Nucleic acids encoding an Anti-HJV antibody and uses thereof

Abstract

Aspects of the application provide an anti-hemojuvelin (HJV) antibody, nucleic acids encoding the same, and methods producing the same.

Description

NUCLEIC ACIDS ENCODING AN ANTI-HJV ANTIBODY AND USES THEREOFRELATED APPLICATION

[0001] This application claims the benefit under 35 U.S.C. § 119(e) of US Provisional Application No. 63 / 654,624, filed May 31, 2024, entitled “NUCLEIC ACIDS ENCODING AN ANTI-HJV ANTIBODY AND USES THEREOF” the content of which is hereby incorporated by reference herein in its entirety for all purposes.REFERENCE TO AN ELECTRONIC SEQUENCE LISTING

[0002] The contents of the electronic sequence listing (D084270017WO00-SEQ-VLJ.xml; Size: 39,826 bytes; and Date of Creation: May 28, 2025) are herein incorporated by reference in its entirety.BACKGROUND

[0003] Iron is a key component of oxygen-transporting storage molecules, such as hemoglobin and myoglobin. Iron deficiency results in anemia, while iron overload leads to tissue damage and fibrosis. Hepcidin is a key peptide hormonal regulator of systemic iron homeostasis. It exerts its regulatory function by binding to the cellular iron exporter ferroportin, a transmembrane protein present on hepatocytes, enterocytes in the duodenum, macrophages, and adipocytes. The binding of hepcidin promotes ferroportin degradation, preventing the export of iron from cells and release of iron into the plasma.SUMMARY

[0004] Aspects of the disclosure provide nucleic acids encoding an antibody that binds to Hemojuvelin (HJV), and methods of producing the same. In some embodiments, an anti-HJV antibody described herein comprises a signal peptide. In some embodiments, the present disclosure provides methods of producing an anti-HJV antibody using nucleic acids encoding a signal peptide and the heavy chain of the antibody, and nucleic acids encoding the signal peptide and the light chain of the antibody.

[0005] In some aspects, the present disclosure provides an isolated nucleic acid encoding a heavy chain variable region (VH) and / or a light chain variable region (VL) of an anti- hemojuvelin (HJV) antibody comprising: (a) a nucleic acid sequence at least 80% identical to SEQ ID NO: 28; and / or (b) a nucleic acid sequence at least 80% identical to SEQ ID NO: 29.

[0006] In some embodiments, the isolated nucleic acid comprising the nucleic acid sequence of SEQ ID NO: 28. In some embodiments, the isolated nucleic acid comprising the nucleic acid sequence of SEQ ID NO: 29. In some embodiments, the isolated nucleic acid comprising the nucleic acid sequence of SEQ ID NO: 28 and SEQ ID NO: 29.

[0007] In some embodiments, the isolated nucleic acid comprises: (a) a nucleic acid at least 80% identical to SEQ ID NO: 19; and / or (b) a nucleic acid at least 80% identical to SEQ ID NO: 20.

[0008] In some embodiments, the isolated nucleic acid comprises the nucleic acid sequence of SEQ ID NO: 19. In some embodiments, the isolated nucleic acid comprises the nucleic acid sequence of SEQ ID NO: 20. In some embodiments, the isolated nucleic acid comprises the nucleic acid sequence of SEQ ID NO: 19 and SEQ ID NO: 20.

[0009] In some embodiments, the heavy chain and / or the light chain of the antibody comprise a signal peptide. In some embodiments, the signal peptide comprises the amino acid sequence of SEQ ID NO: 15. In some embodiments, the nucleic acid encoding the signal peptide comprises a nucleic acid sequence at least 80% identical to SEQ ID NOs: 21 or 32. In some embodiments, the nucleic acid encoding the signal peptide comprises the nucleic acid sequence of SEQ ID NO: 21. In some embodiments, the nucleic acid encoding the signal peptide comprises the nucleic acid sequence of SEQ ID NO: 32.

[0010] In some embodiments, the isolated nucleic acid comprises: (a) a nucleic acid sequence that is at least 80% identical to SEQ ID NO: 22; and / or (b) a nucleic acid sequence that is at least 80% identical to SEQ ID NO: 23. In some embodiments, the isolated nucleic acid comprises the nucleic acid sequence of SEQ ID NO: 22. In some embodiments, the isolated nucleic acid comprises the nucleic acid sequence of SEQ ID NO: 23. In some embodiments, the isolated nucleic acid comprises the nucleic acid sequence of SEQ ID NO: 22 and SEQ ID NO: 23.

[0011] In some aspects, the present disclosure provides an antibody comprising: (a) a heavy chain comprising the amino acid sequence encoded by SEQ ID NOs: 19 or 22; and (b) a light chain comprising the amino acid sequence encoded by SEQ ID NOs: 20 or 23.

[0012] In some aspects, the present disclosure provides a vector comprising the isolated nucleic acid encoding the VH and / or VL, or heavy chain and / or light chain of an- anti-HJV antibody described herein.

[0013] In some aspects, the present disclosure provides a host cell comprising the isolated nucleic acid, the antibody, or the vector described herein. In some embodiments, the host cell is a Chinese hamster ovary (CHO) cell, a dhfr’CHO cell, a human embryonic kidney(HEK)-293 cell, a verda reno (VERO) cell, a nonsecreting null (NSO) cell, a human embryonic retinal (PER.C6) cell, an Sp2 / 0 cell, a baby hamster kidney (BHK) cell, a Madin- Darby Canine Kidney (MDCK) cell, a Madin-Darby Bovine Kidney (MDBK) cell, or a monkey kidney CV1 line transformed by SV40 (COS) cell. In some embodiments, the host cell is a dhfr’CHO cell. In some embodiments, the host cell is a CHO DG44 cell.

[0014] In some aspects, the present disclosure provides a method of producing an anti-HJV antibody, the method comprising: (i) culturing the host cell comprising the isolated nucleic acid or the vector encoding the VH and / or VL under conditions allowing for expression of the antibody; and (ii) harvesting the cultured host cell or culture medium for collection of the anti-HJV antibody. In some aspects, the present disclosure provides a method of producing an anti-HJV antibody, the method comprising: (i) culturing the host cell comprising the isolated nucleic acid or the vector encoding the heavy chain and / or light chain under conditions allowing for expression of the antibody; and (ii) harvesting the cultured host cell or culture medium for collection of the anti-HJV antibody. In some embodiments, the method further comprises purifying the anti-HJV antibody.

[0015] In some aspects, the present disclosure provides a composition comprising the isolated nucleic acid, the vector, the antibody or the host cell described herein.

[0016] In some aspects, the present disclosure provides a method of producing an anti-hemojuvelin (HJV) antibody, the method comprising: (i) culturing a host cell comprising a nucleic acid that encodes a light chain and / or a heavy chain of an anti-HJV antibody, wherein: (a) the nucleic acid encoding the heavy chain is at least 80% identical to SEQ ID NOs: 19; and / or (b) the nucleic acid encoding the light chain is at least 80% identical to SEQ ID NOs: 20; and (ii) harvesting the cultured host cell or culture medium for collection of the antibody. In some embodiments, the method further comprises purifying the anti-HJV antibody. In some embodiments, the nucleic acid encoding the heavy chain comprises the nucleic acid sequence of SEQ ID NO: 19. In some embodiments, the nucleic acid encoding the light chain comprises the nucleic acid sequence of SEQ ID NO: 20. In some embodiments, the nucleic acid further encodes a signal peptide for the heavy chain and / or a signal peptide for the light chain. In some embodiments, the nucleic acid encoding the signal peptide is at least 80% identical to SEQ ID NO: 21 or 32. In some embodiments, the nucleic acid encoding the heavy chain comprises the nucleic acid sequence of SEQ ID NO: 22. In some embodiments, the nucleic acid encoding the light chain comprises the nucleic acid sequence of SEQ ID NO: 23.DETAILED DESCRIPTION

[0017] The present disclosure, at least in part, is based on the development of nucleic acids encoding an anti-Hemojuvelin (HJV) antibody (e.g., the antibody listed in Table 1) which has high binding affinity and specificity to human HJV. In some embodiments, also provided herein are methods of making anti-HJV antibodies (e.g., the antibody listed in Table 1) using the nucleic acids described herein. In some embodiments, an anti-HJV antibody described herein comprises a signal peptide. In some embodiments, the present disclosure provides methods of producing an anti-HJV antibody using nucleic acids encoding a signal peptide and the heavy chain of the antibody, and nucleic acids encoding the signal peptide and the light chain of the antibody.

[0018] The foregoing and other aspects, implementations, acts, functionalities, features, and embodiments of the present teachings can be more fully understood from the following description.I. Definitions

[0019] Affinity Matured Antibody: As used herein, the term “Affinity Matured Antibody” is used to refer to an antibody with one or more alterations in one or more CDRs, which result in an improvement in the affinity (i.e. KD, kd or ka) of the antibody for a target antigen compared to a parent antibody, which does not possess the alteration(s). Exemplary affinity matured antibodies will have nanomolar or even picomolar affinities for the target antigen. A variety of procedures for producing affinity matured antibodies are known in the art, including the screening of a combinatory antibody library that has been prepared using bio-display. For example, Marks et al., BioTechnology, 10: 779-783 (1992) describes affinity maturation by VH and VL domain shuffling. Random mutagenesis of CDR and / or framework residues is described by 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): 3310-3319 (1995); and Hawkins et al, J. Mol. Biol., 226: 889-896 (1992). Selective mutation at selective mutagenesis positions and at contact or hypermutation positions with an activity-enhancing amino acid residue is described in U.S. Pat. No. 6,914,128 Bl.

[0020] Antibody: As used herein, the term “antibody” refers to a polypeptide that includes at least one immunoglobulin variable domain or at least one antigenic determinant (e.g., paratope that specifically binds to an antigen). In some embodiments, an antibody is a full-length antibody. In some embodiments, an antibody is a chimeric antibody. In some embodiments, an antibody is a humanized antibody. In some embodiments, an antibody is a Fab fragment, a F(ab')2 fragment, an Fv fragment, or an scFv fragment. In some embodiments, an antibody is a nanobody derived from a camelid antibody or a nanobody derived from shark antibody. In some embodiments, an antibody is a diabody. In some embodiments, an antibody comprises a framework having a human germline sequence. In another embodiment, an antibody comprises a heavy chain constant domain selected from the group consisting of IgG, IgGl, IgG2, IgG2A, IgG2B, IgG2C, IgG3, IgG4, IgAl, IgA2, IgD, IgM, and IgE constant domains. In some embodiments, an antibody comprises a heavy (H) chain variable region (abbreviated herein as VH), and / or a light (L) chain variable region (abbreviated herein as VL). In some embodiments, an antibody comprises a constant domain (e.g., an Fc region). An immunoglobulin constant domain refers to a heavy or light chain constant domain. Human IgG heavy chain and light chain constant domain amino acid sequences and their functional variations are known. With respect to the heavy chain, in some embodiments, the heavy chain of an antibody described herein can be an alpha (a), delta (5), epsilon (a), gamma (y) or mu (p) heavy chain. In some embodiments, the heavy chain of an antibody described herein can comprise a human alpha (a), delta (5), epsilon (a), gamma (y) or mu (p) heavy chain. In a particular embodiment, an antibody described herein comprises a human gamma 1 CHI, CH2, and / or CH3 domain. In some embodiments, the amino acid sequence of the VH domain comprises the amino acid sequence of a human gamma (y) heavy chain constant region, such as any known in the art. Non-limiting examples of human constant region sequences have been described in the art (see, e.g., U.S. Pat. No. 5,693,780 and Kabat E A et al., (1991) supra). In some embodiments, the VH domain comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 98%, or at least 99% identical to any of the variable chain constant regions provided herein. In some embodiments, an antibody is modified, e.g., modified via glycosylation, phosphorylation, sumoylation, and / or methylation. In some embodiments, an antibody is a glycosylated antibody, which is conjugated to one or more sugar or carbohydrate molecules. In some embodiments, the one or more sugar or carbohydrate molecules are conjugated to the antibody via N-glycosylation, O- glycosylation, C-glycosylation, glypiation (GPI anchor attachment), and / or phosphoglycosylation. In some embodiments, the one or more sugar or carbohydrate molecules are monosaccharides, disaccharides, oligosaccharides, or glycans. In some embodiments, the one or more sugar or carbohydrate molecules is a branched oligosaccharide or a branched glycan. In some embodiments, the one or more sugar or carbohydratemolecules include a mannose unit, a glucose unit, an N-acetylglucosamine unit, or a phospholipid unit. In some embodiments, an antibody is a construct that comprises a polypeptide comprising one or more antigen binding fragments of the disclosure linked to a linker polypeptide or an immunoglobulin constant domain. Linker polypeptides comprise two or more amino acid residues joined by peptide bonds and are used to link one or more antigen binding portions. Examples of linker polypeptides have been reported (see, e.g., Holliger, P., et al. (1993) Proc. Natl. Acad. Sci. USA 90:6444-6448; Poljak, R. J., et al. (1994) Structure 2: 1121-1123). Still further, an antibody may be part of a larger immunoadhesion molecule, formed by covalent or noncovalent association of the antibody or antibody portion with one or more other proteins or peptides. Examples of such immunoadhesion molecules include the use of a streptavidin core region to make a tetrameric scFv molecule (see, e.g., Kipriyanov, S. M., et al. (1995) Human Antibodies and Hybridomas 6:93-101) and the use of a cysteine residue, a marker peptide, and a C-terminal polyhistidine tag to make bivalent and biotinylated scFv molecules (see, e.g., Kipriyanov, S. M., et al. (1994) Mol. Immunol. 31 : 1047-1058).

[0021] Approximately: As used herein, the term “approximately” or “about,” as applied to one or more values of interest refers to a value that is similar to a stated reference value. In certain embodiments, the term “approximately” or “about” refers to a range of values that fall within 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or less in either direction (greater than or less than) of the stated reference value unless otherwise stated or otherwise evident from the context (except where such number would exceed 100% of a possible value).

[0022] CDR: As used herein, the term "CDR" refers to the complementarity determining region (CDR) within antibody variable sequences. A typical antibody molecule comprises a heavy chain variable region (VH) and a light chain variable region (VL), which are usually involved in antigen binding. The VH and VL regions can be further subdivided into regions of hypervariability, also known as “complementarity determining regions” (“CDRs”), interspersed with regions that are more conserved, which are known as “framework regions” (“FR”). Each VH and VL is typically composed of three CDRs and four FRs, arranged from amino-terminus to carboxy -terminus in the following order: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4. The extent of the FRs and CDRs can be precisely identified using methodology known in the art, for example, by the Kabat definition, the IMGT definition, the Chothia definition, the AbM definition, and / or the contact definition, all of which are well known in the art (see, e.g., Kabat, E.A., et al. (1991) Sequences of Proteins of Immunological Interest,Fifth Edition, U.S. Department of Health and Human Services, NIH Publication No. 91-3242; IMGT®, the international ImMunoGeneTics information system® imgt.org, Lefranc, M.-P. et al., Nucleic Acids Res., 27:209-212 (1999); Ruiz, M. et al., Nucleic Acids Res., 28:219- 221 (2000); Lefranc, M.-P., Nucleic Acids Res., 29:207-209 (2001); Lefranc, M.-P., Nucleic Acids Res., 31 :307-310 (2003); Lefranc, M.-P. et al., In Silico Biol., 5, 0006 (2004) [Epub], 5:45-60 (2005); Lefranc, M.-P. et al., Nucleic Acids Res., 33:D593-597 (2005); Lefranc, M - P. et al., Nucleic Acids Res., 37:D1006-1012 (2009); Lefranc, M.-P. et al., Nucleic Acids Res., 43:D413-422 (2015); Chothia et al., (1989) Nature 342:877; Chothia, C. et al. (1987) J. Mol. Biol. 196:901-917, Al-lazikani et al (1997) J. Molec. Biol. 273:927-948; and Almagro, J. Mol. Recognit. 17: 132-143 (2004)). See also hgmp.mrc.ac.uk and bioinf.org.uk / abs. As used herein, a CDR may refer to a CDR defined by any method known in the art. Two antibodies having the same CDR means that the two antibodies have the same amino acid sequence of that CDR as determined by the same method, for example, the IMGT definition.

[0023] Generally, there are three CDRs in each of the variable regions of the heavy chain and the light chain, which are designated CDR1, CDR2 and CDR3, for each of the variable regions. The term "CDR set" as used herein refers to a group of three CDRs that occur in a single variable region capable of binding the antigen. The exact boundaries of these CDRs have been defined differently according to different systems. The system described by Kabat (Kabat et al., Sequences of Proteins of Immunological Interest (National Institutes of Health, Bethesda, Md. (1987) and (1991)) not only provides an unambiguous residue numbering system applicable to any variable region of an antibody, but also provides precise residue boundaries defining the three CDRs. These CDRs may be referred to as Kabat CDRs. Subportions of CDRs may be designated as LI, L2 and L3 or Hl, H2, and H3 where the "L" and the "H" designate the light chain and the heavy chains regions, respectively. These regions may be referred to as Chothia CDRs, which have boundaries that overlap with Kabat CDRs. Other boundaries defining CDRs overlapping with the Kabat CDRs have been described by Padlan (FASEB J. 9: 133-139 (1995)) and MacCallum (J Mol Biol 262(5):732-45 (1996)). Still other CDR boundary definitions may not strictly follow one of the above systems, but will nonetheless overlap with the Kabat CDRs, although they may be shortened or lengthened in light of prediction or experimental findings that particular residues or groups of residues or even entire CDRs do not significantly impact antigen binding. The methods used herein may utilize CDRs defined according to any of these systems, although preferred embodiments use Kabat or Chothia defined CDRs.

[0024] Complementary: As used herein, the term “complementary” refers to the capacity for precise pairing between two nucleotides or two sets of nucleotides. In particular, complementary is a term that characterizes an extent of hydrogen bond pairing that brings about binding between two nucleotides or two sets of nucleotides. For example, if a base at one position of an oligonucleotide is capable of hydrogen bonding with a base at the corresponding position of a target nucleic acid (e.g., an mRNA), then the bases are considered complementary to each other at that position. Base pairings may include canonical Watson-Crick base pairing and non-Watson-Crick base pairing (e.g., Wobble base pairing and Hoogsteen base pairing). For example, in some embodiments, for complementary base pairings, adenosine-type bases (A) are complementary to thymidine-type bases (T) or uracil- type bases (U), that cytosine-type bases (C) are complementary to guanosine-type bases (G), and that universal bases such as 3 -nitropyrrole or 5-nitroindole can hybridize to and are considered complementary to any A, C, U, or T. Inosine (I) has also been considered in the art to be a universal base and is considered complementary to any A, C, U or T.

[0025] Conservative amino acid substitution: As used herein, a “conservative amino acid substitution” refers to an amino acid substitution that does not alter the relative charge or size characteristics of the protein in which the amino acid substitution is made. Variants can be prepared according to methods for altering polypeptide sequence known to one of ordinary skill in the art such as are found in references which compile such methods. See, e.g., Molecular Cloning: A Laboratory Manual, J. Sambrook, et al., eds., Fourth Edition, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York, 2012, or Current Protocols in Molecular Biology, F.M. Ausubel, et al., eds., John Wiley & Sons, Inc., New York. Conservative substitutions of amino acids include substitutions made amongst amino acids within the following groups: (a) M, I, L, V; (b) F, Y, W; (c) K, R, H; (d) A, G; (e) S, T; (f) Q, N; and (g) E, D.

[0026] Cross-reactive: As used herein and in the context of a targeting agent (e.g., an antibody), the term “cross-reactive,” refers to a property of the agent being capable of specifically binding to more than one antigen of a similar type or class (e.g., antigens of multiple homologs, paralogs, or orthologs) with similar affinity or avidity. For example, in some embodiments, an anti-HJV antibody that is cross-reactive against human and nonhuman primate antigens of a similar type or class (e.g., a human hemojuvelin and non-human primate hemojuvelin) is capable of binding to the human antigen and non-human primate antigens with a similar affinity or avidity. In some embodiments, an antibody is cross- reactive against a human antigen and a rodent antigen of a similar type or class. In someembodiments, an antibody is cross-reactive against a rodent antigen and a non-human primate antigen of a similar type or class. In some embodiments, an antibody is cross-reactive against a human antigen, a non-human primate antigen, and a rodent antigen of a similar type or class.

[0027] Framework: As used herein, the term "framework" or "framework sequence" refers to the remaining sequences of a variable region minus the CDRs. Because the exact definition of a CDR sequence can be determined by different systems, the meaning of a framework sequence is subject to correspondingly different interpretations. The six CDRs (CDR-L1, CDR-L2, and CDR-L3 of the light chain and CDR-H1, CDR-H2, and CDR-H3 of the heavy chain) also divide the framework regions on the light chain and the heavy chain into four subregions (FR1, FR2, FR3, and FR4) on each chain, in which CDR1 is positioned between FR1 and FR2, CDR2 between FR2 and FR3, and CDR3 between FR3 and FR4. Without specifying the particular sub-regions as FR1, FR2, FR3, or FR4, a framework region, as referred by others, represents the combined FRs within the variable region of a single, naturally-occurring immunoglobulin chain. As used herein, a FR represents one of the four sub-regions, and FRs represent two or more of the four sub-regions constituting a framework region. Human heavy chain and light chain acceptor sequences are known in the art. In one embodiment, the acceptor sequences known in the art may be used in the antibodies disclosed herein.

[0028] Hemojuvelin (HJV): As used herein, the term “hemojuvelin (HJV)” (also known as repulsive guidance molecule C (RGMc) or hemochromatosis type 2 protein (HFE2)) refers to a membrane-bound and soluble form protein that regulates hepcidin production through the BMP / SMAD signaling pathway. The HFE2 gene encodes two known classes of GPI- anchored and glycosylated HJV molecules, which are targeted to the membrane and undergo distinct fates. HJV exists in multiple isoforms, including two soluble isoforms and two membrane-associated isoforms. In some embodiments, a predominant membrane-associated isoform is a disulfide-linked two-chain form composed of N- and C-terminal fragments. In some embodiments, a full-length single-chain isoform associates with the membrane but is released from the cell surface and accumulates in extracellular fluid. In some embodiments, HJV may be of human (e.g., NCBI Gene ID 148738), non-human primate (e.g., NCBI Gene ID 698805), or rodent (e.g., NCBI Gene ID 69585 or NCBI Gene ID 310681) origin. In addition to HJV (RGMc), the repulsive guidance molecule family includes repulsive guidance molecule A (RGMa) and repulsive guidance molecule B (RGMb). RGMa and RGMb are expressed in the central nervous system during development and are thought to beinvolved in controlling axonal patterning and neuronal survival, while HJV is produced in the liver and in cardiac and skeletal muscle.

[0029] Human antibody: As used herein, the term "human antibody" includes antibodies having variable and constant regions derived from human germline immunoglobulin sequences. The human antibodies of the disclosure may include amino acid residues not encoded by human germline immunoglobulin sequences (e.g., mutations introduced by random or site-specific mutagenesis in vitro or by somatic mutation in vivo), for example in the CDRs and, in particular, CDR3. However, the term "human antibody", as used herein, does not include antibodies in which CDR sequences derived from the germline of another mammalian species, such as a mouse, have been grafted onto human framework sequences.

[0030] Humanized antibody: As used herein, the term "humanized antibody" refers to antibodies which comprise heavy and light chain variable region sequences from a nonhuman species (e.g., a mouse) but in which at least a portion of the VH and / or VL sequence has been altered to be more "human -like", i.e., more similar to human germline variable sequences. One type of humanized antibody is a CDR-grafted antibody, in which human CDR sequences are introduced into non-human VH and VL sequences to replace the corresponding nonhuman CDR sequences. In some embodiments, humanized anti-HJV antibodies and antigen binding portions are provided. Such antibodies may be generated by obtaining murine anti-HJV monoclonal antibodies using traditional hybridoma technology followed by humanization using in vitro genetic engineering (see, e.g., Kasaian et al., PCT Publication No. WO 2005 / 123126 A2).

[0031] Identity: As used herein, the terms “identity,” “identical,” and “homology” refer to the percent identity between two nucleic acids (e.g., polynucleotides or oligonucleotides) or two polypeptide moieties. Identity is readily determined by one of skill in the art by, for example, the use of algorithms and computer programs known by those of skill in the art. As described herein, alignments between sequences of nucleic acids or polypeptides are performed using any of a variety of publicly or commercially available Multiple Sequence Alignment Programs (such as, for example "Clustal W") accessible through Web Servers on the internet. Alternatively, Vector NTI utilities may also be used. There are also a number of algorithms known in the art that can be used to measure nucleotide sequence identity, including those contained in the programs described above. As another example, polynucleotide sequences can be compared using BLASTN, which provides alignments and percent sequence identity of the regions of the best overlap between the query and search sequences. Similar programs are available for the comparison of amino acid sequences, e.g.,the "Clustal X" program, BLASTP. Typically, any of these programs are used at default settings, although one of skill in the art can alter these settings as needed. Alternatively, one of skill in the art can utilize another algorithm or computer program that provides at least the level of identity or alignment as that provided by the referenced algorithms and programs. Alignments may be used to identify corresponding amino acids between two proteins or peptides. A “corresponding amino acid” is an amino acid of a protein or peptide sequence that has been aligned with an amino acid of another protein or peptide sequence. Corresponding amino acids may be identical or non-identical. A corresponding amino acid that is a non-identical amino acid may be referred to as a variant amino acid.

[0032] Isolated antibody: As used herein, the term "isolated antibody" refers to an antibody that is substantially free of other antibodies having different antigenic specificities (e.g., an isolated antibody that specifically binds HJV is substantially free of antibodies that specifically bind antigens other than HJV). An isolated antibody that specifically binds HJV may, however, have cross-reactivity to other antigens, such as other repulsive guidance molecule (RGM) proteins (e.g., RGMa and / or RGMb). Moreover, an isolated antibody may be substantially free of other cellular material and / or chemicals.

[0033] Kabat numbering: As used herein, the terms "Kabat numbering," "Kabat definitions,” and "Kabat labeling" are used interchangeably. These terms, which are recognized in the art, refer to a system of numbering amino acid residues which are more variable (i.e. hypervariable) than other amino acid residues in the heavy and light chain variable regions of an antibody, or an antigen binding portion thereof (Kabat et al. (1971) Ann. NY Acad, Sci. 190:382-391 and, Kabat, E. A., et al. (1991) Sequences of Proteins of Immunological Interest, Fifth Edition, U.S. Department of Health and Human Services, NIH Publication No. 91-3242). For the heavy chain variable region, the hypervariable region ranges from amino acid positions 31 to 35 for CDR1, amino acid positions 50 to 65 for CDR2, and amino acid positions 95 to 102 for CDR3. For the light chain variable region, the hypervariable region ranges from amino acid positions 24 to 34 for CDR1, amino acid positions 50 to 56 for CDR2, and amino acid positions 89 to 97 for CDR3.

[0034] Recombinant antibody: As used herein, the term "recombinant human antibody" includes all human antibodies that are prepared, expressed, created or isolated by recombinant means, such as antibodies expressed using a recombinant expression vector transfected into a host cell (described in more details in this disclosure), antibodies isolated from a recombinant, combinatorial human antibody library (see, e.g., Hoogenboom H. R., (1997) TIB Tech. 15:62-70; Azzazy H., and Highsmith W. E., (2002) Clin. Biochem. 35:425-445; Gavilondo J. V., and Larrick J. W. (2002) BioTechniques 29: 128-145; Hoogenboom H., and Chames P. (2000) Immunology Today 21 :371-378), antibodies isolated from an animal (e.g., a mouse) that is transgenic for human immunoglobulin genes (see, e.g, Taylor, L. D., et al. (1992) Nucl. Acids Res. 20:6287-6295; Kellermann S-A., and Green L. L. (2002) Current Opinion in Biotechnology 13:593-597; Little M. et al (2000) Immunology Today 21 :364-370) or antibodies prepared, expressed, created, or isolated by any other means that involves splicing of human immunoglobulin gene sequences to other DNA sequences. Such recombinant human antibodies have variable and constant regions derived from human germline immunoglobulin sequences. In certain embodiments, however, such recombinant human antibodies are subjected to in vitro mutagenesis (or, when an animal transgenic for human Ig sequences is used, in vivo somatic mutagenesis) and thus the amino acid sequences of the VH and VL regions of the recombinant antibodies are sequences that, while derived from and related to human germline VH and VL sequences, may not naturally exist within the human antibody germline repertoire in vivo. In some embodiments, fully human antibodies are capable of binding human hemojuvelin which can be generated using techniques well known in the art, such as, but not limited to, using human Ig phage libraries such as those disclosed in Jermutus et al. (PCT publication No. WO 2005 / 007699 A2).

[0035] Selective: As used herein, the term “selective” or “selectively” refers to the ability of a molecule to produce an effect in relation to its target molecule compared to a reference molecule. For example, a molecule that selectively inhibits its target molecule means that this molecule is capable of inhibiting its target molecule to a degree that is distinguishable from a reference molecule in an inhibition assay or other inhibitory context. For example, with respect to an inhibitor, the term “selectively inhibits” refers to the ability of the inhibitor to inhibit its target molecule with a degree that is distinguishable from a reference molecule that is not substantially inhibited in an inhibition assay, e.g, to an extent that permit selective inhibition of the target molecule, as described herein. For example, the half maximal inhibitory concentration (IC50) for the target molecule and / or the reference molecule can be tested in a kinase potency assay as described in Asshoff et al., Momelotinib inhibits ACVR1 / ALK2, decreases hepcidin production, and ameliorates anemia of chronic disease in rodents. Blood. 2017 Mar 30; 129(13): 1823-1830 (e.g., Kinase potency assay by Carna Biosciences). In this assay, inhibitor solution (e.g., solution containing the selective inhibitor to be tested) / kinase substrate is mixed with target molecule solution (e.g, ALK2) or reference molecule solution (e.g., JAK1 or JAK2), and incubated under room temperature for 1 hour. Once the reaction is terminated, the signal produced by enzymatic activity on the substratecan be measured. The half maximal inhibitor concentration for the target molecule and the reference molecule can be calculated. In some embodiments, a molecule described herein selectively binds to a target molecule. In some embodiments, a molecule described herein selectively inhibits to a target molecule. In some embodiments, a molecule described herein selectively antagonizes a target molecule. In some embodiments, a molecule described herein selectively neutralizes to a target molecule.

[0036] Specifically binds: As used herein, the term “specifically binds” refers to the ability of a molecule to bind to a binding partner with a degree of affinity or avidity that enables the molecule to be used to distinguish the binding partner from an appropriate control in a binding assay or other binding context. With respect to an antibody, the term, “specifically binds”, refers to the ability of the antibody to bind to a specific antigen with a degree of affinity or avidity, compared with an appropriate reference antigen or antigens, that enables the antibody to be used to distinguish the specific antigen from others, e.g., to an extent that permits preferential targeting to certain cells, e.g., muscle cells, through binding to the antigen, as described herein. In some embodiments, an antibody specifically binds to a target if the antibody has a KD for binding the target of at least about 10'4M, 10'5M, 10'6M, 10'7M, 10'8M, 10'9M, IO'10M, 10'11M, 10'12M, 10'13M, or less. In some embodiments, an antibody specifically binds to hemojuvelin.II. Anti-Hemojuvelin (HJV) Antibodies

[0037] Provided herein is an antibody that binds to human HJV with high specificity and affinity. In some embodiments, the anti-HJV antibody selectively binds HJV (RGMc) over RGMa and RGMb. In some embodiments, the anti-HJV antibody binds to one or more proteins of the repulsive guidance molecule (RGM) family, including RGMa, RGMb, and RGMc (HJV). In some embodiments, the anti-HJV antibody specifically binds to any extracellular epitope of HJV or an epitope that becomes exposed to the antibody. In some embodiments, the anti-HJV antibody provided herein binds specifically to HJV from humans, non-human primates, mice, rats, etc. In some embodiments, the anti-HJV antibody binds to human HJV. In some embodiments, the anti-HJV antibody binds to an amino acid segment of a human and / or a non-human primate HJV. In some embodiments, the anti-HJV antibody binds to an amino acid segment of both a human and a non-human primate HJV.

[0038] In some embodiments, the anti-HJV antibody specifically binds to an epitope on human HJV. Human HJV is a 426 amino acid protein with a predicted N-terminal signalpeptide of 31 amino acids and a C-terminal GPI-attachment signal of 45 amino acids. An exemplary human HJV amino acid sequence is set forth in SEQ ID NO: 16:MGEPGQSPSPRSSHGSPPTLSTLTLLLLLCGHAHSQCKILRCNAEYVSSTLSL RGGGSSGALRGGGGGGRGGGVGSGGLCRALRSYALCTRRTARTCRGDLAFHSA VHGIEDLMIQHNCSRQGPTAPPPPRGPALPGAGSGLPAPDPCDYEGRFSRLHG RPPGFLHCASFGDPHVRSFHHHFHTCRVQGAWPLLDNDFLFVQATSSPMALGA NATATRKLTI I FKNMQECIDQKVYQAEVDNLPVAFEDGSINGGDRPGGSSLSI QTANPGNHVE I QAAY I GTT 111 RQTAGQLS FS I KVAEDVAMAFSAEQDLQLCV GGCPPSQRLSRSERNRRGAITIDTARRLCKEGLPVEDAYFHSCVFDVLISGDP NFTVAAQAALEDARAFLPDLEKLHLFPSDAGVPLSSATLLAPLLSGLFVLWLCIQ (SEQ ID NO: 16)

[0039] In some embodiments, the anti-HJV antibody described herein may bind to a fragment of human HJV. The fragment of HJV may be between about 5 and about 425 amino acids, between about 10 and about 400 amino acids, between about 50 and about 350 amino acids, between about 100 and about 300 amino acids, between about 150 and about 250 amino acids, between about 200 and about 300 amino acids, or between about 75 and about 150 amino acids in length. The fragment may comprise a contiguous number of amino acids from HJV (RGMc). An exemplary amino acid of a HJV fragment is set forth in SEQ ID NO: 17:QCKILRCNAEYVSSTLSLRGGGSSGALRGGGGGGRGGGVGSGGLCRALRSYAL CTRRTARTCRGDLAFHSAVHGIEDLMIQHNCSRQGPTAPPPPRGPALPGAGSG LPAPDPCDYEGRFSRLHGRPPGFLHCASFGDPHVRSFHHHFHTCRVQGAWPLL DND FL FVQAT S S PMALGANATAT RKLT 11 FKNMQE C I DQKVYQAE VDNL PVAF EDGSINGGDRPGGSSLSIQTANPGNHVEIQAAYIGTTI I IRQTAGQLSFSIKV AEDVAMAFSAEQDLQLCVGGCPPSQRLSRSERNRRGAITIDTARRLCKEGLPV EDAYFHSCVFDVLISGDPNFTVAAQAALEDARAFLPDLEKLHLFPSD (SEQ ID NO: 17)

[0040] In some embodiments, the anti-HJV antibody binds to different epitopes within a human HJV or a human HJV fragment.

[0041] In some embodiments, the anti-HJV antibody interacts with an epitope within amino acids 160-190 of SEQ ID NO: 17. In some embodiments, the anti-HJV antibody interacts with an epitope having an amino acid sequence of amino acids 170-183 of SEQ ID NO: 17. In some embodiments, the anti-HJV antibody interacts with an epitope having the amino acid sequence of SSPMALGANATATR (SEQ ID NO: 18). In some embodiments, the anti-HJV antibody interacts with different segments within SSPMALGANATATR (SEQ ID NO: 18). In some embodiments, the anti-HJV antibody interacts with amino acids 170-171, amino acids 171-180, amino acids 180-182, and amino acids 182-183 of SEQ ID NO: 17. In someembodiments, the anti-HJV antibody interacts with amino acids 170 (S), 171 (S), 180 (T), 182 (T) and 183 (R) of SEQ ID NO: 17. In some embodiments, the anti-HJV antibody interacts with the epitope SSPMALGANATATR (SEQ ID NO: 18). In some embodiments, the anti- HJV antibody interacts with amino acids 170 (S), 171 (S), 180 (T), 182 (T) and 183 (R) of SEQ ID NO: 17.

[0042] In some embodiments, the anti-HJV antibody is an affinity matured clone. In some embodiments, the anti- HJV antibody specifically binds HJV (e.g., human or non-human primate HJV) with binding affinity (e.g., as indicated by KD) of about 10'4M, 10'5M, 10'6M, IO’7M, IO’8M, IO’9M, IO’10M, 10’11M, IO’12M, IO’13M, or less. For example, the anti-HJV antibody of the present disclosure can bind to a hemojuvelin protein (e.g., human hemojuvelin) with an affinity between 5 pM and 500 nM, e.g., between 50 pM and 100 nM, e.g., between 500 pM and 50 nM. The affinity and binding kinetics of the anti-HJV antibody can be tested using any suitable method including, but not limited to, biosensor technology (e.g, OCTET or BIACORE). In some embodiments, the anti- HJV antibody binds to HJV with a KD of sub-nanomolar range. In some embodiments, the anti- HJV antibody selectively binds to RGMc, but not RGMa or RGMb.

[0043] Binding affinity (or binding specificity) can be determined by a variety of methods including equilibrium dialysis, equilibrium binding, gel filtration, ELISA, surface plasmon resonance (SPR), fl orescent activated cell sorting (FACS) or spectroscopy (e.g., using a fluorescence assay). Exemplary conditions for evaluating binding affinity are in HBS-P buffer (10 mM HEPES pH7.4, 150 mM NaCl, 0.005% (v / v) surfactant P20) and PBS buffer (lOmM PO4-3, 137mM NaCl, and 2.7mM KC1). These techniques can be used to measure the concentration of bound proteins as a function of target protein concentration. The concentration of bound protein ([Bound]) is generally related to the concentration of free target protein ([Free]) by the following equation: [Bound] = [Free] / (Kd+[Free])

[0044] In some embodiments, the anti-HJV antibody comprises a signal peptide. A signal peptide, also known as a signal sequence, leader sequence, or leader peptide, is a short peptide generally present at the N-terminus of newly synthesized proteins that are destined for the secretory pathway. Signal peptide refers to a short peptide (e.g., 5-30 amino acids in length, such as 22-26 amino acids in length) at the N-terminus of a polypeptide that directs a polypeptide towards the secretory pathway (e.g., the extracellular space). The signal peptide is typically cleaved during secretion of the polypeptide. The signal peptide may direct the polypeptide to an intracellular compartment or organelle, e.g., the Golgi apparatus. A signal peptide may be identified by homology, or biological activity, to a peptide with the knownfunction of targeting a polypeptide to a particular region of the cell. In some embodiments, a signal peptide plays a crucial role in directing a nascent protein to the endoplasmic reticulum (ER) in eukaryotic cells (e.g., in a host cell). In some embodiments, the anti-HJV antibody comprises a signal peptide in the heavy and / or light chain (e.g., an N-terminal signal peptide). In some embodiments, the signal peptide comprises the amino acid sequence MLRGPGPGLLLAVLCLGTAVRCTEA (SEQ ID NO: 15). In some embodiments, the amino acid sequence of the signal peptide is at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 15. In some embodiments, the nucleic acid encoding the signal peptide comprises a nucleic acid sequence set forth in SEQ ID NO: 21. In some embodiments, the nucleic acid encoding the signal peptide comprises a nucleic acid sequence that is at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the nucleic acid sequence set forth in SEQ ID NO: 21. In some embodiments, a signal peptide is cleaved off of the heavy and / or light chain (e.g., by a signal peptidase) to produce a mature antibody.

[0045] Exemplary amino acid sequences of the anti-HJV antibody are provided herein in Table 1.Table 1. Amino acid sequences of an anti-HJV antibody (CDRs according to Kabat definition).

[0046] In some embodiments, the N-terminal of the heavy chain of the anti-HJV antibody described herein is glutamic acid (E). In some embodiments, the glutamic acid can cyclize spontaneously to pyroglutamic acid by post-translational modification. Spontaneouscyclization of glutamic acid to pyroglutamic acid has been previously described, e.g., Chelius et al., Formation of Pyroglutamic Acid From N-terminal Glutamic Acid in Immunoglobulin Gamma Antibodies, Anal Chem. 2006;78(7):2370-2376. In some embodiments, the N- terminal of the heavy chain of the anti-HJV antibody described herein is a pyroglutamic acid. In some embodiments, the anti-HJV antibodies having N-terminal pyroglutamic acid are impurities in the population of anti-HJV antibodies (e.g., less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, less than 0.5%, less than 0.1%, less than 0.05%, or less than 0.01%) in the population of anti-HJV antibody. In some embodiments, the population of the anti-HJV antibodies comprises a mixture of anti-HJV antibodies having glutamic acid or pyroglutamic acid at the N-terminal of the heavy chain.

[0047] Also within the scope of the present disclosure are functional variants of any of the exemplary anti-HJV antibodies as disclosed herein. A functional variant may contain one or more amino acid residue variations in the VH and / or VL, or in one or more of the HC CDRs and / or one or more of the LC CDRs as relative to the reference antibody, while retaining substantially similar binding and biological activities e.g., substantially similar binding affinity, binding specificity, inhibitory activity, anti-inflammatory activity, or a combination thereof) as the reference antibody. It should be appreciated that conservative amino acid substitutions may be made to provide functionally equivalent variants of the anti-HJV antibody. In some aspects, the disclosure embraces sequence alterations that result in conservative amino acid substitutions. As used herein, a conservative amino acid substitution refers to an amino acid substitution that does not alter the relative charge or size characteristics of the protein in which the amino acid substitution is made. Variants can be prepared according to methods for altering polypeptide sequence known to one of ordinary skill in the art, such as are found in references that compile such methods, e.g., Molecular Cloning: A Laboratory Manual, J. Sambrook, et al., eds., Second Edition, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York, 1989, or Current Protocols in Molecular Biology, F.M. Ausubel, et al., eds., John Wiley & Sons, Inc., New York. Conservative substitutions of amino acids include substitutions made among amino acids within the following groups: (a) M, I, L, V; (b) F, Y, W; (c) K, R, H; (d) A, G; (e) S, T; (f) Q, N; and (g) E, D. Therefore, one can make conservative amino acid substitutions to the amino acid sequence of the proteins and polypeptides disclosed herein.

[0048] In some embodiments, the anti-HJV antibodies of the present disclosure comprises one or more of the HC CDRs (e.g., HC CDR1, HC CDR2, or HC CDR3) amino acid sequences from any one of the anti-HJV antibodies selected from Table 1. In someembodiments, the anti-HJV antibodies of the present disclosure comprise the HC CDR1, HC CDR2, and HC CDR3 as provided for any one of the antibodies elected from Table 1. In some embodiments, the anti-HJV antibodies of the present disclosure comprises one or more of the LC CDRs (e.g., LC CDR1, LC CDR2, or LC CDR3) amino acid sequences from any one of the anti-HJV antibodies selected from Table 1. In some embodiments, the anti-HJV antibodies of the present disclosure comprise the LC CDR1, LC CDR2, and LC CDR3as provided for any one of the anti-HJV antibodies selected from Table 1.

[0049] In some embodiments, the anti-HJV antibodies of the present disclosure comprises the HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and LC CDR3 as provided for any one of the anti-HJV antibodies selected from Table 1. In some embodiments, antibody heavy and light chain CDR3 domains may play a particularly important role in the binding specificity / affinity of an antibody for an antigen. Accordingly, the anti-HJV antibodies of the disclosure may include at least the heavy and / or light chain CDR3s of the anti-HJV antibodies selected from Table 1.

[0050] Also within the scope of the present disclosure are functional variants of any of the exemplary anti-HJV antibodies as disclosed herein. A functional variant may contain one or more amino acid residue variations in the VH and / or VL, or in one or more of the HC CDRs and / or one or more of the LC CDRs as relative to the reference antibody, while retaining substantially similar binding and biological activities e.g., substantially similar binding affinity, binding specificity, inhibitory activity, anti-inflammatory activity, or a combination thereof) as the reference antibody.

[0051] In some embodiments, any of the anti-HJV antibodies of the disclosure have one or more CDRs (e.g., HC CDR or LC CDR) sequences substantially similar to any of the HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 sequences from one of the anti-HJV antibodies selected from Table 1. In some embodiments, the position of one or more CDRs along the VH (e.g, HC CDR1, HC CDR2, or HC CDR3) and / or VL (e.g, LC CDR1, LC CDR2, or LC CDR3) region of an antibody described herein can vary by one, two, three, four, five, or six amino acid positions so long as immunospecific binding to hemojuvelin (e.g, human hemojuvelin) is maintained (e.g, substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% of the binding of the original antibody from which it is derived). For example, in some embodiments, the position defining a CDR of any antibody described herein can vary by shifting the N-terminal and / or C-terminal boundary of the CDR by one, two, three, four, five, or six amino acids, relative to the CDR position of any one of the antibodies described herein,so long as immunospecific binding to hemojuvelin (e.g., human hemojuvelin) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% of the binding of the original antibody from which it is derived). In another embodiment, the length of one or more CDRs along the VH (e.g., HC CDR1, HC CDR2, or HC CDR3) and / or VL (e g., LC CDR1, LC CDR2, or LC CDR3) region of an antibody described herein can vary (e.g., be shorter or longer) by one, two, three, four, five, or more amino acids, so long as immunospecific binding to hemojuvelin (e.g., human hemojuvelin) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% of the binding of the original antibody from which it is derived).

[0052] Accordingly, in some embodiments, a HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 described herein may be one, two, three, four, five or more amino acids shorter than one or more of the CDRs described herein (e.g., CDRS from any of the anti-HJV antibodies selected from Table 1) so long as immunospecific binding to hemojuvelin (e.g., human hemojuvelin) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% relative to the binding of the original antibody from which it is derived). In some embodiments, a HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 described herein may be one, two, three, four, five or more amino acids longer than one or more of the CDRs described herein (e.g., CDRS from any of the anti-HJV antibodies selected from Table 1) so long as immunospecific binding to hemojuvelin (e.g., human hemojuvelin) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% relative to the binding of the original antibody from which it is derived). In some embodiments, the amino portion of a HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 described herein can be extended by one, two, three, four, five or more amino acids compared to one or more of the CDRs described herein (e.g., CDRS from any of the anti-HJV antibodies selected from Table 1) so long as immunospecific binding to hemojuvelin (e.g., human hemojuvelin) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% relative to the binding of the original antibody from which it is derived). In some embodiments, the carboxy portion of a HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 described herein can be extended by one, two, three, four, five or more amino acids compared to one or more of the CDRs described herein (e.g., CDRS from any of the anti-HJV antibodies selected from Table 1) so long asimmunospecific binding to hemojuvelin (e.g., human hemojuvelin) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% relative to the binding of the original antibody from which it is derived). In some embodiments, the amino portion of a HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 described herein can be shortened by one, two, three, four, five or more amino acids compared to one or more of the CDRs described herein (e.g., CDRS from any of the anti-HJV antibodies selected from Table 1) so long as immunospecific binding to hemojuvelin (e.g., human hemojuvelin) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% relative to the binding of the original antibody from which it is derived). In some embodiments, the carboxy portion of a HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 described herein can be shortened by one, two, three, four, five or more amino acids compared to one or more of the CDRs described herein (e.g., CDRS from any of the anti-HJV antibodies selected from Table 1) so long as immunospecific binding to hemojuvelin (e.g., human hemojuvelin) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% relative to the binding of the original antibody from which it is derived). Any method can be used to ascertain whether immunospecific binding to hemojuvelin (e.g., human hemojuvelin) is maintained, for example, using binding assays and conditions described in the art.

[0053] In some examples, any of the anti-HJV antibodies of the disclosure have one or more CDR (e.g., HC CDR or LC CDR) sequences substantially similar to any one of the anti- HJV antibodies selected from Table 1. For example, the antibodies may include one or more CDR sequence(s) from any of the anti-HJV antibodies selected from Table 1 containing up to 5, 4, 3, 2, or 1 amino acid residue variations as compared to the corresponding CDR region in any one of the CDRs provided herein (e.g., CDRs from any of the anti-HJV antibodies selected from Table 1) so long as immunospecific binding to hemojuvelin (e.g., human hemojuvelin) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% relative to the binding of the original antibody from which it is derived). In some embodiments, any of the amino acid variations in any of the CDRs provided herein may be conservative variations. Conservative variations can be introduced into the CDRs at positions where the residues are not likely to be involved in interacting with a hemojuvelin protein (e.g., a human hemojuvelin protein), for example, as determined based on a crystal structure. Some aspects of the disclosure provide anti-HJV antibodies that comprise one or more of the heavy chain variable (VH) and / or lightchain variable (VL) domains provided herein. In some embodiments, any of the VH domains provided herein include one or more of the HC CDR sequences (e.g., HC CDR1, HC CDR2, and HC CDR3) provided herein, for example, any of the CDR-H sequences provided in any one of the anti-HJV selected from Table 1. In some embodiments, any of the VL domains provided herein include one or more of the CDR-L sequences (e.g., LC CDR1, LC CDR2, and LC CDR3) provided herein, for example, any of the LC CDR sequences provided in any one of the anti-HJV antibodies selected from Table 1.

[0054] The CDRs of an antibody may have different amino acid sequences when different definition systems are used (e.g., the IMGT definition, the Kabat definition, or the Chothia definition). A definition system annotates each amino acid in a given antibody sequence (e.g., VH or VL sequence) with a number, and numbers corresponding to the heavy chain and light chain CDRs are provided in Table 2. The CDRs listed in Table 1 are defined in accordance with the Kabat definition. One skilled in the art is able to derive the CDR sequences using the different numbering systems for the anti-HJV antibodies provided in Table 1.Table 2. CDR Definitions1IMGT®, the international ImMunoGeneTics information system®, imgt.org, Lefranc, M.-P. et al., Nucleic Acids Res., 27:209-212 (1999)2Kabat et al. (1991) Sequences of Proteins of Immunological Interest, Fifth Edition, U.S. Department of Health and Human Services, NIH Publication No. 91-32423Chothia et al., J. Mol. Biol. 196:901-917 (1987))

[0055] In some embodiments, the anti-HJV antibodies of the disclosure include any antibody that includes a heavy chain variable domain and / or a light chain variable domain of any one of the anti-HJV antibodies selected from Table 1, and variants thereof. In some embodiments, anti-HJV antibodies of the disclosure include any antibody that includes the heavy chain variable and light chain variable pairs of any anti-HJV antibodies selected from Table 1.

[0056] Aspects of the disclosure provide anti-HJV antibodies having a heavy chain variable (VH) and / or a light chain variable (VL) domain amino acid sequence homologous to any of those described herein. In some embodiments, the anti-HJV antibody comprises a heavy chain variable sequence or a light chain variable sequence that is at least 75% (e.g., 80%, 85%, 90%, 95%, 98%, or 99%) identical to the heavy chain variable sequence and / or any light chain variable sequence of any one of the anti-HJV antibodies selected from Table 1. In some embodiments, the homologous heavy chain variable and / or a light chain variable amino acid sequences do not vary within any of the CDR sequences provided herein. For example, in some embodiments, the degree of sequence variation (e.g., 75%, 80%, 85%, 90%, 95%, 98%, or 99%) may occur within a heavy chain variable and / or a light chain variable sequence excluding any of the CDR sequences provided herein. In some embodiments, any of the anti- HJV antibodies provided herein comprise a heavy chain variable sequence and a light chain variable sequence that comprises a framework sequence that is at least 75%, 80%, 85%, 90%, 95%, 98%, or 99% identical to the framework sequence of any anti-HJV antibodies selected from Table 1.

[0057] In some embodiments, the anti-HJV antibody of the present disclosure is a humanized antibody (e.g., a humanized variant containing one or more CDRs of Table 1). In some embodiments, the anti-HJV antibody of the present disclosure comprises a HC CDR1, a HC CDR2, a HC CDR3, a LC CDR1, a LC CDR2, and a LC CDR3 that are the same as the HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and LC CDR3 shown in Table 1, and comprises a humanized heavy chain variable region and / or a humanized light chain variable region.

[0058] Humanized antibodies are human immunoglobulins (recipient antibody) in which residues from a complementary determining region (CDR) of the recipient are replaced by residues from a CDR of a non-human species (donor antibody) such as mouse, rat, or rabbit having the desired specificity, affinity, and capacity. In some embodiments, Fv framework region (FR) residues of the human immunoglobulin are replaced by corresponding non- human residues. Furthermore, the humanized antibody may comprise residues that are found neither in the recipient antibody nor in the imported CDR or framework sequences, but are included to further refine and optimize antibody performance. In general, the humanized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the CDR regions correspond to those of a non-human immunoglobulin and all or substantially all of the FR regions are those of a human immunoglobulin consensus sequence. The humanized antibody optimally also will compriseat least a portion of an immunoglobulin constant region or domain (Fc), typically that of a human immunoglobulin. Antibodies may have Fc regions modified as described in WO 99 / 58572. Other forms of humanized antibodies have one or more CDRs (one, two, three, four, five, six) which are altered with respect to the original antibody, which are also termed one or more CDRs derived from one or more CDRs from the original antibody. Humanized antibodies may also involve affinity maturation.

[0059] In some embodiments, humanization is achieved by grafting the CDRs (e.g., as shown in Table 1) into the human variable domains (e.g., IGKV1-NL1*O1 and IGHVl-3*01 human variable domain). In some embodiments, the anti-HJV antibody of the present disclosure is a humanized variant comprising one or more amino acid substitutions (e.g., in the VH framework region) as compared with any one of the VHs listed in Table 1, and / or one or more amino acid substitutions (e.g., in the VL framework region) as compared with any one of the VLs listed in Table 1.

[0060] In some embodiments, the anti-HJV antibody of the present disclosure is a humanized antibody comprising a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH of any of the anti-HJV antibodies listed in Table 1. Alternatively or in addition, the anti-HJV antibody of the present disclosure is a humanized antibody comprising a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL of any one of the anti-HJV antibodies listed in Table 1.

[0061] In some embodiments, the anti-HJV antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 7. Alternatively or in addition, the anti-HJV antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 8.

[0062] In some embodiments, the anti-HJV antibody comprises an HC CDR1 having the amino acid sequence of SEQ ID NO: 1, an HC CDR2 having the amino acid sequence of SEQ ID NO: 2, an HC CDR3 having the amino acid sequence of SEQ ID NO: 3, an LC CDR1 having the amino acid sequence of SEQ ID NO: 4, an LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and an LC CDR3 having the amino acid sequence of SEQ ID NO: 6.

[0063] In some embodiments, anti-HJV antibody of the present disclosure comprises an HC CDR1, HC CDR2, and HC CDR3, which collectively contain no more than 5 amino acidvariations (e.g., no more than 5, 4, 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 2, and HC CDR3 having the amino acid sequence of SEQ ID NO: 3. “Collectively,” as used anywhere in the present disclosure, means that the total number of amino acid variations in all of the three heavy chain CDRs within the defined range. Alternatively or in addition, the anti-HJV antibody of the present disclosure comprises an LC CDR1, LC CDR2, and LC CDR3, which collectively contain no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2 or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 4, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6.

[0064] In some embodiments, the anti-HJV antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 2, and HC CDR3 having the amino acid sequence of SEQ ID NO: 3. Alternatively or in addition, the anti-HJV antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the to the LC CDR1 having the amino acid sequence of SEQ ID NO: 4, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6.

[0065] In some embodiments, the anti-HJV antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 2, and HC CDR3 having the amino acid sequence of SEQ ID NO: 3. Alternatively or in addition, the anti-HJV antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the to the LC CDR1 having the aminoacid sequence of SEQ ID NO: 4, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6.

[0066] In some embodiments, the anti-HJV antibody of the present disclosure comprises: an HC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1; an HC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared to the HC CDR2 having the amino acid sequence of SEQ ID NO: 2; and / or an HC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared to the HC CDR3 having the amino acid sequence of SEQ ID NO: 3. Alternatively or in addition, the anti-HJV antibody of the present disclosure comprises: an LC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared to the LC CDR1 having the amino acid sequence of SEQ ID NO: 4; an LC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared to the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or an LC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared to the LC CDR3 having the amino acid sequence of SEQ ID NO: 6.

[0067] In some embodiments, the anti-HJV antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 7. Alternatively or in addition, the anti-HJV antibody comprises a VL comprising the amino acid sequence of SEQ ID NO: 8.

[0068] In some embodiments, the anti-HJV antibody of the present disclosure comprises a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16,15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared to the VH as set forth in SEQ ID NO: 7. Alternatively or in addition, the anti-HJV antibody of the present disclosure comprises a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared to the VL as set forth in SEQ ID NO: 8. In some embodiments, the number of amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) may occur within a VH of SEQ ID NO: 7 and / or a VL of SEQ ID NO: 8 excluding any of the CDR sequences therein. In some embodiments, an anti-HJV antibodies provided herein comprise a heavy chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17,16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VH of SEQ ID NO: 7, and / or a light chain variable sequence that comprises aframework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VL of SEQ ID NO: 8.

[0069] In some embodiments, the anti-HJV antibody of the present disclosure comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the VH as set forth in SEQ ID NO: 7. Alternatively or in addition, the anti-HJV antibody of the present disclosure comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the VL as set forth in SEQ ID NO: 8. In some embodiments, the degree of sequence variation (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) may occur within a VH of SEQ ID NO: 7, and / or a VL of SEQ ID NO: 8 excluding any of the CDR sequences therein. In some embodiments, an anti-HJV antibody provided herein comprise a heavy chain variable sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VH of SEQ ID NO: 7, and / or a light chain variable sequence that comprises a framework sequence that at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VL of SEQ ID NO: 8.

[0070] In some embodiments, an anti-HJV antibody of the present disclosure comprises a VL domain and / or VH domain of any one of the anti-HJV antibodies selected from Table 1, and comprises a constant region comprising the amino acid sequences of the constant regions of an IgG, IgE, IgM, IgD, IgA or IgY immunoglobulin molecule, any class (e.g., IgGl, IgG2, IgG3, IgG4, IgAl and IgA2), or any subclass (e.g., IgG2a and IgG2b) of immunoglobulin molecule. Non-limiting examples of human constant regions are described in the art, e.g., see Kabat E A et al., (1991) supra. In some embodiments, an anti-HJV antibody described herein comprises a human IgGl constant region or a variant thereof. An example of a human IgGl constant region is given below: ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTF PAVLQSSGLYSLSSWTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCWVDVSHEDPEVKFN WYVDGVEVHNAKTKPREEQYNSTYRWSVLTVLHQDWLNGKEYKCKVSNKALP APIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWE SNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNH YTQKSLSLSPGK (SEQ ID NO: 30)

[0001] In some embodiments, the heavy chain of any of the anti-HJV antibodies described herein comprises a mutant human IgGl constant region. For example, the introduction of LAL A mutations (a mutant derived from mAb bl2 that has been mutated to replace the lower hinge residues Leu234 Leu235 with Ala234 and Ala235) in the CH2 domain of human IgGl is known to reduce Fcg receptor binding (Bruhns, P., et al. (2009) and Xu, D. et al. (2000)). Exemplary mutant human IgGl constant region comprising the LALA mutations are provided below in SEQ ID NOs: 9 and 27 (mutations bonded and underlined):ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGL YSLSSWTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPEAAGGPSVF LFPPKPKDTLMISRTPEVTCVWDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRW SVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSL TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSV MHEALHNHYTQKSLSLSPGK (SEQ ID NO: 9)ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGL YSLSSWTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPEAAGGPSVF LFPPKPKDTLMISRTPEVTCVWDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRW SVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSL TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSV MHEALHNHYTQKSLSLSPGK (SEQ ID NO: 27)

[0071] In some embodiments, the light chain of any of the anti-HJV antibodies described herein may further comprise a light chain constant region (CL), which can be any CL known in the art. In some examples, the CL is a kappa light chain. In other examples, the CL is a lambda light chain. In some embodiments, the CL is a kappa light chain, the sequence of which is provided below:RTVAAPSVFI FPPSDEQLKSGTASWCLLNNFYPREAKVQWKVDNALQSGNSQ ESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC (SEQ ID NO: 11)

[0072] In some embodiments, during the production of the antibodies, particularly with Chinese Hamster Ovary Cells (CHO cells), it can be appreciated that the lysine at the C- terminus of the heavy chain is cleaved. Accordingly, a human IgGl constant region within a secreted antibody can be: ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTF PAVLQSSGLYSLSSWTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKT HTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCWVDVSHEDPEVKFN WYVDGVEVHNAKTKPREEQYNSTYRWSVLTVLHQDWLNGKEYKCKVSNKALP APIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWE SNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNH YTQKSLSLSPG (SEQ ID NO: 31)

[0002] In some embodiments, an exemplary mutant human IgGl comprising the LALA mutations in a secreted antibody are provided in SEQ ID NOs: 10 and 33 below: ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGL YSLSSWTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPEAAGGPSVF LFPPKPKDTLMISRTPEVTCVWDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRW SVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSL TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSV MHEALHNHYTQKSLSLSPG (SEQ ID NO: 10)ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGL YSLSSWTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPEAAGGPSVF LFPPKPKDTLMISRTPEVTCVWDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRW SVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSL TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSV MHEALHNHYTQKSLSLSPG (SEQ ID NO: 33)

[0073] In some embodiments, the anti-HJV antibody comprises a heavy chain constant region that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NOs: 9 or 10. Alternative or in addition, in some embodiments, the anti-HJV antibody comprises a light chain constant region that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 11.

[0074] In some embodiments, the anti-HJV antibody comprises a heavy chain constant region that contains no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17,16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared to SEQ ID NOs: 9 or 10. Alternative or in addition, in some embodiments, the anti-HJV antibody comprises a light chain constant region that contains no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared to SEQ ID NO: 11.

[0075] In some embodiments, the anti-HJV antibody comprises a heavy chain containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared to the heavy chain as set forth in SEQ ID NOs: 12 or 13. Alternatively or in addition, the anti-HJV antibody comprises a light chain containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18,17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared to the light chain as set forth in SEQ ID NO: 14. In some embodiments, the anti-HJV antibody described herein comprises a heavy chain comprising an amino acid sequence that is at least 80 is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NOs: 12 or 13. Alternatively or in addition, the anti-HJV antibody described herein comprises a light chain comprising an amino acid sequence that is at least 80% is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 14. In some embodiments, the anti-HJV antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NOs: 12 or 13. In some embodiments, the anti-HJV antibody comprises a light chain comprising the amino acid sequence of SEQ ID NO: 14. In some embodiments, the anti-HJV antibody comprises a heavy chain having the amino acid sequence set forth in SEQ ID NOs: 12 or 13, and a light chain having the amino acid sequence set forth in SEQ ID NO: 14.

[0076] In some embodiments, an anti-HJV antibody described herein comprises a signal peptide at the N-terminal of the heavy chain, and / or a signal peptide at the N-terminal of the light chain. In some embodiments, the signal peptide comprises the amino acid sequence of SEQ ID NO: 15. Accordingly, in some embodiments, in some embodiments, the anti-HJV antibody comprises a heavy chain containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared to the heavy chain as set forth in SEQ ID NOs: 24 or 25. Alternativelyor in addition, the anti-HJV antibody comprises a light chain containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared to the heavy chain as set forth in SEQ ID NO: 26. In some embodiments, the anti-HJV antibody described herein comprises a heavy chain comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NOs: 24 or 25. Alternatively or in addition, the anti-HJV antibody described herein comprises a light chain comprising an amino acid sequence that is at least 80% is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 26. In some embodiments, the anti-HJV antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NOs: 24 or 25. In some embodiments, the anti-HJV antibody comprises a light chain comprising the amino acid sequence of SEQ ID NO: 26. In some embodiments, the anti-HJV antibody comprises a heavy chain having the amino acid sequence set forth in SEQ ID NOs: 24 or 25, and a light chain having the amino acid sequence set forth in SEQ ID NO: 26.

[0077] The anti-HJV antibody described herein can be in any antibody form, including, but not limited to, intact (i.e., full-length) antibodies, antigen-binding fragments thereof (such as Fab, F(ab'), F(ab')2, Fv), single chain antibodies, bi-specific antibodies, or nanobodies. In some embodiments, the anti-HJV antibody described herein is a scFv. In some embodiments, the anti-HJV antibody described herein is a scFv-Fab (e.g., scFv fused to a portion of a constant region).

[0078] In some embodiments, conservative mutations can be introduced into antibody sequences (e.g., CDRs or framework sequences) at positions where the residues are not likely to be involved in interacting with a target antigen (e.g., hemojuvelin), for example, as determined based on a crystal structure. In some embodiments, one, two or more mutations (e.g., amino acid substitutions) are introduced into the Fc region of an anti-HJV antibody described herein (e.g., in a CH2 domain (residues 231-340 of human IgGl) and / or CH3 domain (residues 341-447 of human IgGl) and / or the hinge region, with numbering according to the Kabat numbering system (e.g., the EU index in Kabat)) to alter one or more functional properties of the antibody, such as serum half-life, complement fixation, Fc receptor binding and / or antigen-dependent cellular cytotoxicity.

[0079] In some embodiments, an anti-HJV antibody is modified, e.g., via glycosylation, phosphorylation, sumoylation, and / or methylation. In some embodiments, an anti-HJV antibody is glycosylated at position N295 (Kabat numbering; N297 under EU numbering). In some embodiments, an antibody is a glycosylated antibody, which is conjugated to one or more sugar or carbohydrate molecules. In some embodiments, the one or more sugar or carbohydrate molecules are conjugated to the antibody via N-glycosylation, O-glycosylation, C-glycosylation, glypiation (GPI anchor attachment), and / or phosphoglycosylation. In some embodiments, the one or more sugar or carbohydrate molecules are monosaccharides, disaccharides, oligosaccharides, or glycans. In some embodiments, the one or more sugar or carbohydrate molecule is a branched oligosaccharide or a branched glycan. In some embodiments, the one or more sugar or carbohydrate molecule includes a mannose unit, a glucose unit, an N-acetylglucosamine unit, an N-acetylgalactosamine unit, a galactose unit, a fucose unit, or a phospholipid unit. In some embodiments, there are about 1-10, about 1-5, about 5-10, about 1-4, about 1-3, or about 2 sugar molecules. In some embodiments, a glycosylated antibody is fully or partially glycosylated. In some embodiments, an antibody is glycosylated by chemical reactions or by enzymatic means. In some embodiments, an antibody is glycosylated in vitro or inside a cell, which may optionally be deficient in an enzyme in the N- or O- glycosylation pathway, e.g. a glycosyltransferase. In some embodiments, an antibody is functionalized with sugar or carbohydrate molecules as described in International Patent Application Publication WO2014065661, published on May 1, 2014, entitled, “Modified antibody, antibody-conjugate and process for the preparation thereof".III. Preparation of anti-HJV Antibody

[0080] An antibody capable of binding HJV as described herein can be made by any method known in the art. See, for example, Harlow and Lane, (1998) Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory, New York.

[0081] In some embodiments, the anti-HJV antibody is prepared by recombinant technology as exemplified below. Nucleic acids encoding the VH and / or VL, or heavy chain and / or light chain of an anti-HJV antibody (e.g., the nucleic acid sequences of Table 3) can be cloned into an expression vector, each nucleotide sequence being operably linked to a suitable promoter. In one example, each of the nucleotide sequences encoding VH and / or VL, or the heavy chain and the light chain is operably linked to a distinct promoter. Alternatively, the nucleotide sequences encoding VH and / or VL, or the heavy chain and the light chain canbe operably linked with a single promoter, such that both heavy and light chains are expressed from the same promoter. When necessary, an internal ribosome entry site (IRES) or T2 peptide coding sequence can be inserted between the sequences encoding VH and / or VL, or the heavy chain and the light chain of the anti-HJV antibody.

[0082] In some examples, the nucleotide sequences encoding the two chains of the antibody are cloned into two vectors, which can be introduced into the same or different cells. When the heavy chain and the light chain are expressed in different cells, each of them can be isolated from the host cells expression such, and the isolated heavy chains and light chains can be mixed and incubated under suitable conditions allowing for the formation of the antibody.

[0083] Generally, a nucleic acid sequence encoding one or all chains of an antibody (e.g., the nucleic acids listed in Table 3) can be cloned into a suitable expression vector and operably linked with a suitable promoter using methods known in the art. For example, the nucleotide sequence and vector can be contacted under suitable conditions with a restriction enzyme to create complementary ends on each molecule that can pair with each other and be joined together with a ligase. Alternatively, synthetic nucleic acid linkers can be ligated to the termini of a gene. These synthetic linkers contain nucleic acid sequences that correspond to a particular restriction site in the vector. The selection of expression vectors / promoters would depend on the type of host cells used for production of the anti-HJV antibody.

[0084] A variety of promoters can be used for expression of the anti-HJV antibody, including, but not limited to, cytomegalovirus (CMV) intermediate early promoter, a viral LTR, such as the Rous sarcoma virus LTR, HIV-LTR, HTLV-1 LTR, the simian virus 40 (SV40) early promoter, E. coli lac UV promoter, and the herpes simplex tk virus promoter.

[0085] Regulatable promoters can also be used. Such regulatable promoters include, but are not limited to, those using the lac repressor from E. coli as a transcription modulator to regulate transcription from lac operator bearing mammalian cell promoters [Brown, M. et al., Cell, 49:603-612 (1987)], those using the tetracycline repressor (tetR) [Gossen, M., and Bujard, H., Proc. Natl. Acad. Sci. USA 89:5547-555115 (1992); Yao, F. et al., Human Gene Therapy, 9: 1939-1950 (1998); Shockelt, P., et al., Proc. Natl. Acad. Sci. USA, 92:6522-6526 (1995)]. Other systems include FK506 dimer, VP16 or p65 using astradiol, RU486, diphenol murislerone, or rapamycin. Inducible systems are available from Invitrogen, Clontech and Ariad, among others.

[0086] Regulatable promoters that include a repressor with the operon can be used. In some embodiments, the lac repressor from E. coli can function as a transcriptional modulator toregulate transcription from lac operator-bearing mammalian cell promoters [M. Brown et al., Cell, 49:603-612 (1987)]; Gossen and Bujard (1992); [M. Gossen et al., Natl. Acad. Sci. USA, 89:5547-5551(1992)] combined the tetracycline repressor (tetR) with the transcription activator (VP 16) to create a tetR-mammalian cell transcription activator fusion protein, tTa (tetR- VP 16), with the tetO bearing minimal promoter derived from the human cytomegalovirus (hCMV) promoter to create a tetR-tet operator system to control gene expression in mammalian cells. In some embodiments, a tetracycline inducible switch is used. The tetracycline repressor (tetR) alone, rather than the tetR-mammalian cell transcription factor fusion derivatives can function as potent trans-modulator to regulate gene expression in mammalian cells when the tetracycline operator is properly positioned downstream for the TATA element of the CMVIE promoter (Yao et al., Human Gene Therapy). One advantage of this tetracycline inducible switch is that it does not require the use of a tetracycline repressor-mammalian cells transactivator or repressor fusion protein to achieve its regulatable effects, which in some instances can be toxic to cells (Gossen 5 et al., Natl. Acad. Sci. USA, 89:5547-5551 (1992); Shockett et al., Proc. Natl. Acad. Sci. USA, 92:6522-6526 (1995)).

[0087] In some embodiments, the vector can contain, for example, some or all of the following: a selectable marker gene, such as the neomycin gene for selection of stable or transient transfectants in mammalian cells; enhancer / promoter sequences from the immediate early gene of human CMV for high levels of transcription; transcription termination and RNA processing signals from SV40 for mRNA stability; SV40 polyoma origins of replication and ColEl for proper episomal replication; internal ribosome binding sites (IRESes), versatile multiple cloning sites; and T7 and SP6 RNA promoters for in vitro transcription of sense and antisense RNA. Suitable vectors and methods for producing vectors containing transgenes are well known and available in the art. Examples of polyadenylation signals useful to practice the methods described herein include, but are not limited to, human collagen I polyadenylation signal, human collagen II polyadenylation signal, and SV40 polyadenylation signal.

[0088] One or more vectors (e.g., expression vectors) comprising nucleic acids encoding the anti-HJV antibody (e.g., VH and / or VL, or heavy chain and / or light chain of the anti-HJV antibody) may be introduced into suitable host cells for producing the antibodies. Nonlimiting examples of the host cells include Chinese hamster ovary (CHO) cells, dhfr-CHO cells (e.g., CHO DG44 cells), human embryonic kidney (HEK)-293 cells, verda reno (VERO) cells, nonsecreting null (NS0) cells, human embryonic retinal (PER.C6) cells, Sp2 / 0 cells,baby hamster kidney (BHK) cells, Madin-Darby Canine Kidney (MDCK) cells, Madin-Darby Bovine Kidney (MDBK) cells, and monkey kidney CV1 line transformed by SV40 (COS) cells. In some embodiments, the host cell expressing the anti-HJV is a CHO cell. In some embodiments, the host cell expressing the anti-HJV is a dhfr-CHO cell. In some embodiments, the host cell expressing the anti-HJV is a CHO DG44 cell. The host cells can be cultured under suitable conditions for expression of the anti-HJV antibody or any polypeptide chain thereof. The anti-HJV antibody or polypeptide chains thereof can be recovered by the cultured cells (e.g, from the cells or the culture supernatant) via a conventional method, e.g, affinity purification. If necessary, polypeptide chains of the anti- HJV antibody can be incubated under suitable conditions for a suitable period of time allowing for production of the antibody. In some embodiments, the host cell comprises the nucleic acid encoding the VH and / or VL if the anti-HJV antibody. In some embodiments, the host cell comprises the nucleic acid encoding the heavy chain of the anti-HJV antibody. In some embodiments, the host cell comprises the nucleic acid encoding the light chain of the anti-HJV antibody. In some embodiments, the host cell comprises the nucleic acid encoding the heavy chain and the nucleic acid encoding the light chain.

[0089] In some embodiments, methods for preparing the anti-HJV antibody described herein involve a recombinant expression vector that encodes both the heavy chain and the light chain of the anti-HJV antibody, as also described herein. The recombinant expression vector(s) can be introduced into a suitable host cell (e.g., a dhfr-CHO cell) by a conventional method, e.g., calcium phosphate mediated transfection. Positive transformant host cells can be selected and cultured under suitable conditions allowing for the expression of the two polypeptide chains that form the antibody, which can be recovered from the cells or from the culture medium. When necessary, the two chains recovered from the host cells can be incubated under suitable conditions allowing for the formation of the antibody.

[0090] In some embodiments, two recombinant expression vectors are provided, one encoding the heavy chain of the anti-HJV antibody and the other encoding the light chain of the anti-HJV antibody. Both of the two recombinant expression vectors can be introduced into a suitable host cell (e.g., dhfr-CHO cell) by a conventional method, e.g., calcium phosphate-mediated transfection.

[0091] Alternatively, each of the expression vectors can be introduced into a suitable host cell. Positive transformants can be selected and cultured under suitable conditions allowing for the expression of the polypeptide chains of the antibody. When the two expression vectors are introduced into the same host cells, the antibody produced therein can be recovered fromthe host cells or from the culture medium. If necessary, the polypeptide chains can be recovered from the host cells or from the culture medium and then incubated under suitable conditions allowing for formation of the antibody. When the two expression vectors are introduced into different host cells, each of them can be recovered from the corresponding host cells or from the corresponding culture media. The two polypeptide chains can then be incubated under suitable conditions for formation of the antibody.

[0092] Standard molecular biology techniques may be used to prepare the recombinant expression vector, transfect the host cells, select for transformants, culture the host cells and recovery of the antibodies from the culture medium. For example, some antibodies can be isolated by affinity chromatography with a Protein A or Protein G coupled matrix.

[0093] In some embodiments, the present disclosure also provides nucleic acid sequence encoding a heavy chain and / or a light chain of an anti-HJV antibody with a signal peptide (e.g., signal peptide comprising the amino acid sequence set forth in SEQ ID NO: 15. In some embodiments, the nucleic acid sequence encoding the signal peptide comprising the amino acid sequence set forth in SEQ ID NO: 15 comprises a nucleic acid sequence at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NOs: 21 or 32. In some embodiments, the nucleic acid sequence encoding the signal peptide comprising the amino acid sequence set forth in SEQ ID NO: 15 comprises the nucleic acid sequence of SEQ ID NOs: 21 or 32. In some embodiments, the nucleic acid sequence encoding the heavy chain signal peptide comprising the amino acid sequence set forth in SEQ ID NO: 15 comprises the nucleic acid sequence of SEQ ID NO: 21. In some embodiments, the nucleic acid sequence encoding the light chain signal peptide comprising the amino acid sequence set forth in SEQ ID NO: 15 comprises the nucleic acid sequence of SEQ ID NO: 32.

[0094] Any of the nucleic acids encoding VH, VL, the heavy chain, the light chain, or both of an anti-HJV antibody as described herein (e.g., as provided in Table 3), vectors (e.g., expression vectors) containing such; and host cells comprising the vectors are within the scope of the present disclosure.Table 3. Nucleic acid sequences encoding components of an anti-HJV antibody.

[0095] In some embodiments, the present disclosure provides an isolated nucleic acid encoding the VH and / or VL of an anti-HJV antibody described herein. In some embodiments, an isolated nucleic acid encoding the VH and / or VL of an anti-HJV antibody comprises a nucleic acid sequence at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 28, and / or a nucleic acid sequence at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 29. In some embodiments, the present disclosure provides a vector comprising the isolated nucleic acid encoding the VH and / or VL of an anti-HJV antibody described herein. In some embodiments, a vector comprising the isolated nucleic acid encoding the VH and / or VL of an anti-HJV antibody comprises a nucleic acid sequence at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 28, and / or a nucleic acid sequence at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 29.

[0096] In some embodiments, the present disclosure provides an isolated nucleic acid encoding the heavy chain and / or light chain of an anti-HJV antibody described herein. In some embodiments, an isolated nucleic acid encoding the heavy chain and / or the light chain of an anti-HJV antibody comprises a nucleic acid sequence at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 19, and / or a nucleic acid sequence at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 20. In some embodiments, the present disclosure provides a vector comprising the isolated nucleic acid encoding the heavy chain and / or the light chain of an anti-HJV antibody described herein. In some embodiments, a vector comprising the isolated nucleic acid encoding the heavy chain and / or the light chain of an anti-HJV antibody comprises a nucleic acid sequence at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 19, and / or a nucleic acid sequence at least 80% (e.g., at least 80%, at least 85%, at least 90%, atleast 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 20.

[0097] In some embodiments, the present disclosure provides an isolated nucleic acid encoding the heavy chain including signal peptide and / or light chain including signal peptide of an anti-HJV antibody described herein. In some embodiments, an isolated nucleic acid encoding the heavy chain including signal peptide and / or the light chain including signal peptide of an anti-HJV antibody comprises a nucleic acid sequence at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ IDNO: 22, and / or a nucleic acid sequence at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 23. In some embodiments, the present disclosure provides a vector comprising the isolated nucleic acid encoding the heavy chain including signal peptide and / or the light chain including signal peptide of an anti-HJV antibody described herein. In some embodiments, a vector comprising the isolated nucleic acid encoding the heavy chain including signal peptide and / or the light chain including signal peptide of an anti-HJV antibody comprises a nucleic acid sequence at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 22, and / or a nucleic acid sequence at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 23.

[0098] In some embodiments, the anti-HJV antibody described herein is produced by expressing in a host cell (i) a nucleic acid that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 28, and / or (ii) a nucleic acid that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 29.

[0099] In some embodiments, the anti-HJV antibody described herein is produced by expressing in a host cell (i) a nucleic acid that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 19, and / or (ii) anucleic acid that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 20.[000100] In some embodiments, the anti-HJV antibody described herein is produced by expressing in a host cell (i) a nucleic acid that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 22, and / or (ii) a nucleic acid that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to SEQ ID NO: 23.IV. Pharmaceutical Compositions[000101] The antibody, as well as the encoding nucleic acids or nucleic acid sets, vectors comprising such, or host cells comprising the vectors as described herein can be mixed with a pharmaceutically acceptable carrier (excipient) to form a pharmaceutical composition for use in an animal subject e.g., a human). “Acceptable” means that the carrier must be compatible with the active ingredient of the composition (and preferably, capable of stabilizing the active ingredient) and not deleterious to the subject. Pharmaceutically acceptable excipients (carriers) include buffers, which are well known in the art. See, e.g., Remington: The Science and Practice of Pharmacy 20th Ed. (2000) Lippincott Williams and Wilkins, Ed. K. E. Hoover.[000102] The anti-HJV antibody containing a pharmaceutical composition as disclosed herein may further comprise a suitable buffer agent. A buffer agent is a weak acid or base used to maintain the pH of a solution near a chosen value after the addition of another acid or base. In some examples, the buffer agent disclosed herein can be a buffer agent capable of maintaining physiological pH despite changes in carbon dioxide concentration (produced by cellular respiration). Exemplary buffer agents include, but are not limited, to a HEPES (4-(2- hy droxy ethyl)- 1 -piperazineethanesulfonic acid) buffer, Dulbeco’s phosphate-buffered saline (DPBS) buffer, or Phosphate-buffered Saline (PBS) buffer. Such buffers may comprise disodium hydrogen phosphate and sodium chloride, or potassium dihydrogen phosphate and potassium chloride.[000103] In some embodiments, the buffer agent in the pharmaceutical composition described herein may maintain a pH value of about 5-8. For example, the pH of the pharmaceutical composition can be about 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, or 8.0. In other examples,the pharmaceutical composition may have a pH value lower than 7, for example, about 7, 6.8, 6.5, 6.3, 6, 5.8, 5.5, 5.3, or 5.[000104] In some embodiments, a pharmaceutical composition described herein comprises one or more suitable salts. A salt is an ionic compound that can be formed by the neutralization reaction of an acid and a base. See, e.g., Skoog, D.A; West, D.M.; Holler, J.F.; Crouch, S.R. (2004) “chapters 14-16”. Fundamentals of Analytical Chemistry (8th ed.). Salts are composed of related numbers of cations (positively charged ions) and anions (negative ions) so that the product is electrically neutral (without a net charge).[000105] In some embodiments, a pharmaceutical composition can comprise a pharmaceutically acceptable carrier, excipient, or stabilizer in the form of lyophilized formulations or aqueous solutions. See, e.g., Remington: The Science and Practice of Pharmacy 20th Ed. (2000) Lippincott Williams and Wilkins, Ed. K. E. Hoover. In some embodiments, the pharmaceutical composition can be formulated for intravenous injection. In some embodiments, the pharmaceutical composition can be formulated for subcutaneous injection.[000106] The pharmaceutical compositions to be used for in vivo administration must be sterile. This is readily accomplished by, for example, filtration through sterile filtration membranes. Therapeutic antibody compositions are generally placed into a container having a sterile access port, for example, an intravenous or subcutaneous solution bag or vial having a stopper pierceable by a hypodermic injection needle.VI. Equivalents and Scope[000107] In the claims, articles such as “a,” “an,” and “the” may mean one or more than one unless indicated to the contrary or otherwise evident from the context. Claims or descriptions that include “or” between one or more members of a group are considered satisfied if one, more than one, or all of the group members are present in, employed in, or otherwise relevant to a given product or process unless indicated to the contrary or otherwise evident from the context. The invention includes embodiments in which exactly one member of the group is present in, employed in, or otherwise relevant to a given product or process. The invention includes embodiments in which more than one, or all of the group members are present in, employed in, or otherwise relevant to a given product or process.[000108] Furthermore, the invention encompasses all variations, combinations, and permutations in which one or more limitations, elements, clauses, and descriptive terms from one or more of the listed claims is introduced into another claim. For example, any claim thatis dependent on another claim can be modified to include one or more limitations found in any other claim that is dependent on the same base claim. Where elements are presented as lists, e.g., in Markush group format, each subgroup of the elements is also disclosed, and any element(s) can be removed from the group. It should it be understood that, in general, where the invention, or aspects of the invention, is / are referred to as comprising particular elements and / or features, certain embodiments of the invention or aspects of the invention consist, or consist essentially of, such elements and / or features. For purposes of simplicity, those embodiments have not been specifically set forth in haec verba herein.[000109] The phrase “and / or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, z.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and / or” should be construed in the same fashion, z.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and / or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and / or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.[000110] As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” shall be interpreted as being inclusive, z.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of’ or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (z.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law.[000111] As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elementsand not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and / or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.[000112] It should also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited.[000113] In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, z.e., to mean including but not limited to. Only the transitional phrases “consisting of’ and “consisting essentially of’ shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03. It should be appreciated that embodiments described in this document using an open-ended transitional phrase (e.g., “comprising”) are also contemplated, in alternative embodiments, as “consisting of’ and “consisting essentially of’ the feature described by the open-ended transitional phrase. For example, if the application describes “a composition comprising A and B,” the application also contemplates the alternative embodiments “a composition consisting of A and B” and “a composition consisting essentially of A and B.”[000114] Where ranges are given, endpoints are included. Furthermore, unless otherwise indicated or otherwise evident from the context and understanding of one of ordinary skill in the art, values that are expressed as ranges can assume any specific value or sub-range within the stated ranges in different embodiments of the invention, to the tenth of the unit of the lower limit of the range, unless the context clearly dictates otherwise.[000115] This application refers to various issued patents, published patent applications, journal articles, and other publications, all of which are incorporated herein by reference. Ifthere is a conflict between any of the incorporated references and the instant specification, the specification shall control. In addition, any particular embodiment of the present invention that falls within the prior art may be explicitly excluded from any one or more of the claims. Because such embodiments are deemed to be known to one of ordinary skill in the art, they may be excluded even if the exclusion is not set forth explicitly herein. Any particular embodiment of the invention can be excluded from any claim, for any reason, whether or not related to the existence of prior art.[000116] Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation many equivalents to the specific embodiments described herein. The scope of the present embodiments described herein is not intended to be limited to the above Description, but rather is as set forth in the appended claims. Those of ordinary skill in the art will appreciate that various changes and modifications to this description may be made without departing from the spirit or scope of the present invention, as defined in the following claims.[000117] The recitation of a listing of chemical groups in any definition of a variable herein includes definitions of that variable as any single group or combination of listed groups. The recitation of an embodiment for a variable herein includes that embodiment as any single embodiment or in combination with any other embodiments or portions thereof. The recitation of an embodiment herein includes that embodiment as any single embodiment or in combination with any other embodiments or portions thereof.

Claims

CLAIMSWhat is claimed is:

1. An isolated nucleic acid encoding a heavy chain variable region (VH) and / or a light chain variable region (VL) of an anti-hemojuvelin (HJV) antibody comprising:(a) a nucleic acid sequence at least 80% identical to SEQ ID NO: 28; and / or(b) a nucleic acid sequence at least 80% identical to SEQ ID NO: 29.

2. The isolated nucleic acid of claim 1, wherein the isolated nucleic acid comprising the nucleic acid sequence of SEQ ID NO: 28.

3. The isolated nucleic acid of claim 1 or 2, wherein the isolated nucleic acid comprising the nucleic acid sequence of SEQ ID NO: 29.

4. The isolated nucleic of any one of claims 1-3, wherein the isolated nucleic acid comprises:(a) a nucleic acid at least 80% identical to SEQ ID NO: 19; and / or(b) a nucleic acid at least 80% identical to SEQ ID NO: 20.

5. The isolated nucleic acid of any one of claims 1-4, wherein the isolated nucleic acid comprises the nucleic acid sequence of SEQ ID NO: 19.

6. The isolated nucleic acid of any one of claims 1-5, wherein the isolated nucleic acid comprises the nucleic acid sequence of SEQ ID NO: 20.

7. The isolated nucleic acid of any one of claims 1-6, wherein the heavy chain and / or the light chain of the antibody comprise a signal peptide.

8. The isolated nucleic acid of claim 7, wherein the signal peptide comprises the amino acid sequence of SEQ ID NO: 15.

9. The isolated nucleic acid of claim 7 or 8, wherein the nucleic acid encoding the signal peptide comprises a nucleic acid sequence at least 80% identical to SEQ ID NOs: 21 or 32.

10. The isolated nucleic acid of any one of claims 7-9, wherein the nucleic acid encoding the signal peptide comprises the nucleic acid sequence of SEQ ID NO: 21.

11. The isolated nucleic acid of any one of claims 7-9, wherein the nucleic acid encoding the signal peptide comprises the nucleic acid sequence of SEQ ID NO: 32.

12. The isolated nucleic acid of any one of claims 4-7, wherein the isolated nucleic acid comprises:(a) a nucleic acid sequence that is at least 80% identical to SEQ ID NO: 22; and / or(b) a nucleic acid sequence that is at least 80% identical to SEQ ID NO: 23.

13. The isolated nucleic acid of any one of claims 4-12, wherein the isolated nucleic acid comprises the nucleic acid sequence of SEQ ID NO: 22.

14. The isolated nucleic acid of any one of claims 4-13, wherein the isolated nucleic acid comprises the nucleic acid sequence of SEQ ID NO: 23.

15. An antibody comprising:(a) a heavy chain comprising the amino acid sequence encoded by SEQ ID NOs: 19 or 22; and(b) a light chain comprising the amino acid sequence encoded by SEQ ID NOs: 20 or 23.

16. A vector comprising the nucleic acid of any one of claims 1-14.

17. A host cell comprising the nucleic acid of any one of claims 1-14, the antibody of claim 15, or the vector of claim 16.

18. The host cell of claim 17, wherein the host cell is a Chinese hamster ovary (CHO) cell, a dhfr’CHO cell, a human embryonic kidney (HEK)-293 cell, a verda reno (VERO) cell,a nonsecreting null (NSO) cell, a human embryonic retinal (PER.C6) cell, an Sp2 / 0 cell, a baby hamster kidney (BHK) cell, a Madin-Darby Canine Kidney (MDCK) cell, a Madin- Darby Bovine Kidney (MDBK) cell, or a monkey kidney CV1 line transformed by SV40 (COS) cell.

19. The host cell of claim 17 or 18, wherein the host cell is a dhfr’CHO cell.

20. The host cell of any one of claims 17-19, wherein the host cell is a CHO DG44 cell.

21. A method of producing an anti-HJV antibody, the method comprising:(i) culturing the host cell of any one of claims 17-20 under conditions allowing for expression of the antibody; and(ii) harvesting the cultured host cell or culture medium for collection of the anti- HJV antibody.

22. The method of claim 21, further comprising purifying the anti-HJV antibody.

23. A composition comprising the nucleic acid of any one of claims 1-14, the vector of claim 16, or the host cell of any one of claims 17-19.

24. A method of producing an anti-hemojuvelin (HJV) antibody, the method comprising:(i) culturing a host cell comprising a nucleic acid that encodes a light chain and / or a heavy chain of an anti-HJV antibody, wherein:(a) the nucleic acid encoding the heavy chain is at least 80% identical to SEQ ID NO: 19; and / or(b) the nucleic acid encoding the light chain is at least 80% identical to SEQ ID NO: 20; and(ii) harvesting the cultured host cell or culture medium for collection of the antibody.

25. The method of claim 24, further comprising purifying the anti-HJV antibody.

26. The method of claim 24 or 25, wherein the nucleic acid encoding the heavy chain comprises the nucleic acid sequence of SEQ ID NO: 19.

27. The method of any one of claims 24-26, wherein the nucleic acid encoding the light chain comprises the nucleic acid sequence of SEQ ID NO: 20.

28. The method of any one of claims 24-27, wherein the nucleic acid further encodes a signal peptide for the heavy chain and / or a signal peptide for the light chain.

29. The method of claim 27 or 28, wherein the nucleic acid encoding the signal peptide is at least 80% identical to SEQ ID NOs: 21 or 32.

30. The method of claim 28 or 29, wherein the nucleic acid encoding the heavy chain comprises the nucleic acid sequence of SEQ ID NO: 22.

31. The method of any one of claims 28-30, wherein the nucleic acid encoding the light chain comprises the nucleic acid sequence of SEQ ID NO: 23.

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