleic acid, or gene editing agent, preferably an anti-C1r antibody. In some embodiments, the anti-C1r antibody inhibits the interaction between C1r and C1q, or between C1r and C1s, or the anti-C1r antibody inhibits the catalytic activity of C1r, or inhibits the processing of pro-C1r to the active protease.

[0029] In some embodiments, an inhibitor of the classical complement pathway is a C1s inhibitor, such as a small molecule, antibody, aptamer, antisense nucleic acid, or gene editing agent, preferably an anti-C1s antibody. In some embodiments, the anti-C1s antibody inhibits the interaction between C1s and C1q, or between C1s and C1r, or between C1s and C2 or C4, or the anti-C1s antibody inhibits the catalytic activity of C1s, or inhibits the processing of pro-C1s to the active protease, or binds to the activated form of C1s. In some embodiments, the antibody is stimumab.

[0030] In some embodiments, an inhibitor of the classical complement pathway is an anti-C1 complex antibody, and optionally, the anti-C1 complex antibody inhibits the activation of C1r or C1s, or blocks their ability to act on C2 or C4. The anti-C1 complex antibody binds to a combinatorial epitope within the C1 complex, and the combinatorial epitope includes amino acids of both C1q and C1s, both C1q and C1r, both C1r and C1s, or each of C1q, C1r, and C1s.

[0031] In some embodiments, an inhibitor of the classical complement pathway is a C2 inhibitor, such as a small molecule, antibody, aptamer, antisense nucleic acid, or gene editing agent. The C2 inhibitor can be ARGX-117 (Argenx).

[0032] In some embodiments, inhibitors of the classical complement pathway are C3 inhibitors, such as small molecules, antibodies, aptamers, antisense nucleic acids, or gene editing agents. The C3 inhibitor can be APL-9 (Apellis) or AMY-101 (Amyndas).

[0033] In some embodiments, inhibitors of the classical complement pathway are C4 inhibitors, such as small molecules, antibodies, aptamers, antisense nucleic acids, or gene editing agents. BRIEF DESCRIPTION OF THE DRAWINGS

[0034]

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DETAILED DESCRIPTION OF THE INVENTION

[0035] This description should not be understood in a limiting sense and is made merely for the purpose of illustrating the general principles of the present invention. The section titles and overall structure of this specification are for convenience only and are not intended to limit the present invention.

[0036] In lupus nephritis (LN), inhibition of C1q by anti-C1q inhibitors, including but not limited to anti-C1q Fab fragments, as evaluated by free C1q in serum or plasma, reduces downstream complement activation (e.g., complement factors C4 and its activation products, C2 and its activation products, C3 and its activation products, C5 and its activation products, etc.) and complement-mediated renal inflammation.

[0037] Lupus nephritis can be an autoimmune disease with unique C1q / classical complement cascade involvement. Systemic lupus erythematosus (SLE) is driven by autoantibodies against a number of autoantigens (including DNA) (Figure 1). Normal clearance of immune complexes (ICs) is overwhelmed. Excessive IC and C1q glomerular deposition induce local complement-mediated inflammation and disrupt the structure and function of the glomerular basement membrane (GBM) (Figure 2). The data disclosed herein show that high plasma C4d / C4 identifies lupus nephritis patients with diseases mediated by activation of the classical complement pathway. Pathogenic anti-C1q antibodies (PACA) amplify complement activation and perpetuate tissue damage. Complement activation via the classical pathway can be measured by the C4d / C4 ratio with high specificity.

[0038] Precision medicine strategies unique to lupus nephritis The data from Example 1 demonstrate that patients identified by use of a model that evaluates elevated C4d levels and / or elevated C4d / C4 ratios show clinical improvement with anti-C1q antibody treatment. The data from Example 1 also show a strong association between high C4d / C4 ratios and the presence of PACA, as well as strong associations between other complement factors in LN patients, e.g., C4d / C4 and C4d have a strong inverse correlation with C2b and C2b / C2 (Figure 22). The correlations are used to select patients most likely to respond to therapies having the classical complement pathway, more specifically anti-C1q therapy. Similarly, Figure 22 shows a correlation matrix indicating inverse or positive correlations between other complement factors (such as C4x levels, C4x / C4 ratios, C4 levels, C1sC1 inhibitor levels, C1sC1 inhibitor / C1s ratios, C1s levels, C2b levels, C2b / C2 ratios, C2 levels, pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) levels, etc.) in lupus nephritis patients, suggesting coordinated pathway activity.

[0039] The present disclosure generally relates to methods of treating lupus nephritis in a subject in need thereof. The method includes determining that the subject has at least one of the following characteristics: an elevated C4x level, an elevated C4x / C4 ratio, a decreased C4 level, an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, or an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level. C4x can be selected from the group consisting of C4a and C4d. The method further includes, for example, administering to the subject an inhibitor of the classical complement pathway if the subject has an elevated C4x level, an elevated C4x / C4 ratio, a decreased C4 level, an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, or an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level. A therapeutically effective amount of the inhibitor can be administered.

[0040] All sequences recited in the present disclosure are incorporated by reference from U.S. Patent No. 10,316,081, U.S. Patent Application No. 14 / 890,811, U.S. Patent No. 8,877,197, U.S. Patent No. 9,708,394, U.S. Patent Application No. 15 / 360,549, U.S. Patent No. 9,562,106, U.S. Patent No. 10,450,382, U.S. Patent No. 10,457,745, International Patent Application No. PCT / US2018 / 022462 (each of which is incorporated herein by reference for the antibodies and related compositions that it discloses).

[0041] Definitions As used herein, "a" or "an" can mean one or more. When used in a claim(s) herein, the term "a" or "an" can mean one or more when used in conjunction with the term "comprising". For example, a reference to "an antibody" is a reference to one or more antibodies. As used herein, "another" can mean at least a second or more.

[0042] As used herein, a "reference level" relates to a predetermined standard used as a reference for evaluating a value or data obtained from a sample taken from an individual. The reference level can be an absolute value, a relative value, a value having an upper or lower limit, a range of values, an average value, a median value, an average value, or a value compared to a specific control value or baseline value. The reference level can be based, for example, on an individual sample value such as a value obtained from a sample from the subject being tested but at an earlier time point. The reference level can be based, for example, on a number of samples from a population of subjects of the same chronological age, sex, disease state, or otherwise matched group, or on a pool of samples that includes or excludes the sample being tested. The reference level can also be determined from a representative number of samples (e.g., plasma) from different individuals suffering from lupus nephritis. The reference level can also be determined from biological samples from individuals not suffering from lupus nephritis (i.e., normal or healthy subjects of similar age). These biological samples from individuals suffering from lupus nephritis or not suffering from lupus nephritis can include, for example, tissue biopsies, blood, plasma, serum, fecal samples, urine, cerebrospinal fluid, cervical cells (pap smear), or semen. A representative sample can include measurements from at least 10, 20, 30, 40, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1,000 or more individuals.

[0043] The term "immunoglobulin" (Ig) is used interchangeably with "antibody" in this specification. The term "antibody" as used herein is used in the broadest sense and specifically includes monoclonal antibodies, polyclonal antibodies, multispecific antibodies (e.g., bispecific antibodies) formed from at least two intact antibodies, antibody fragments only if they exhibit biological activity, and antibody derivatives.

[0044] The basic four-chain antibody unit is a heterotetrameric glycoprotein composed of two identical light (L) chains and two identical heavy (H) chains. V H and V L When paired together, a single antigen-binding site is formed. For the structure and properties of different classes of antibodies, see, for example, Basic and Clinical Immunology, 8th Ed., Daniel P. Stites, Abba I. Terr and Tristram G. Parslow (eds), Appleton & Lange, Norwalk, CT, 1994, page 71 and Chapter 6.

[0045] L chains derived from any vertebrate species can be assigned to one of two distinct types, called kappa ("κ") and lambda ("λ"), based on the amino acid sequences of their constant domains. Immunoglobulins can be assigned to different classes or isotypes according to the amino acid sequences of their heavy chain constant domains (CH). There are five classes of immunoglobulins: IgA, IgD, IgE, IgG, and IgM (each having heavy chains designated alpha ("α"), delta ("δ"), epsilon ("ε"), gamma ("γ"), and mu ("μ"), respectively). The γ and α classes are further classified into subclasses (isotypes) based on relatively minor differences in CH sequence and function; for example, humans express the following subclasses: IgG1, IgG2, IgG3, IgG4, IgA1, and IgA2. The subunit structures and three-dimensional configurations of different classes of immunoglobulins are well known and are generally described, for example, in Abbas et al., Cellular and Molecular Immunology, 4 th ed. (W.B. Saunders Co., 2000).

[0046] As used herein, the term "agent" describes any molecule, such as a protein or pharmaceutical, that has the ability to modulate synaptic loss, particularly via the complement pathway. Candidate agents also include genetic elements, such as antisense and RNAi molecules that inhibit C1q expression, and constructs that encode complement inhibitors, such as CD59, etc. Candidate agents encompass many chemical classes, but typically are organic molecules that include small organic compounds having a molecular weight greater than 50 Daltons and less than 2500 Daltons. Candidate agents contain functional groups necessary for structural interaction with proteins, particularly hydrogen bonding, and typically contain at least one amine, carbonyl, hydroxyl or carboxyl group, preferably at least two of these chemical functional groups. Candidate agents often contain cyclic carbon or heterocyclic structures and / or aromatic or polyaromatic structures that are substituted with one or more of the above functional groups. Candidate agents are also found among biomolecules, including peptides, saccharides, fatty acids, steroids, purines, pyrimidines, derivatives, structural analogs or combinations thereof. Generally, a mixture of multiple assays is performed in parallel at different agent concentrations to obtain different responses to different concentrations. Typically, one of these concentrations functions as a negative control, i.e., zero concentration or below the detection level.

[0047] The "variable region" or "variable domain" of an antibody refers to the amino-terminal domain of the heavy or light chain of the antibody. The variable domains of the heavy and light chains can be referred to as "V H " and "V L ", respectively. These domains are generally the most variable parts of the antibody (compared to other antibodies of the same class) and contain the antigen-binding site.

[0048] The term "variable" refers to the fact that certain segments of the variable domain have significantly different sequences depending on the antibody. The V domain mediates antigen binding and defines the specificity of a particular antibody for its particular antigen. However, the variability is not evenly distributed throughout the variable domain. Rather, it is concentrated in three segments called hypervariable regions (HVRs) in both the light-chain variable domain and the heavy-chain variable domain. The more highly conserved portions of the variable domain are called framework regions (FRs). The variable domains of the native heavy and light chains each adopt a β-sheet conformation connected by three HVRs that in some cases form loops that partly form part of the β-sheet structure, including four FR regions that greatly adopt the β-sheet conformation. The HVRs within each chain are juxtaposed and linked to each other by the FR regions and, together with the HVRs of the other chain, contribute to the formation of the antigen-binding site of the antibody (see Kabat et al., Sequences of Immunological Interest, Fifth Edition, National Institute of Health, Bethesda, MD (1991)). The constant domains are not directly involved in binding of the antibody to the antigen but exhibit various effector functions, such as the involvement of the antibody in antibody-dependent cell cytotoxicity.

[0049] As used herein, the terms "CDR" or "complementary determining region" are intended to mean the non - contiguous antigen - binding sites found within the variable regions of heavy - chain polypeptides and light - chain polypeptides. CDRs are described by Kabat et al., J. Biol. Chem. 252:6609 - 6616 (1977), Kabat et al., U.S. Dept. of Health and Human Services, "Sequences of proteins of immunological interest" (1991) (also referred to herein as Kabat 1991), Chothia et al., J. Mol. Biol. 196:901 - 917 (1987) (also referred to herein as Chothia 1987), and MacCallum et al., J. Mol. Biol. 262:732 - 745 (1996), and the definitions include amino - acid residue overlaps or subsets when compared to each other. Nevertheless, the application of any definition for referring to the CDRs of an antibody or a grafted antibody or its variant is intended to be within the scope of the terms defined and used herein.

[0050] As used herein, the terms "CDR - L1", "CDR - L2", and "CDR - L3" refer to the first, second, and third CDRs, respectively, in the light - chain variable region. As used herein, the terms "CDR - H1", "CDR - H2", and "CDR - H3" refer to the first, second, and third CDRs, respectively, in the heavy - chain variable region. As used herein, the terms "CDR - 1", "CDR - 2", and "CDR - 3" refer to the first, second, and third CDRs, respectively, in the variable region of either chain.

[0051] As used herein, the term "monoclonal antibody" refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies in the population are identical except for possible naturally occurring mutations and / or post-translational modifications (e.g., isomerization, amidation) that may be present in minor amounts. Monoclonal antibodies are highly specific and are directed against a single antigenic site. In contrast to polyclonal antibody preparations, which typically include different antibodies directed against different determinants (epitopes), each monoclonal antibody is directed against a single determinant on the antigen. In addition to their specificity, monoclonal antibodies are advantageous in that they are typically synthesized by hybridoma culture and are free of other immunoglobulins. The modifier "monoclonal" indicates the characteristic of the antibody as being obtained from a substantially homogeneous population of antibodies and should not be construed as requiring production of the antibody by any particular method. For example, monoclonal antibodies used in accordance with the present disclosure can be made by a variety of techniques, e.g., the hybridoma method (e.g., Kohler and Milstein., Nature, 256:495-97 (1975), Hongo et al., Hybridoma, 14(3):253-260 (1995), Harlow et al., Antibodies: A Laboratory Manual, (Cold Spring Harbor Laboratory Press, 2d ed. 1988), Hammerling et al., in: Monoclonal Antibodies and T-Cell Hybridomas 563-681 (Elsevier, N.Y., 1981)), recombinant DNA methods (e.g., see U.S. Patent No. 4,816,567), phage display technology (e.g., Clackson et al., Nature, 352:624-628 (1991), Marks et al., J. Mol. Biol. 222:581-597 (1992), Sidhu et al., J. Mol. Biol. 338(2):299-310 (2004), Lee et al., J. Mol. Biol. 340(5):1073-1093 (2004), Fellouse, Proc. Nat'l Acad. Sci.USA 101(34):12467-472(2004), and Lee et al., J. Immunol. Methods 284(1-2):119-132(2004), and techniques for generating human or human-like antibodies in animals having all or part of a human immunoglobulin locus or gene encoding a human immunoglobulin sequence (e.g., see WO1998 / 24893, WO1996 / 34096, WO1996 / 33735, WO1991 / 10741, Jakobovits et al., Proc. Nat'l Acad. Sci. USA 90:2551(1993), Jakobovits et al., Nature 362:255-258(1993), Bruggemann et al., Year in Immunol. 7:33(1993), U.S. Patent Nos. 5,545,807, 5,545,806, 5,569,825, 5,625,126, 5,633,425, and 5,661,016, Marks et al., Bio / Technology 10:779-783(1992), Lonberg et al., Nature 368:856-859(1994), Morrison, Nature 368:812-813(1994), Fishwild et al., Nature Biotechnol. 14:845-851(1996), Neuberger, Nature Biotechnol. 14:826(1996), and Lonberg and Huszar, Intern. Rev. Immunol. 13:65-93(1995)).

[0052] A "full-length antibody" is typically a heterotetrameric glycoprotein of approximately 150,000 daltons, containing two identical light (L) chains and two identical heavy (H) chains. Each light chain is linked to a heavy chain by one covalent disulfide bond, while the number of disulfide bonds varies between the heavy chains of different immunoglobulin isotypes. Each heavy and light chain also has regularly spaced intrachain disulfide bridges. Each heavy chain has, at one end, a variable domain (V H ) followed by several constant domains. Each light chain has, at one end, a variable domain (VL ) having a constant domain at the other end, and the constant domain of the light chain is aligned with the first constant domain of the heavy chain, and the variable domain of the light chain is aligned with the variable domain of the heavy chain. Specific amino acid residues are thought to form an interface between the light chain variable domain and the heavy chain variable domain.

[0053] The terms "full-length antibody", "intact antibody" and "complete antibody" are used interchangeably to refer to an antibody in a substantially intact form, as opposed to an antibody fragment or antibody derivative. Specifically, a complete antibody includes those having a heavy chain and a light chain that includes an Fc region. The constant domain can be a native sequence constant domain (e.g., a human native sequence constant domain) or an amino acid sequence variant thereof. Optionally, an intact antibody can have one or more effector functions.

[0054] An "antibody fragment" or "functional fragment" of an antibody includes a portion of an intact antibody, preferably the antigen-binding and / or variable region of the intact antibody or an F region of the antibody that retains or has modified FcR-binding ability. Examples of antibody fragments include Fab, Fab', F(ab') 2 and Fv fragments; diabodies; and linear antibodies (see U.S. Patent No. 5,641,870, Example 2; Zapata et al., Protein Eng. 8(10):1057-1062 (1995)). Additional examples of antibody fragments include antibody derivatives such as single-chain antibody molecules, single-arm antibodies, antibodies having a single antigen-binding arm, monovalent antibodies, and multispecific antibodies formed from antibody fragments.

[0055] The term "single-arm antibody" as used herein is used to cover antibodies that contain a single antigen-binding arm. A single-arm antibody may include an antigen-binding arm and an Fc region, the single antigen-binding arm includes a light-chain variable domain and a heavy-chain variable domain, and the Fc region includes a complex of a first and a second Fc polypeptide. In some embodiments, one of the Fc polypeptides is an N-terminally truncated heavy chain, but not both. In some embodiments, the antibody can be a bivalent antibody, where one arm binds to C1q and the other arm binds to a different antigen. Depending on the other antigen, such an antibody does not cross-link and activate C1q.

[0056] "Antibody having a single antigen-binding arm", as used herein, means an antibody that includes a single antigen-binding arm and an Fc region, and the antigen-binding arm includes a light-chain variable domain and a heavy-chain variable domain. In some embodiments, the antibody further includes an inactive antigen-binding arm that cannot bind to an antigen or an arm that binds to a different antigen. In some embodiments, the Fc region includes a complex of a first Fc polypeptide and a second Fc polypeptide.

[0057] An "antibody derivative" is any construct that includes the antigen-binding region of an antibody. Examples of antibody derivatives include single-chain antibody molecules, single-arm antibodies, antibodies having a single antigen-binding arm, monovalent antibodies, and multispecific antibodies formed from antibody fragments.

[0058] Papain digestion of an antibody produces two identical antigen-binding fragments called "Fab" fragments and one residual "Fc" fragment, designated to reflect its ability to crystallize readily. A Fab fragment consists of the entire L chain plus the variable region domain of the H chain (V H ), and the first constant domain of one heavy chain (C H 1). Each Fab fragment is monovalent with respect to antigen binding, i.e., has a single antigen-binding site. Pepsin treatment of an antibody produces a single large F(ab’) 2resulting in fragments that approximately correspond to two disulfide - linked Fab fragments with different antigen - binding activities and that can still cross - link antigens. The Fab’ fragment differs from the Fab fragment by having several additional residues containing one or more cysteines from the antibody hinge region at the carboxy - terminus of the C H H1 domain. Fab’ - SH is the designation herein for Fab’ where the cysteine residue(s) of the constant domain have free thiol groups. F(ab’) 2 antibody fragments were originally generated as pairs of Fab’ fragments having hinge cysteines in between. Other chemical couplings of antibody fragments are also known.

[0059] The Fc fragment contains the carboxy - terminal portions of both H - chains held together by disulfides. The effector functions of an antibody are determined by sequences in the Fc region, which is also recognized by Fc receptors (FcRs) found on certain cell types.

[0060] The term “Fc region” as used herein is used to define the C - terminal region of an immunoglobulin heavy chain and includes native - sequence Fc regions and variant Fc regions. The boundaries of the Fc region of an immunoglobulin heavy chain can vary, but the human IgG heavy - chain Fc region is typically defined as extending from the amino - acid residue at position Cys226 or Pro230 to its carboxyl terminus. The C - terminal lysine (residue 447 according to the EU numbering system) of the Fc region may be removed, for example, during antibody production or purification or by recombinant manipulation of the nucleic acid encoding the antibody heavy chain. Thus, a composition of intact antibodies may include an antibody population in which all K447 residues have been removed, an antibody population in which no K447 residues have been removed, and an antibody population having a mixture of antibodies with and without the K447 residue. Native - sequence Fc regions suitable for use in the antibodies of the present disclosure include human IgG1, IgG2, IgG3, and IgG4.

[0061] The "native sequence Fc region" includes an amino acid sequence identical to that of the Fc region found in nature. Native sequence human Fc regions include the native sequence human IgG1 Fc region (non-A and A allotypes), the native sequence human IgG2 Fc region, the native sequence human IgG3 Fc region, and the native sequence human IgG4 Fc region, as well as naturally occurring variants thereof.

[0062] The "variant Fc region" includes an amino acid sequence that is different from that of the native sequence Fc region by at least one amino acid modification, preferably one or more amino acid substitutions (multiple possible). Preferably, the variant Fc region has at least one amino acid substitution compared to the native sequence Fc region or the Fc region of the parent polypeptide, for example, about 1 to about 10 amino acid substitutions, and preferably about 1 to about 5 amino acid substitutions, in the native sequence Fc region or in the Fc region of the parent polypeptide. The variant Fc regions herein preferably have at least about 80% homology, and most preferably at least about 90% homology, more preferably at least about 95% homology with the native sequence Fc region and / or the Fc region of the parent polypeptide.

[0063] "Fc receptor" or "FcR" refers to a receptor that binds to the Fc region of an antibody. Preferred FcRs are native sequence human FcRs. Further, preferred FcRs bind to IgG antibodies (gamma receptors) and include receptors of the FcγRI, FcγRII, and FcγRIII subclasses, including allelic variants and alternative splicing forms of these receptors. Among the FcγRII receptors, there are FcγRIIA ("activating receptor") and FcγRIIB ("inhibitory receptor"), which mainly have similar amino acid sequences with different cytoplasmic domains. The activating receptor FcγRIIA contains an immunoreceptor tyrosine-based activation motif ("ITAM") in its cytoplasmic domain. The inhibitory receptor FcγRIIB contains an immunoreceptor tyrosine-based inhibitory motif ("ITIM") in its cytoplasmic domain. (See, for example, M. Daeron, Annu. Rev. Immunol. 15:203-234 (1997)). FcRs are reviewed in Ravetch and Kinet, Annu. Rev. Immunol. 9:457-92 (1991), Capel et al., Immunomethods 4:25-34 (1994), and de Haas et al., J. Lab. Clin. Med. 126:330-41 (1995). Other FcRs, including those to be identified in the future, are encompassed by the term "FcR" herein. FcRs can also increase the serum half-life of antibodies.

[0064] The in vivo binding to FcRn and serum half-life of a human FcRn high-affinity binding polypeptide can be assayed, for example, in transgenic mice expressing human FcRn or transfected human cell lines, or in primates administered with a polypeptide having a variant Fc region. WO2004 / 42072 (Presta) describes antibody variants with improved or reduced binding to FcRs. See also, for example, Shields et al., J. Biol. Chem. 9(2):6591-6604 (2001).

[0065] "Fv" is the smallest antibody fragment containing the complete antigen recognition site and antigen binding site. This fragment consists of a dimer in which one heavy chain variable region domain and one light chain variable region domain are tightly associated by non-covalent bonds. The folding of these two domains gives rise to six hypervariable loops (three loops each from the H chain and L chain), which provide the amino acid residues for antigen binding and confer antigen binding specificity to the antibody. However, even a single variable domain (or half of the Fv containing only three HVRs specific for the antigen), although having a lower affinity than the full binding site, has the ability to recognize and bind the antigen.

[0066] "Single-chain Fv", also abbreviated as "sFv" or "scFv", is an antibody fragment containing a VH antibody domain and a VL antibody domain connected by a single polypeptide chain. Preferably, the sFv polypeptide further contains a polypeptide linker between the V H domain and the V L domain, enabling the sFv to form the structure desired for antigen binding. For an overview of sFv, see Pluckthun in The Pharmacology of Monoclonal Antibodies, vol. 113, Rosenberg and Moore eds., Springer-Verlag, New York, pp. 269-315 (1994).

[0067] The term "diabody" refers to a small antibody fragment prepared by constructing an sFv fragment (see previous paragraph) using a short linker (about 5-10 residues) between the V H domain and the V L domain to achieve inter-chain rather than intra-chain V domain pairing, thereby obtaining a bivalent fragment, i.e., a fragment with two antigen binding sites. Bispecific diabodies are composed of the V H and V LIt is a heterodimer of two "crossed" sFv fragments where the domains are present in different polypeptide chains. Diabodies are described in more detail, for example, in EP 404,097, WO 1993 / 011161, WO / 2009 / 121948, WO / 2014 / 191493, Hollinger et al., Proc. Nat’l Acad. Sci. USA 90:6444-48 (1993).

[0068] As used herein, a "chimeric antibody" is an antibody (immunoglobulin) in which a portion of the heavy and / or light chain is identical or homologous to the corresponding sequence in an antibody derived from a particular species or belonging to a particular antibody class or subclass, while the remainder of the chain(s) is identical or homologous to the corresponding sequence in an antibody derived from another species or belonging to another antibody class or subclass, and fragments of such antibodies, insofar as they exhibit the desired biological activity (U.S. Patent No. 4,816,567, Morrison et al., Proc. Nat‘l Acad. Sci. USA, 81:6851-55 (1984)). Chimeric antibodies of interest herein include PRIMATIZED™ antibodies, where the antigen-binding region of the antibody is derived, for example, from an antibody generated by immunizing a cynomolgus macaque with the antigen of interest. As used herein, a "humanized antibody" is a subset of a "chimeric antibody".

[0069] The "humanized" form of a non-human (e.g., murine) antibody is a chimeric antibody that contains minimal sequences derived from non-human immunoglobulins. In some embodiments, a humanized antibody is a human immunoglobulin (recipient antibody) in which residues from the recipient's HVRs have been replaced with residues from the HVRs of a non-human species such as a mouse, rat, rabbit, or non-human primate (donor antibody) that have the desired specificity, affinity, and / or potency. In some examples, the FR residues of the human immunoglobulin are replaced with the corresponding non-human residues. Additionally, a humanized antibody can contain residues that are not found in either the recipient antibody or the donor antibody. These modifications can be made to further improve the performance of the antibody, such as its binding affinity. Generally, a humanized antibody will comprise substantially all of at least one, typically two, variable domains, wherein all or substantially all of the hypervariable loops correspond to those of the non-human immunoglobulin sequence and all or substantially all of the FR regions correspond to those of the human immunoglobulin sequence, although the FR regions can include one or more individual FR residue substitutions that improve the performance of the antibody, such as binding affinity, isomerization, immunogenicity, etc. The number of these amino acid substitutions in the FRs is typically six or less in the H chain and three or less in the L chain. A humanized antibody can also optionally include at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin. For further details, see, for example, Jones et al., Nature 321:522-525 (1986), Riechmann et al., Nature 332:323-329 (1988), and Presta, Curr. Op. Struct. Biol. 2:593-596 (1992). See, for example, Vaswani and Hamilton, Ann. Allergy, Asthma & Immunol. 1:105-115 (1998), Harris, Biochem. Soc. Transactions 23:1035-1038 (1995), Hurle and Gross, Curr. Op. Biotech. 5:428-433 (1994), as well as U.S. Patent Nos. 6,982,321 and 7,087,409.

[0070] "Human antibody" refers to an antibody having an amino acid sequence corresponding to the amino acid sequence of an antibody produced by a human, and / or an antibody produced using any of the techniques for producing human antibodies disclosed herein. This definition of human antibody specifically excludes humanized antibodies containing non-human antigen-binding residues. Human antibodies can be generated using various techniques known in the art, including phage display libraries. Hoogenboom and Winter, J. Mol. Biol., 227:381 (1991), Marks et al., J. Mol. Biol., 222:581 (1991). The methods described in Cole et al., Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, p. 77 (1985), Boerner et al., J. Immunol., 147(1):86-95 (1991) can also be utilized for the preparation of human monoclonal antibodies. See also van Dijk and van de Winkel, Curr. Opin. Pharmacol. 5:368-74 (2001). Human antibodies can be prepared, for example, by administering an antigen to a transgenic animal whose endogenous locus has been inactivated but has been modified to produce such antibodies in response to antigen challenge (see, for example, U.S. Pat. Nos. 6,075,181 and 6,150,584 for XENOMOUSE (trademark) technology). See also, for example, Li et al., Proc. Nat'l Acad. Sci. USA, 103:3557-3562 (2006) for human antibodies generated by human B cell hybridoma technology.

[0071] As used herein, the terms "hypervariable region", "HVR" or "HV" refer to regions of an antibody variable domain that are hypervariable and / or form structurally defined loops. Generally, an antibody contains six HVRs, three in VH (H1, H2, H3) and three in VL (L1, L2, L3). In a natural antibody, H3 and L3 exhibit the highest diversity among these six HVRs, and in particular, H3 is thought to play a unique role in conferring excellent specificity to the antibody. See, e.g., Xu et al., Immunity 13:37-45 (2000), Johnson and Wu in Methods in Molecular Biology 248:1-25 (Lo, ed., Human Press, Totowa, NJ, 2003)). In fact, naturally occurring camelid antibodies consisting only of heavy chains are functional and stable in the absence of light chains. See, e.g., Hamers-Casterman et al., Nature 363:446-448 (1993) and Sheriff et al., Nature Struct. Biol. 3:733-736 (1996).

[0072] Several HVR descriptions are used herein and are included herein. The HVRs that are Kabat complementarity determining regions (CDRs) are based on sequence variability and are the most commonly used (Kabat et al., supra). Chothia, in contrast, refers to the positions of structural loops (Chothia and Lesk J. Mol. Biol. 196:901-917 (1987)). AbM HVRs represent a compromise between Kabat CDRs and Chothia structural loops and are used by Oxford Molecular's AbM antibody modeling software. "Contact" HVRs are based on analysis of available complex crystal structures. Residues derived from each of these HVRs are described below. [Table 1]

[0073] The HVR may include "extended HVR" as follows: 24-36 or 24-34 (L1), 46-56 or 50-56 (L2), and 89-97 or 89-96 (L3) in VL, and 26-35 (H1), 50-65 or 49-65 (preferred embodiment) (H2), and 93-102, 94-102, or 95-102 (H3) in VH. The variable domain residues are numbered according to Kabat et al. as described above for each of these extended HVR definitions.

[0074] "Framework" or "FR" residues are variable domain residues other than the HVR residues defined herein.

[0075] The phrases "variable domain residue numbering as in Kabat" or "amino acid position numbering as in Kabat", and variations thereof, refer to the numbering system used for the heavy chain variable domain or light chain variable domain of the antibody compilation in Kabat et al. as described above. Using this numbering system, the actual linear amino acid sequence may contain fewer or additional amino acids corresponding to deletions or insertions in the FR or HVR of the variable domain. For example, the heavy chain variable domain may include a single amino acid insertion (residue 52a according to Kabat) after residue 52 of H2, and residues inserted after residue 82 of the heavy chain FR residues (e.g., residues 82a, 82b, and 82c, etc. according to Kabat). The Kabat numbering of residues can be determined for a given antibody by alignment in the homologous regions between the sequence of the antibody and the sequence numbered by "standard" Kabat.

[0076] The Kabat numbering system is generally used when referring to residues within the variable domains (generally residues 1 to 107 of the light chain and 1 to 113 of the heavy chain) (e.g., Kabat et al., Sequences of Immunological Interest. 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991)). The "EU numbering system" or "EU index" is generally used when referring to residues within the constant regions of the immunoglobulin heavy chains (e.g., the EU index reported in the above Kabat et al.). "EU index as in Kabat" refers to the residue numbering of human IgG1 EU antibodies. Unless otherwise stated herein, references to residue numbers in the variable domain of an antibody mean residue numbering according to the Kabat numbering system. Unless otherwise stated herein, references to residue numbers in the constant domain of an antibody mean residue numbering according to the EU numbering system (e.g., see U.S. Patent Publication No. 2010-280227).

[0077] "Acceptor human framework", as used herein, is a framework that includes the amino acid sequence of a VL framework or a VH framework derived from a human immunoglobulin framework or a human consensus framework. An acceptor human framework "derived from" a human immunoglobulin framework or a human consensus framework may contain the same amino acid sequence, or it may contain existing amino acid sequence variations. In some embodiments, the number of existing amino acid variations is 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, or 2 or less. When existing amino acid variations are present in VH, preferably they are present only in 3, 2, or 1 of positions 71H, 73H, and 78H; for example, the amino acid residues at those positions can be 71A, 73T, and / or 78A. In some embodiments, the VL acceptor human framework is identical in sequence to the VL human immunoglobulin framework sequence or the human consensus framework sequence.

[0078] "Human consensus framework" is a framework that represents the amino acid residues that most commonly occur in the selection of human immunoglobulin VL or VH framework sequences. Generally, the selection of human immunoglobulin VL or VH sequences is made from subgroups of variable domain sequences. Generally, the subgroups of sequences are subgroups such as those in Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, MD (1991). Examples include those related to VL, and the subgroups can be subgroup kappa I, kappa II, kappa III, or kappa IV as in the above Kabat et al. Additionally, for VH, the subgroups can be subgroup I, subgroup II, or subgroup III as in the above Kabat et al.

[0079] "Amino acid modification" at a specified position refers to substitution or deletion of the specified residue, or insertion of at least one amino acid residue adjacent to the specified residue. An insertion "adjacent" to the specified residue means an insertion within one or two residues thereof. The insertion can be on the N-terminal side or the C-terminal side of the specified residue. Preferred amino acid modifications herein are substitutions.

[0080] An "affinity matured" antibody has one or more changes in one or more of its HVRs, and these changes result in an improvement in the affinity of the antibody for an antigen as compared to the parental antibody that does not have these change(s). In some embodiments, the affinity matured antibody has a nanomolar or even picomolar affinity for the target antigen. Affinity matured antibodies are produced by procedures known in the art. For example, Marks et al., Bio / Technology 10:779--783 (1992) describes affinity maturation by VH domain and VL domain shuffling. Random mutagenesis of HVRs and / or framework residues is described, for example, in Barbas et al. Proc Nat. Acad. Sci. USA 91:3809-3813 (1994), Schier et al. Gene 169:147-155 (1995), Yelton et al. J. Immunol. 155:1994-2004 (1995), Jackson et al., J. Immunol. 154(7):3310-9 (1995), and Hawkins et al, J. Mol. Biol. 226:889-896 (1992).

[0081] As used herein, the terms "specifically recognize" or "specifically bind" refer to a measurable and reproducible interaction, such as an attraction or binding, between a target and an antibody, that determines the presence of the target in the presence of a heterogeneous population of molecules, including biological molecules. For example, an antibody that specifically or preferentially binds to a target or epitope binds to this target or epitope with higher affinity, avidity, more readily, and / or for a longer duration than it binds to other targets or other epitopes of the target. For example, it is understood that an antibody (or site) that specifically or preferentially binds to a first target may or may not specifically or preferentially bind to a second target. Thus, "specific binding" or "preferential binding" does not necessarily require exclusive binding (although it can include exclusive binding). An antibody that specifically binds to a target has an association constant of at least about 10 3 M -1 or 10 4 M -1 , sometimes about 10 5 M -1 or 10 6 M -1 , in other instances about 10 6 M -1 or 10 7 M -1 , about 10 8 M -1 ~10 9 M -1 , or about 10 10 M -1 ~10 11 M -1 or higher. A variety of immunoassay formats can be used to select antibodies that are specifically immunoreactive with a particular protein. For example, solid-phase ELISA immunoassays are routinely used to select monoclonal antibodies that are specifically immunoreactive with a protein. For a description of immunoassay formats and conditions that can be used to determine specific immunoreactivity, see, for example, Harlow and Lane (1988) Antibodies, A Laboratory Manual, Cold Spring Harbor Publications, New York.

[0082] "Identity", as used herein, refers to amino acid residues being identical between sequences at any particular position in an aligned array. "Similarity", as used herein, refers to amino acid residues being of a similar type between sequences at any particular position in an aligned array. For example, leucine can be used in place of isoleucine or valine. Other amino acids that can often be substituted for each other include - phenylalanine, tyrosine, and tryptophan (amino acids having aromatic side chains); - lysine, arginine, and histidine (amino acids having basic side chains); - aspartate and glutamate (amino acids having acidic side chains); - asparagine and glutamine (amino acids having amide side chains); and - cysteine and methionine (amino acids having sulfur - containing side chains), but are not limited thereto.

[0083] The degree of identity and similarity can be readily calculated. (See, for example, Computational Molecular Biology, Lesk, A.M., ed., Oxford University Press, New York, 1988, Biocomputing. Informatics and Genome Projects, Smith, D.W., ed., Academic Press, New York, 1993, Computer Analysis of Sequence Data, Part 1, Griffin, A.M., and Griffin, H.G., eds., Humana Press, New Jersey, 1994, Sequence Analysis in Molecular Biology, von Heinje, G., Academic Press, 1987, and Sequence Analysis Primer, Gribskov, M. and Devereux, J., eds., M Stockton Press, New York, 1991).

[0084] As used herein, the "interaction" between a complement protein and a second protein includes, but is not limited to, protein-protein interaction, physical interaction, chemical interaction, binding, covalent bond, and ionic bond. As used herein, an antibody "inhibits the interaction" between two proteins if the antibody disrupts, reduces, or completely eliminates the interaction between the two proteins. An antibody or fragment thereof "inhibits the interaction" between two proteins if the antibody or fragment thereof binds to one of the two proteins.

[0085] A "blocking" antibody, "antagonist" antibody, "inhibitory" antibody, or "neutralizing" antibody is an antibody that inhibits or reduces one or more biological activities of the antigen to which it binds, e.g., the interaction with one or more proteins. In some embodiments, the blocking antibody, antagonist antibody, inhibitory antibody, or "neutralizing" antibody substantially or completely inhibits one or more biological activities or interactions of the antigen.

[0086] The term "inhibitor" refers to a compound that has the ability to inhibit the biological function of a target biomolecule, e.g., an mRNA or a protein, whether by decreasing the activity or expression of the target biomolecule. An inhibitor can be an antibody, a small molecule, or a nucleic acid molecule. The term "antagonist" refers to a compound that binds to a receptor and blocks or attenuates the biological response of the receptor. The term "inhibitor" can also refer to an "antagonist".

[0087] Antibody "effector function" refers to the biological activity attributed to the Fc region of the antibody (native sequence Fc region or amino acid sequence variant Fc region) and varies depending on the antibody isotype.

[0088] As used herein, the term "affinity" is the equilibrium constant for the reversible binding of two substances (e.g., an antibody and an antigen), and is expressed as the dissociation constant (KD). The affinity is at least 1-fold higher, at least 2-fold higher, at least 3-fold higher, at least 4-fold higher, at least 5-fold higher, at least 6-fold higher, at least 7-fold higher, at least 8-fold higher, at least 9-fold higher, at least 10-fold higher, at least 20-fold higher, at least 30-fold higher, at least 40-fold higher, at least 50-fold higher, at least 60-fold higher, at least 70-fold higher, at least 80-fold higher, at least 90-fold higher, at least 100-fold higher, or at least 1,000-fold higher, or more, than the affinity of the antibody for an unrelated amino acid sequence. The affinity of the antibody for the target protein can be, for example, from about 100 nanomolar concentration (nM) to about 0.1 nM, from about 100 nM to about 1 picomolar concentration (pM), or from about 100 nM to about 1 femtomolar concentration (fM) or more. As used herein, the term "avidity" refers to the resistance of a complex of two or more substances to dissociation upon dilution. The terms "immunoreactive" and "preferentially binds" are used interchangeably herein with respect to an antibody and / or an antigen-binding fragment.

[0089] The term "binds" refers to the direct association between two molecules by covalent, electrostatic, hydrophobic, and ionic and / or hydrogen bond interactions, including interactions such as salt bridges and water bridges. For example, the subject anti-C1s antibody specifically binds to an epitope within the complement C1s protein. "Specific binding" refers to binding with an affinity of at least about 10 -7 M or more, for example, 5×10 -7 M, 10 -8 M, 5×10 -8 M, and binding at higher affinities. "Nonspecific binding" refers to binding with an affinity of less than about 10 -7 M, for example, 10 -6 M, 10 -5 M, 10 -4 M, etc.

[0090] "k onThe term "___" as used herein is intended to refer to the rate constant for the association of an antibody with an antigen.

[0091] "k off " as used herein is intended to refer to the rate constant for the dissociation of an antibody from an antibody / antigen complex.

[0092] "K D " as used herein is intended to refer to the equilibrium dissociation constant of an antibody-antigen interaction.

[0093] As used herein, with respect to a peptide, polypeptide, or antibody sequence, "percent amino acid sequence identity (%)" and "homology" refer to the percentage of amino acid residues in a candidate sequence that are identical to the amino acid residues in a particular peptide or polypeptide sequence, without considering any conservative substitutions as part of the sequence identity, after aligning the sequences to achieve the maximum percent sequence identity and introducing gaps as necessary. Alignments for the purpose of determining percent amino acid sequence identity can be achieved in various ways within the skill in the art using, for example, publicly available computer software such as BLAST, BLAST-2, ALIGN, or MEGALIGN™ (DNASTAR) software. One of ordinary skill in the art can determine appropriate parameters for measuring the alignment, including any algorithm necessary to achieve the maximum alignment over the full length of the sequences being compared.

[0094] "Biological sample" encompasses a variety of sample types obtained from an individual and can be used in diagnostic or monitoring assays. This definition includes blood and other liquid samples of biological origin, solid tissue samples such as biopsy specimens or tissue cultures or cells derived therefrom, and their progeny. The definition also includes samples that have been manipulated in any way after their procurement, for example, by treatment with reagents, solubilization, or concentration for certain components such as polynucleotides. The term "biological sample" includes clinical samples and also includes cultured cells, cell supernatants, cell lysates, serum, plasma, biological fluids, and tissue samples. The term "biological sample" includes urine, saliva, cerebrospinal fluid, interstitial fluid, ocular fluid, synovial fluid, blood fractions such as plasma and serum, etc. The term "biological sample" also includes solid tissue samples, tissue culture samples, and cell samples.

[0095] "Host cell" includes individual cells or cell cultures that can be or are recipients for vectors (s) for the incorporation of polynucleotide inserts. Host cells include the progeny of a single host cell, which progeny may not necessarily be identical (either in morphology or in genomic DNA complement) to the original parent cell due to natural, accidental, or intentional mutations. Host cells include cells transfected in vivo with the polynucleotide (s) of the present disclosure.

[0096] As used herein, "carrier" includes a pharmaceutically acceptable carrier, excipient, or stabilizer that is non-toxic to the cells or mammals being exposed thereto at the dosages and concentrations employed. Often, a physiologically acceptable carrier is an aqueous pH buffer. Examples of physiologically acceptable carriers include buffers such as phosphates, citrates, and other organic acids; antioxidants including ascorbic acid; low molecular weight (less than about 10 residues) polypeptides; proteins such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, arginine, or lysine; monosaccharides, disaccharides, and other carbohydrates including glucose, mannose, or dextrin; chelating agents such as EDTA; sugar alcohols such as mannitol or sorbitol; salt-forming counterions such as sodium; and / or nonionic surfactants such as TWEEN®, polyethylene glycol (PEG), and PLURONICS®.

[0097] The term "pathogenic anti-C1q antibody" or "pathogenic anti-C1q antibodies" or "PACA" or "PACAs" as used herein refers to endogenous autoantibodies against C1q that selectively recognize neoepitopes within the collagen tail of C1q when bound to a substrate, thereby mobilizing additional C1q. PACAs consist of four IgG subclasses, IgG1, IgG2, IgG3, and IgG4, designated PACA1, PACA2, PACA3, and PACA4, respectively. PACAs recognize the collagen tail of C1q when it is bound to a substrate and mobilize additional C1q via the Fc region, thereby enhancing C1q activity. Without wishing to be bound by theory, PACAs can amplify glomerular injury when bound to C1q that has already been brought to the site by other types of glomerular-reactive autoantibodies within the glomerulus.

[0098] As used herein, the term "subject" refers to a living mammal and may be used interchangeably with the term "patient". Examples of mammals include any member of the mammalian class: humans, non-human primates such as chimpanzees, and other apes and monkey species; farm animals such as cows, horses, sheep, goats, pigs; domestic animals such as rabbits, dogs, and cats; and laboratory animals including rodents such as rats, mice and guinea pigs, but are not limited thereto. The term does not denote a particular age or sex.

[0099] As used herein, the terms "treating" or "treatment" include reducing, halting, or reversing the symptoms, clinical signs, or underlying pathology of a disorder, stabilizing or improving the disorder in a subject, or reducing the likelihood that the disorder in the subject will deteriorate to the same extent it would if the subject were not treated.

[0100] The term "therapeutically effective amount" of a compound with respect to a method of treating a subject refers to the amount of the compound(s) in a preparation that, when administered as part of a desired dosing regimen (for a mammal, preferably a human), e.g., at a reasonable benefit / risk ratio applicable to any medical treatment, treats the disorder or condition, or alleviates the symptoms, improves the condition, or delays the onset of the disease condition, in accordance with clinically acceptable standards, for therapeutic purposes or for aesthetic purposes. The therapeutically effective amount herein may vary depending on factors such as the disease state of the patient, age, sex, and weight of the individual, as well as the ability of the antibody to elicit the desired response in the individual.

[0101] As used herein, an "at-risk" individual for developing a particular disease, disorder, or medical condition may not exhibit a detectable disease or symptom of a disease, and may not have exhibited a detectable disease or symptom of a disease prior to the treatment methods described herein. "At-risk" indicates that the individual has one or more risk factors that are measurable parameters that correlate with the development of a particular disease, disorder, or medical condition, as are known in the art. An individual having one or more of these risk factors is more likely to develop a particular disease, disorder, or medical condition than an individual not having one or more of these risk factors.

[0102] "Chronic" administration refers to the administration of a drug(s) continuously, as opposed to an acute mode, in order to maintain an initial therapeutic effect (activity) over a long period of time. "Intermittent" administration refers to a treatment that is not administered continuously without interruption, but rather is inherently cyclic / periodic.

[0103] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, but the preferred methods and materials are described herein. All publications mentioned herein are incorporated herein by reference to describe and disclose, for example, the methods and / or materials cited in the publications, such as Sambrook et al., Molecular Cloning: A Laboratory Manual 3d edition (2001) Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y.; Current Protocols in Molecular Biology (F.M. Ausubel, et al. eds., (2003)); the series Methods in Enzymology (Academic Press, Inc.): PCR 2: A Practical Approach (M.J. MacPherson, B.D. Hames and G.R. Taylor eds. (1995)), Harlow and Lane, eds. (1988) Antibodies, A Laboratory Manual, and Animal Cell Culture (R.I. Freshney, ed. (1987)); Oligonucleotide Synthesis (M.J. Gait, ed., 1984); Methods in Molecular Biology, Humana Press; Cell Biology: A Laboratory Notebook (J.E. Cellis, ed., 1998) Academic Press; Animal Cell Culture (R.I. Freshney), ed., 1987); Introduction to Cell and Tissue Culture (J.P. Mather and P.E.R. Roberts, 1998) Plenum Press; Cell and Tissue Culture: Laboratory Procedures (A. Doyle, J.B. Griffiths, and D.G.Disclosed and described are widely used methodologies described in, for example, Newell, eds., 1993 - 8) J. Wiley and Sons; Handbook of Experimental Immunology (D.M. Weir and C.C. Blackwell, eds.); Gene Transfer Vectors for Mammalian Cells (J.M. Miller and M.P. Calos, eds., 1987); PCR: The Polymerase Chain Reaction, (Mullis et al., eds., 1994); Current Protocols in Immunology (J.E. Coligan et al., eds., 1991); Short Protocols in Molecular Biology (Wiley and Sons, 1999); Immunobiology (C.A. Janeway and P. Travers, 1997); Antibodies (P. Finch, 1997); Antibodies: A Practical Approach (D. Catty., ed., IRL Press, 1988 - 1989); Monoclonal Antibodies: A Practical Approach (P. Shepherd and C. Dean, eds., Oxford University Press, 2000); Using Antibodies: A Laboratory Manual (E. Harlow and D. Lane (Cold Spring Harbor Laboratory Press, 1999); The Antibodies (M. Zanetti and J.D. Capra, eds., Harwood Academic Publishers, 1995); and Cancer: Principles and Practice of Oncology (V.T. DeVita et al., eds., J.B. Lippincott Company, 1993).

[0104] C1q inhibitor Inhibitors of the classical complement pathway may be C1q inhibitors, such as small molecules, antibodies, aptamers, antisense nucleic acids, or gene editing agents.

[0105] The anti-C1q antibodies disclosed herein are potent inhibitors of C1q.

[0106] C1q is a 460 kDa large multimeric protein consisting of 18 polypeptide chains (6 C1q A chains, 6 C1q B chains, and 6 C1q C chains). C1r and C1s complement proteins bind to the C1q tail region to form the C1 complex (C1qr 2 s 2 ).

[0107] Suitable inhibitors include complement factor C1q in the C1 complex of the classical complement activation pathway and / or antibodies that bind to C1q. The bound complement factor can be derived from any organism having a complement system, including, but not limited to, any mammalian organism, such as human, mouse, rat, rabbit, monkey, dog, cat, cow, horse, camel, sheep, goat, or pig.

[0108] As used herein, "C1 complex" refers to a protein complex (e.g., C1qr 2 s 2 ) that can include, but is not limited to, one C1q protein, two C1r proteins, and two C1s proteins.

[0109] As used herein, "complement factor C1q" refers to both wild-type sequences and naturally occurring variant sequences.

[0110] Non-limiting examples of complement factor C1q recognized by the antibodies of the present disclosure are human C1q containing the three polypeptide chains A, B, and C: C1q, chain A (Homo sapiens), accession number protein database: NP_057075.1; GenBank number: NM_015991: >gi|7705753|ref|NP_057075.1|Complement C1q Subcomponent subunit A precursor [Homo sapiens] (SEQ ID NO: 1) MEGPRGWLVLCVLAISLASMVTEDLCRAPDGKKGEAGRPGRRGRPGLKGEQGEPGAPGIRTGIQGLKGDQGEPGPSGNPGKVGYPGPSGPLGARGIPGIKGTKGSPGNIKDQPRPAFSAIRRNPPMGGNVVIFDTVITNQEEPYQNHSGRFVCTVPGYYYFTFQVLSQWEICLSIVSSSRGQVRRSLGFCDTTNKGLFQVVSGGMVLQLQQGDQVWVEKDPKKGHIYQGSEADSVFSGFLIFPSA。

[0111] C1q, chain B (Homo sapiens), accession number protein Database: NP_000482.3; GenBank number: NM_000491.3: >gi|87298828|ref|NP_000482.3|Complement Clq Subcomponent subunit B precursor [Homo sapiens] (SEQ ID NO: 52) MMMKIPWGSIPVLMLLLLLGLIDISQAQLSCTGPPAIPGIPGIPGTPGPDGQPGTPGIKGEKGLPGLAGDHGEFGEKGDPGIPGNPGKVGPKGPMGPKGGPGAPGAPGPKGESGDYKATQKIAFSATRTINVPLRRDQTIRFDHVITNMNNNYEPRSGKFTCKVPGLYYFTYHASSRGNLCVNLMRGRERAQKVVTFCDYAYNTFQVTTGGMVLKLEQGENVFLQATDKNSLLGMEGANSIFSGFLLFPDMEA。

[0112] C1q, chain C (Homo sapiens), accession number protein Database: NP_001107573.1; GenBank number: NM_001114101.1: >gi|166235903|ref|NP_001107573.1|Complement C1q Subcomponent subunit C precursor [Homo sapiens] (SEQ ID NO: 53) MDVGPSSLPHLGLKLLLLLLLLPLRGQANTGCYGIPGMPGLPGAPGKDGYDGLPGPKGEPGIPAIPGIRGPKGQKGEPGLPGHPGKNGPMGPPGMPGVPGPMGIPGEPGEEGRYKQKFQSVFTVTRQTHQPPAPNSLIRFNAVLTNPQGDYDTSTGKFTCKVPGLYYFVYHASHTANLCVLLYRSGVKVVTFCGHTSKTNQVNSGGVLLRLQVGEEVWLAVNDYYDMVGIQGSDSVFSGFLLFPD。

[0113] Accordingly, the anti-C1q antibodies of the present disclosure can bind to polypeptide chain A, polypeptide chain B, and / or polypeptide chain C of the C1q protein. In some embodiments, the anti-C1q antibodies of the present disclosure bind to polypeptide chain A, polypeptide chain B, and / or polypeptide chain C of human C1q or a homolog thereof, such as mouse, rat, rabbit, monkey, dog, cat, cow, horse, camel, sheep, goat, or pig C1q. In some embodiments, the anti-C1q antibody is a human antibody, a humanized antibody, or a chimeric antibody.

[0114] Other anti-C1q antibodies suitable for binding to C1q protein are well known in the art and include, for example, antibody catalog numbers: AF2379, AF1696, MAB1696, and MAB23791 (R&D System), NBP1-87492, NB100-64420, H00000712-B01P, H00000712-D01P, and H00000712-D01 (Novus Biologicals), MA1-83963, MA1-40311, PA5-14208, PA5-29586, and PA1-36177 (ThermoFisher Scientific), ab71940, ab11861, ab4223, ab72355, ab182451, ab46191, ab227072, ab182940, ab216979, and ab235454 (abcam), etc. Further, multiple siRNAs, shRNAs, CRISPR constructs for reducing C1q expression, for example, SiRNA products #sc-43651, sc-44962, sc-105153, sc-141842, ShRNA products #sc-43651-SH, sc-43651-V, sc-44962-SH, sc-44962-V, sc-105153-SH, sc-105153-V, sc-141842-SH, sc-141842-V, CRISPR products #sc-419385, sc-419385-HDR, sc-419385-NIC, sc-419385-NIC-2, sc-402156, sc-402156-KO-2, sc-404309, sc-404309-HDR, sc-404309-NIC, sc-404309-NIC-2, sc-419386, sc-419386-HDR, sc-419386-NIC, sc-419386-NIC-2 (Santa Cruz Biotechnology, etc.) can be found in the commercial product lists of the companies referenced above.

[0115] Light chain and heavy chain hypervariable region sequences and variable domain sequences of antibody M1 (Mab1) (incorporated by reference from U.S. Patent No. 9,708,394) Using standard techniques, the nucleic acid and amino acid sequences encoding the light chain variable domain and heavy chain variable domain of antibody M1 were determined. The amino acid sequence of the light chain variable domain of antibody M1 is as follows:

[0116] TIFF2025516671000002.tif14167

[0117] The hypervariable regions (HVRs) of the light chain variable domain are indicated by bold and underlined characters. In some embodiments, HVR-L1 of the M1 light chain variable domain has the sequence RASKSINKYLA (SEQ ID NO: 5), HVR-L2 of the M1 light chain variable domain has the sequence SGSTLQS (SEQ ID NO: 6), and HVR-L3 of the M1 light chain variable domain has the sequence QQHNEYPLT (SEQ ID NO: 7).

[0118] The amino acid sequence of the heavy chain variable domain of antibody M1 is as follows:

[0119] TIFF2025516671000003.tif14167

[0120] The hypervariable regions (HVRs) of the heavy chain variable domain are indicated by bold and underlined characters. In some embodiments, HVR-H1 of the M1 heavy chain variable domain has the sequence GYHFTSYWMH (SEQ ID NO: 9), HVR-H2 of the M1 heavy chain variable domain has the sequence VIHPNSGSINYNEKFES (SEQ ID NO: 10), and HVR-H3 of the M1 heavy chain variable domain has the sequence ERDSTEVLPMDY (SEQ ID NO: 11).

[0121] The nucleic acid sequence encoding the light chain variable domain was determined to be as follows: GATGTCCAGATAACCCAGTCTCCATCTTATCTTGCTGCATCTCCTGGAGAAACCATTACTATTAATTGCAGGGCAAGTAAGAGCATTAACAAATATTTAGCCTGGTATCAAGAGAAACCTGGGAAAACTAATAAGCTTCTTATCTACTCTGGATCCACTTTGCAATCTGGAATTCCATCAAGGTTCAGTGGCAGTGGATCTGGTACAGATTTCACTCTCACCATCAGTAGCCTGGAGCCTGAAGATTTTGCAATGTATTACTGTCAACAACATAATGAATACCCGCTCACGTTCGGTGCTGGGACCAAGCTGGAGCTGAAA (SEQ ID NO: 12).

[0122] The nucleic acid sequence encoding the heavy chain variable domain was determined to be as follows: CAGGTCCAACTGCAGCAGCCTGGGGCTGAGCTGGTAAAGCCTGGGGCTTCAGTGAAGTTGTCCTGCAAGTCTTCTGGCTACCATTTCACCAGCTACTGGATGCACTGGGTGAAGCAGAGGCCTGGACAAGGCCTTGAGTGGATTGGAGTGATTCATCCTAATAGTGGTAGTATTAACTACAATGAGAAGTTCGAGAGCAAGGCCACACTGACTGTAGACAAATCCTCCAGCACAGCCTACATGCAACTCAGCAGCCTGACATCTGAGGACTCGGCGGTCTATTATTGTGCAGGAGAGAGAGATTCTACGGAGGTTCTCCCTATGGACTACTGGGGTCAAGGAACCTCAGTCACCGTCTCCTCA (SEQ ID NO: 13).

[0123] Mab1-Fab is the Fab of the Mab1 (M1) antibody.

[0124] Mab3 is a mouse anti-C1q antibody derived from the Mab1 antibody and optimized for mouse experiments.

[0125] Deposit of the substance The following substances have been deposited with the American Type Culture Collection, ATCC Patent Depository, 10801 University Blvd., Manassas, Va. 20110-2209, USA (ATCC) in accordance with the Budapest Treaty. [Table 2]

[0126] A hybridoma cell line (mouse hybridoma C1qM1 7788--1(M)051613) that produces the M1 antibody has been deposited with the ATCC, subject to the condition that access to the culture will be available during the pendency of the patent application and for 30 years, or until five years after the most recent claim, or for the longer of the term of the patent. The deposit will be replaced if it becomes non-viable during that period. The deposit will be available as required by foreign patent laws in countries in which corresponding applications or their progeny are filed. However, it should be understood that the availability of the deposit does not constitute a license to practice the invention outside the scope of the patent rights granted by government action.

[0127] Disclosed herein is a method of administering an anti-C1q antibody comprising a light chain variable domain and a heavy chain variable domain. The antibody can bind to at least human C1q, mouse C1q, or rat C1q. The antibody can be a humanized antibody, a chimeric antibody, or a human antibody. The antibody can be a monoclonal antibody, an antibody fragment thereof, and / or an antibody derivative thereof. The light chain variable domain comprises HVR-L1, HVR-L2, and HVR-L3 of monoclonal antibody M1 produced by a hybridoma cell line deposited under accession number PTA-120399. The heavy chain variable domain comprises HVR-H1, HVR-H2, and HVR-H3 of monoclonal antibody M1 produced by a hybridoma cell line deposited under ATCC accession number PTA-120399.

[0128] In some embodiments, the amino acid sequences of the light chain variable domain and the heavy chain variable domain include one or more of SEQ ID NO: 5 for HVR-L1, SEQ ID NO: 6 for HVR-L2, SEQ ID NO: 7 for HVR-L3, SEQ ID NO: 9 for HVR-H1, SEQ ID NO: 10 for HVR-H2, and SEQ ID NO: 11 for HVR-H3.

[0129] The antibody may preferably contain a light chain variable domain amino acid sequence that is at least 85%, 90%, or 95% identical to SEQ ID NO: 4 while retaining HVR-L1 RASKSINKYLA (SEQ ID NO: 5), HVR-L2 SGSTLQS (SEQ ID NO: 6), and HVR-L3 QQHNEYPLT (SEQ ID NO: 7). The antibody may preferably contain a heavy chain variable domain amino acid sequence that is at least 85%, 90%, or 95% identical to SEQ ID NO: 8 while retaining HVR-H1 GYHFTSYWMH (SEQ ID NO: 9), HVR-H2 VIHPNSGSINYNEKFES (SEQ ID NO: 10), and HVR-H3 ERDSTEVLPMDY (SEQ ID NO: 11).

[0130] Disclosed herein is a method of administering an anti-C1q antibody that inhibits the interaction between C1q and autoantibodies. In preferred embodiments, the anti-C1q antibody causes clearance of C1q from circulation or tissue.

[0131] In some embodiments, the anti-C1q antibodies of the present disclosure inhibit the interaction between C1q and C1s. In some embodiments, the anti-C1q antibodies inhibit the interaction between C1q and C1r. In some embodiments, the anti-C1q antibodies inhibit the interactions between C1q and C1s and between C1q and C1r. In some embodiments, the anti-C1q antibodies inhibit the interaction between C1q and another antibody, such as an autoantibody. In preferred embodiments, the anti-C1q antibodies cause clearance of C1q from the circulation or tissue. In some embodiments, the anti-C1q antibodies inhibit each interaction with a stoichiometry of less than 2.5:1, 2.0:1, 1.5:1, or 1.0:1. In some embodiments, the C1q antibodies inhibit interactions such as the C1q-C1s interaction with C1q and anti-C1q antibodies at approximately equimolar concentrations. In other embodiments, the anti-C1q antibodies bind to C1q with a stoichiometry of less than 20:1, less than 19.5:1, less than 19:1, less than 18.5:1, less than 18:1, less than 17.5:1, less than 17:1, less than 16.5:1, less than 16:1, less than 15.5:1, less than 15:1, less than 14.5:1, less than 14:1, less than 13.5:1, less than 13:1, less than 12.5:1, less than 12:1, less than 11.5:1, less than 11:1, less than 10.5:1, less than 10:1, less than 9.5:1, less than 9:1, less than 8.5:1, less than 8:1, less than 7.5:1, less than 7:1, less than 6.5:1, less than 6:1, less than 5.5:1, less than 5:1, less than 4.5:1, less than 4:1, less than 3.5:1, less than 3:1, less than 2.5:1, less than 2.0:1, less than 1.5:1, or less than 1.0:1. In certain embodiments, the anti-C1q antibodies bind to C1q with a binding stoichiometry in the range of 20:1 to 1.0:1 or less than 1.0:1. In certain embodiments, the anti-C1q antibodies bind to C1q with a binding stoichiometry in the range of 6:1 to 1.0:1 or less than 1.0:1. In certain embodiments, the anti-C1q antibodies bind to C1q with a binding stoichiometry in the range of 2.5:1 to 1.0:1 or less than 1.0:1. In some embodiments, the anti-C1q antibodies inhibit the interaction between C1q and C1r, or between C1q and C1s, or between C1q and both C1r and C1s.In some embodiments, the anti-C1q antibody inhibits the interaction between C1q and C1r, between C1q and C1s, and / or between C1q and both C1r and C1s. In some embodiments, the anti-C1q antibody binds to the A chain of C1q. In other embodiments, the anti-C1q antibody binds to the B chain of C1q. In other embodiments, the anti-C1q antibody binds to the C chain of C1q. In some embodiments, the anti-C1q antibody binds to the A chain, the B chain, and / or the C chain of C1q. In some embodiments, the anti-C1q antibody binds to the globular domain of the A chain, B chain, and / or C chain of C1q. In other embodiments, the anti-C1q antibody binds to the collagen-like domain of the A chain, B chain, and / or C chain of C1q.

[0132] When the antibodies of the present disclosure inhibit the interaction between two or more complement factors, for example, the interaction between C1q and C1s, or the interaction between C1q and C1r, the interaction that occurs in the presence of the antibody may be at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 99% reduced compared to a control in the absence of the antibody of the present disclosure. In certain embodiments, the interaction that occurs in the presence of the antibody is reduced by an amount in the range of at least 30% to at least 99% compared to a control in the absence of the antibody of the present disclosure.

[0133] In some embodiments, the antibody of the present disclosure inhibits C2 or C4 cleavage by at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 99%, or by an amount in the range of at least 30% to at least 99%, compared to a control in the absence of the antibody of the present disclosure. Methods for measuring C2 or C4 cleavage are well known in the art. The EC of the antibody of the present disclosure with respect to C2 or C4 cleavage 50The value may be less than 3 μg / ml, 2.5 μg / ml, 2.0 μg / ml, 1.5 μg / ml, 1.0 μg / ml, 0.5 μg / ml, 0.25 μg / ml, 0.1 μg / ml, 0.05 μg / ml. In some embodiments, the antibody of the present disclosure inhibits C2 or C4 cleavage with approximately equimolar concentrations of C1q and each anti-C1q antibody.

[0134] In some embodiments, the antibody of the present disclosure inhibits antibody-dependent and complement-dependent cytotoxicity (CDC) by at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 99%, or in the range of at least 30% to at least 99% compared to a control in the absence of the antibody of the present disclosure. The EC of the antibody of the present disclosure with respect to the inhibition of antibody-dependent and complement-dependent cytotoxicity 50 The value can be less than 3 μg / ml, 2.5 μg / ml, 2.0 μg / ml, 1.5 μg / ml, 1.0 μg / ml, 0.5 μg / ml, 0.25 μg / ml, 0.1 μg / ml, 0.05 μg / ml.

[0135] In some embodiments, the antibody of the present disclosure inhibits complement-dependent cell-mediated cytotoxicity (CDCC) by at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 99%, or in the range of at least 30% to at least 99% compared to a control in the absence of the antibody of the present disclosure. Methods for measuring CDCC are well known in the art. The EC of the antibody of the present disclosure with respect to CDCC inhibition 50 The value may be less than 3 μg / ml, 2.5 μg / ml, 2.0 μg / ml, 1.5 μg / ml, 1.0 μg / ml, 0.5 μg / ml, 0.25 μg / ml, 0.1 μg / ml, 0.05 μg / ml. In some embodiments, the antibody of the present disclosure inhibits CDCC but does not inhibit antibody-dependent cell-mediated cytotoxicity (ADCC).

[0136] Humanized anti-complement C1q antibody (incorporated by reference from U.S. Patent No. 10,316,081) The humanized antibodies of the present disclosure specifically bind to complement factor C1q and / or C1q protein in the C1 complex of the classical complement pathway. The humanized anti-C1q antibodies can specifically bind to human C1q, human and mouse C1q, rat C1q, or human C1q, mouse C1q, and rat C1q.

[0137] In some embodiments, the human heavy chain constant region is a human IgG4 heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 47, or an amino acid sequence having at least 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90% homology with SEQ ID NO: 47. The human IgG4 heavy chain constant region may comprise an Fc region having one or more modifications and / or amino acid substitutions according to Kabat numbering. In such cases, the Fc region comprises an amino acid substitution from leucine to glutamate at position 248 (corresponding to the L115E mutation in IgG4), such substitution inhibiting the interaction of the Fc region with Fc receptors. In some embodiments, the Fc region comprises an amino acid substitution from serine to proline at position 241 (corresponding to S108P in IgG4), such substitution preventing arm switching in the antibody.

[0138] The amino acid sequence of the human IgG4 (S241P L248E; corresponding to S108P and L115E of SEQ ID NO: 47) heavy chain constant domain is as follows: ASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTKTYTCNVDHKPSNTKVDKRVESKYGPPCPPCPAPEFEGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK (SEQ ID NO: 47).

[0139] The antibody may comprise a heavy chain variable domain and a light chain variable domain, and the heavy chain variable domain comprises an amino acid sequence selected from any one of SEQ ID NOs: 31 to 34, or an amino acid sequence having at least about 90% homology with an amino acid sequence selected from any one of SEQ ID NOs: 31 to 34. In certain such embodiments, the light chain variable domain comprises an amino acid sequence selected from any one of SEQ ID NOs: 35 to 38, or an amino acid sequence having at least about 90% homology with an amino acid sequence selected from any one of SEQ ID NOs: 35 to 38.

[0140] The amino acid sequence of the heavy chain variable domain variant 1 (VH1) is

[0141] TIFF2025516671000005.tif14167. The hypervariable regions (HVRs) of VH1 are indicated by bold and underlined characters.

[0142] The amino acid sequence of the heavy chain variable domain variant 2 (VH2) is

[0143] TIFF2025516671000006.tif is 14167. The hypervariable region (HVR) of VH2 is indicated by bold and underlined characters.

[0144] The amino acid sequence of variable heavy domain variant 3 (VH3) is,

[0145] TIFF2025516671000007.tif is 14167. The hypervariable region (HVR) of VH3 is indicated by bold and underlined characters.

[0146] The amino acid sequence of variable heavy domain variant 4 (VH4) is,

[0147] TIFF2025516671000008.tif is 14168. The hypervariable region (HVR) of VH4 is indicated by bold and underlined characters.

[0148] The amino acid sequence of variable kappa light domain variant 1 (Vκ1) is,

[0149] TIFF2025516671000009.tif is 14167. The hypervariable region (HVR) of Vκ1 is indicated by bold and underlined characters.

[0150] The amino acid sequence of variable kappa light domain variant 2 (Vκ2) is,

[0151] TIFF2025516671000010.tif is 14167. The hypervariable region (HVR) of Vκ2 is indicated by bold and underlined characters.

[0152] The amino acid sequence of variable kappa light domain variant 3 (Vκ3) is,

[0153] TIFF2025516671000011.tif is 14167. The hypervariable region (HVR) of Vκ3 is indicated by bold and underlined characters.

[0154] The amino acid sequence of kappa light chain variable domain variant 4 (Vκ4) is

[0155] TIFF2025516671000012.tif14167. The hypervariable regions (HVRs) of Vκ4 are indicated by bold and underlined characters.

[0156] The antibody may contain a light chain variable domain amino acid sequence that is at least 85%, 90%, or 95% identical to SEQ ID NOs: 35 - 38 while retaining HVR-L1 RASKSINKYLA (SEQ ID NO: 5), HVR-L2 SGSTLQS (SEQ ID NO: 6), and HVR-L3 QQHNEYPLT (SEQ ID NO: 7). The antibody preferably contains a heavy chain variable domain amino acid sequence that is at least 85%, 90%, or 95% identical to SEQ ID NOs: 31 - 34 while retaining HVR-H1 GYHFTSYWMH (SEQ ID NO: 9), HVR-H2 VIHPNSGSINYNEKFES (SEQ ID NO: 10), and HVR-H3 ERDSTEVLPMDY (SEQ ID NO: 11).

[0157] In some embodiments, the antibody contains the light chain variable domain amino acid sequence of SEQ ID NO: 35 and the heavy chain variable domain amino acid sequence of SEQ ID NO: 31. In some embodiments, the antibody contains the light chain variable domain amino acid sequence of SEQ ID NO: 36 and the heavy chain variable domain amino acid sequence of SEQ ID NO: 32. In some embodiments, the antibody contains the light chain variable domain amino acid sequence of SEQ ID NO: 37 and the heavy chain variable domain amino acid sequence of SEQ ID NO: 33. In some embodiments, the antibody contains the light chain variable domain amino acid sequence of SEQ ID NO: 38 and the heavy chain variable domain amino acid sequence of SEQ ID NO: 34.

[0158] The full-length antibody Mab2 contains heavy chain variable domain variant 3 (VH3) (SEQ ID NO: 33) and kappa light chain variable domain variant 3 (Vκ3) (SEQ ID NO: 37). Mab2-Fab is the Fab of the Mab2 antibody.

[0159] The antibody may contain a heavy chain and a light chain, the heavy chain contains the amino acid sequence of SEQ ID NO: 14, and the light chain contains the amino acid sequence of SEQ ID NO: 40.

[0160] The amino acid sequence of the heavy chain is

[0161] TIFF2025516671000013.tif43168. The hypervariable region (HVR) of VH3 is indicated by bold and underlined characters.

[0162] The amino acid sequence of the light chain is as follows.

[0163] TIFF2025516671000014.tif25168

[0164] The complementarity-determining region (CDR) of SEQ ID NO: 40 is indicated by bold and underlined characters.

[0165] In some embodiments, the humanized anti-C1q antibody of the present disclosure comprises a heavy chain variable region containing a Fab region and a heavy chain constant region containing an Fc region, wherein the Fab region specifically binds to the C1q protein of the present disclosure, but the Fc region is incapable of binding to the C1q protein. In some embodiments, the Fc region is derived from a human IgG1, IgG2, IgG3, or IgG4 isotype. In some embodiments, the Fc region is incapable of inducing complement activity and / or incapable of inducing antibody-dependent cell cytotoxicity (ADCC). In some embodiments, the Fc region comprises one or more modifications including, but not limited to, amino acid substitutions. In certain embodiments, the Fc region of the humanized anti-C1q antibody of the present disclosure comprises an amino acid substitution at position 248 according to the Kabat numbering convention or at a position corresponding to position 248 according to the Kabat numbering convention, and / or at position 241 according to the Kabat numbering convention or at a position corresponding to position 241 according to the Kabat numbering convention. In some embodiments, the amino acid substitution at position 248 or at a position corresponding to position 248 inhibits the interaction of the Fc region with the Fc receptor. In some embodiments, the amino acid substitution at position 248 or at a position corresponding to position 248 is an amino acid substitution from leucine to glutamate. In some embodiments, the amino acid substitution at position 241 or at a position corresponding to position 241 prevents arm switching in the antibody. In some embodiments, the amino acid substitution at position 241 or at a position corresponding to position 241 is an amino acid substitution from serine to proline. In certain embodiments, the Fc region of the humanized anti-C1q antibody of the present disclosure comprises the amino acid sequence of SEQ ID NO: 47, or an amino acid sequence having at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, or at least about 95% homology with the amino acid sequence of SEQ ID NO: 47.

[0166] Anti-C1q Fab fragment (e.g., FabA) All anti-C1q antibody Fab fragment sequences are incorporated by reference from U.S. Patent No. 10,723,788 (which is incorporated herein by reference for the antibodies and related compositions disclosed therein).

[0167] In certain embodiments, the present disclosure provides an anti-C1q antibody Fab fragment that binds to a C1q protein comprising a heavy chain (V H / C H 1) and a light chain (V L / C L ), wherein the anti-C1q antibody Fab fragment has six complementarity determining regions (CDRs) (three each derived from V L and V H ) (HCDR1, HCDR2, HCDR3, and LCDR1, LCDR2, LCDR3). The heavy chain of the antibody Fab fragment is cleaved after the first heavy chain domain of IgG1 (SEQ ID NO: 39) and comprises the following amino acid sequence.

[0168] TIFF2025516671000015.tif25168

[0169] The complementarity determining regions (CDRs) of SEQ ID NO: 39 are indicated by bold and underlined letters.

[0170] The light chain domain of the antibody Fab fragment comprises the following amino acid sequence (SEQ ID NO: 40).

[0171] TIFF2025516671000016.tif25168

[0172] The complementarity determining regions (CDRs) of SEQ ID NO: 40 are indicated by bold and underlined letters.

[0173] FabA is an anti-C1q antibody Fab fragment comprising a heavy chain domain comprising SEQ ID NO: 39 and a light chain domain comprising SEQ ID NO: 40.

[0174] Mab1-Fab is the Fab of the Mab1 (M1) antibody.

[0175] Mab2-Fab is the Fab of the Mab2 antibody.

[0176] Mab3-Fab is the Fab of the Mab3 antibody.

[0177] Anti-C1q single-arm antibody All anti-C1q single-arm antibody sequences are disclosed in U.S. Patent Application No. 63 / 288,883 and U.S. Patent Application No. 63 / 288,885, which are hereby incorporated by reference herein for the antibodies and related compositions they disclose.

[0178] In certain embodiments, the present disclosure provides antibodies that bind to proteins in the complement cascade, such as the C1q protein. The antibody that binds to C1q comprises a single C1q antigen-binding arm and an Fc region. The single C1q antigen-binding arm may comprise a light chain variable domain and a heavy chain variable domain. The Fc region may comprise a complex of a first and a second Fc polypeptide. The Fc region may comprise an Fcγ receptor binding site mutation. The antibody may be of the IgG4 class. In some embodiments, one of the Fc polypeptides is a truncated heavy chain at the N-terminus, but not both. In some embodiments, the Fcγ receptor is FcγRI, FcγRII, or FcγRIII, preferably FcγRI. The Fcγ receptor binding site mutation may comprise the IgG4 L115E mutation.

[0179] TIFF2025516671000017.tif25168

[0180] The complementarity-determining regions (CDRs) of SEQ ID NO: 40 are indicated by bold and underlined letters. In some embodiments, HVR-L1 of the light chain variable domain has the sequence RASKSINKYLA (SEQ ID NO: 5), HVR-L2 of the light chain variable domain has the sequence SGSTLQS (SEQ ID NO: 6), and HVR-L3 of the light chain variable domain has the sequence QQHNEYPLT (SEQ ID NO: 7).

[0181] The light chain of the single-arm antibody may comprise the following light chain variable domain amino acid sequence:

[0182] TIFF2025516671000018.tif15167

[0183] The single-arm antibody may preferably contain the light-chain variable domain amino acid sequence that is at least 85%, 90%, or 95% identical to SEQ ID NO: 10 while retaining HVR-L1 RASKSINKYLA (SEQ ID NO: 5), HVR-L2 SGSTLQS (SEQ ID NO: 6), and HVR-L3 QQHNEYPLT (SEQ ID NO: 7).

[0184] The single-arm antibody may contain the following amino acid sequence of kappa light-chain variable domain variant 1 (Vκ1):

[0185] TIFF2025516671000019.tif14168The hypervariable regions (HVRs) of Vκ1 are indicated by bold and underlined characters.

[0186] The single-arm antibody may contain the following amino acid sequence of kappa light-chain variable domain variant 2 (Vκ2):

[0187] TIFF2025516671000020.tif14167The hypervariable regions (HVRs) of Vκ2 are indicated by bold and underlined characters.

[0188] The single-arm antibody may contain the following amino acid sequence of kappa light-chain variable domain variant 3 (Vκ3):

[0189] TIFF2025516671000021.tif14167The hypervariable regions (HVRs) of Vκ3 are indicated by bold and underlined characters.

[0190] The single-arm antibody may contain the following amino acid sequence of kappa light-chain variable domain variant 4 (Vκ4):

[0191] TIFF2025516671000022.tif14167The hypervariable regions (HVRs) of Vκ4 are indicated by bold and underlined characters.

[0192] The single-arm antibody may contain a light-chain variable domain amino acid sequence that is at least 85%, 90%, or 95% identical to SEQ ID NOs: 11-14 while retaining HVR-L1 RASKSINKYLA (SEQ ID NO: 5), HVR-L2 SGSTLQS (SEQ ID NO: 6), and HVR-L3 QQHNEYPLT (SEQ ID NO: 7).

[0193] The antibody can be of the IgG4 class. The sequence of the IgG4 heavy chain is as follows.

[0194] TIFF2025516671000023.tif38166

[0195] The domains of IgG4 are as follows: CH1: 1-98, hinge: 99-110, CH2: 111-220, and CH3: 221-327. IgG4 can contain mutations. For example, S108P mutation (for IgG4 arm exchange), L115E mutation (for FcR binding), T246W mutation (for knob-in-hole mutation), T246S mutation (for knob-in-hole mutation), L248A mutation (for knob-in-hole mutation), Y187V mutation (for knob-in-hole mutation), and / or N187A (aglycosylation for FcR binding), N187Q (aglycosylation for FcR binding), or N187G (aglycosylation for FcR binding).

[0196] One heavy chain (heavy chain 1 domain) of the single-arm antibody of the single-arm antibody may contain the following amino acid sequence (SEQ ID NO: 2).

[0197] TIFF2025516671000024.tif43168

[0198] The complementarity-determining regions (CDRs) of SEQ ID NO: 2 are indicated by bold and underlined text. The knob-in-hole T366W mutation of SEQ ID NO: 2 (corresponding to the IgG4 T246W mutation) is indicated by underlined text. The S241P (corresponding to S108P in the case of IgG4 arm swapping) and L248E (corresponding to the L115E mutation in the case of FcR) mutations are represented in bold. In some embodiments, HVR-H1 of the heavy chain variable domain has the sequence GYHFTSYWMH (SEQ ID NO: 9), HVR-H2 of the heavy chain variable domain has the sequence VIHPNSGSINYNEKFES (SEQ ID NO: 10), and HVR-H3 of the heavy chain variable domain has the sequence ERDSTEVLPMDY (SEQ ID NO: 11).

[0199] One heavy chain (heavy chain 1 domain) of a single-arm antibody of the single-arm antibody may comprise the following amino acid sequence (SEQ ID NO: 20).

[0200] TIFF2025516671000025.tif43168

[0201] The complementarity-determining regions (CDRs) of SEQ ID NO: 20 are indicated by bold and underlined text. The knob-in-hole T366W mutation of SEQ ID NO: 20 (corresponding to the IgG4 T246W mutation) is indicated by underlined text. The S241P (corresponding to S108P in the case of IgG4 arm swapping) and L248E (corresponding to the L115E mutation) mutations are represented in bold.

[0202] The antibody can be of the IgG1 class. The sequence of the IgG1 heavy chain is as follows.

[0203] TIFF2025516671000026.tif38165

[0204] The domains of IgG1 are as follows: CH1: 1-98, hinge: 99-110, CH2: 111-223, and CH3: 224-330. IgG1 may contain mutations. For example, L117A mutation (for FcR binding), L118A mutation (for FcR binding), T249W mutation (for knob-in-hole mutation), T249S mutation (for knob-in-hole mutation), L251A mutation (for knob-in-hole mutation), and / or Y290V mutation (for knob-in-hole mutation).

[0205] One heavy chain (heavy chain 1 domain) of a single-arm antibody may contain the following amino acid sequence (SEQ ID NO: 21).

[0206] TIFF2025516671000027.tif43167

[0207] The complementarity-determining regions (CDRs) of SEQ ID NO: 21 are indicated by bold and underlined characters. The knob-in-hole T366W mutation of SEQ ID NO: 21 (corresponding to the IgG1 T249W mutation) is indicated by underlined text. The L234A (corresponding to the IgG1 L117A mutation) and L235A (corresponding to the IgG1 L1178 mutation) mutations are indicated by bold characters.

[0208] Heavy chain 1 of a single-arm antibody may contain the following heavy chain variable domain amino acid sequence:

[0209] TIFF2025516671000028.tif14168

[0210] The single-arm antibody may preferably contain a heavy chain variable domain amino acid sequence that is at least 85%, 90%, or 95% identical to SEQ ID NO: 15 while retaining HVR-H1 GYHFTSYWMH (SEQ ID NO: 9), HVR-H2 VIHPNSGSINYNEKFES (SEQ ID NO: 10), and HVR-H3 ERDSTEVLPMDY (SEQ ID NO: 11).

[0211] The single-arm antibody has the following amino acid sequence of heavy chain variable domain variant 1 (VH1):

[0212] It may include TIFF2025516671000029.tif14168. The hypervariable region (HVR) of VH1 is indicated by bold and underlined characters.

[0213] The single-arm antibody may have the following amino acid sequence of variable heavy-chain domain variant 2 (VH2):

[0214] It may include TIFF2025516671000030.tif14168. The hypervariable region (HVR) of VH2 is indicated by bold and underlined characters.

[0215] The single-arm antibody may have the following amino acid sequence of variable heavy-chain domain variant 3 (VH3):

[0216] It may include TIFF2025516671000031.tif14167. The hypervariable region (HVR) of VH3 is indicated by bold and underlined characters.

[0217] The single-arm antibody may have the following amino acid sequence of variable heavy-chain domain variant 4 (VH4):

[0218] It may include TIFF2025516671000032.tif14167. The hypervariable region (HVR) of VH4 is indicated by bold and underlined characters.

[0219] The single-arm antibody may retain HVR-H1 GYHFTSYWMH (SEQ ID NO: 9), HVR-H2 VIHPNSGSINYNEKFES (SEQ ID NO: 10), and HVR-H3 ERDSTEVLPMDY (SEQ ID NO: 11), and may include a variable heavy-chain domain amino acid sequence that is at least 85%, 90%, or 95% identical to SEQ ID NOs: 16-19.

[0220] The second heavy chain (heavy-chain 2 domain) of the single-arm antibody with an N-terminal truncation may include the following amino acid sequence (SEQ ID NO: 3).

[0221] TIFF2025516671000033.tif24167

[0222] There are no heavy chain variable domains and CDRs in Sequence No. 3. The knob-in-hole T366S / L368A / Y407V mutation in Sequence No. 3 is indicated by the underlined text. The S241P and L248E mutations are shown in bold.

[0223] The second heavy chain (heavy chain 2 domain) of the single-arm antibody with an N-terminally truncated single-arm antibody may contain the following amino acid sequence (Sequence No. 42).

[0224] TIFF2025516671000034.tif25168

[0225] The second heavy chain (heavy chain 2 domain) of the single-arm antibody with an N-terminally truncated single-arm antibody may contain the following amino acid sequence (Sequence No. 43).

[0226] TIFF2025516671000035.tif25168

[0227] There are no heavy chain variable domains and CDRs in Sequence No. 43. The knob-in-hole T366S / L368A / Y407V mutation in Sequence No. 43 is indicated by underlined text. The L234A and L235A mutations are shown in bold.

[0228] The second heavy chain (heavy chain 2 domain) of the antibody may contain any one of the following amino acid sequences (Sequence Nos. 44 - 49, 65):

[0229] TIFF2025516671000036.tif42168

[0230] TIFF2025516671000037.tif42168

[0231] TIFF2025516671000038.tif43168

[0232] TIFF2025516671000039.tif43167

[0233] The second heavy chain of the antibody (heavy chain 2 domain) may include any one of the following amino acid sequences (SEQ ID NOs: 48-51):

[0234] TIFF2025516671000040.tif43168

[0235] TIFF2025516671000041.tif43168

[0236] TIFF2025516671000042.tif43168

[0237] TIFF2025516671000043.tif43168

[0238] The CDRs within the second heavy chain variable domain are mutated at SEQ ID NOs: 44-51 to prevent binding to C1q. The CDR mutations are indicated by bold and underlined letters. The knob-in-hole T366S / L368A / Y407V mutations of SEQ ID NOs: 44-51 are shown in underlined text.

[0239] In some embodiments, the antibody that binds to C1q is a light chain domain comprising the amino acid sequence of SEQ ID NO: 40, a first heavy chain domain comprising the amino acid sequence of SEQ ID NO: 2, a second heavy chain domain comprising the amino acid sequence of SEQ ID NO: 3, wherein the second heavy chain domain is an N-terminal truncated heavy chain.

[0240] C1s inhibitor Inhibitors of the classical complement pathway may be C1s inhibitors, such as small molecules, antibodies, aptamers, antisense nucleic acids, or gene editing agents.

[0241] Exemplary C1s small molecule inhibitors are described in U.S. Patent Application No. 17 / 379,334 and U.S. Patent Application No. 18 / 097,811, the contents of which are incorporated herein by reference.

[0242] Anti-complement C1s antibody Suitable inhibitors include antibodies that bind to complement C1s protein (i.e., anti-complement C1s antibodies, also referred to herein as anti-C1s antibodies and C1s antibodies) and nucleic acid molecules encoding such antibodies. Complement C1s is upstream in the complement cascade and is an attractive target because it has a narrow range of substrate specificities. Furthermore, it is possible to obtain antibodies (e.g., but not limited to, monoclonal antibodies) that specifically bind to the activated form of C1s.

[0243] All of the sequences listed in the following two paragraphs are incorporated by reference from U.S. Patent Application No. 14 / 890,811 (which is incorporated herein by reference for the antibodies and related compositions it discloses).

[0244] In certain embodiments, methods of administering an anti-C1s antibody are disclosed herein. The antibody can be a murine antibody, a humanized antibody, or a chimeric antibody. In some embodiments, the light chain variable domain includes HVR-L1, HVR-L2, and HVR-L3, and the heavy chain includes HVR-H1, HVR-H2, and HVR-H3 of the murine anti-human C1s monoclonal antibody 5A1 produced by the hybridoma cell line deposited with the ATCC on May 15, 2013 or its progeny (ATCC Accession No. PTA-120351). In other embodiments, the light chain variable domain includes HVR-L1, HVR-L2, and HVR-L3, and the heavy chain variable domain includes HVR-H1, HVR-H2, and HVR-H3 of the murine anti-human C1s monoclonal antibody 5C12 produced by the hybridoma cell line deposited with the ATCC on May 15, 2013 or its progeny (ATCC Accession No. PTA-120352).

[0245] In some embodiments, the antibody specifically binds to C1s or pro-C1s and inhibits its biological activity, such as C1s binding to C1q, C1s binding to C1r, or C1s binding to C2 or C4. The biological activity can be the proteolytic enzyme activity of C1s, the conversion of pro-C1s to the active protease, or the proteolytic cleavage of C2 or C4. In certain embodiments, the biological activity is the activation of the classical complement activation pathway, the activation of antibody and complement-dependent cytotoxicity, or C1F hemolysis.

[0246] All anti-C1s antibody sequences are incorporated by reference from U.S. Patent No. 8,877,197, which is incorporated herein by reference for the antibodies and related compositions it discloses.

[0247] In some embodiments, the anti-C1s antibody (e.g., the subject antibody that specifically binds to an epitope in the complement C1s protein) comprises a light chain region comprising CDRs selected from SEQ ID NO: 54, SEQ ID NO: 55, and SEQ ID NO: 56, and a heavy chain region comprising CDRs selected from SEQ ID NO: 57, SEQ ID NO: 58, and SEQ ID NO: 59. In some of these embodiments, the anti-C1s antibody comprises a humanized VH and / or VL framework region. SEQ ID NO: 54: SSVSSSYLHWYQ, SEQ ID NO: 55: STSNLASGVP, SEQ ID NO: 56: HQYYRLPPIT, SEQ ID NO: 57: GFTFSNYAMSWV, SEQ ID NO: 58: ISSGGSHTYY, SEQ ID NO: 59: ARLFTGYAMDY.

[0248] In some embodiments, the anti-C1s antibody of the disclosure comprises a light chain variable region comprising the amino acid sequence SEQ ID NO: 21.

[0249] In some embodiments, the anti-C1s antibody of the disclosure comprises a heavy chain variable region comprising the amino acid sequence SEQ ID NO: 22.

[0250] TIFF2025516671000044.tif14167

[0251] TIFF2025516671000045.tif14167

[0252] In some embodiments, the anti-C1s antibody of the present disclosure comprises a light chain variable region comprising the amino acid sequence SEQ ID NO: 23.

[0253] In some embodiments, the anti-C1s antibody of the present disclosure comprises a heavy chain variable region comprising the amino acid sequence SEQ ID NO: 24.

[0254] TIFF2025516671000046.tif14168

[0255] TIFF2025516671000047.tif14168

[0256] In some embodiments, the anti-C1s antibody of the present disclosure comprises a light chain comprising the amino acid sequence SEQ ID NO: 25.

[0257] In some embodiments, the anti-C1s antibody of the present disclosure comprises a heavy chain comprising the amino acid sequence SEQ ID NO: 26.

[0258] The stimumab antibody comprises a light chain comprising the amino acid sequence of SEQ ID NO: 25 and a heavy chain comprising the amino acid sequence of SEQ ID NO: 26.

[0259] TIFF2025516671000048.tif25168

[0260] TIFF2025516671000049.tif43167

[0261] In some embodiments, the anti-C1s antibody of the present disclosure comprises a light chain region comprising a CDR selected from SEQ ID NO: 27, SEQ ID NO: 28, and SEQ ID NO: 56, and a heavy chain region comprising a CDR selected from SEQ ID NO: 29, SEQ ID NO: 30, and SEQ ID NO: 61. In some of these embodiments, the anti-C1s antibody comprises a humanized VH and / or VL framework region. SEQ ID NO: 27: TASSSVSSSYLH, SEQ ID NO: 28: STSNLAS, SEQ ID NO: 56: HQYYRLPPIT, SEQ ID NO: 29: NYAMS, SEQ ID NO: 30: TISSGGSHTYYLDSVKG, SEQ ID NO: 61: LFTGYAMDY.

[0262] In some embodiments, the anti-C1s antibody of the present disclosure comprises a light chain variable region comprising the amino acid sequence of SEQ ID NO: 32.

[0263] In some embodiments, the anti-C1s antibody of the present disclosure comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 33. QIVLTQSPAIMSASLGERVTMTCTASSSVSSSYLHWYQQKPGSSPKLWIYSTSNLASGVPARFSGSGSGTFYSLTISSMEAEDDATYYCHQYYRLPPITFGAGTKLELK (SEQ ID NO: 62) EVMLVESGGALVKPGGSLKLSCAASGFTFSNYAMSWVRQIPEKRLEWVATISSGGSHTYYLDSVKGRFTISRDNARDTLYLQMSSLRSEDTALYYCARLFTGYAMDYWGQGTSVTVSS (SEQ ID NO: 63)

[0264] The anti-C1s antibody can be selected from an antigen-binding fragment, Ig monomer, Fab fragment, F(ab’) 2 fragment, Fd fragment, scFv, scAb, dAb, Fv, single-domain heavy chain antibody, single-domain light chain antibody, monospecific antibody, bispecific antibody, or multispecific antibody.

[0265] This specification discloses a method of administering an antibody that competes for binding to an epitope to which antibody IPN003 (also referred to herein as "IPN-M34" or "M34" or "TNT003") binds, for example, an antibody comprising the variable domain of antibody IPN003 such as antibody IPN003.

[0266] All anti-C1s antibody sequences are incorporated by reference from U.S. Patent Application No. 17 / 749,362, which is incorporated herein by reference for the antibodies and related compositions it discloses.

[0267] In some embodiments, the anti-C1s antibody of the present disclosure comprises (1) a heavy chain variable region comprising HCDR1, HCDR2, and HCDR3, and (2) a light chain variable region comprising LCDR1, LCDR2, and LCDR3, (a) HCDR1 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 66, 72, 78, 84, 89, 94, 99, 103, and 107, (b) HCDR2 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 67, 73, 79, 85, 90, 95, 100, 104, or 108, (c) HCDR3 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 68, 74, 80, 101, 105, or 109, (d) LCDR1 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 69, 75, 81, 86, 91, 96, 102, 106, or 110, (e) LCDR2 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 70, 76, 82, 87, 92, or 97, (f) LCDR3 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 71, 77, 83, 88, 93, or 98. [Table 3]

[0268] C1r inhibitor Inhibitors of the classical complement pathway may be C1r inhibitors, such as small molecules, antibodies, aptamers, antisense nucleic acids, or gene editing agents.

[0269] The anti-C1r antibodies disclosed herein are potent inhibitors of C1r.

[0270] The anti-C1r antibodies disclosed herein inhibit the interaction between C1r and C1q, or between C1r and C1s, or the anti-C1r antibodies inhibit the catalytic activity of C1r, or inhibit the processing of pro-C1r to the active protease.

[0271] C1 complex inhibitor Inhibitors of the classical complement pathway may be C1 inhibitors, such as small molecules, antibodies, aptamers, antisense nucleic acids, or gene editing agents.

[0272] The anti-C1 complex antibodies disclosed herein are potent inhibitors of the C1 complex.

[0273] The anti-C1 complex antibodies disclosed herein inhibit the activation of C1r or C1s, or block their ability to act on C2 or C4. The anti-C1 complex antibodies disclosed herein bind to a combined epitope within the C1 complex, and the combined epitope includes amino acids of both C1q and C1s, both C1q and C1r, both C1r and C1s, or each of C1q, C1r, and C1s.

[0274] C2 inhibitor Inhibitors of the classical complement pathway may be C2 inhibitors, such as small molecules, antibodies, aptamers, antisense nucleic acids, or gene editing agents.

[0275] The anti-C2 inhibitors disclosed herein are potent inhibitors of C2. In some embodiments, the C2 inhibitor is ARGX-117 (ArgenX) described in U.S. Patent No. 11,161,900, the content of which is incorporated herein by reference.

[0276] All anti-C2 antibody sequences are incorporated by reference from U.S. Patent No. 11,161,900, which is incorporated herein by reference for the antibodies and related compositions it discloses.

[0277] In some embodiments, the anti-C2 antibodies of the present disclosure include (1) a heavy chain variable region comprising HCDR1, HCDR2, and HCDR3, and (2) a light chain variable region comprising LCDR1, LCDR2, and LCDR3, wherein HCDR1 comprises the amino acid sequence of SEQ ID NO: 111 (DYNMD), HCDR2 comprises the amino acid sequence of SEQ ID NO: 112 (DINPNYESTGYNQKFKG), HCDR3 comprises the amino acid sequence of SEQ ID NO: 113 (EDDHDAFAY), LCDR1 comprises the amino acid sequence of SEQ ID NO: 114 (RASKSVRTSGYNYMH), LCDR2 comprises the amino acid sequence of SEQ ID NO: 115 (LASNLKS), and LCDR3 comprises the amino acid sequence of SEQ ID NO: 116 (QHSRELPYT).

[0278] In some embodiments, the anti-C2 antibodies of the present disclosure include a VH domain comprising the amino acid sequence shown in SEQ ID NO: 118 and a VL domain comprising the amino acid sequence shown in SEQ ID NO: 117. DNVLTQSPDSLAVSLGERATISCRASKSVRTSGYNYMHWYQQKPGQPPKLLIYLASNLKSGVPDRFSGSGSGTDFTLTISSLQAEDAATYYCQHSRELPYTFGQGTKLEIK (SEQ ID NO: 117) EVQLVQSGAEVKKPGASVKVSCKASGYTFTDYNMDWVRQATGQGLEWIGDINPNYESTGYNQKFKGRATMTVDKSISTAYMELSSLRSEDTAVYYCAREDDHDAFAYWGQGTLVTVSS (SEQ ID NO: 118).

[0279] C3 inhibitor Inhibitors of the classical complement pathway may be C3 inhibitors, such as small molecules, antibodies, aptamers, antisense nucleic acids, or gene editing agents.

[0280] The anti-C3 inhibitors disclosed herein are potent inhibitors of C3. In some embodiments, the C3 inhibitor is APL-9 (Apellis) and / or AMY-101 (Amyndas) and / or IVT CB 2782-PEG (Catalyst Biosciences and Biogen).

[0281] C4 inhibitor Inhibitors of the classical complement pathway may be C4 inhibitors, such as small molecules, antibodies, aptamers, antisense nucleic acids, or gene editing agents.

[0282] The anti-C4 inhibitors disclosed herein are potent inhibitors of C4.

[0283] Inhibition of complement Several molecules that inhibit complement activity are known. In addition to known compounds, suitable inhibitors can be screened by the methods described herein. As described above, normal cells can produce proteins that block complement activity, such as CD59, C1 inhibitor, etc. In some embodiments of the present disclosure, complement is inhibited by upregulating the expression of genes encoding such polypeptides.

[0284] Modifications of molecules that block complement activation are also known in the art. For example, such molecules include, but are not limited to, modified complement receptors such as soluble CR1. The mature protein of the most common allotype of CR1 contains 1998 amino acid residues: an extracellular domain of 1930 residues, a transmembrane region of 25 residues, and a cytoplasmic domain of 43 residues. The entire extracellular domain consists of 30 repeat units called short consensus repeats (SCRs) or complement control protein repeats (CCPRs), each consisting of 60-70 amino acid residues. Recent data indicate that C1q binds specifically to human CR1. Thus, CR1 recognizes all three complement opsonins, namely, C3b, C4b, and C1q. A soluble version of recombinant human CR1 (sCR1) lacking the transmembrane and cytoplasmic domains has been generated and shown to retain all the known functions of native CR1. The cardioprotective role of sCR1 in animal models of ischemia / reperfusion injury has been confirmed. Several types of human C1q receptors (C1qR) have been described. These include a ubiquitously distributed 60-67 kDa receptor, designated cC1qR, which binds to the collagen-like domain of C1q. This C1qR variant has been shown to be calreticulin; a 126 kDa receptor that regulates monocyte phagocytosis. gC1qR is not a membrane-bound molecule but rather a secreted soluble protein that has an affinity for the globular region of C1q and can act as a fluid-phase regulator of complement activation.

[0285] Decay-accelerating factor (DAF) (CD55) is composed of four SCRs and a serine / threonine-rich domain capable of extensive O-linked glycosylation. DAF is attached to the cell membrane by a glycosylphosphatidylinositol (GPI) anchor and acts by dissociating C3 and C5 convertases through its ability to bind to C4b and C3b. A soluble version of DAF (sDAF) has been shown to inhibit complement activation.

[0286] C1 inhibitor, a member of the "serpin" family of serine protease inhibitors, is a highly glycosylated plasma protein that prevents fluid-phase C1 activation. C1 inhibitor regulates the classical pathway of complement activation by blocking the active sites of C1r and C1s and dissociating them from C1q.

[0287] Peptide inhibitors of complement activation include C5a, and other inhibitory molecules include fucoidan.

[0288] Method of treatment The present disclosure generally relates to a method for treating lupus nephritis in a subject in need thereof. The method includes determining that the subject has at least one of the following characteristics: an elevated C4x level, an elevated C4x / C4 ratio, a decreased C4 level, an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, or an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level. C4x can be selected from C4a and C4d. The method further includes, for example, administering to the subject an inhibitor of the classical complement pathway if the subject has an elevated C4x level, an elevated C4x / C4 ratio, a decreased C4 level, an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, or an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level. In some embodiments, the subject has at least two of the characteristics. For example, the characteristics can be selected from an elevated C4x level, an elevated C4x / C4 ratio, and a decreased C4 level, and / or the characteristics can be selected from the group consisting of an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, and a decreased C1s level. In some embodiments, the subject further has an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level. In some embodiments, the subject has at least one of the following additional characteristics: an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C3 level. In some embodiments, the subject further has an elevated UPCR as yet another additional characteristic. A therapeutically effective amount of the inhibitor can be administered.

[0289] We observed evidence of complement activation in lupus nephritis patients compared to healthy controls. Specifically, the levels of C4a, C4d, C1sC1 inhibitor, PACA1, and PACA3, and the ratios of C4a / C4, C4d / C4, C1sC1 inhibitor / C1s, C2b / C2, and C3a / C3 were highly elevated in lupus nephritis patients, while the levels of C4, C1s, C2, and C3 were decreased in lupus nephritis patients. More specifically, the level of C4d and the C4d / C4 ratio were highly increased in lupus nephritis patients with flares, but it was observed that the levels of C1q, C1s, C2, and C4 decreased in line with activation of the classical complement pathway (increased activation and component consumption).

[0290] Data from Example 1 demonstrate that patients identified by use of a model that evaluates elevated C4d levels and / or elevated C4d / C4 ratios show potential clinical improvement with anti-C1q antibody treatment. Further, these data suggest that a subset of LN patients showing high levels of C4a, C4d, C1sC1 inhibitor, PACA1, PACA3, C4a / C4 are those with C1sC1 inhibitor / C1s, C2b / C2 or decreased levels of C4, C1s, C2 are also likely to benefit from therapy with classical complement inhibitors, or more specifically anti-C1q therapy. Treatment with an anti-C1q antibody (e.g., a full-length anti-C1q antibody or its Fab fragment) provides a clinical benefit in lupus nephritis patients identified by use of a model that evaluates complement levels and / or PACA levels alone or in combination with UPCR, as shown in Example 4. Consideration of complement levels (e.g., C4a, C4d, C4, C2b, C2, C1sC1 inhibitor, C1s, C3a, C3a, C3, PACA1, PACA3, and the ratios of C4a / C4, C4d / C4, C1sC1 inhibitor / C1s, C2b / C2 and C3a / C3) and / or PACA levels alone or in combination with UPCR, and the use of anti-C1q antibodies, more specifically anti-C1q antibody fragments (e.g., Fab), will reliably provide a clinical benefit in lupus nephritis patients.

[0291] Systemic lupus erythematosus (SLE) is a biologically and clinically heterogeneous autoimmune disease, characterized by a wide range of diverse clinical manifestations, particularly renal involvement. Renal involvement in SLE is referred to as LN. LN occurs in up to 50% to 60% of SLE patients within the first 10 years of the disease and is a major cause of morbidity and mortality in SLE.

[0292] Class III (focal proliferative) and Class IV (diffuse proliferative) LN according to the International Society of Nephrology / Renal Pathology Society (ISN / RPS) clinicopathological classification system are considered to be more severe, with a worse prognosis than Class I (minimal disease) or Class II (mesangial proliferative) disease, and warrant treatment with potent immunosuppressive agents such as cyclophosphamide, mycophenolate mofetil (MMF), and high-dose glucocorticoids. Both Class III and IV LN can have active (proliferative), inactive (sclerotic), or a combination of active and inactive lesions. Additionally, Class V (membranous) glomerulonephritis can occur independently or coexist with Class III and IV LN.

[0293] There remains a large unmet need for new treatment options in LN that are safe and effective and that provide rapid and sustained clinical benefit. Guidelines for the management of LN have been developed worldwide, but currently, it is unclear which treatment is most suitable for individual patients. Therefore, a precision medicine approach is warranted to identify patients who are likely to respond better to a particular therapy and to avoid exposure to potentially harmful agents that are less likely to provide benefit.

[0294] Approximately 5 million people worldwide suffer from some form of lupus, and LN is estimated to affect about half of SLE patients during their lifetime. LN, particularly class III / IV proliferative glomerulonephritis, is a severe and life-threatening disease associated with a six-fold increased mortality compared to the general population. In addition, lupus patients who develop ESRD have a 26-fold increased risk of death and more than twice the risk associated with malignancies or cardiovascular diseases. LN conveys a more than two-fold increased risk of death compared to extrarenal SLE.

[0295] Class III / IV LN is typically treated with immunosuppressive agents such as cyclophosphamide, MMF, azathioprine, and glucocorticoids, and calcineurin inhibitors and rituximab can be used in refractory cases. All of these agents have the potential for significant toxicity, and 50% - 80% of patients receiving these standard treatments can achieve a renal response within one year, but most of these responses are only partial remissions. Furthermore, 30% of LN patients progress to ESRD despite receiving standard treatment. Two advanced therapies, belimumab and voclosporin, have recently been approved for use in class III / IV LN in addition to standard treatment, but in important trials, only about 30% - 40% of patients achieved a complete renal response with chronic administration of these agents. A significant unmet need remains for the development of safe and effective therapies for LN tailored to these patients.

[0296] Autoantibodies against various autoantigens such as double-stranded DNA, RNA, and nucleosomes are thought to contribute to the pathogenesis of lupus. In addition, autoantibodies targeting the collagen-like stalk domain of C1q are highly enriched in patients with LN, can amplify complement-mediated inflammation in LN, and are associated with disease flares. Autoantibodies bind to their cognate antigens and form immune complexes that deposit in the renal vascular wall, glomeruli, and interstitium in LN. Immune complexes trigger the activation of the classical complement cascade, with C1q acting as the most proximal step in this pathway. Through a series of recruitment steps and enzymatic reactions, C1q and its downstream components, such as C4, C3, and their activation products, deposit in the renal tissue of most LN patients. These signaling events lead to the activation of antigen-presenting cells, the release of inflammatory mediators, and the recruitment of additional innate and adaptive immune cells, resulting in the disruption of the structure and function of the glomerular basement membrane (GBM), the development of proteinuria, and subsequent tissue damage. Pathogenic anti-C1q autoantibodies (PACA) can further amplify inflammation via the classical complement pathway by binding to C1q associated with immune complexes present in renal tissue, thereby inducing even more complement activation (Figure 2). Importantly, PACA binds to the tail region of substrate-bound C1q, whereas FabA recognizes the head region of C1q and prevents C1q from binding to its substrate in the first place. Thus, FabA not only inhibits the most proximal step in classical complement pathway activation but also inhibits classical pathway amplification mediated by PACA.

[0297] Complement factor C4 and its activation product C4d are important biomarkers in LN. Reduced levels of C4 and increased amounts of C4d in the activation of the circulating signal of the classical complement pathway are associated with active LN. Plasma C4d levels are strongly correlated with C4d deposition in kidney tissue from patients with active LN. The C4d / C4 ratio is elevated in active LN compared to SLE patients without LN, patients with the autoimmune kidney disease IgA nephropathy, and healthy controls. Furthermore, the C4d / C4 ratio accurately predicts the presence of active LN to a greater extent than other biomarkers (e.g., C3, C4, and C4d). Thus, C4d / C4 can identify active LN patients who are most likely to respond to therapies targeting the classical complement cascade. Similarly, as shown herein, LN patients have elevated C4x levels, elevated C4x / C4 ratios, reduced C4 levels, elevated C1sC1 inhibitor levels, elevated C1sC1 inhibitor / C1s ratios, reduced C1s levels, elevated C2b levels, elevated C2b / C2 ratios, reduced C2 levels, elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) levels.

[0298] Example 1 shows that the C4d / C4 ratio was also correlated with the levels of autoantibodies against C1q isotypes 1 and 3, which are known to activate the classical pathway. These data indicate that a subset of LN patients with high C4d / C4 ratios, along with specific markers of classical pathway activation, are likely to benefit from classical complement inhibitors, or more specifically, anti-C1q therapy. Furthermore, these data suggest that a subset of LN patients showing high levels of C4a, C4d, C1sC1 inhibitor, PACA1, PACA3, C4a / C4, is gC1sC1 inhibitor / C1s, and levels of C2b / C2 or reduced C4, C1s, C2 are likely to benefit from therapy with classical complement inhibitors, or more specifically, anti-C1q therapy.

[0299] In addition, higher circulating levels of C4a, C4d, C1sC1 inhibitor, PACA1, PACA3 and C2b / C2 ratio, C1sC1 inhibitor / C1s ratio and C3a / C3 ratio, as well as decreased levels of C4, C2, C1s, and C3 in patients with active LN, suggest that complement may drive disease progression and severity (Figs. 21A - O).

[0300] The high correlations between complement factors in LN patients suggest coordinated pathway activity (Figs. 6 and 22). In healthy controls, no correlations were observed (Fig. 7). The data show a strong association between high C4d / C4 ratio and the presence of PACA. The data also show strong associations between other complement factors in LN patients, such as C4d / C4 and C4d having a strong positive correlation, and C2b and C2b / C2 having a strong inverse correlation (Fig. 22). The correlations are used to select patients most likely to respond to therapies having the classical complement pathway, more specifically anti - C1q therapy.

[0301] C4d / C4 is reduced by flare - after events by standard treatment, but the effect is not durable (Fig. 9). Fig. 10 shows the changes in urinary protein / creatinine ratio (UPCR) and C4 in response to standard treatment regimens. The elevated level of C4 is approximately equivalent to the reduction of C4d / C4 (C4d is new and not regularly monitored). The rising C4 level coincides with improved UPCR. The C4 level after a declining flare episode suggests residual inflammation that may lead to flare recurrence. The data also show that clinical C4 measurements track the UPCR trajectory (Fig. 11). The rising and falling C4d / C4 correlate with improvement in disease activity (Fig. 12). Also, low C4 and high C4d / C4 correlate with disease activity.

[0302] The presence of C4d in renal biopsy indicates the involvement of classical complement and unique specificity of C4d as a biomarker. The deposition of C4d in renal biopsy suggests the involvement of the classical complement pathway in LN (Figure 15). Furthermore, the high accuracy of this biomarker identifies SLE patients with LN (Figure 16). The high sensitivity and specificity of C4d / C4 as a diagnostic biomarker for other things (e.g., albuminuria, anti-DNA antibodies) suggest a potential causal role of classical complement in LN.

[0303] Plasma C4d can inform the level of C4d in kidney tissue.

[0304] Together, this data provides strong scientific and clinical rationale for evaluating anti-C1q therapeutics in patients with class III / IV LN with evidence of classical complement pathway activation.

[0305] Patients with active LN having a high C4d / C4 ratio are likely to have higher PACA1 (Figures 8A - 8B). PACA1 is likely to function as an additional factor to amplify disease severity. The improved C4d / C4 ratio after treatment further supports the relevance of the complement pathway in disease pathology (Figures 9 and 10).

[0306] PACA1 (pathogenic anti-C1q antibody) levels remain elevated throughout the course of treatment. Patients with active LN having a high C4d / C4 ratio are likely to have higher PACA1 (Figures 8A - 8B). PACA1 is likely to function as an additional factor to amplify disease severity. PACA (pathogenic anti-C1q antibody) levels correlate with classical complement activation in lupus nephritis patients. The improved C4d / C4 ratio after treatment further supports the relevance of the complement pathway in disease pathology.

[0307] PACA is different from other therapeutic anti-C1q antibodies, such as other therapeutic antibodies and antibody fragments designed to inhibit Mab2 and C1q functions. Mab2 and other therapeutic antibodies and antibody fragments recognize the substrate-binding head groups of C1q and prevent C1q substrate binding / activation. In contrast, PACA recognizes C1q when its collagen tail is bound to the substrate, recruits additional C1q via the Fc region, thereby enhancing C1q activity.

[0308] Findings are described herein that PACA plasma titers correlate with the degree of kidney injury in lupus nephritis patients, as evaluated by the urinary protein / creatinine ratio (UPCR) as a measure of proteinuria. In Example 3 below, PACA of IgG1 (i.e., PACA1) and IgG3 isotype (i.e., PACA3) provided the strongest correlation with UPCR, but there was no significant correlation with the levels of IgG2 and IgG4 antibodies to C1q (Figure 13). These results are important because IgG1 and IgG3 are the antibody isotypes that most strongly recruit additional C1q (complement-fixing isotypes), whereas IgG2 and IgG4 recruit little or no C1q to immune complexes and are thus not associated with increased disease levels. IgM antibodies strongly activate C1q, but they are characteristic of acute disease and are not expected to circulate at significant levels in chronic diseases such as lupus nephritis. PACA1 and PACA3 levels also correlate with C4d and C4d / C4 ratio (Figure 14).

[0309] Furthermore, initial studies using animal models of lupus nephritis have reported a causal relationship between anti-C1q antibodies and kidney damage. Administration of PACA significantly exacerbates the disease with a substantial increase in complement deposition in the subendothelial space of glomeruli (Figures 17 and 18). PACA is also characterized by its ability to selectively bind to substrate-bound C1q and activate the classical complement pathway. Binding of PACA to substrate-bound C1q is not affected by soluble C1q (Figure 19). Thus, PACA correlates with disease severity and is the complement-activating IgG1 and IgG3 isotypes of antibodies that do not fix C1q, as opposed to IgG4. Anti-C1q IgG1 and IgG3 levels (not IgG4 levels) correlate with the serum C4d / C4 ratio (Figure 20). This is consistent with the complement-activating ability of the antibody isotypes.

[0310] The present disclosure generally relates to a method for treating lupus nephritis in a subject in need thereof. The method includes determining that the subject has at least one of the following characteristics: elevated C4x level, elevated C4x / C4 ratio, decreased C4 level, elevated C1sC1 inhibitor level, elevated C1sC1 inhibitor / C1s ratio, decreased C1s level, elevated C2b level, elevated C2b / C2 ratio, decreased C2 level, or elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) levels. C4x can be C4a or C4d. The method further includes, for example, administering an inhibitor of the classical complement pathway to the subject if the subject has an elevated C4x level, elevated C4x / C4 ratio, decreased C4 level, elevated C1sC1 inhibitor level, elevated C1sC1 inhibitor / C1s ratio, decreased C1s level, elevated C2b level, elevated C2b / C2 ratio, decreased C2 level, or elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) levels. In some embodiments, the subject has at least two of the characteristics. For example, the characteristics can be selected from an elevated C4x level, elevated C4x / C4 ratio, and decreased C4 level, and / or the characteristics can be selected from the group consisting of an elevated C1sC1 inhibitor level, elevated C1sC1 inhibitor / C1s ratio, and decreased C1s level. In some embodiments, the subject further has elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) levels. In some embodiments, the subject has at least one of the following additional characteristics: elevated C3a level, elevated C3a / C3 ratio, or decreased C3 level. In some embodiments, the subject further has elevated UPCR as yet another additional characteristic. A therapeutically effective amount of the inhibitor can be administered.

[0311] In some embodiments, the subject has an elevated C4x level. In some embodiments, the subject further has at least one of the following additional features: an elevated C4x / C4 ratio, a decreased C4 level, an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C3 level. In some embodiments, the elevated C4x level is higher than the C4x level in a normal or healthy subject, higher than the C4x level in a normal or healthy subject of a similar age, or higher than a reference C4x level. The reference C4x level can be a value equal to or greater than the mean or median of the C4x levels in samples from lupus nephritis subjects, or a value equal to or greater than the mean or median of the C4x levels in samples from lupus nephritis subjects of a similar age. The reference C4x level can be a value at or above the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C4x levels in samples from lupus nephritis subjects. The reference C4x level can be a value at or above the 70th percentile of the C4x levels in samples from lupus nephritis subjects. The reference C4x level can be a value at or above the 75th percentile of the C4x levels in samples from lupus nephritis subjects. The reference C4x level can be a value at or above the 80th percentile of the C4x levels in samples from lupus nephritis subjects. The reference C4x level can be a value at or above the 85th percentile of the C4x levels in samples from lupus nephritis subjects. The reference C4x level can be a value at or above the 90th percentile of the C4x levels in samples from lupus nephritis subjects. The reference C4x level can be a value at or above the 95th percentile of the C4x levels in samples from lupus nephritis subjects. The reference C4x level can be a value at or above the 100th percentile of the C4x levels in samples from lupus nephritis subjects.The reference C4x level can be a value at or above the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C4x levels in samples from lupus nephritis subjects of the same age. The reference C4x level can be a value at or above the 70th percentile of the C4x levels in samples from lupus nephritis subjects of the same age. The reference C4x level can be a value at or above the 75th percentile of the C4x levels in samples from lupus nephritis subjects of the same age. The reference C4x level can be a value at or above the 80th percentile of the C4x levels in samples from lupus nephritis subjects of the same age. The reference C4x level can be a value at or above the 85th percentile of the C4x levels in samples from lupus nephritis subjects of the same age. The reference C4x level can be a value at or above the 90th percentile of the C4x levels in samples from lupus nephritis subjects of the same age. The reference C4x level can be a value at or above the 95th percentile of the C4x levels in samples from lupus nephritis subjects of the same age. The reference C4x level can be a value at or above the 100th percentile of the C4x levels in samples from lupus nephritis subjects of the same age. The reference C4x level can be a value at or above the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the C4x levels in samples from normal or healthy subjects. The reference C4x level can be a value at or above the 70th percentile of the C4x levels in samples from normal or healthy subjects. The reference C4x level can be a value at or above the 75th percentile of the C4x levels in samples from normal or healthy subjects. The reference C4x level can be a value at or above the 80th percentile of the C4x levels in samples from normal or healthy subjects. The reference C4x level can be a value at or above the 85th percentile of the C4x levels in samples from normal or healthy subjects. The reference C4x level can be a value at or above the 90th percentile of the C4x levels in samples from normal or healthy subjects. The reference C4x level can be a value at or above the 95th percentile of the C4x levels in samples from normal or healthy subjects.The reference C4x level can be a value that is at least the 100th percentile of the C4x levels in samples from normal or healthy subjects. The reference C4x level can be a value that is at least the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the C4x levels in samples from normal or healthy subjects of similar age. The reference C4x level can be a value that is at least the 70th percentile of the C4x levels in samples from normal or healthy subjects of similar age. The reference C4x level can be a value that is at least the 75th percentile of the C4x levels in samples from normal or healthy subjects of similar age. The reference C4x level can be a value that is at least the 80th percentile of the C4x levels in samples from normal or healthy subjects of similar age. The reference C4x level can be a value that is at least the 85th percentile of the C4x levels in samples from normal or healthy subjects of similar age. The reference C4x level can be a value that is at least the 90th percentile of the C4x levels in samples from normal or healthy subjects of similar age. The reference C4x level can be a value that is at least the 95th percentile of the C4x levels in samples from normal or healthy subjects of similar age. The reference C4x level can be a value that is at least the 100th percentile of the C4x levels in samples from normal or healthy subjects of similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis. In some embodiments, the elevated C4x level is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% higher than the reference C4x level, or the elevated C4x level is at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% higher than the reference C4x level.

[0312] In some embodiments, the subject has an elevated C4x / C4 ratio. In some embodiments, the subject further has at least one of the following additional features: an elevated C4x level, a decreased C4 level, an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C3 level. In some embodiments, the elevated C4x / C4 ratio is greater than the C4x / C4 ratio in a normal or healthy subject, greater than the C4x / C4 ratio in a normal or healthy subject of a similar age, or greater than a reference C4x / C4 ratio. The reference C4x / C4 ratio can be a value greater than or equal to the mean or median of the C4x / C4 ratio in samples from lupus nephritis subjects, or a value greater than or equal to the mean or median of the C4x / C4 ratio in samples from lupus nephritis subjects of a similar age. The reference C4x / C4 ratio can be a value at the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile or greater of the C4x / C4 ratio in samples from lupus nephritis subjects. The reference C4x / C4 ratio can be a value at the 70th percentile or greater of the C4x / C4 ratio in samples from lupus nephritis subjects. The reference C4x / C4 ratio can be a value at the 75th percentile or greater of the C4x / C4 ratio in samples from lupus nephritis subjects. The reference C4x / C4 ratio can be a value at the 80th percentile or greater of the C4x level in samples from lupus nephritis subjects. The reference C4x / C4 ratio can be a value at the 85th percentile or greater of the C4x / C4 ratio in samples from lupus nephritis subjects. The reference C4x / C4 ratio can be a value at the 90th percentile or greater of the C4x / C4 ratio in samples from lupus nephritis subjects. The reference C4x / C4 ratio can be a value at the 95th percentile or greater of the C4x / C4 ratio in samples from lupus nephritis subjects.The reference C4x / C4 ratio can be a value that is at or above the 100th percentile of the C4x / C4 ratio in samples derived from subjects with lupus nephritis. The reference C4x / C4 ratio can be a value that is at the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile or above of the C4x / C4 ratio in samples derived from subjects with lupus nephritis of similar age. The reference C4x / C4 ratio can be a value that is at or above the 70th percentile of the C4x / C4 ratio in samples derived from subjects with lupus nephritis of similar age. The reference C4x / C4 ratio can be a value that is at or above the 75th percentile of the C4x / C4 ratio in samples derived from subjects with lupus nephritis of similar age. The reference C4x / C4 ratio can be a value that is at or above the 80th percentile of the C4x / C4 ratio in samples derived from subjects with lupus nephritis of similar age. The reference C4x / C4 ratio can be a value that is at or above the 85th percentile of the C4x / C4 ratio in samples derived from subjects with lupus nephritis of similar age. The reference C4x / C4 ratio can be a value that is at or above the 90th percentile of the C4x / C4 ratio in samples derived from subjects with lupus nephritis of similar age. The reference C4x / C4 ratio can be a value that is at or above the 95th percentile of the C4x / C4 ratio in samples derived from subjects with lupus nephritis of similar age. The reference C4x / C4 ratio can be a value that is at or above the 100th percentile of the C4x / C4 ratio in samples derived from subjects with lupus nephritis of similar age. The reference C4x / C4 ratio can be a value that is at the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile or above of the C4x / C4 ratio in samples derived from normal or healthy subjects. The reference C4x / C4 ratio can be a value that is at or above the 70th percentile of the C4x / C4 ratio in samples derived from normal or healthy subjects. The reference C4x / C4 ratio can be a value that is at or above the 75th percentile of the C4x / C4 ratio in samples derived from normal or healthy subjects. The reference C4x / C4 ratio can be a value that is at or above the 80th percentile of the C4x / C4 ratio in samples derived from normal or healthy subjects. The reference C4x / C4 ratio can be a value that is at or above the 85th percentile of the C4x / C4 ratio in samples derived from normal or healthy subjects.The reference C4x / C4 ratio can be a value at or above the 90th percentile of the C4x / C4 ratio in samples derived from normal or healthy subjects. The reference C4x / C4 ratio can be a value at or above the 95th percentile of the C4x / C4 ratio in samples derived from normal or healthy subjects. The reference C4x / C4 ratio can be a value at or above the 100th percentile of the C4x / C4 ratio in samples derived from normal or healthy subjects with lupus. The reference C4x / C4 ratio can be a value at or above the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the C4x / C4 ratio in samples derived from normal or healthy subjects of similar age. The reference C4x / C4 ratio can be a value at or above the 70th percentile of the C4x / C4 ratio in samples derived from normal or healthy subjects of similar age. The reference C4x / C4 ratio can be a value at or above the 75th percentile of the C4x / C4 ratio in samples derived from normal or healthy subjects of similar age. The reference C4x / C4 ratio can be a value at or above the 80th percentile of the C4x / C4 ratio in samples derived from normal or healthy subjects of similar age. The reference C4x / C4 ratio can be a value at or above the 85th percentile of the C4x / C4 ratio in samples derived from normal or healthy subjects of similar age. The reference C4x / C4 ratio can be a value at or above the 90th percentile of the C4x / C4 ratio in samples derived from normal or healthy subjects of similar age. The reference C4x / C4 ratio can be a value at or above the 95th percentile of the C4x / C4 ratio in samples derived from normal or healthy subjects of similar age. The reference C4x / C4 ratio can be a value at or above the 100th percentile of the C4x / C4 ratio in samples derived from normal or healthy subjects with lupus of similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis.In some embodiments, the elevated C4x / C4 ratio is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% greater than the reference C4x / C4 ratio, or at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% greater than the reference C4x / C4 ratio.

[0313] In some embodiments, the subject has a decreased C4 level. In some embodiments, the subject further has at least one of the following additional features: an elevated C4x level, an elevated C4x / C4 ratio, an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C3 level. In some embodiments, the decreased C4 level is less than the C4 level in a normal or healthy subject. The decreased C4 level can be less than the C4 level in a normal or healthy subject of the same age, less than a reference C4 level, or a value less than the mean or median C4 level in a sample from a lupus nephritis subject. In some embodiments, the reference C4 level is a value less than or equal to the mean or median C4 level in a sample from a lupus nephritis subject of the same age. The reference C4 level can be a value at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C4 levels in samples from lupus nephritis subjects of the same age. The reference C4 level can be a value at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C4 levels in samples from lupus nephritis subjects of the same age. The reference C4 level can be a value at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C4 levels in samples from normal or healthy subjects.The reference C4 level can be a value at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C4 levels in samples derived from normal or healthy subjects of similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis. In some embodiments, the decreased C4 level is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% lower than the reference C4 level, or at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 50% lower than the reference C4 level.

[0314] In some embodiments, the subject has an elevated C1sC1 inhibitor level. In some embodiments, the subject has at least one of the following additional features: an elevated C4x level, an elevated C4x / C4 ratio, a decreased C4 level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C3 level. In some embodiments, the elevated C1sC1 inhibitor level is higher than the C1sC1 inhibitor level in a normal or healthy subject, higher than the C1sC1 inhibitor level in a normal or healthy subject of a similar age, or higher than a reference C1sC1 inhibitor level. The reference C1sC1 inhibitor level can be a value equal to or greater than the mean or median of the C1sC1 inhibitor levels in samples from lupus nephritis subjects, or a value equal to or greater than the mean or median of the C1sC1 inhibitor levels in samples from lupus nephritis subjects of a similar age. The reference C1sC1 inhibitor level can be a value at or above the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C1sC1 inhibitor levels in samples from lupus nephritis subjects. The reference C1sC1 inhibitor level can be a value at or above the 70th percentile of the C1sC1 inhibitor levels in samples from lupus nephritis subjects. The reference C1sC1 inhibitor level can be a value at or above the 75th percentile of the C1sC1 inhibitor levels in samples from lupus nephritis subjects. The reference C1sC1 inhibitor level can be a value at or above the 80th percentile of the C1sC1 inhibitor levels in samples from lupus nephritis subjects. The reference C1sC1 inhibitor level can be a value at or above the 85th percentile of the C1sC1 inhibitor levels in samples from lupus nephritis subjects. The reference C1sC1 inhibitor level can be a value at or above the 90th percentile of the C1sC1 inhibitor levels in samples from lupus nephritis subjects.The reference C1sC1 inhibitor level can be a value at or above the 95th percentile of the C1sC1 inhibitor level in samples derived from subjects with lupus nephritis. The reference C1sC1 inhibitor level can be a value at or above the 100th percentile of the C1sC1 inhibitor level in samples derived from subjects with lupus nephritis. The reference C1sC1 inhibitor level can be a value at the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile or above of the C1sC1 inhibitor level in samples derived from subjects with lupus nephritis of a similar age. The reference C1sC1 inhibitor level can be a value at or above the 70th percentile of the C1sC1 inhibitor level in samples derived from subjects with lupus nephritis of a similar age. The reference C1sC1 inhibitor level can be a value at or above the 75th percentile of the C1sC1 inhibitor level in samples derived from subjects with lupus nephritis of a similar age. The reference C1sC1 inhibitor level can be a value at or above the 80th percentile of the C1sC1 inhibitor level in samples derived from subjects with lupus nephritis of a similar age. The reference C1sC1 inhibitor level can be a value at or above the 85th percentile of the C1sC1 inhibitor level in samples derived from subjects with lupus nephritis of a similar age. The reference C1sC1 inhibitor level can be a value at or above the 90th percentile of the C1sC1 inhibitor level in samples derived from subjects with lupus nephritis of a similar age. The reference C1sC1 inhibitor level can be a value at or above the 95th percentile of the C1sC1 inhibitor level in samples derived from subjects with lupus nephritis of a similar age. The reference C1sC1 inhibitor level can be a value at or above the 100th percentile of the C1sC1 inhibitor level in samples derived from subjects with lupus nephritis of a similar age. The reference C1sC1 inhibitor level can be a value at the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile or above of the C1sC1 inhibitor level in samples derived from normal or healthy subjects. The reference C1sC1 inhibitor level can be a value at or above the 70th percentile of the C1sC1 inhibitor level in samples derived from normal or healthy subjects. The reference C1sC1 inhibitor level can be a value at or above the 75th percentile of the C1sC1 inhibitor level in samples derived from normal or healthy subjects.The reference C1sC1 inhibitor level can be a value that is at least the 80th percentile of the C1sC1 inhibitor level in a sample from a normal or healthy subject. The reference C1sC1 inhibitor level can be a value that is at least the 85th percentile of the C1sC1 inhibitor level in a sample from a normal or healthy subject. The reference C1sC1 inhibitor level can be a value that is at least the 90th percentile of the C1sC1 inhibitor level in a sample from a normal or healthy subject. The reference C1sC1 inhibitor level can be a value that is at least the 95th percentile of the C1sC1 inhibitor level in a sample from a normal or healthy subject. The reference C1sC1 inhibitor level can be a value that is at least the 100th percentile of the C1sC1 inhibitor level in a sample from a normal or healthy subject. The reference C1sC1 inhibitor level can be a value that is at least the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the C1sC1 inhibitor level in a sample from a normal or healthy subject of similar age. The reference C1sC1 inhibitor level can be a value that is at least the 70th percentile of the C1sC1 inhibitor level in a sample from a normal or healthy subject of similar age. The reference C1sC1 inhibitor level can be a value that is at least the 75th percentile of the C1sC1 inhibitor level in a sample from a normal or healthy subject of similar age. The reference C1sC1 inhibitor level can be a value that is at least the 80th percentile of the C1sC1 inhibitor level in a sample from a normal or healthy subject of similar age. The reference C1sC1 inhibitor level can be a value that is at least the 85th percentile of the C1sC1 inhibitor level in a sample from a normal or healthy subject of similar age. The reference C1sC1 inhibitor level can be a value that is at least the 90th percentile of the C1sC1 inhibitor level in a sample from a normal or healthy subject of similar age. The reference C1sC1 inhibitor level can be a value that is at least the 95th percentile of the C1sC1 inhibitor level in a sample from a normal or healthy subject of similar age. The reference C1sC1 inhibitor level can be a value that is at least the 100th percentile of the C1sC1 inhibitor level in a sample from a normal or healthy subject of similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis.In some embodiments, the elevated C1sC1 inhibitor level is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% higher than the reference C1sC1 inhibitor level, or at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% higher than the reference C1sC1 inhibitor level.

[0315] In some embodiments, the subject has an elevated C1sC1 inhibitor / C1s ratio. In some embodiments, the subject has at least one of the following additional features: an elevated C4x level, a decreased C4 level, an elevated C4x / C4 ratio, an elevated C1sC1 inhibitor level, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C3 level. In some embodiments, the elevated C1sC1 inhibitor / C1s ratio is greater than the C1sC1 inhibitor / C1s ratio in a normal or healthy subject. In some embodiments, the elevated C1sC1 inhibitor / C1s ratio is greater than the C1sC1 inhibitor / C1s ratio in a normal or healthy subject of the same age. In some embodiments, the elevated C1sC1 inhibitor / C1s ratio is greater than a reference C1sC1 inhibitor / C1s ratio. In some embodiments, the reference C1sC1 inhibitor / C1s ratio is a value equal to or greater than the mean or median of the C1sC1 inhibitor / C1s ratio in samples from lupus nephritis subjects. In some embodiments, the reference C1sC1 inhibitor / C1s ratio is a value equal to or greater than the mean or median of the C1sC1 inhibitor / C1s ratio in samples from lupus nephritis subjects of the same age. In some embodiments, the reference C1sC1 inhibitor / C1s ratio is a value at the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile or greater of the C1sC1 inhibitor / C1s ratio in samples from lupus nephritis subjects. The reference C1sC1 inhibitor / C1s ratio can be a value at the 70th percentile or greater of the C1sC1 inhibitor / C1s ratio in samples from lupus nephritis subjects. The reference C1sC1 inhibitor / C1s ratio can be a value at the 75th percentile or greater of the C1sC1 inhibitor / C1s ratio in samples from lupus nephritis subjects. The reference C1sC1 inhibitor / C1s ratio can be a value at the 80th percentile or greater of the C1sC1 inhibitor / C1s ratio in samples from lupus nephritis subjects.The reference C1s C1 inhibitor / C1s ratio can be a value that is at least the 85th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from lupus nephritis subjects. The reference C1s C1 inhibitor / C1s ratio can be a value that is at least the 90th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from lupus nephritis subjects. The reference C1s C1 inhibitor / C1s ratio can be a value that is at least the 95th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from lupus nephritis subjects. The reference C1s C1 inhibitor / C1s ratio can be a value that is at least the 100th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from lupus nephritis subjects. In some embodiments, the reference C1s C1 inhibitor / C1s ratio is a value that is the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile or higher of the C1s C1 inhibitor / C1s ratio in samples derived from lupus nephritis subjects of the same age. The reference C1s C1 inhibitor / C1s ratio can be a value that is at least the 70th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from lupus nephritis subjects of the same age. The reference C1s C1 inhibitor / C1s ratio can be a value that is at least the 75th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from lupus nephritis subjects of the same age. The reference C1s C1 inhibitor / C1s ratio can be a value that is at least the 80th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from lupus nephritis subjects of the same age. The reference C1s C1 inhibitor / C1s ratio can be a value that is at least the 85th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from lupus nephritis subjects of the same age. The reference C1s C1 inhibitor / C1s ratio can be a value that is at least the 90th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from lupus nephritis subjects of the same age. The reference C1s C1 inhibitor / C1s ratio can be a value that is at least the 95th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from lupus nephritis subjects of the same age. The reference C1s C1 inhibitor / C1s ratio can be a value that is at least the 100th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from lupus nephritis subjects of the same age.In some embodiments, the reference C1s C1 inhibitor / C1s ratio is a value that is at or above the 50th percentile, 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from normal or healthy subjects. The reference C1s C1 inhibitor / C1s ratio can be a value that is at or above the 70th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from normal or healthy subjects. The reference C1s C1 inhibitor / C1s ratio can be a value that is at or above the 75th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from normal or healthy subjects. The reference C1s C1 inhibitor / C1s ratio can be a value that is at or above the 80th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from normal or healthy subjects. The reference C1s C1 inhibitor / C1s ratio can be a value that is at or above the 85th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from normal or healthy subjects. The reference C1s C1 inhibitor / C1s ratio can be a value that is at or above the 90th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from normal or healthy subjects. The reference C1s C1 inhibitor / C1s ratio can be a value that is at or above the 95th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from normal or healthy subjects. The reference C1s C1 inhibitor / C1s ratio can be a value that is at or above the 100th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from normal or healthy subjects. In some embodiments, the reference C1s C1 inhibitor / C1s ratio is a value that is at or above the 50th percentile, 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from normal or healthy subjects of the same age. The reference C1s C1 inhibitor / C1s ratio can be a value that is at or above the 70th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from normal or healthy subjects of the same age.The reference C1s C1 inhibitor / C1s ratio can be a value that is at least the 75th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from normal or healthy subjects of the same age. The reference C1s C1 inhibitor / C1s ratio can be a value that is at least the 80th percentile of the C1s C1 inhibitor / C1s in samples derived from normal or healthy subjects of the same age. The reference C1s C1 inhibitor / C1s ratio can be a value that is at least the 85th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from normal or healthy subjects of the same age. The reference C1s C1 inhibitor / C1s ratio can be a value that is at least the 90th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from normal or healthy subjects of the same age. The reference C1s C1 inhibitor / C1s ratio can be a value that is at least the 95th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from normal or healthy subjects of the same age. The reference C1s C1 inhibitor / C1s ratio can be a value that is at least the 100th percentile of the C1s C1 inhibitor / C1s ratio in samples derived from normal or healthy subjects of the same age. In some embodiments, the normal or healthy subject does not have lupus nephritis. In some embodiments, the elevated C1s C1 inhibitor / C1s ratio is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% greater than the reference C1s C1 inhibitor / C1s ratio. In some embodiments, the elevated C1s C1 inhibitor / C1s ratio is at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% greater than the reference C1s C1 inhibitor / C1s ratio.

[0316] In some embodiments, the subject has a decreased C1s level. In some embodiments, the subject has at least one of the following additional features: an increased C4x level, an increased C4x / C4 ratio, a decreased C4 level, an increased C1sC1 inhibitor / C1s ratio, a decreased C1sC1 inhibitor level, an increased C2b level, an increased C2b / C2 ratio, a decreased C2 level, an increased pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an increased C3a level, an increased C3a / C3 ratio, or a decreased C3 level. In some embodiments, the decreased C1s level is less than the C1s level in a normal or healthy subject. In some embodiments, the decreased C1s level is less than the C1s level in a normal or healthy subject of the same age. In some embodiments, the decreased C1s level is less than a reference C1s level. In some embodiments, the reference C1s level is a value that is less than the average or median C1s level in samples from lupus nephritis subjects. In some embodiments, the reference C1s level is a value that is less than the average or median C1s level in samples from lupus nephritis subjects of the same age. In some embodiments, the reference C1s level is a value that is less than or equal to the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C1s level in samples from lupus nephritis subjects. In some embodiments, the reference C1s level is a value that is less than or equal to the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C1s level in samples from lupus nephritis subjects of the same age.In some embodiments, the reference C1s level is a value that is at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C1s levels in samples from normal or healthy subjects. In some embodiments, the reference C1s level is a value that is at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C1s levels in samples from normal or healthy subjects of similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis. In some embodiments, the decreased C1s level is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% lower than the reference C4 level. In some embodiments, the decreased C1s level is at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% lower than the reference C4 level.

[0317] In some embodiments, the subject has an elevated C2b level. In some embodiments, the subject has at least one of the following additional features: an elevated C4x level, an elevated C4x / C4 ratio, a decreased C4 level, an elevated C1sC1 inhibitor / C1s ratio, an elevated C1sC1 inhibitor level, a decreased C1s level, an elevated C2b / C2 ratio, a decreased C2 level, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C3 level. In some embodiments, the elevated C2b level is higher than the C2b level in a normal or healthy subject, or the elevated C2b level is higher than the C2b level in a normal or healthy subject of a similar age, or higher than a reference C2b level. The reference C2b level can be a value equal to or greater than the average or median of the C2b levels in samples from lupus nephritis subjects, or a value equal to or greater than the average or median of the C2b levels in samples from lupus nephritis subjects of a similar age. The reference C2b level can be a value at or above the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C2b levels in samples from lupus nephritis subjects. The reference C2b level can be a value at or above the 70th percentile of the C2b levels in samples from lupus nephritis subjects. The reference C2b level can be a value at or above the 75th percentile of the C2b levels in samples from lupus nephritis subjects. The reference C2b level can be a value at or above the 80th percentile of the C2b levels in samples from lupus nephritis subjects. The reference C2b level can be a value at or above the 85th percentile of the C2b levels in samples from lupus nephritis subjects. The reference C2b level can be a value at or above the 90th percentile of the C2b levels in samples from lupus nephritis subjects. The reference C2b level can be a value at or above the 95th percentile of the C2b levels in samples from lupus nephritis subjects. The reference C2b level can be a value at or above the 100th percentile of the C2b levels in samples from lupus nephritis subjects.The reference C2b level can be a value at or above the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C2b levels in samples from lupus nephritis subjects of similar age. The reference C2b level can be a value at or above the 70th percentile of the C2b levels in samples from lupus nephritis subjects of similar age. The reference C2b level can be a value at or above the 75th percentile of the C2b levels in samples from lupus nephritis subjects of similar age. The reference C2b level can be a value at or above the 80th percentile of the C2b levels in samples from lupus nephritis subjects of similar age. The reference C2b level can be a value at or above the 85th percentile of the C2b levels in samples from lupus nephritis subjects of similar age. The reference C2b level can be a value at or above the 90th percentile of the C2b levels in samples from lupus nephritis subjects of similar age. The reference C2b level can be a value at or above the 95th percentile of the C2b levels in samples from lupus nephritis subjects of similar age. The reference C2b level can be a value at or above the 100th percentile of the C2b levels in samples from lupus nephritis subjects of similar age. The reference C2b level can be a value at or above the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the C2b levels in samples from normal or healthy subjects. The reference C2b level can be a value at or above the 70th percentile of the C2b levels in samples from normal or healthy subjects. The reference C2b level can be a value at or above the 75th percentile of the C2b levels in samples from normal or healthy subjects. The reference C2b level can be a value at or above the 80th percentile of the C2b levels in samples from normal or healthy subjects. The reference C2b level can be a value at or above the 85th percentile of the C2b levels in samples from normal or healthy subjects. The reference C2b level can be a value at or above the 90th percentile of the C2b levels in samples from normal or healthy subjects. The reference C2b level can be a value at or above the 95th percentile of the C2b levels in samples from normal or healthy subjects.The reference C2b level can be a value that is at or above the 100th percentile of the C2b levels in samples from normal or healthy subjects. The reference C2b level can be a value that is at or above the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the C2b levels in samples from normal or healthy subjects of a similar age. The reference C2b level can be a value that is at or above the 70th percentile of the C2b levels in samples from normal or healthy subjects of a similar age. The reference C2b level can be a value that is at or above the 75th percentile of the C2b levels in samples from normal or healthy subjects of a similar age. The reference C2b level can be a value that is at or above the 80th percentile of the C2b levels in samples from normal or healthy subjects of a similar age. The reference C2b level can be a value that is at or above the 85th percentile of the C2b levels in samples from normal or healthy subjects of a similar age. The reference C2b level can be a value that is at or above the 90th percentile of the C2b levels in samples from normal or healthy subjects of a similar age. The reference C2b level can be a value that is at or above the 95th percentile of the C2b levels in samples from normal or healthy subjects of a similar age. The reference C2b level can be a value that is at or above the 100th percentile of the C2b levels in samples from normal or healthy subjects of a similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis. In some embodiments, the elevated C2b level is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% higher than the reference C2b level, or at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% higher than the reference C2b level.

[0318] In some embodiments, the subject has an elevated C2b / C2 ratio. In some embodiments, the subject has at least one of the following additional features: an elevated C4x level, an elevated C4x / C4 ratio, a decreased C4 level, an elevated C1sC1 inhibitor / C1s ratio, an elevated C1sC1 inhibitor level, a decreased C1s level, a decreased C2 level, an elevated C2b level, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C3 level. In some embodiments, the elevated C2b / C2 ratio is greater than the C2b / C2 ratio in a normal or healthy subject. In some embodiments, the elevated C2b / C2 ratio is greater than the C2b / C2 ratio in a normal or healthy subject of similar age. In some embodiments, the elevated C2b / C2 ratio is greater than a reference C2b / C2 ratio. In some embodiments, the reference C2b / C2 ratio is a value that is equal to or greater than the mean or median of the C2b / C2 ratio in samples derived from lupus nephritis subjects. In some embodiments, the reference C2b / C2 ratio is a value that is equal to or greater than the mean or median of the C2b / C2 ratio in samples derived from lupus nephritis subjects of similar age. In some embodiments, the reference C2b / C2 ratio is a value that is at or above the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C2b / C2 ratio in samples derived from lupus nephritis subjects. In some embodiments, the reference C2b / C2 ratio is a value that is at or above the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C2b / C2 ratio in samples derived from lupus nephritis subjects of similar age.In some embodiments, the reference C2b / C2 ratio is a value that is at or above the 50th percentile, 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C2b / C2 ratio in samples from normal or healthy subjects. In some embodiments, the reference C2b / C2 ratio is a value that is at or above the 50th percentile, 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C2b / C2 ratio in samples from normal or healthy subjects of similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis. In some embodiments, the elevated C2b / C2 ratio is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% greater than the reference C2b / C2 ratio. In some embodiments, the elevated C2b / C2 ratio is at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% greater than the reference C2b / C2 ratio.

[0319] In some embodiments, the subject has a decreased C2 level. In some embodiments, the subject has at least one of the following additional features: an increased C4x level, an increased C4x / C4 ratio, a decreased C4 level, an increased C1sC1 inhibitor / C1s ratio, an increased C1sC1 inhibitor level, a decreased C1s level, an increased C2b level, an increased C2b / C2 ratio, an increased pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an increased C3a level, an increased C3a / C3 ratio, or a decreased C3 level. In some embodiments, the decreased C2 level is less than the C2 level in a normal or healthy subject, less than the C2 level in a normal or healthy subject of the same age, or less than a reference C2 level. The reference C2 level can be a value that is greater than or equal to the average or median C2 level in a sample from a lupus nephritis subject, or a value that is greater than or equal to the average or median C2 level in a sample from a lupus nephritis subject of the same age. The reference C2 level can be a value that is at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C2 level in a sample from a lupus nephritis subject. The reference C2 level can be a value that is at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C2 level in a sample from a lupus nephritis subject of the same age.The reference C2 level can be the value at the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile or below of the C2 level in samples from normal or healthy subjects, or can be the value at the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile or below of the C2 level in samples from normal or healthy subjects of similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis. In some embodiments, the decreased C2 level is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% lower than the reference C2 level, or is at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% lower than the reference C2 level.

[0320] In some embodiments, the subject has elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) levels. In some embodiments, the subject has at least one of the following additional features: elevated C4x level, elevated C4x / C4 ratio, decreased C4 level, elevated C1sC1 inhibitor / C1s ratio, elevated C1sC1 inhibitor level, decreased C1s level, elevated C2b level, elevated C2b / C2 ratio, decreased C2 level, elevated C3a level, elevated C3a / C3 ratio, or decreased C3 level. In some embodiments, the elevated PACA1 and / or PACA3 levels are higher than the PACA1 and / or PACA3 levels in a normal or healthy subject, higher than the PACA1 and / or PACA3 levels in a normal or healthy subject of similar age, or higher than a reference PACA1 and / or PACA3 level. The reference PACA1 and / or PACA3 level can be a value greater than or equal to the mean or median of the PACA1 and / or PACA3 levels in samples from lupus nephritis subjects, or a value greater than or equal to the mean or median of the PACA1 and / or PACA3 levels in samples from lupus nephritis subjects of similar age. The reference PACA1 and / or PACA3 level can be a value at or above the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the PACA1 and / or PACA3 levels in samples from lupus nephritis subjects. The reference PACA1 and / or PACA3 level can be a value at or above the 70th percentile of the PACA1 and / or PACA3 levels in samples from lupus nephritis subjects. The reference PACA1 and / or PACA3 level can be a value at or above the 75th percentile of the PACA1 and / or PACA3 levels in samples from lupus nephritis subjects. The reference PACA1 and / or PACA3 level can be a value at or above the 80th percentile of the PACA1 and / or PACA3 levels in samples from lupus nephritis subjects.The reference PACA1 and / or PACA3 level can be a value at or above the 85th percentile of the PACA1 and / or PACA3 level in a sample from a lupus nephritis subject. The reference PACA1 and / or PACA3 level can be a value at or above the 90th percentile of the PACA1 and / or PACA3 level in a sample from a lupus nephritis subject. The reference PACA1 and / or PACA3 level can be a value at or above the 95th percentile of the PACA1 and / or PACA3 level in a sample from a lupus nephritis subject. The reference PACA1 and / or PACA3 level can be a value at or above the 100th percentile of the PACA1 and / or PACA3 level in a sample from a lupus nephritis subject. The reference PACA1 and / or PACA3 level can be a value at the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile or above of the PACA1 and / or PACA3 level in a sample from a lupus nephritis subject of similar age. The reference PACA1 and / or PACA3 level can be a value at or above the 70th percentile of the PACA1 and / or PACA3 level in a sample from a lupus nephritis subject of similar age. The reference PACA1 and / or PACA3 level can be a value at or above the 75th percentile of the PACA1 and / or PACA3 level in a sample from a lupus nephritis subject of similar age. The reference PACA1 and / or PACA3 level can be a value at or above the 80th percentile of the PACA1 and / or PACA3 level in a sample from a lupus nephritis subject of similar age. The reference PACA1 and / or PACA3 level can be a value at or above the 85th percentile of the PACA1 and / or PACA3 level in a sample from a lupus nephritis subject of similar age. The reference PACA1 and / or PACA3 level can be a value at or above the 90th percentile of the PACA1 and / or PACA3 level in a sample from a lupus nephritis subject of similar age.The reference PACA1 and / or PACA3 levels can be values at or above the 95th percentile of the PACA1 and / or PACA3 levels in samples derived from lupus nephritis subjects of similar age. The reference PACA1 and / or PACA3 levels can be values at or above the 100th percentile of the PACA1 and / or PACA3 levels in samples derived from lupus nephritis subjects of similar age. The reference PACA1 and / or PACA3 levels can be values at or above the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the PACA1 and / or PACA3 levels in samples derived from normal or healthy subjects. The reference PACA1 and / or PACA3 levels can be values at or above the 70th percentile of the PACA1 and / or PACA3 levels in samples derived from normal or healthy subjects. The reference PACA1 and / or PACA3 levels can be values at or above the 75th percentile of the PACA1 and / or PACA3 levels in samples derived from normal or healthy subjects. The reference PACA1 and / or PACA3 levels can be values at or above the 80th percentile of the PACA1 and / or PACA3 levels in samples derived from normal or healthy subjects. The reference PACA1 and / or PACA3 levels can be values at or above the 85th percentile of the PACA1 and / or PACA3 levels in samples derived from normal or healthy subjects. The reference PACA1 and / or PACA3 levels can be values at or above the 90th percentile of the PACA1 and / or PACA3 levels in samples derived from normal or healthy subjects. The reference PACA1 and / or PACA3 levels can be values at or above the 95th percentile of the PACA1 and / or PACA3 levels in samples derived from normal or healthy subjects. The reference PACA1 and / or PACA3 levels can be values at or above the 100th percentile of the PACA1 and / or PACA3 levels in samples derived from normal or healthy subjects of similar age. The reference PACA1 and / or PACA3 levels can be values at or above the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the PACA1 and / or PACA3 levels in samples derived from normal or healthy subjects of similar age.The reference PACA1 and / or PACA3 levels can be values at or above the 70th percentile of the PACA1 and / or PACA3 levels in samples from normal or healthy subjects of similar age. The reference PACA1 and / or PACA3 levels can be values at or above the 75th percentile of the PACA1 and / or PACA3 levels in samples from normal or healthy subjects of similar age. The reference PACA1 and / or PACA3 levels can be values at or above the 80th percentile of the PACA1 and / or PACA3 levels in samples from normal or healthy subjects of similar age. The reference PACA1 and / or PACA3 levels can be values at or above the 85th percentile of the PACA1 and / or PACA3 levels in samples from normal or healthy subjects of similar age. The reference PACA1 and / or PACA3 levels can be values at or above the 90th percentile of the PACA1 and / or PACA3 levels in samples from normal or healthy subjects of similar age. The reference PACA1 and / or PACA3 levels can be values at or above the 95th percentile of the PACA1 and / or PACA3 levels in samples from normal or healthy subjects of similar age. The reference PACA1 and / or PACA3 levels can be values at or above the 100th percentile of the PACA1 and / or PACA3 levels in samples from normal or healthy subjects of similar age. In some embodiments, the normal or healthy subject does not have lupus nephritis. In some embodiments, the elevated PACA1 and / or PACA3 levels are at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% higher than the reference PACA1 and / or PACA3 levels, or at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% higher than the reference PACA1 and / or PACA3 levels.

[0321] In some embodiments, the subject has elevated C3a levels. In some embodiments, the subject has at least one of the following additional features: elevated C4x / C4 ratio, decreased C4 levels, elevated C1sC1 inhibitor levels, elevated C1sC1 inhibitor / C1s ratio, decreased C1s levels, elevated C2b levels, elevated C2b / C2 ratio, decreased C2 levels, elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) levels, elevated C4x levels, elevated C3a / C3 ratio, or decreased C3 levels. In some embodiments, the elevated C3a levels are higher than the C3a levels in a normal or healthy subject. In some embodiments, the elevated C3a levels are higher than the C3a levels in a normal or healthy subject of the same age. In some embodiments, the elevated C3a levels are higher than a reference C3a level. In some embodiments, the reference C3a level is a value equal to or greater than the mean or median of the C3a levels in samples from lupus nephritis subjects. In some embodiments, the reference C3a level is a value equal to or greater than the mean or median of the C3a levels in samples from lupus nephritis subjects of the same age. In some embodiments, the reference C3a level is a value at or above the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the C3a levels in samples from lupus nephritis subjects. The reference C3a level can be a value at or above the 70th percentile of the C3a levels in samples from lupus nephritis subjects. The reference C3a level can be a value at or above the 75th percentile of the C3a levels in samples from lupus nephritis subjects. The reference C3a level can be a value at or above the 80th percentile of the C3a levels in samples from lupus nephritis subjects. The reference C3a level can be a value at or above the 85th percentile of the C3a levels in samples from lupus nephritis subjects. The reference C3a level can be a value at or above the 90th percentile of the C3a levels in samples from lupus nephritis subjects.The reference C3a level can be a value that is at least the 95th percentile of the C3a levels in samples from subjects with lupus nephritis. The reference C3a level can be a value that is at least the 100th percentile of the C3a levels in samples from subjects with lupus nephritis. In some embodiments, the reference C3a level can be the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile or greater of the C3a levels in samples from subjects with lupus nephritis of a similar age. The reference C3a level can be a value that is at least the 70th percentile of the C3a levels in samples from subjects with lupus nephritis of a similar age. The reference C3a level can be a value that is at least the 75th percentile of the C3a levels in samples from subjects with lupus nephritis of a similar age. The reference C3a level can be a value that is at least the 80th percentile of the C3a levels in samples from subjects with lupus nephritis of a similar age. The reference C3a level can be a value that is at least the 85th percentile of the C3a levels in samples from subjects with lupus nephritis of a similar age. The reference C3a level can be a value that is at least the 90th percentile of the C3a levels in samples from subjects with lupus nephritis of a similar age. The reference C3a level can be a value that is at least the 95th percentile of the C3a levels in samples from subjects with lupus nephritis of a similar age. The reference C3a level can be a value that is at least the 100th percentile of the C3a levels in samples from subjects with lupus nephritis of a similar age. In some embodiments, the reference C3a level is the 50th, 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile or greater of the C3a levels in samples from normal or healthy subjects. The reference C3a level can be a value that is at least the 70th percentile of the C3a levels in samples from normal or healthy subjects. The reference C3a level can be a value that is at least the 75th percentile of the C3a levels in samples from normal or healthy subjects.The reference C3a level can be a value that is at least the 80th percentile of the C3a levels in samples from normal or healthy subjects. The reference C3a level can be a value that is at least the 85th percentile of the C3a levels in samples from normal or healthy subjects. The reference C3a level can be a value that is at least the 90th percentile of the C3a levels in samples from normal or healthy subjects. The reference C3a level can be a value that is at least the 95th percentile of the C3a levels in samples from normal or healthy subjects. The reference C3a level can be a value that is at least the 100th percentile of the C3a levels in samples from normal or healthy subjects. In some embodiments, the reference C3a level is a value that is at least the 50th, 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile of the C3a levels in samples from normal or healthy subjects of a similar age. The reference C3a level can be a value that is at least the 70th percentile of the C3a levels in samples from normal or healthy subjects of a similar age. The reference C3a level can be a value that is at least the 75th percentile of the C3a levels in samples from normal or healthy subjects of a similar age. The reference C3a level can be a value that is at least the 80th percentile of the C3a levels in samples from normal or healthy subjects of a similar age. The reference C3a level can be a value that is at least the 85th percentile of the C3a levels in samples from normal or healthy subjects of a similar age. The reference C3a level can be a value that is at least the 90th percentile of the C3a levels in samples from normal or healthy subjects of a similar age. The reference C3a level can be a value that is at least the 95th percentile of the C3a levels in samples from normal or healthy subjects of a similar age. The reference C3a level can be a value that is at least the 100th percentile of the C3a levels in samples from normal or healthy subjects of a similar age. In some embodiments, the normal or healthy subjects do not have lupus nephritis.In some embodiments, the decreased C3a level is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% higher than the reference C3a level. In some embodiments, the increased C3a level is at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% higher than the reference C3a level.

[0322] In some embodiments, the subject has an elevated C3a / C3 ratio. In some embodiments, the subject has at least one of the following additional features: an elevated C4x level, a decreased C4 level, an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C4x / C4 ratio, or a decreased C3 level. In some embodiments, the elevated C3a / C3 ratio is greater than the C3a / C3 ratio in a normal or healthy subject. In some embodiments, the elevated C3a / C3 ratio is greater than the C3a / C3 ratio in a normal or healthy subject of the same age. In some embodiments, the elevated C3a / C3 ratio is greater than a reference C3a / C3 ratio. In some embodiments, the reference C3a / C3 ratio is a value equal to or greater than the average or median of the C3a / C3 ratios in samples from lupus nephritis subjects. In some embodiments, the reference C3a / C3 ratio is a value equal to or greater than the average or median of the C3a / C3 ratios in samples from lupus nephritis subjects of the same age. In some embodiments, the reference C3a / C3 ratio is a value at or above the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C3a / C3 ratios in samples from lupus nephritis subjects. The reference C3a / C3 ratio can be a value at or above the 70th percentile of the C3a / C3 ratios in samples from lupus nephritis subjects. The reference C3a / C3 ratio can be a value at or above the 75th percentile of the C3a / C3 ratios in samples from lupus nephritis subjects. The reference C3a / C3 ratio can be a value at or above the 80th percentile of the C3a / C3 ratios in samples from lupus nephritis subjects. The reference C3a / C3 ratio can be a value at or above the 85th percentile of the C3a / C3 ratios in samples from lupus nephritis subjects. The reference C3a / C3 ratio can be a value at or above the 90th percentile of the C3a / C3 ratios in samples from lupus nephritis subjects.The reference C3a / C3 ratio can be a value that is greater than or equal to the 95th percentile of the C3a / C3 ratio in samples derived from lupus nephritis subjects. The reference C3a / C3 ratio can be a value that is greater than or equal to the 100th percentile of the C3a / C3 ratio in samples derived from lupus nephritis subjects. In some embodiments, the reference C3a / C3 ratio is a value that is greater than or equal to the 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C3a / C3 ratio in samples derived from lupus nephritis subjects of a similar age. The reference C3a / C3 ratio can be a value that is greater than or equal to the 70th percentile of the C3a / C3 ratio in samples derived from lupus nephritis subjects of a similar age. The reference C3a / C3 ratio can be a value that is greater than or equal to the 75th percentile of the C3a / C3 ratio in samples derived from lupus nephritis subjects of a similar age. The reference C3a / C3 ratio can be a value that is greater than or equal to the 80th percentile of the C3a / C3 ratio in samples derived from lupus nephritis subjects of a similar age. The reference C3a / C3 ratio can be a value that is greater than or equal to the 85th percentile of the C3a / C3 ratio in samples derived from lupus nephritis subjects of a similar age. The reference C3a / C3 ratio can be a value that is greater than or equal to the 90th percentile of the C3a / C3 ratio in samples derived from lupus nephritis subjects of a similar age. The reference C3a / C3 ratio can be a value that is greater than or equal to the 95th percentile of the C3a / C3 ratio in samples derived from lupus nephritis subjects of a similar age. The reference C3a / C3 ratio can be a value that is greater than or equal to the 100th percentile of the C3a / C3 ratio in samples derived from lupus nephritis subjects of a similar age. In some embodiments, the reference C3a / C3 ratio is a value that is greater than or equal to the 50th percentile, 55th percentile, 60th percentile, 65th percentile, 70th percentile, 75th percentile, 80th percentile, 85th percentile, 90th percentile, 95th percentile, or 100th percentile of the C3a / C3 ratio in samples derived from normal or healthy subjects. The reference C3a / C3 ratio can be a value that is greater than or equal to the 70th percentile of the C3a / C3 ratio in samples derived from normal or healthy subjects. The reference C3a / C3 ratio can be a value that is greater than or equal to the 75th percentile of the C3a / C3 ratio in samples derived from normal or healthy subjects.The reference C3a / C3 ratio can be a value that is at least the 80th percentile of the C3a / C3 ratio in samples from normal or healthy subjects. The reference C3a / C3 ratio can be a value that is at least the 85th percentile of the C3a / C3 ratio in samples from normal or healthy subjects. The reference C3a / C3 ratio can be a value that is at least the 90th percentile of the C3a / C3 ratio in samples from normal or healthy subjects. The reference C3a / C3 ratio can be a value that is at least the 95th percentile of the C3a / C3 ratio in samples from normal or healthy subjects. The reference C3a / C3 ratio can be a value that is at least the 100th percentile of the C3a / C3 ratio in samples from normal or healthy subjects. In some embodiments, the reference C3a / C3 ratio is the 50th, 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile or greater of the C3a / C3 ratio in samples from normal or healthy subjects of a similar age. The reference C3a / C3 ratio can be a value that is at least the 70th percentile of the C3a / C3 ratio in samples from normal or healthy subjects of a similar age. The reference C3a / C3 ratio can be a value that is at least the 75th percentile of the C3a / C3 ratio in samples from normal or healthy subjects of a similar age. The reference C3a / C3 ratio can be a value that is at least the 80th percentile of the C3a / C3 ratio in samples from normal or healthy subjects of a similar age. The reference C3a / C3 ratio can be a value that is at least the 85th percentile of the C3a / C3 ratio in samples from normal or healthy subjects of a similar age. The reference C3a / C3 ratio can be a value that is at least the 90th percentile of the C3a / C3 ratio in samples from normal or healthy subjects of a similar age. The reference C3a / C3 ratio can be a value that is at least the 95th percentile of the C3a / C3 ratio in samples from normal or healthy subjects of a similar age. The reference C3a / C3 ratio can be a value that is at least the 100th percentile of the C3a / C3 ratio in samples from normal or healthy subjects of a similar age. In some embodiments, the normal or healthy subjects do not have lupus nephritis.In some embodiments, the elevated C3a / C3 ratio is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% greater than the reference C3a / C3 ratio. In some embodiments, the elevated C3a / C3 ratio is at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% greater than the reference C3a / C3 ratio.

[0323] In some embodiments, the subject has a decreased C3 level. In some embodiments, the subject has at least one of the following additional features: an elevated C4x level, an elevated C4x / C4 ratio, an elevated C1sC1 inhibitor level, an elevated C1sC1 inhibitor / C1s ratio, a decreased C1s level, an elevated C2b level, an elevated C2b / C2 ratio, a decreased C2 level, an elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) level, an elevated C3a level, an elevated C3a / C3 ratio, or a decreased C4 level. In some embodiments, the decreased C3 level is less than the C3 level in a normal or healthy subject. In some embodiments, the decreased C3 level is less than the C3 level in a normal or healthy subject of the same age. In some embodiments, the decreased C3 level is less than a reference C3 level. In some embodiments, the reference C3 level is a value that is less than the average or median C3 level in samples derived from lupus nephritis subjects. In some embodiments, the reference C3 level is a value that is less than the average or median C3 level in samples derived from lupus nephritis subjects of the same age. In some embodiments, the reference C3 level is a value that is less than or equal to the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C3 level in samples derived from lupus nephritis subjects. In some embodiments, the reference C3 level is a value that is less than or equal to the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C3 level in samples derived from lupus nephritis subjects of the same age.In some embodiments, the reference C3 level is a value that is at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C3 levels in samples from normal or healthy subjects. In some embodiments, the reference C3 level is a value that is at or below the 55th percentile, 50th percentile, 45th percentile, 40th percentile, 35th percentile, 30th percentile, 25th percentile, 20th percentile, 15th percentile, 10th percentile, 5th percentile, or 0th percentile of the C3 levels in samples from normal or healthy subjects of similar age. In some embodiments, the normal or healthy subjects do not have lupus nephritis. In some embodiments, the decreased C3 level is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% lower than the reference C4 level. In some embodiments, the decreased C3 level is at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, or 400% - 500% lower than the reference C4 level.

[0324] In some embodiments, the C4x level, or the C4x / C4 ratio, or the C4 level, or the C1sC1 inhibitor level, or the C1sC1 inhibitor / C1s ratio, or the C1s level, or the C2b level, or the C2b / C2 ratio, or the C2 level, or the PACA1 and / or PACA3 level, or the C3a level, or the C3a / C3 ratio, or the C3 level is measured in a biological sample. In some embodiments, the C4x level, or the C4x / C4 ratio, or the C4 level, or the C1sC1 inhibitor level, or the C1sC1 inhibitor / C1s ratio, or the C1s level, or the C2b level, or the C2b / C2 ratio, or the C2 level, or the PACA1 and / or PACA3 level, or the C3a level, or the C3a / C3 ratio, or the C3 level is measured in plasma or urine. In some embodiments, the C4x level, or the C4x / C4 ratio, or the C4 level, or the C1sC1 inhibitor level, or the C1sC1 inhibitor / C1s ratio, or the C1s level, or the C2b level, or the C2b / C2 ratio, or the C2 level, or the PACA1 and / or PACA3 level, or the C3a level, or the C3a / C3 ratio, or the C3 level is measured less than about 12 months prior to administration of a therapeutically effective amount of an inhibitor of the classical complement pathway. In some embodiments, the C4x level, or the C4x / C4 ratio, or the C4 level, or the C1sC1 inhibitor level, or the C1sC1 inhibitor / C1s ratio, or the C1s level, or the C2b level, or the C2b / C2 ratio, or the C2 level, or the PACA1 and / or PACA3 level, or the C3a level, or the C3a / C3 ratio, or the C3 level is measured less than about 6 months prior to administration of the inhibitor. In some embodiments, the C4x level, or the C4x / C4 ratio, or the C4 level, or the C1sC1 inhibitor level, or the C1sC1 inhibitor / C1s ratio, or the C1s level, or the C2b level, or the C2b / C2 ratio, or the C2 level, or the PACA1 and / or PACA3 level, or the C3a level, or the C3a / C3 ratio, or the C3 level is measured less than about 3 months prior to administration of the inhibitor.In some embodiments, the C4x level, or the C4x / C4 ratio, or the C4 level, or the C1sC1 inhibitor level, or the C1sC1 inhibitor / C1s ratio, or the C1s level, or the C2b level, or the C2b / C2 ratio, or the C2 level, or the PACA1 and / or PACA3 level, or the C3a level, or the C3a / C3 ratio, or the C3 level is measured less than about one month prior to administration of the inhibitor.

[0325] In some embodiments, the subject has an elevated urinary protein / creatinine ratio (UPCR) level. In some embodiments, the elevated UPCR level is higher than the UPCR level in a normal or healthy subject, higher than the UPCR level in a normal or healthy subject of similar age, or higher than a reference UPCR level. The reference UPCR level can be about 0.5 g / g, 1.0 g / g, 1.5 g / g, 2.0 g / g, 2.5 g / g, 3.0 g / g, 3.5 g / g, 4.0 g / g, 4.5 g / g, or 5.0 g / g or more. The elevated UPCR level can be at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 150%, 200%, 250%, 300%, 350%, 400%, 450%, 500%, 550%, 600%, 650%, 700%, 750%, 800%, 850%, 900%, 950%, 1000%, 2000%, 3000%, 4000%, or 5000% higher than the UPCR level in a normal or healthy subject or the reference UPCR level. The elevated UPCR level can be at least 1% - 10%, 10% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, 60% - 70%, 70% - 80%, 80% - 90%, 90% - 100%, 100% - 200%, 200% - 300%, 300% - 400%, 400% - 500%, 500% - 600%, 600% - 700%, 700% - 800%, 800% - 900%, 900% - 1000%, 1000% - 2000%, 2000% - 3000%, 3000% - 4000%, or 4000 - 5000% higher than the UPCR level in a normal or healthy subject or the reference UPCR level. In some embodiments, the UPCR level is measured in urine.

[0326] In some embodiments, the classical complement inhibitor is a C1 inhibitor, such as a small molecule, an antibody, an aptamer, an antisense nucleic acid, or a gene editing agent. In some embodiments, the antibody is a monoclonal antibody, a polyclonal antibody, a recombinant antibody, a humanized antibody, a human antibody, a chimeric antibody, a monovalent antibody, a multispecific antibody, or an antibody derivative thereof.

[0327] In some embodiments, the inhibitor of the classical complement pathway is a C1q inhibitor, such as a small molecule, an antibody, an aptamer, an antisense nucleic acid, or a gene editing agent. In some embodiments, the antibody is a monoclonal antibody, a polyclonal antibody, a recombinant antibody, a humanized antibody, a human antibody, a chimeric antibody, a monovalent antibody, a multispecific antibody, or an antibody derivative thereof. The antibody may be an anti-C1q antibody. In some embodiments, the antibody derivative is a single-arm antibody.

[0328] In some embodiments, the antibody is administered at a dose of at least 50 mg / kg, or at a dose of 50 mg / kg to 200 mg / kg. The antibody can be administered at a dose of 50 mg / kg, 55 mg / kg, 60 mg / kg, 65 mg / kg, 70 mg / kg, 75 mg / kg, 80 mg / kg, 85 mg / kg, 90 mg / kg, 95 mg / kg, 100 mg / kg, 105 mg / kg, 110 mg / kg, 115 mg / kg, 120 mg / kg, 125 mg / kg, 130 mg / kg, 135 mg / kg, 140 mg / kg, 145 mg / kg, 150 mg / kg, 155 mg / kg, 160 mg / kg, 165 mg / kg, 170 mg / kg, 175 mg / kg, 180 mg / kg, 185 mg / kg, 190 mg / kg, 195 mg / kg, or 200 mg / kg. In some embodiments, the antibody is administered up to a total of at least 50 mg. The antibody can be administered up to a total dose of 50 mg, 55 mg, 60 mg, 65 mg, 70 mg, 75 mg, 80 mg, 85 mg, 90 mg, 95 mg, 100 mg, 105 mg, 110 mg, 115 mg, 120 mg, 125 mg, 130 mg, 135 mg, 140 mg, 145 mg, 150 mg, 155 mg, 160 mg, 165 mg, 170 mg, 175 mg, 180 mg, 185 mg, 190 mg, 195 mg, or 200 mg. In some embodiments, the antibody is administered daily, once a week, once every two weeks, once a month, once every six weeks, or once every two months. In some embodiments, the antibody is administered for at least 3 months, 6 months, at least 7 months, at least 8 months, at least 9 months, at least 10 months, at least 11 months, or at least 12 months, preferably for at least 6 months. The antibody can be administered throughout the patient's life or intermittently throughout the patient's life, for example, in response to a flare. In some embodiments, the antibody is administered at a dose of 75 mg / kg on days 1 and 5 or 6. In some embodiments, the antibody is further administered at a dose of 100 mg / kg every two weeks. In some embodiments, the antibody is administered intravenously.

[0329] In some embodiments, the antibody is an antibody fragment such as a Fab fragment, a Fab' fragment, an F(ab')2 fragment, an Fv fragment, a diabody, or a single-chain antibody molecule. In some embodiments, the antibody fragment is administered at a total dose of at least 250 mg, or up to a total dose of 250 mg to 1000 mg. In some embodiments, the antibody fragment is administered at a total dose of 250 mg, 275 mg, 300 mg, 325 mg, 350 mg, 375 mg, 400 mg, 425 mg, 450 mg, 475 mg, 500 mg, 525 mg, 550 mg, 575 mg, 600 mg, 625 mg, 650 mg, 675 mg, 700 mg, 725 mg, 750 mg, 775 mg, 800 mg, 825 mg, 850 mg, 875 mg, 900 mg, 925 mg, 950 mg, 975 mg, 1000 mg, 1250 mg, 1275 mg, 1300 mg, 1325 mg, 1350 mg, 1375 mg, 1400 mg, 1425 mg, 1450 mg, 1475 mg, 1500 mg, 1525 mg, 1550 mg, 1575 mg, 1600 mg, 1625 mg, 1650 mg, 1675 mg, 1700 mg, 1725 mg, 1750 mg, 1775 mg, 1800 mg, 1825 mg, 1850 mg, 1875 mg, 1900 mg, 1925 mg, 1950 mg, 1975 mg, 2000 mg, 2250 mg, 2275 mg, 2300 mg, 2325 mg, 2350 mg, 2375 mg, 2400 mg, 2425 mg, 2450 mg, 2475 mg, 2500 mg, 2525 mg, 2550 mg, 2575 mg, 2600 mg, 2625 mg, 2650 mg, 2675 mg, 2700 mg, 2725 mg, 2750 mg, 2775 mg, 2800 mg, 2825 mg, 2850 mg, 2875 mg, 2900 mg, 2925 mg, 2950 mg, 2975 mg, or up to a total dose of 3000 mg. In some embodiments, the antibody fragment is administered at a total dose of about 750 mg. In some embodiments, the antibody fragment is administered once daily, once every two days, once every three days, once every four days, once every five days, or once every six days, once a week, once every two weeks, or once a month. In some embodiments, the antibody fragment is administered three times a week.In some embodiments, the antibody fragment is administered for at least 3 months, 6 months, at least 7 months, at least 8 months, at least 9 months, at least 10 months, at least 11 months, or at least 12 months. The antibody fragment can be administered over the lifetime of the patient or intermittently over the lifetime of the patient, for example, in response to a flare. In some embodiments, the antibody fragment is administered subcutaneously.

[0330] In some embodiments, the anti-C1q antibody inhibits the interaction between C1q and the autoantibody or between C1q and C1r or between C1q and C1s, and / or promotes the clearance of C1q from circulation or tissue. In some embodiments, the antibody comprises a light chain variable domain comprising HVR-L1 having the amino acid sequence of SEQ ID NO: 5, HVR-L2 having the amino acid of SEQ ID NO: 6, and HVR-L3 having the amino acid of SEQ ID NO: 7, and / or a heavy chain variable domain comprising HVR-H1 having the amino acid sequence of SEQ ID NO: 9, HVR-H2 having the amino acid of SEQ ID NO: 10, and HVR-H3 having the amino acid of SEQ ID NO: 11. In some embodiments, the antibody comprises a light chain variable domain comprising an amino acid sequence having at least about 95% homology with an amino acid sequence selected from SEQ ID NOs: 4 and 35-38, the light chain variable domain comprising HVR-L1 having the amino acid sequence of SEQ ID NO: 5, HVR-L2 having the amino acid of SEQ ID NO: 6, and HVR-L3 having the amino acid of SEQ ID NO: 7, preferably, the light chain variable domain comprises an amino acid sequence selected from SEQ ID NOs: 4 and 35-38. In some embodiments, the antibody comprises a light chain variable domain comprising an amino acid sequence having at least about 95% homology with an amino acid sequence selected from SEQ ID NOs: 8 and 31-34, the heavy chain variable domain comprising HVR-H1 having the amino acid sequence of SEQ ID NO: 9, HVR-H2 having the amino acid of SEQ ID NO: 10, and HVR-H3 having the amino acid of SEQ ID NO: 11, preferably, the heavy chain variable domain comprises an amino acid sequence selected from SEQ ID NOs: 8 and 31-34. In some embodiments, the antibody comprises a light chain domain comprising the amino acid sequence of SEQ ID NO: 40, a first heavy chain domain comprising the amino acid sequence of SEQ ID NO: 2, and a second heavy chain domain comprising the amino acid sequence of SEQ ID NO: 3, the second heavy chain domain being an N-terminal truncated heavy chain. In some embodiments, the antibody fragment comprises a heavy chain Fab fragment of SEQ ID NO: 39 and a light chain Fab fragment of SEQ ID NO: 40.

[0331] In some embodiments, an inhibitor of the classical complement pathway is a C1r inhibitor, e.g., a small molecule, an antibody, an aptamer, an antisense nucleic acid, or a gene editing agent, preferably an anti-C1r antibody. In some embodiments, the anti-C1r antibody inhibits the interaction between C1r and C1q, or between C1r and C1s, or the anti-C1r antibody inhibits the catalytic activity of C1r, or inhibits the processing of pro-C1r to the active protease.

[0332] In some embodiments, an inhibitor of the classical complement pathway is a C1s inhibitor, e.g., a small molecule, an antibody, an aptamer, an antisense nucleic acid, or a gene editing agent, preferably an anti-C1s antibody. In some embodiments, the anti-C1s antibody inhibits the interaction between C1s and C1q, or between C1s and C1r, or between C1s and C2 or C4, or the anti-C1s antibody inhibits the catalytic activity of C1s, or inhibits the processing of pro-C1s to the active protease, or binds to the activated form of C1s. In some embodiments, the antibody is stilmumab.

[0333] In some embodiments, an inhibitor of the classical complement pathway is an anti-C1 complex antibody, and optionally, the anti-C1 complex antibody inhibits the activation of C1r or C1s, or blocks their ability to act on C2 or C4. The anti-C1 complex antibody binds to a combined epitope within the C1 complex, and the combined epitope includes amino acids of both C1q and C1s, both C1q and C1r, both C1r and C1s, or each of C1q, C1r, and C1s.

[0334] In some embodiments, an inhibitor of the classical complement pathway is a C2 inhibitor, e.g., a small molecule, an antibody, an aptamer, an antisense nucleic acid, or a gene editing agent. The C2 inhibitor can be ARGX-117 (Argenx).

[0335] In some embodiments, an inhibitor of the classical complement pathway is a C3 inhibitor, e.g., a small molecule, an antibody, an aptamer, an antisense nucleic acid, or a gene editing agent. The C3 inhibitor can be APL-9 (Apellis) or AMY-101 (Amyndas).

[0336] In some embodiments, an inhibitor of the classical complement pathway is a C4 inhibitor, e.g., a small molecule, an antibody, an aptamer, an antisense nucleic acid, or a gene editing agent.

Example

[0337] Example 1: Improved Model for Predicting and Treating Lupus We observed evidence of complement activation in lupus nephritis patients compared to healthy controls. Specifically, the levels of C4a, C4d, C1sC1 inhibitor, PACA1, PACA3, and the ratios of C4a / C4, C4d / C4, C1sC1 inhibitor / C1s, C2b / C2, and C3a / C3 were very elevated in lupus nephritis patients, while the levels of C4, C1s, C2, and C3 were decreased in lupus nephritis patients. More specifically, the level of C4d and the C4d / C4 ratio were very increased in lupus nephritis patients with flares, while the levels of C1q, C1s, C2, and C4 were observed to decrease in line with activation of the classical complement pathway (increased activation and component consumption). The C4d / C4 ratio was also correlated with the levels of autoantibodies against C1q isotypes 1 and 3, which are known to activate the classical pathway. These data indicated that a subset of LN patients showing a high C4d / C4 ratio along with specific markers of classical pathway activation is likely to benefit from classical complement inhibitors, or more specifically, anti-C1q therapy. Furthermore, these data suggest that a subset of LN patients showing high levels of C4a, C4d, C1sC1 inhibitor, PACA1, PACA3, C4a / C4 is gC1sC1 inhibitor / C1s, and decreased levels of C2b / C2 or C4, C1s, C2 are likely to benefit from therapy with classical complement inhibitors, or more specifically, anti-C1q therapy.

Table 4

[0338] Patient attributes are shown in Figure 3. SELENA-SLEDAI uses the overall disease activity objective. Disease activity is evaluated by scoring 24 weighted disease activity descriptors of SLE as "present" or "absent" over the previous 10 days. See Bombardier C et al Arthritis Rheum 1992, Petri M.Ann Rheum Dis 2007, Petri et al N.Engl J Med 2005.

[0339] The following results were obtained. The C4d / C4 ratio was elevated in lupus nephritis (LN) patients, suggesting a role for the classical complement pathway in mediating the disease. Classical complement pathway activation is concentrated in LN. LN patients have upregulation of C1 inhibitor, probably due to chronic complement activation. There is a high correlation among complement factors in LN. PACA (pathogenic anti-C1q antibody) levels correlate with classical complement activation in lupus nephritis patients. The improved C4d / C4 ratio after treatment further supports the relevance of the complement pathway in disease pathology. Clinical C4 measurements track the UPCR (urine protein / creatinine ratio) trajectory. In this dataset, the C4d / C4 ratio is driven by low C4 (suggesting that patients do not have high C4 copy numbers). In patients with high disease activity, there is a transient decrease in the C4d / C4 ratio. However, those levels remain high compared to patients with low disease activity and healthy controls.

[0340] Classical complement pathway activation is concentrated in LN. Higher circulating C4d / C4 ratios in patients with active LN suggest that complement may drive disease progression and severity (Figure 4). LN patients with high C4d / C4 ratios show coordinated classical complement activation (Figure 5). The data show a reduction in classical substrates and an increase in products in LN patients compared to healthy controls.

[0341] In addition, higher circulating levels of C4a, C4d, C1sC1 inhibitor, PACA1, PACA3 and C2b / C2 ratio, C1sC1 inhibitor / C1s ratio and C3a / C3 ratio, as well as decreased levels of C4, C2, C1s, and C3 in patients with active LN, suggest that complement may drive disease progression and severity. (Figs. 21A - O).

[0342] High correlation between complement factors in LN. The high correlation between complement factors in LN patients suggests coordinated pathway activity (Figs. 6 and 22). In healthy controls, no correlation was observed (Fig. 7). The data show a strong association between high C4d / C4 ratio and the presence of PACA. The data also show strong associations between other cofactors in LN patients, for example, C4d / C4 and C4d have a strong positive correlation, and C2b and C2b / C2 have a strong inverse correlation (Fig. 22). The correlation is used to select patients most likely to respond to therapies with classical complement pathway, more specifically anti - C1q therapy.

[0343] PACA levels correlate with classical complement activation in lupus nephritis patients PACA1 levels remain elevated throughout the course of treatment. Active LN patients with high C4d / C4 ratio are likely to have higher PACA1 (Figs. 8A - 8B). PACA1 is likely to function as an additional factor to amplify disease severity. A subset of patients with high PACA do not have low C4.

[0344] Improved C4d / C4 ratio after treatment further supports the relevance of the complement pathway in disease pathology C4d / C4 reduces post-flare events with standard treatment, but the effect lacks durability (Figure 9). Figure 10 shows the changes in urinary protein / creatinine ratio (UPCR) and C4 in response to standard treatment. The elevated level of C4 is approximately equivalent to the reduction in C4d / C4 (C4d is novel and not regularly monitored). The rising C4 level coincides with an improved UPCR. The C4 level after a declining flare episode suggests residual inflammation that may lead to flare recurrence.

[0345] For example, anti-C1q treatment such as anti-C1q Fab (e.g., FabA) has the opportunity to improve the depth and durability of response in these patients by preventing complement activation. Anti-C1q Fab, FabA, may improve the proportion of complete responders by directly targeting the classical complement.

[0346] Data also show that clinical C4 measurement tracks the UPCR trajectory (Figure 11). The rising and falling C4d / C4 correlate with improved disease activity (Figure 12).

[0347] Summary In a cohort of 40 LN patients, the C4a, C4d, C1sC1 inhibitor, C3a, PACA1, PACA3 and C4a / C4, C4d / C4, C2b / C2, C3a / C3, and C1sC1 inhibitor / C1s ratios were found to be higher than in healthy controls, particularly those with active disease, indicating the involvement of classical complement activation in disease pathology. In addition, C4, C1, C2, and C3 were found to be lower than in healthy controls, particularly those with active disease, also indicating the involvement of classical complement activation in disease pathology. There is correlative evidence that PACA1 amplifies disease severity. In standard treatment, C4d / C4 did not normalize in non-responders, suggesting that existing treatments do not address the underlying disease cause in these patients. Patients with high C4d / C4 benefit from therapies targeting C1q, which inhibits activation of the disease-mediated pathway. Selecting patients with C4d / C4 opens the opportunity to target patients with complement activation as a major disease driver (and thus most likely to achieve improved outcomes) and to identify patients in earlier disease states (more likely to achieve superior outcomes). Selecting patients with at least elevated C4a, C4d, C1sC1 inhibitor, PACA1, PACA3 and C4a / C4 ratio, C2b / C2 ratio and C1sC1 inhibitor / C1s ratio, and reduced C4, C2 and C1s levels also opens the opportunity to target patients with complement activation as a major disease driver (and thus most likely to achieve improved outcomes) and to identify patients in earlier disease states (more likely to achieve superior outcomes).

[0348] Example 2: A single-arm, Phase 1b, open-label trial to evaluate the safety, tolerability, and pharmacodynamics of repeated subcutaneous FabA administration by standard treatment in adult participants with lupus nephritis The trial consists of a screening period of up to 8 weeks (56 days), an intervention period of approximately 3 weeks (22 days), and a post-treatment follow-up period of approximately 11 weeks (80 days). The maximum duration of participation is approximately 158 days (about 23 weeks). Participants are administered FabA 750 mg via an SC infusion pump three times a week, with a dosing interval of 3 days or less. The total dose administered in this LN trial is within the safety range established in non-clinical toxicity trials. In particular, in a non-clinical 4-week GLP toxicity trial in cynomolgus monkeys at SC doses up to 1500 mg human equivalent per day, no safety findings were observed (no observed adverse effect level [NOAEL] of 20 mg / kg per day, the maximum dose tested), during which complete C1q inhibition was observed in serum during the dosing interval.

[0349] Screening visits (-8 weeks, -6 weeks, and -2 weeks): All subjects undergo the study screening procedure within 56 days prior to dosing with FabA. Renal biopsy is required for participants who have not had a renal biopsy within 24 months of screening.

[0350] This study investigates the safety and PD effects of FabA administered via an SC infusion pump in participants with ISN / RPS class III / IV (±V) LN. Participants showing proteinuria in the range of 0.5 - 3.0 g / g / day using UPCR and evidence of classical complement activation (high C4d / C4 ratio) receive FabA in addition to stable standard therapy. This population is considered to have an incomplete renal response despite previous induction therapy with treatments such as cyclophosphamide, MMF, rituximab, and glucocorticoids.

[0351] A high C4d / C4 ratio is used to identify LN participants with classical complement pathway activation and ongoing renal inflammation. Approximately half of LN patients with a high C4d / C4 ratio have proteinuria in the range of 0.5 - 3.0 g / g / day (the remaining patients have proteinuria > 3.0 g / g / day), suggesting the presence of residual renal disease activity.

[0352] For the genetic studies related to this trial, samples (saliva or existing blood samples) are collected.

[0353] All participants are administered FabA 750 mg SC three times a week for approximately 3 weeks (10 doses) via an SC infusion pump, with a dosing interval of 3 days or less.

[0354] Example 3: The PACA plasma titer correlates with the degree of kidney injury in lupus nephritis patients. The PACA plasma titer correlates with the degree of kidney injury in lupus nephritis patients as evaluated by the urinary protein / creatinine ratio (UPCR) as a measure of proteinuria. PACA of IgG1 and IgG3 isotypes provided the strongest correlation with UPCR, but there was no significant correlation with the levels of IgG2 and IgG4 antibodies against C1q (Figure 13). These results are important because IgG1 and IgG3 are the antibody isotypes that most strongly mobilize additional C1q (the complement-fixing isotype), whereas IgG2 and IgG4 mobilize little or no C1q to immune complexes and are thus not associated with increasing disease levels. IgM antibodies strongly activate C1q, but they are characteristic of acute disease and are not expected to circulate at significant levels in chronic diseases such as lupus nephritis. PACA1 and PACA3 levels also correlate with C4d and the C4d / C4 ratio (Figure 14).

[0355] Furthermore, initial studies using animal models of lupus nephritis have reported a causal relationship between anti-C1q antibodies and kidney damage. Administration of PACA significantly exacerbates the disease with a substantial increase in complement deposition in the subendothelial space of glomeruli (Figures 17 and 18). PACA also selectively binds to substrate-bound C1q and is characterized by the ability to activate the classical complement pathway. PACA binding to substrate-bound C1q is not affected by soluble C1q (Figure 19). Thus, PACA correlates with disease severity and is complement-activating IgG1 and IgG3 isotypes that do not fix C1q over IgG4. Anti-C1q IgG1 and IgG3 levels (not IgG4 levels) correlate with the serum C4d / C4 ratio (Figure 20). This is consistent with the complement-activating ability of the antibody isotype.

[0356] Complement factor C4 and its activation product C4d are important biomarkers in LN. Reduced levels of C4 and increased amounts of C4d in the circulating signal activation of the classical complement pathway are associated with active LN. Plasma C4d levels are strongly associated with C4d deposition in kidney tissue from patients with active LN. The C4d / C4 ratio is elevated in active LN compared to SLE patients without LN, patients with the autoimmune kidney disease IgA nephropathy, and healthy controls. Furthermore, the C4d / C4 ratio accurately predicts the presence of active LN to a greater extent than other biomarkers (e.g., C3, C4, and C4d). Thus, C4d / C4 can identify patients with active LN who are most likely to respond to therapies targeting the classical complement cascade.

[0357] Together, this data provides strong scientific and clinical rationale for evaluating anti-C1q therapeutic agents in patients with class III / IV LN with evidence of classical complement pathway activation.

[0358] Example 4: Single-Arm, Phase 1b, Open-Label Trial to Evaluate the Safety, Tolerability, and Pharmacokinetics of Repeated Subcutaneous Administration of FabA by Standard Therapy in Adult Participants with Lupus Nephritis The trial consists of a screening period of up to 8 weeks (56 days), an intervention period of approximately 3 weeks (22 days), and a post-treatment follow-up period of approximately 11 weeks (80 days). The maximum duration of participation is approximately 158 days (about 23 weeks). Participants are administered FabA 750 mg via an SC infusion pump three times a week, with a dosing interval of 3 days or less. The total dose administered in this LN trial is within the safety range established in non-clinical toxicity trials. In particular, in a non-clinical 4-week GLP toxicity trial in cynomolgus monkeys at SC doses up to 1500 mg human equivalent per day, no safety findings were observed (no observed adverse effect level [NOAEL] of 20 mg / kg per day, the maximum dose tested), during which complete C1q inhibition was observed in serum during the dosing intervals.

[0359] Screening visits (-8 weeks, -6 weeks, and -2 weeks): All subjects undergo the study screening procedure within 56 days prior to dosing with FabA. Participants who have not had a renal biopsy within 24 months of screening require a renal biopsy.

[0360] This study investigates the safety and PD effects of FabA administered via an SC infusion pump in participants with ISN / RPS class III / IV (±V) LN. Participants demonstrating proteinuria in the range of 0.5 - 3.0 g / g / day using UPCR and evidence of classical complement activation (high C4d / C4 ratio) receive FabA in addition to stable standard therapy. This population is considered to have an incomplete renal response despite previous induction therapy with treatments such as cyclophosphamide, MMF, rituximab, and glucocorticoids.

[0361] A high C4d / C4 ratio is used to identify LN participants with classical complement pathway activation and ongoing kidney inflammation. A high C4d / C4 ratio in this study is defined as LN patients having a C4d / C4 ratio above the median in samples derived from LN subjects. Since approximately half of LN patients with a high C4d / C4 ratio have proteinuria in the range of 0.5 - 3.0 g / g / day (the remaining patients have proteinuria above 3.0 g / g / day), this suggests the presence of residual kidney disease activity.

[0362] For genetic studies related to this trial, samples (saliva or existing blood samples) are collected.

[0363] All participants are administered FabA 750 mg SC three times a week for approximately three weeks (10 doses) via a SC infusion pump, with an administration interval of three days or less.

[0364] Four patients completed treatment and screening is ongoing. Interim data showed that the C4d / C4 ratio decreased with treatment in all four patients and returned to baseline after cessation (Figure 23A). In addition, inhibition of C1q led to normalization of downstream markers including C3 and C59b, indicating that the classical pathway is an important driver of complement activation in these LN patients (Figures 23B - F). No consistent trend in the urinary protein creatinine ratio was observed in this short - term treatment trial.

[0365] In this interim analysis, subcutaneously administered FabA was well - tolerated and C1q target engagement and complement inhibition were demonstrated in four patients. In addition, normalization of all downstream components including C3 and C59 - b suggests that the classical pathway is a major driver of complement activation in these LN patients. These interim results support the use of anti - C1q therapy in a subset of LN patients.

[0366] Example 5: General Method The complement protein C4d is measured using the SVAR C4d ELISA kit (SVAR, COMPL C4d RUO). The levels of PACA1, PACA3, and the complement proteins C1s, C1sC1inh, C2, C2b, C4, C4a, C3, C3a, and C3d are measured in plasma samples using sandwich ELISA.

[0367] A black 96-well plate (Costar #3925) was coated overnight at 4 °C with 75 μL of 2 - 3 μg / mL capture antibody in bicarbonate buffer (pH 9.4). The next day, the plate was washed with dPBS (pH 7.4) and blocked with dPBS buffer containing 3% bovine serum albumin (BSA). Standards for the complement proteins C1s, C1sC1inh, C2, C2b, C4, C4a, C3, C3a, and C3d were purchased from Complement Tech and prepared in dPBS containing 0.3% BSA, 0.01 M EDTA, and 0.1% Tween (assay buffer respectively) in the range of 100 - 0.045, 1000 - 0.45, 200 - 0.09, 30 - 0.013, 100 - 0.04, 500 - 0.22, 100 - 0.045, 0.5 - 0.004, and 50 - 0.002 ng / mL. Standards for PACA1 (ATUM, 63044) and PACA3 (ATUM, 63050) were prepared in dPBS containing 0.3% BSA, 0.01 M EDTA, 0.1% Tween, and 1 M NaCl (high-salt assay buffer) in the range of 300 - 0.02 ng / mL. Plasma samples were diluted in the range of 30000 (C1), 90 (C1sC1inh), 8000 (C2), 2000 (C2b), 400,000 (C4), 200 (C4a), 200000 (C3), 50000 (C3a), 200000 (C3d) in assay buffer, and 20 (PACA1, PACA3) in the above high-salt assay buffer.

[0368] After 1 hour of incubation, remove the blocking buffer from the plate. Add standards and samples at 75 μL per well and incubate at 4 °C overnight with shaking at 300 rpm. Next, wash the plate three times with dPBS containing 0.05% Tween. Then, add 75 μL of the appropriate alkaline phosphatase-conjugated detection antibody to all wells. Incubate the plate for 1 hour with shaking at room temperature, wash three times with dPBS containing 0.05% Tween, and then develop using 75 μL of alkaline phosphatase substrate (Life Technologies, T2214). After a 20-minute incubation, read the plate using a luminometer. Standards are fitted using 4PL logistic fitting, unknowns are converted to concentration, corrected for dilution, and then plotted using appropriate plotting software, which in some of these examples is GraphPad Prism.

[0369] Incorporation by reference All publications, patents, and patent applications mentioned in this specification are hereby incorporated by reference in their entirety as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. In case of conflict, this application, including any definitions herein, will control.

[0370] Equivalents One of ordinary skill in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.

Claims

1. A composition comprising an anti-C1q antibody for the treatment of lupus nephritis in a subject requiring treatment, wherein the subject has been determined to have elevated levels of pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3).

2. The composition according to claim 1, wherein the subject has an increased C4d / C4 ratio.

3. The composition according to claim 2, wherein the elevated C4d / C4 ratio is greater than the C4d / C4 ratio in a normal or healthy subject, and optionally greater than the C4d / C4 ratio in a normal or healthy subject of the same age.

4. The aforementioned increased C4d / C4 ratio is greater than the reference C4d / C4 ratio. In some cases, the aforementioned standard C4d / C4 ratio is greater than or equal to the mean or median C4d / C4 ratio in samples derived from subjects with lupus nephritis; The aforementioned reference C4d / C4 ratio is greater than or equal to the mean or median C4d / C4 ratio in samples derived from lupus nephritis subjects of similar age; The aforementioned reference C4d / C4 ratio is a value of the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile or higher of the C4d / C4 ratio in samples derived from subjects with lupus nephritis; The aforementioned reference C4d / C4 ratio is a value of the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile or higher of the C4d / C4 ratio in samples derived from subjects with lupus nephritis of similar age; The aforementioned reference C4d / C4 ratio is a value of the 50th, 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile or higher of the C4d / C4 ratio in a sample derived from a normal or healthy subject; The aforementioned reference C4d / C4 ratio is a value of the 50th, 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile or higher of the C4d / C4 ratio in samples derived from normal or healthy subjects of similar age; The increased C4d / C4 ratio is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% greater than the reference C4d / C4 ratio; or, The increased C4d / C4 ratio is at least 1% to 10%, 10% to 20%, 20% to 30%, 30% to 40%, 40% to 50%, 50% to 60%, 60% to 70%, 70% to 80%, 80% to 90%, 90% to 100%, 100% to 200%, 200% to 300%, 300% to 400%, or 400% to 500% greater than the reference C4d / C4 ratio. The composition according to claim 2.

5. The aforementioned subject has the following additional characteristics: a. Elevated C4a levels, b. Increased C4a / C4 ratio, c. Decreased C4 level, d. Increased C1s C1 inhibitor / C1s ratio, e. Elevated C1sC1 inhibitor levels, f. Decreased C1s level, g. Elevated C2b levels, h. Increased C2b / C2 ratio, i. Decreased C2 level, j. Elevated C3a level, k. Increased C3a / C3 ratio, or l. The composition according to any one of claims 1 to 4, having at least one of the reduced C3 levels.

6. The elevated PACA1 and / or PACA3 levels are higher than those in normal or healthy subjects. The composition according to any one of claims 1 to 4, wherein the PACA1 and / or PACA3 levels are, in some cases, higher than those in normal or healthy subjects of similar age.

7. If the elevated PACA1 and / or PACA3 levels are higher than the reference PACA1 and / or PACA3 levels, In some cases, the aforementioned standard PACA1 and / or PACA3 levels are equal to or greater than the mean or median PACA1 and / or PACA3 levels in samples derived from subjects with lupus nephritis; The aforementioned criterion PACA1 and / or PACA3 levels are equal to or greater than the mean or median PACA1 and / or PACA3 levels in samples derived from lupus nephritis subjects of similar age; The aforementioned standard PACA1 and / or PACA3 levels are values ​​of the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile or higher for PACA1 and / or PACA3 levels in samples derived from subjects with lupus nephritis; The aforementioned reference PACA1 and / or PACA3 levels are values ​​of the 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile or higher for PACA1 and / or PACA3 levels in samples derived from subjects with lupus nephritis of similar age; The aforementioned standard PACA1 and / or PACA3 levels are values ​​of the 50th, 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile or higher for PACA1 and / or PACA3 levels in a sample derived from a normal or healthy subject; The aforementioned reference PACA1 and / or PACA3 levels are values ​​of the 50th, 55th, 60th, 65th, 70th, 75th, 80th, 85th, 90th, 95th, or 100th percentile or higher for PACA1 and / or PACA3 levels in samples derived from normal or healthy subjects of similar age; The elevated PACA1 and / or PACA3 levels are at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, or 500% higher than the reference PACA1 and / or PACA3 levels; or The elevated PACA1 and / or PACA3 levels are at least 1% to 10%, 10% to 20%, 20% to 30%, 30% to 40%, 40% to 50%, 50% to 60%, 60% to 70%, 70% to 80%, 80% to 90%, 90% to 100%, 100% to 200%, 200% to 300%, 300% to 400%, or 400% to 500% higher than the reference PACA1 and / or PACA3 levels. The composition according to any one of claims 1 to 4.

8. The composition according to any one of claims 2 to 4, wherein the C4d level, or the C4d / C4 ratio, or the C4 level, or the PACA1 and / or PACA3 level is measured in plasma or urine.

9. The subject has an elevated urinary protein / creatinine ratio (UPCR) level, In some cases, the elevated UPCR levels may be higher than those in normal or healthy subjects; The elevated UPCR level is higher than the UPCR level in normal or healthy subjects of similar age; or The aforementioned elevated UPCR level is higher than the reference UPCR level. Furthermore, in some cases, the aforementioned standard UPCR level may be approximately 0.5 g / g, 1.0 g / g, 1.5 g / g, 2.0 g / g, 2.5 g / g, 3.0 g / g, 3.5 g / g, 4.0 g / g, 4.5 g / g, or 5.0 g / g or higher. Preferably, the elevated UPCR level is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 150%, 200%, 250%, 300%, 350%, 400%, 450%, 500%, 550%, 600%, 650%, 700%, 750%, 800%, 850%, 900%, 950%, 1000%, 2000%, 3000%, 4000%, or 5000% higher; or The elevated UPCR level is at least 1% to 10%, 10% to 20%, 20% to 30%, 30% to 40%, 40% to 50%, 50% to 60%, 60% to 70%, 70% to 80%, 80% to 90%, 90% to 100%, 100% to 200%, 200% to 300%, 300% to 400%, 400% to 500%, 500% to 600%, 600% to 700%, 700% to 800%, 800% to 900%, 900% to 1000%, 1000% to 2000%, 2000% to 3000%, 3000% to 4000%, or 4000% to 5000% higher than the UPCR level or reference UPCR level in a normal or healthy subject. The composition according to any one of claims 1 to 4.

10. The composition according to any one of claims 1 to 4, wherein the anti-C1q antibody is a monoclonal antibody, a polyclonal antibody, a recombinant antibody, a humanized antibody, a chimeric antibody, a multispecific antibody, an antibody fragment, or an antibody derivative thereof.

11. The anti-C1q antibody is administered at a dose of at least 50 mg / kg; The anti-C1q antibody is administered at a dose of 50 mg / kg to 200 mg / kg; The anti-C1q antibody is administered in doses of 50 mg / kg, 55 mg / kg, 60 mg / kg, 65 mg / kg, 70 mg / kg, 75 mg / kg, 80 mg / kg, 85 mg / kg, 90 mg / kg, 95 mg / kg, 100 mg / kg, 105 mg / kg, 110 mg / kg, 115 mg / kg, 120 mg / kg, 125 mg / kg, 130 mg / kg, 135 mg / kg, 140 mg / kg, 145 mg / kg, 150 mg / kg, 155 mg / kg, 160 mg / kg, 165 mg / kg, 170 mg / kg, 175 mg / kg, 180 mg / kg, 185 mg / kg, 190 mg / kg, 195 mg / kg, or 200 mg / kg; The anti-C1q antibody is administered up to a total of at least 50 mg; or The anti-C1q antibody is administered up to a total dose of 50 mg, 55 mg, 60 mg, 65 mg, 70 mg, 75 mg, 80 mg, 85 mg, 90 mg, 95 mg, 100 mg, 105 mg, 110 mg, 115 mg, 120 mg, 125 mg, 130 mg, 135 mg, 140 mg, 145 mg, 150 mg, 155 mg, 160 mg, 165 mg, 170 mg, 175 mg, 180 mg, 185 mg, 190 mg, 195 mg, or 200 mg. In some cases, the anti-C1q antibody is administered daily; The aforementioned anti-C1q antibody is administered once a week; The aforementioned anti-C1q antibody is administered once every two weeks; The aforementioned anti-C1q antibody is administered once a month; The aforementioned anti-C1q antibody is administered once every six weeks; The aforementioned anti-C1q antibody is administered once every two months; The anti-C1q antibody is administered for at least 3 months, at least 6 months, at least 7 months, at least 8 months, at least 9 months, at least 10 months, at least 11 months, or at least 12 months; The aforementioned anti-C1q antibody is administered for six months; The anti-C1q antibody is administered to the patient throughout their entire life, or intermittently throughout their entire life in response to a flare. The composition according to claim 10.

12. The anti-C1q antibody is administered at a dose of 75 mg / kg on day 1 and on day 5 or day 6. In some cases, the C1q antibody may be further administered at a dose of 100 mg / kg every two weeks. Furthermore, in some cases, the C1q antibody may be administered intravenously. The composition according to claim 10.

13. The anti-C1q antibody is an antibody fragment or derivative selected from the Fab fragment, Fab' fragment, F(ab')2 fragment, Fv fragment, diabody, or single-chain antibody molecule. In some cases, the antibody fragment may be administered up to a total dose of at least 250 mg; The antibody fragment is administered up to a total dose of 250 mg to 1000 mg; or, The aforementioned antibody fragments are 250 mg, 275 mg, 300 mg, 325 mg, 350 mg, 375 mg, 400 mg, 425 mg, 450 mg, 475 mg, 500 mg, 525 mg, 550 mg, 575 mg, 600 mg, 625 mg, 650 mg, 675 mg, 700 mg, 725 mg, 750 mg, 775 mg, 800 mg, 825 mg, 850 mg, 87 5mg, 900mg, 925mg, 950mg, 975mg, 1000mg, 1250mg, 1275mg, 1300mg, 1325mg, 1350mg, 1375mg, 140 0mg, 1425mg, 1450mg, 1475mg, 1500mg, 1525mg, 1550mg, 1575mg, 1600mg, 1625mg, 1650mg, 1675mg, 1700mg, 1725mg, 1750mg, 1775mg, 1800mg, 1825mg, 1850mg, 1875mg, 1900mg, 1925mg, 1950mg, 197 5mg, 2000mg, 2250mg, 2275mg, 2300mg, 2325mg, 2350mg, 2375mg, 2400mg, 2425mg, 2450mg, 2475mg, Administered in doses of 2500 mg, 2525 mg, 2550 mg, 2575 mg, 2600 mg, 2625 mg, 2650 mg, 2675 mg, 2700 mg, 2725 mg, 2750 mg, 2775 mg, 2800 mg, 2825 mg, 2850 mg, 2875 mg, 2900 mg, 2925 mg, 2950 mg, 2975 mg, or up to a total dose of 3000 mg. Furthermore, in some cases, the antibody fragment may be administered daily; The antibody fragment is administered once every two days; The antibody fragment is administered once every three days, once every four days, once every five days, or once every six days; The antibody fragment is administered once a week; The antibody fragment is administered once every two weeks; The antibody fragment is administered once a month; The antibody fragment is administered for at least 3 months, 6 months, at least 7 months, at least 8 months, at least 9 months, at least 10 months, at least 11 months, or at least 12 months; or, The antibody fragment is administered intermittently throughout the patient's entire life, or intermittently throughout the patient's entire life during a flare. Preferably, the antibody fragment is administered subcutaneously. The composition according to claim 10.

14. The anti-C1q antibody comprises a light chain variable domain including HVR-L1 having the amino acid sequence of SEQ ID NO: 5, HVR-L2 having the amino acid sequence of SEQ ID NO: 6, and HVR-L3 having the amino acid sequence of SEQ ID NO: 7, and a heavy chain variable domain including HVR-H1 having the amino acid sequence of SEQ ID NO: 9, HVR-H2 having the amino acid sequence of SEQ ID NO: 10, and HVR-H3 having the amino acid sequence of SEQ ID NO:

11. In some cases, the antibody includes a light chain variable domain having an amino acid sequence having at least about 95% homology to an amino acid sequence selected from SEQ ID NOs. 4 and 35-38, wherein the light chain variable domain includes HVR-L1 having the amino acid sequence of SEQ ID NO. 5, HVR-L2 having the amino acids of SEQ ID NO. 6, and HVR-L3 having the amino acids of SEQ ID NO.

7. Furthermore, in some cases, the light chain variable domain includes an amino acid sequence selected from SEQ ID NOs: 4 and 35-38. Preferably, the antibody comprises a heavy chain variable domain having an amino acid sequence having at least about 95% homology to an amino acid sequence selected from SEQ ID NOs. 8 and 31-34, wherein the heavy chain variable domain comprises HVR-H1 having the amino acid sequence of SEQ ID NOs. 9, HVR-H2 having the amino acids of SEQ ID NOs. 10, and HVR-H3 having the amino acids of SEQ ID NOs.

11. More preferably, the heavy chain variable domain comprises an amino acid sequence selected from SEQ ID NOs: 8 and 31-34. The composition according to any one of claims 1 to 4.

15. The composition according to claim 13, wherein the antibody fragment comprises the heavy chain Fab fragment of SEQ ID NO: 39 and the light chain Fab fragment of SEQ ID NO:

40.

16. Use of an anti-C1q antibody for manufacturing a pharmaceutical product for the treatment of lupus nephritis in a subject requiring treatment, wherein the subject is determined to have elevated pathogenic anti-C1q antibody 1 (PACA1) and / or pathogenic anti-C1q antibody 3 (PACA3) levels.

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