Treatment of complement-mediated diseases and disorders with C3b antibodies

Abstract

The present invention provides, inter alia, anti-C3b antibodies with increased specificity and potency, as well as methods of using the anti-C3b antibodies to treat C3 glomerulopathy, as well as other complement mediated diseases and disorders.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 376,305, filed on September 20, 2022, the entire content of which is hereby incorporated by reference.

[0003] Incorporation of Sequence Listing by Reference

[0004] This application is being filed with an electronically - submitted sequence listing in XML format. The sequence listing file, entitled SVI - 002WO1_SL.xml, was created on September 19, 2023, and is 25 kilobytes in size. The information in the electronic format of the sequence listing is hereby incorporated by reference in its entirety. Background of the Invention

[0005] The complement system is part of the innate immune system that is not adapted to changes over the host's life course, but is recruited and used by the adaptive immune system. For example, the complement system helps or supplements the ability of antibodies and phagocytes to clear pathogens. This complex regulatory pathway allows for a rapid response to pathogenic organisms while protecting host cells from destruction. More than thirty proteins and protein fragments make up the complement system. These proteins act through opsonization (enhancing phagocytosis of antigens), chemotaxis (attracting macrophages and neutrophils), cytolysis (rupturing the membranes of foreign cells), and agglutination (pathogens aggregating and binding together).

[0006] The complement system has three pathways: classical, alternative, and lectin. In the alternative pathway, C3 present in the bloodstream is spontaneously cleaved at a low rate into C3b and C3a. C3b is the larger of the two elements and is considered an important part of the innate immune system. C3b is effective in opsonization: marking pathogens, immune complexes (antigen - antibody), and apoptotic cells for phagocytosis. Additionally, C3b plays a role in the formation of C3 convertase when bound to factor B (C3bBb complex) or in the formation of C5 convertase when bound to C4b and C2b (C4b2b3b complex) or when an additional C3b molecule binds to the C3bBb complex (C3bBb3b complex). C3 glomerulopathy (C3G) is a rare disease characterized by the accumulation of complement factors in the glomeruli due to over - activation and abnormal regulation of the complement alternative pathway (AP). Abnormal control of the complement AP may be due to acquired or genetic abnormalities of complement regulatory proteins. Deposition of complement factors drives glomerular inflammation, leading to proliferative glomerulonephritis. The most common diseases under the C3G umbrella are C3 glomerulonephritis (C3GN), characterized by mesangial, subendothelial, and intramembranous deposits; and dense deposit disease (DDD), characterized by dense deposits along the glomerular and tubular basement membranes. SUMMARY OF THE INVENTION

[0007] The present invention particularly provides anti-C3b antibodies and antibody fragments having enhanced specificity for C3b, and the therapeutic use of such antibodies in the effective treatment of complement-mediated diseases such as C3 glomerulopathy, dense deposit disease (DDD), and C3 glomerulonephritis (C3GN), wet age-related macular degeneration (wAMD), passive Heymann nephritis (NHP), and collagen antibody-induced arthritis (CAIA). In some embodiments, the anti-C3b antibody fragment is a VHH or a VHH fused to an Fc domain. As described herein, the present invention is in part based on the identification of a novel class of anti-C3b specific VHHs that have significantly reduced cross-reactivity with C3. Specifically, the anti-C3b VHHs of the present invention are characterized by high binding affinity for C3b (e.g., C3b K D less than 50 nM) and minimal cross-reactivity with C3 (e.g., the selectivity of C3b for C3 is 10-fold greater). This is significant because the C3b antibodies and VHHs of the present invention selectively bind to C3b, for example, through a new epitope on C3b, and can effectively target C3 convertases in diseased tissues without being saturated by high levels of circulating C3. Thus, relative to other anti-C3b antibodies or anti-C3 antibodies, the C3b antibodies of the present invention can be used at lower doses to achieve a therapeutic effect. As described herein, this is demonstrated by the unexpectedly high potency observed in functional assays relative to prior art antibodies. Accordingly, the present invention provides inventive anti-C3b antibodies and VHHs that (i) inhibit C3 convertase formation and mediate the clearance of C3 deposits; (ii) target solid-phase and liquid-phase alternative pathway C3 convertase activities; (iii) block the interaction of C3b with factor B (fB); (iv) inhibit activities specific for the alternative pathway (AP); (v) limit interference by natural regulators of C3 convertase, such as factor H (fH), DAF, and other inhibitors; (vi) have favorable biophysical and pharmacokinetic properties to allow for extended therapeutic effects (bi-weekly or monthly dosing); and / or (vii) inhibit the stabilization of C3 convertase by C3bNef autoantibodies. The inventive anti-C3b antibodies of the present invention are expected to more effectively treat complement-mediated diseases and disorders.

[0008] In one aspect, the present invention particularly provides an antibody or an antigen-binding fragment thereof that binds to complement component 3b (C3b), the antibody or the antigen-binding fragment thereof comprising an amino acid sequence that is at least 90% identical to SEQ ID NO:10.

[0009] On the one hand, the present invention particularly provides an antibody or an antigen-binding fragment thereof, which binds to complement component 3b (C3b), and the antibody or the antigen-binding fragment thereof comprises an amino acid sequence that is at least 90% identical to SEQ ID NO: 11.

[0010] On the one hand, the present invention particularly provides an antibody or an antigen-binding fragment thereof, which binds to complement component 3b (C3b), and the antibody or the antigen-binding fragment thereof comprises an amino acid sequence that is at least 90% identical to SEQ ID NO: 12.

[0011] On the one hand, the present invention particularly provides an antibody or an antigen-binding fragment thereof, which binds to complement component 3b (C3b), and the antibody or the antigen-binding fragment thereof comprises an amino acid sequence that is at least 90% identical to SEQ ID NO: 13.

[0012] On the one hand, the present invention particularly provides an antibody or an antigen-binding fragment thereof, which binds to C3b, and the antibody or the antigen-binding fragment thereof comprises three complementarity-determining regions (CDR1 to CDR3 respectively), wherein CDR1 comprises NYHMG (SEQ ID NO: 16), CDR2 comprises TIIRTGETIYYADSVKG (SEQ ID NO: 17), and CDR3 comprises ATSGWNIKTVTPYEY (SEQ ID NO: 18).

[0013] On the one hand, the present invention particularly provides an antibody or an antigen-binding fragment thereof, which binds to C3b, and the antibody or the antigen-binding fragment thereof comprises three complementarity-determining regions (CDR1 to CDR3 respectively), wherein CDR1 comprises GRTFSNY (SEQ ID NO: 19), CDR2 comprises IRTGET (SEQ ID NO: 20), and CDR3 comprises ATSGWNIKTVTPYEY (SEQ ID NO: 18).

[0014] On the one hand, the present invention particularly provides an antibody or an antigen-binding fragment thereof, which binds to C3b, and the antibody or the antigen-binding fragment thereof comprises three complementarity-determining regions (CDR1 to CDR3 respectively), wherein CDR1 comprises NYHMG (SEQ ID NO: 16), CDR2 comprises TIIRTGKTIYYADSVKG (SEQ ID NO: 21), and CDR3 comprises ATSGWHIKTVTPYEY (SEQ ID NO: 22).

[0015] On the one hand, the present invention particularly provides an antibody or an antigen-binding fragment thereof, which binds to C3b and comprises three complementarity-determining regions (CDR1 to CDR3 respectively), wherein CDR1 comprises GRTFSNY (SEQ ID NO: 19), CDR2 comprises IRTGKT (SEQ ID NO: 23), and CDR3 comprises ATSGWHIKTVTPYEY (SEQ ID NO: 22).

[0016] On the one hand, the present invention particularly provides an antibody or an antigen-binding fragment thereof, which binds to C3b and comprises three complementarity-determining regions (CDR1 to CDR3 respectively), wherein CDR1 comprises NYHMG (SEQ ID NO: 16), CDR2 comprises TIIRTGTTIYYADSVKG (SEQ ID NO: 24), and CDR3 comprises ATSGWHIKTVTPYEY (SEQ ID NO: 22).

[0017] On the one hand, the present invention particularly provides an antibody or an antigen-binding fragment thereof, which binds to C3b, wherein the binding portion comprises three complementarity-determining regions (CDR1 to CDR3 respectively), wherein CDR1 comprises GRTFSNY (SEQ ID NO: 19), CDR2 comprises IRTGTT (SEQ ID NO: 25), and CDR3 comprises ATSGWHIKTVTPYEY (SEQ ID NO: 22).

[0018] On the one hand, the present invention particularly provides an antibody or an antigen-binding fragment thereof, which binds to C3b and comprises three complementarity-determining regions (CDR1 to CDR3 respectively), wherein CDR1 comprises NYHMG (SEQ ID NO: 16), CDR2 comprises TIIRHGTTIYYADSVKG (SEQ ID NO: 26), and CDR3 comprises ATSGWHIKTVTPYEY (SEQ ID NO: 22).

[0019] On the one hand, the present invention particularly provides an antibody or an antigen-binding fragment thereof, which binds to C3b, wherein the binding portion comprises three complementarity-determining regions (CDR1 to CDR3 respectively), wherein CDR1 comprises GRTFSNY (SEQ ID NO: 19), CDR2 comprises IRHGTT (SEQ ID NO: 27), and CDR3 comprises ATSGWHIKTVTPYEY (SEQ ID NO: 22).

[0020] In some embodiments, the antibody or its antigen-binding fragment is a nanobody (VHH). In some embodiments, the antibody or its antigen-binding fragment is a VHH fused to an Fc domain (VHH-Fc). In some embodiments, the antibody or its antigen-binding fragment is a scFv. In some embodiments, the antibody or its antigen-binding fragment is a Fab. In some embodiments, the antibody or its antigen-binding fragment is a scFv fused to an Fc domain (scFv-Fc). In some embodiments, the antibody or its antigen-binding fragment is a bispecific antibody. In some embodiments, the antibody or its antigen-binding fragment is a minibody (scFv fused to the CH3 domain of Fc). In some embodiments, the antibody or its antigen-binding fragment is a scFab. In some embodiments, the antibody or its antigen-binding fragment is a heavy chain antibody.

[0021] In some embodiments, the VHH comprises SEQ ID NO:10. In some embodiments, the VHH comprises SEQ ID NO:11. In some embodiments, the VHH comprises SEQ ID NO:12. In some embodiments, the VHH comprises SEQ ID NO:13.

[0022] In some embodiments, the antibody or its antigen-binding fragment comprises an Fc domain. In some embodiments, the Fc domain is derived from IgG1. In some embodiments, the Fc domain is derived from IgG2. In some embodiments, the Fc domain is derived from IgG3. In some embodiments, the Fc domain is derived from IgG4.

[0023] In some embodiments, the Fc domain is modified. In some embodiments, the Fc domain is modified to increase the in vivo half-life. In some embodiments, the Fc domain is modified to reduce the in vivo immunogenicity.

[0024] In some embodiments, the Fc domain comprises a T307Q mutation according to the EU index number. In some embodiments, the Fc domain comprises a Q331V mutation according to the EU index number. In some embodiments, the Fc domain comprises an A378V mutation according to the EU index number. In some embodiments, the Fc domain comprises T307Q and Q331V mutations according to the EU index number. In some embodiments, the Fc domain comprises a T307Q mutation according to the EU index number. In some embodiments, the Fc domain comprises T307Q and A378V mutations according to the EU index number. In some embodiments, the Fc domain comprises Q331V and A378V mutations according to the EU index number. In some embodiments, the Fc domain comprises T307Q, Q331V, and A378V mutations according to the EU index number.

[0025] In some embodiments, the Fc domain comprises an S228P mutation according to the EU index numbering.

[0026] In some embodiments, the Fc domain comprises a substitution at position F234 according to the EU index numbering. In some embodiments, the Fc domain comprises a substitution at position L235 according to the EU index numbering. In some embodiments, the Fc domain comprises a substitution at position D265 according to the EU index numbering. In some embodiments, the Fc domain comprises substitutions at positions F234 and L235 according to the EU index numbering. In some embodiments, the Fc domain comprises substitutions at positions F234 and D265 according to the EU index numbering. In some embodiments, the Fc domain comprises substitutions at positions L235 and D265 according to the EU index numbering. In some embodiments, the Fc domain comprises substitutions at positions F234, L235 and D265 according to the EU index numbering.

[0027] In some embodiments, the substitution at position F234 is a hydrophobic amino acid. In some embodiments, the substitution at position F234 is a hydrophobic amino acid selected from the group consisting of alanine, valine, leucine, isoleucine, phenylalanine and tryptophan according to the EU index numbering. In some embodiments, the substitution at position F234 is alanine. In some embodiments, the substitution at position F234 is valine. In some embodiments, the substitution at position F234 is leucine. In some embodiments, the substitution at position F234 is isoleucine. In some embodiments, the substitution at position F234 is phenylalanine. In some embodiments, the substitution at position F234 is tryptophan.

[0028] In some embodiments, the substitution at position L235 is an acidic amino acid according to the EU index numbering. In some embodiments, the substitution at position L235 is an acidic amino acid selected from the group consisting of glutamic acid or aspartic acid. In some embodiments, the substitution at position L235 is glutamic acid. In some embodiments, the substitution at position L235 is aspartic acid.

[0029] In some embodiments, the substitution at position D265 is a non-polar amino acid according to the EU index numbering. In some embodiments, the substitution at position D265 is a non-polar amino acid selected from the group consisting of alanine, cysteine, glycine, isoleucine, leucine, methionine, and valine. In some embodiments, the substitution at position D265 is alanine. In some embodiments, the substitution at position D265 is cysteine. In some embodiments, the substitution at position D265 is glycine. In some embodiments, the substitution at position D265 is isoleucine. In some embodiments, the substitution at position D265 is leucine. In some embodiments, the substitution at position D265 is methionine. In some embodiments, the substitution at position D265 is valine.

[0030] In some embodiments, the Fc domain comprises the F234V mutation according to the EU index numbering. In some embodiments, the Fc domain comprises the L235E mutation according to the EU index numbering. In some embodiments, the Fc domain comprises the D265G mutation according to the EU index numbering. In some embodiments, the Fc domain comprises the F234V, L235E, and D265G mutations according to the EU index numbering. In some embodiments, the Fc domain comprises the F234V, L235E, D265G, and S228P mutations according to the EU index numbering.

[0031] In some embodiments, the Fc domain comprises the T307Q, Q331V, A378V, F234V, L235E, D265G, and S228P mutations according to the EU index numbering.

[0032] In some embodiments, the antibody or fragment thereof inhibits the formation of C3 convertase and / or C5 convertase. In some embodiments, the antibody or fragment thereof does not bind to C3 protein.

[0033] In some embodiments, the antibody or fragment thereof inhibits the activity of C3 convertase. In some embodiments, the antibody or fragment thereof targets the activity of the solid-phase alternative pathway C3 convertase. In some embodiments, the antibody or fragment thereof targets the activity of the fluid-phase alternative pathway C3 convertase. In some embodiments, the antibody or fragment thereof targets the activities of both the solid-phase and fluid-phase alternative pathway C3 convertases.

[0034] In some embodiments, the Fc domain comprises an amino acid sequence that is at least 80% identical to SEQ ID NO:14. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 85% identical to SEQ ID NO:14. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 88% identical to SEQ ID NO:14. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 90% identical to SEQ ID NO:14. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 92% identical to SEQ ID NO:14. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 93% identical to SEQ ID NO:14. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 94% identical to SEQ ID NO:14. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 95% identical to SEQ ID NO:14. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 96% identical to SEQ ID NO:14. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 97% identical to SEQ ID NO:14. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 98% identical to SEQ ID NO:14. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 99% identical to SEQ ID NO:14. In some embodiments, the Fc domain comprises the amino acid sequence of SEQ ID NO:14.

[0035] In some embodiments, the Fc domain comprises an amino acid sequence that is at least 80% identical to SEQ ID NO: 10. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 85% identical to SEQ ID NO: 10. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 88% identical to SEQ ID NO: 10. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 90% identical to SEQ ID NO: 10. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 92% identical to SEQ ID NO: 10. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 93% identical to SEQ ID NO: 10. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 94% identical to SEQ ID NO: 10. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 95% identical to SEQ ID NO: 10. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 96% identical to SEQ ID NO: 10. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 97% identical to SEQ ID NO: 10. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 98% identical to SEQ ID NO: 10. In some embodiments, the Fc domain comprises an amino acid sequence that is at least 99% identical to SEQ ID NO: 10. In some embodiments, the Fc domain comprises the amino acid sequence of SEQ ID NO: 10.

[0036] In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 80% identical to SEQ ID NO:4. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 85% identical to SEQ ID NO:4. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 88% identical to SEQ ID NO:4. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 90% identical to SEQ ID NO:4. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 92% identical to SEQ ID NO:4. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 95% identical to SEQ ID NO:4. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 96% identical to SEQ ID NO:4. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 97% identical to SEQ ID NO:4. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 98% identical to SEQ ID NO:4. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 99% identical to SEQ ID NO:4. In some embodiments, the antibody or antigen-binding fragment thereof comprises the amino acid sequence of SEQ ID NO:4.

[0037] In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 80% identical to SEQ ID NO:5. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 85% identical to SEQ ID NO:5. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 88% identical to SEQ ID NO:5. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 90% identical to SEQ ID NO:5. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 92% identical to SEQ ID NO:5. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 95% identical to SEQ ID NO:5. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 96% identical to SEQ ID NO:5. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 97% identical to SEQ ID NO:5. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 98% identical to SEQ ID NO:5. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 99% identical to SEQ ID NO:5. In some embodiments, the antibody or antigen-binding fragment thereof comprises the amino acid sequence of SEQ ID NO:5.

[0038] In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 80% identical to SEQ ID NO:6. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 85% identical to SEQ ID NO:6. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 88% identical to SEQ ID NO:6. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 90% identical to SEQ ID NO:6. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 92% identical to SEQ ID NO:6. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 95% identical to SEQ ID NO:6. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 96% identical to SEQ ID NO:6. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 97% identical to SEQ ID NO:6. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 98% identical to SEQ ID NO:6. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 99% identical to SEQ ID NO:6. In some embodiments, the antibody or antigen-binding fragment thereof comprises the amino acid sequence of SEQ ID NO:6.

[0039] In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 80% identical to SEQ ID NO:7. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 85% identical to SEQ ID NO:7. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 88% identical to SEQ ID NO:7. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 90% identical to SEQ ID NO:7. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 92% identical to SEQ ID NO:7. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 95% identical to SEQ ID NO:7. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 96% identical to SEQ ID NO:7. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 97% identical to SEQ ID NO:7. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 98% identical to SEQ ID NO:7. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 99% identical to SEQ ID NO:7. In some embodiments, the antibody or antigen-binding fragment thereof comprises the amino acid sequence of SEQ ID NO:7.

[0040] In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 80% identical to SEQ ID NO:8. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 85% identical to SEQ ID NO:8. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 88% identical to SEQ ID NO:8. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 90% identical to SEQ ID NO:8. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 92% identical to SEQ ID NO:8. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 95% identical to SEQ ID NO:8. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 96% identical to SEQ ID NO:8. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 97% identical to SEQ ID NO:8. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 98% identical to SEQ ID NO:8. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 99% identical to SEQ ID NO:8. In some embodiments, the antibody or antigen-binding fragment thereof comprises the amino acid sequence of SEQ ID NO:8.

[0041] In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 80% identical to SEQ ID NO:9. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 85% identical to SEQ ID NO:9. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 88% identical to SEQ ID NO:9. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 90% identical to SEQ ID NO:9. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 92% identical to SEQ ID NO:9. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 95% identical to SEQ ID NO:9. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 96% identical to SEQ ID NO:9. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 97% identical to SEQ ID NO:9. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 98% identical to SEQ ID NO:9. In some embodiments, the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 99% identical to SEQ ID NO:9. In some embodiments, the antibody or antigen-binding fragment thereof comprises the amino acid sequence of SEQ ID NO:9.

[0042] In one aspect, the present invention particularly provides a nucleic acid encoding the antibody or antigen-binding thereof of the present invention. In some embodiments, the nucleic acid is DNA. In some embodiments, the nucleic acid is cDNA. In some embodiments, the nucleic acid is RNA. In some embodiments, the nucleic acid is messenger RNA (mRNA).

[0043] In one aspect, the present invention particularly provides a messenger RNA encoding the antibody or antigen-binding thereof of the present invention.

[0044] In one aspect, the present invention particularly provides a composition comprising a nucleic acid and a delivery agent, the nucleic acid encoding the antibody or antigen-binding thereof of the present invention.

[0045] In some embodiments, the delivery agent is an adeno-associated virus (AAV) vector. In some embodiments, the delivery agent is a lipid nanoparticle (LNP).

[0046] In one aspect, the present invention particularly provides a composition comprising a lipid nanoparticle (LNP) encapsulating messenger RNA, the messenger RNA encoding an anti-C3b antibody or a fragment thereof.

[0047] On the one hand, the present invention particularly provides a method for treating a complement-mediated disease or disorder, the method comprising administering to a subject in need thereof a therapeutically effective amount of said antibody or an antibody of the present invention or an antigen-binding fragment thereof.

[0048] On the one hand, the present invention particularly provides a method for treating a complement-mediated disease or disorder, the method comprising administering to a subject in need thereof a therapeutically effective amount of said mRNA encoding an anti-C3b antibody, or an antibody of the present invention or an antigen-binding fragment thereof.

[0049] On the one hand, the present invention particularly provides a method for treating a complement-mediated disease or disorder, the method comprising administering to a subject in need thereof a therapeutically effective amount of an anti-C3b antibody or a fragment thereof.

[0050] In some embodiments, the complement-mediated disease or disorder is C glomerulopathy or a disease or disorder associated with C3 glomerulopathy. In some embodiments, the disease or disorder associated with C3 glomerulopathy is dense deposit disease (DDD). In some embodiments, the disease or disorder associated with C3 glomerulopathy is C3 glomerulonephritis (C3GN). In some embodiments, the complement-mediated disease or disorder is characterized by the accumulation of C3 complement component in renal tissue. In some embodiments, the subject has symptomatic hematuria, proteinuria, acute kidney injury (AKI) or chronic kidney disease (CKD). In some embodiments, the complement-mediated disease or disorder is paroxysmal nocturnal hemoglobinuria, geographic atrophy or autoimmune hemolytic anemia (AIHA). In some embodiments, the complement-mediated disease or disorder is age-related macular degeneration (AMD). In some embodiments, the complement-mediated disease or disorder is wet age-related macular degeneration (wAMD). In some embodiments, the complement-mediated disease or disorder is passive Heymann nephritis (PHN). BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The drawings are for illustrative purposes only and not for limitation.

[0052] Figure 1A and 1B are exemplary graphs showing the pharmacokinetic effects of Ab1 (in duplicate) and control Ab in cynomolgus monkeys. Figure 1A Shows the levels of Ab1 and control Ab in plasma levels over 20 days. Figure 1B Shows the percentage of remaining antibodies of Ab1 and control Ab in plasma levels over 20 days. Figure 1C and Figure 1D are exemplary graphs showing the C3b antibody levels obtained by capturing human C3b and cynomolgus monkey C3b, respectively. Figure 1EIs an exemplary graph showing plasma antibody levels in an ex vivo C3 deposition assay. Figure 1F Is an exemplary graph showing the inhibition of C3 deposition as measured by absorbance at 450 nm.

[0053] Figure 2 Is an exemplary schematic diagram of a study design for evaluating the efficacy of anti-C3b antibodies in a mouse model of laser-induced choroidal neovascularization (CNV).

[0054] Figure 3A And 3B Is an exemplary graph showing the effect of C3b antibodies on wAMD. Figure 3A Is an exemplary graph showing the FA leakage area on day 7 after treatment with a test antibody and a control. Figure 3B Is an exemplary graph showing the OCT area on day 7 after treatment with a test antibody and a control.

[0055] Figure 4 Is an exemplary schematic diagram of a study design for evaluating the efficacy of anti-C3b antibodies in PHN.

[0056] Figure 5A Is an exemplary graph showing the albumin:creatinine ratio as a urinary biomarker for measuring the effect of C3b antibodies on PHN in a subject. Figure 5B Is an exemplary graph showing the total protein:creatinine level as a urinary biomarker for measuring the effect of C3b antibodies on PHN in a subject.

[0057] Figure 6A Is an exemplary schematic diagram of a study design for testing the efficacy of C3b antibodies in a mouse model of collagen-antibody-induced arthritis. Figure 6B Is an exemplary graph showing the percentage change in hind paw volume at different doses of C3b antibodies compared to a positive control and a negative control.

[0058] Figure 7 Is an exemplary graph showing the inhibition of C3 convertase by Ab4, AMY-101, and LNP023 measured by C3 deposition assay in healthy donors and representative C3G patients.

[0059] Definition

[0060] To make the present invention easier to understand, certain terms are first defined below. Additional definitions of the following terms and other terms are set forth throughout the specification. Publications and other reference materials mentioned herein that describe the background of the present invention and provide additional details regarding its practice are hereby incorporated by reference.

[0061] Antibody: As used herein, the term "antibody" refers to an immunoglobulin molecule and the immunologically active portion of an immunoglobulin (Ig) molecule, i.e., a molecule that contains an antigen-binding site that binds an antigen (immunologically reacts with the antigen). "Binding" or "immunologically reacting with" means that the antibody reacts with one or more desired antigenic determinants. Antibodies include antibody fragments. Antibodies also include, but are not limited to, polyclonal, monoclonal, chimeric dAb (domain antibody), single-chain, single-domain antibody (VHH), antigen-binding site fused to a constant region (Fc), Fab, Fab', F(ab')2 fragments, scFv, and Fab expression libraries. An antibody can be a full antibody, or an immunoglobulin, or an antibody fragment.

[0062] Amino acid: As used herein, the term "amino acid" in its broadest sense refers to any compound and / or substance that can be incorporated into a polypeptide chain. In some embodiments, an amino acid has the general structure H 2 N–C(H)(R)–COOH. In some embodiments, the amino acid is a naturally occurring amino acid. In some embodiments, the amino acid is a synthetic amino acid; in some embodiments, the amino acid is a d-amino acid; in some embodiments, the amino acid is an l-amino acid. A "standard amino acid" refers to any one of the twenty standard l-amino acids commonly found in naturally occurring peptides. A "non-standard amino acid" refers to any amino acid other than a standard amino acid, whether prepared synthetically or obtained from natural sources. As used herein, "synthetic amino acid" encompasses chemically modified amino acids, including but not limited to salts, amino acid derivatives (such as amides) and / or substitutions. Amino acids, including the carboxyl and / or amino-terminal amino acids in a peptide, can be modified by methylation, amidation, acetylation, protecting groups, and / or substitution by other chemical groups, and such modifications can alter the circulating half-life of the peptide without adversely affecting its activity. Amino acids can participate in disulfide bonds. Amino acids can contain one or more post-translational modifications, such as binding to one or more chemical entities (e.g., methyl, acetate group, acetyl, phosphate group, formyl moiety, isoprenyl group, sulfate group, polyethylene glycol moiety, lipid moiety, carbohydrate moiety, biotin moiety, etc.). The terms "amino acid" and "amino acid residue" are used interchangeably and can refer to free amino acids and / or amino acid residues of a peptide. It will be apparent from the context in which the term is used whether it refers to a free amino acid or a residue of a peptide.

[0063] Improve: As used herein, the term "improve" refers to the prevention, reduction, or alleviation of a condition or the improvement of the condition of a subject. Improvement includes, but does not require, complete recovery or complete prevention of a disease symptom. In some embodiments, improvement can refer to partial recovery or prevention of a disease symptom. In some embodiments, improvement includes an increase in the level of a relevant protein or its activity that is lacking in a relevant diseased tissue.

[0064] About or approximately: As used herein, when applied to one or more values of interest, the terms “about” or “approximately” refer to a value similar to the reference value.

[0065] Delivery: As used herein, the term “delivery” encompasses both local delivery and systemic delivery.

[0066] Improve, increase, inhibit or decrease: As used herein, the terms “improve”, “increase”, “inhibit” or “decrease” or their grammatical equivalents refer to a value relative to a baseline measurement, which is the measurement in the same individual before initiation of the treatment described herein, or in a control subject (or control subjects) in the absence of the treatment described herein (e.g., a subject administered a placebo). A “control subject” is a subject having the same form of disease as the treated subject and is of approximately the same age as the treated subject.

[0067] Inhibition or inhibiting: As used herein, “inhibition” or “inhibiting” or grammatical equivalents mean a reduction, decrease or inhibition of biological activity. Neutralization: As used herein, neutralization means a reduction or inhibition of the biological activity of the protein to which the neutralizing antibody binds, in this case an anti-C3b antibody, such as a reduction or inhibition of any of the complement system component signalings, e.g., as measured by a C3b-mediated response. The reduction or inhibition of biological activity can be partial or complete. The degree to which an antibody neutralizes C3b is referred to as its neutralizing potency.

[0068] Patient: The term “patient” refers to any organism to which the provided composition can be administered, e.g., for experimental, diagnostic, prophylactic, cosmetic, and / or therapeutic purposes. Typical patients include animals (e.g., mammals such as mice, rats, rabbits, non-human primates, and / or humans). In some embodiments, the patient is a human. Humans include pre-birth and post-birth forms.

[0069] Pharmaceutically acceptable: As used herein, the term “pharmaceutically acceptable” refers to a substance that is suitable, within the scope of sound medical judgment, for contact with the tissues of humans and animals without excessive toxicity, irritation, allergic response, or other problems or complications, commensurate with a reasonable benefit / risk ratio.

[0070] Substantial identity: The phrase "substantial identity" is used herein to refer to a comparison between amino acid or nucleic acid sequences. As would be understood by one of ordinary skill in the art, two sequences are generally considered to be "substantially identical" if they contain the same residues at corresponding positions. As is well known in the art, any of a variety of algorithms can be used to compare amino acid or nucleic acid sequences, including those available in commercial computer programs, such as BLASTN for nucleotide sequences, and BLASTP, Gapped BLAST, and PSI-BLAST for amino acid sequences. Exemplary such programs are described in: Altschul et al., Basic local alignment search tool, J Mol. Biol., 215(3):403-410, 1990; Altschul et al., Methods in Enzymology; Altschul et al., Nucleic Acids Res. 25:3389-3402, 1997; Baxevanis et al., Bioinformatics: A Practical Guide to the Analysis of Genes and Proteins, Wiley, 1998; and Misener et al. (eds.), Bioinformatics Methods and Protocols (Methods in Molecular Biology, Vol. 132), Humana Press, 1999. In addition to identifying identical sequences, the above programs generally also provide an indication of the degree of identity. In some embodiments, two sequences are considered to be substantially identical if at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more of the corresponding residues of the two sequences are identical over the relevant residue segments. In some embodiments, the relevant segment is the complete sequence.In some embodiments, the relevant segment is at least 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500 or more residues.

[0071] Subject: As used herein, the term "subject" refers to a human or any non-human animal (e.g., mouse, rat, rabbit, dog, cat, cow, pig, sheep, horse or primate). Humans include pre-birth and post-birth forms. In many embodiments, the subject is a human. A subject can be a patient, which refers to a person who goes to a healthcare provider for diagnosis or treatment of a disease. The term "subject" is used interchangeably herein with "individual" or "patient". A subject may have or be susceptible to a disease or disorder, but may or may not display symptoms of the disease or disorder.

[0072] Substantially: As used herein, the term "substantially" refers to a qualitative condition that exhibits the entire range or nearly the entire range or degree of the characteristic or property of interest. One of ordinary skill in the biological arts will understand that biological and chemical phenomena rarely (if ever) achieve completion and / or continue to completion or achieve or avoid absolute results. Thus, the term "substantially" is used herein to capture the inherent lack of potential completeness of many biological and chemical phenomena.

[0073] Systemic distribution or delivery: As used herein, the terms "systemic distribution", "systemic delivery" or grammatical equivalents refer to a delivery or distribution mechanism or method that affects the entire body or entire organism. Generally, systemic distribution or delivery is accomplished through the body's circulatory system, such as the blood. In contrast to the definition of "local distribution or delivery".

[0074] Therapeutically effective amount: As used herein, the term "therapeutically effective amount" of a therapeutic agent means an amount sufficient to treat, diagnose, prevent and / or delay the onset of symptoms of a disease, disorder and / or condition when administered to a subject having or susceptible to the disease, disorder and / or condition. In some embodiments, a "therapeutically effective amount" is sufficient to prevent the progression of a disease condition, the onset of one or more symptoms or complications associated with the condition, or a significant increase or decrease in the level of one or more biomarkers associated with the condition from its normal level. For example, a "therapeutically effective amount" is sufficient to prevent the progression of symptoms or complications associated with the complement system. One of ordinary skill in the art will understand that a therapeutically effective amount is typically administered via a dosing regimen that includes at least one unit dose.

[0075] Treatment: As used herein, the term "treat / treatment / treating" refers to any method for partially or completely alleviating, ameliorating, mitigating, inhibiting, preventing one or more symptoms or features of a particular disease, disorder, and / or condition, delaying its onset, reducing its severity, and / or reducing its incidence. Treatment can be administered to a subject who does not exhibit signs of the disease and / or exhibits only early signs of the disease in order to reduce the risk of developing lesions associated with the disease. In some embodiments, the term "treatment" or its grammatical equivalents refers to preventing the onset of a disease condition, one or more symptoms associated with the condition, or a significant increase or decrease in the level of one or more biomarkers associated with the condition from its normal level. For example, treating a patient with a complement-mediated disorder (e.g., C3 glomerulopathy) includes preventing the progression of symptoms or complications associated with the complement-mediated disorder, such as preventing C3 deposition. Detailed Description

[0076] The present invention particularly provides anti-C3b antibodies. Antibodies also include, but are not limited to, polyclonal, monoclonal, chimeric dAbs (domain antibodies), single-chain, single-domain antibodies (VHHs), single-domain antibody Fc fusions (VHH-Fc), antigen-binding sites fused to a constant region (Fc), Fabs, Fab', F(ab')2 fragments, scFvs, and Fab expression libraries. The novel anti-C3b antibodies of the present invention, such as single-domain antibodies (VHHs), single-domain antibody Fc fusions (VHH-Fc), and antigen-binding sites fused to a constant region (Fc), can effectively interfere with the formation of the C3 convertase (C3bBP) of the alternative pathway and thereby prevent the cascade from proceeding downstream to the amplification loop of the complement cascade.

[0077] In some embodiments, the C3b antibodies of the present invention selectively bind to C3b, inhibit C3 convertase formation, and mediate the clearance of C3 deposits. The present invention also provides methods for treating complement-mediated diseases and disorders with the anti-C3b antibodies further described herein. The anti-C3b antibodies of the present invention are characterized by having a high binding affinity for human C3b (e.g., C3b K D less than 50 nM) and minimal cross-reactivity with C3 (e.g., the selectivity of C3b is 10-fold greater than that of C3). They selectively bind to C3b through, for example, a novel epitope on C3b and can effectively target the C3 convertase in diseased tissues without being saturated by high levels of circulating C3. Due to the selective binding of the present invention, the present invention can be used at a lower dose to achieve a therapeutic effect compared to other anti-C3b antibodies or anti-C3 antibodies.

[0078] In some embodiments, the antibody or an antibody fragment thereof is a single domain antibody (VHH). The VHH selectively binds to C3b and inhibits C3 convertase formation and mediates the clearance of C3 deposits. The VHH-Fc fusion has high binding affinity and minimal cross-reactivity with C3b, inhibits C3 convertase formation and mediates the clearance of C3 deposits. The present invention provides inventive anti-C3b antibodies that (i) inhibit C3 convertase formation and mediate the clearance of C3 deposits; (ii) block the interaction of C3b with factor B (fB); (iii) inhibit activity specific to the alternative pathway (AP); (iv) limit interference by natural regulators of C3 convertase, such as factor H (fH), DAF, and other inhibitors; and / or (vii) inhibit the stabilization of C3 convertase by C3bNef autoantibodies.

[0079] In some embodiments, the antibody or an antibody fragment thereof is a VHH-Fc fusion. The VHH-Fc fusion selectively binds to C3b and inhibits C3 convertase formation and mediates the clearance of C3 deposits. The VHH-Fc fusion has high binding affinity and minimal cross-reactivity with C3b, inhibits C3 convertase formation and mediates the clearance of C3 deposits. The present invention provides inventive anti-C3b antibodies that (i) inhibit C3 convertase formation and mediate the clearance of C3 deposits; (ii) block the interaction of C3b with factor B (fB); (iii) inhibit activity specific to the alternative pathway (AP); (iv) limit interference by natural regulators of C3 convertase, such as factor H (fH), DAF, and other inhibitors; and / or (vii) inhibit the stabilization of C3 convertase by C3bNef autoantibodies.

[0080] In some embodiments, the antibodies of the present invention perform one or more of the following functions: (i) inhibit C3 convertase formation and mediate the clearance of C3 deposits; (ii) target solid-phase and liquid-phase alternative pathway C3 convertase activity; (iii) block the interaction of C3b with factor B (fB); (iv) inhibit activity specific to the alternative pathway (AP); (v) limit interference by natural regulators of C3 convertase, such as factor H (fH), DAF, and other inhibitors; (vi) have favorable biophysical and pharmacokinetic properties to allow for extended therapeutic effects (bi-weekly or monthly dosing); and / or (vii) inhibit the stabilization of C3 convertase by C3bNef autoantibodies. The present invention also provides antibody sets that specifically and selectively bind to human C3b and inhibit C3 convertase activity. The set includes antibodies that differ from C3 in their epitope, affinity, and selectivity for C3b.

[0081] Aspects of the present invention are described in detail in the following sections. The use of sections is not intended to limit the present invention. Each section can be applied to any aspect of the present invention. In this application, unless otherwise stated, the use of "or" means "and / or".

[0082] Complement system

[0083] The complement system is part of the innate immune system that is not adapted to changes during the host's life but is recruited and used by the adaptive immune system. For example, the complement system helps or supplements the ability of antibodies and phagocytes to clear pathogens. This complex regulatory pathway allows for a rapid response to pathogenic organisms while protecting host cells from destruction. More than thirty proteins and protein fragments make up the complement system. These proteins act through opsonization (enhancing phagocytosis of antigens), chemotaxis (attracting macrophages and neutrophils), cytolysis (rupturing the membranes of foreign cells), and agglutination (pathogens aggregating and binding together). The complement system has three pathways: classical, alternative, and lectin. The classical pathway (CP) is activated by certain isotypes of antibodies bound to antigens. The alternative pathway (AP) is activated on the surface of microbial cells in the absence of antibodies. The lectin pathway is activated by plasma lectins that bind to mannose residues on microbes. Although the complement activation pathways differ in their mode of initiation, all of these pathways can generate enzyme complexes capable of cleaving the most abundant complement protein, C3.

[0084] Classical pathway (CP)

[0085] The classical pathway (so named because it was discovered first) uses a plasma protein called C1q to detect antibodies bound to the surface of microbes or other structures. Once C1q binds to the Fc portion of the antibody, two associated serine proteases called C1r and C1s become active and initiate a proteolytic cascade involving other complement proteins. The classical pathway is one of the major effector mechanisms of the humoral arm of the adaptive immune response. Soluble proteins of the innate immune system called pentraxins can also bind to C1q and initiate the classical pathway.

[0086] Lectin pathway

[0087] The lectin pathway is triggered by a plasma protein called mannose-binding lectin (MBL), which recognizes terminal mannose residues on microbial glycoproteins and glycolipids, similar to the mannose receptor on the phagocytic cell membrane described previously. MBL is a member of the collectin family with a hexameric structure similar to the C1q component of the complement system. After MBL binds to a microbe, two zymogens called MASP1 (mannose-associated serine protease 1 or mannose-binding lectin-associated serine protease) and MASP2, which have functions similar to C1r and C1s, associate with MBL and initiate the same downstream proteolytic steps as the classical pathway. The central event in complement activation is the proteolytic cleavage of the complement protein C3 to produce bioactive products, and the subsequent covalent attachment of the C3 product called C3b to the surface of the microbial cell or to an antibody bound to an antigen. Complement activation depends on the production of two proteolytic complexes: the C3 convertase, which cleaves C3 into two proteolytic fragments called C3a and C3b; and the C5 convertase, which cleaves C5 into C5a and C5b.

[0088] Alternative pathway (AP)

[0089] The third pathway of complement activation is called the alternative pathway because it was discovered as the second or "alternative" pathway of complement activation after the classical pathway had been defined. This pathway can occur on the surface of many microbes in the absence of specific antibodies, and the pathway results in the production of a unique C3 convertase named C3bBb. In contrast to the classical complement activation pathway and the MB-lectin complement activation pathway, the alternative pathway does not rely on pathogen-binding proteins for initiation but is initiated by the spontaneous hydrolysis of C3. Many mechanisms ensure that the activation pathway will occur only on the surface of pathogens.

[0090] C3 convertase and C3b

[0091] C3 is abundant in plasma and C3b is generated at a significant rate by spontaneous cleavage (also known as 'tickover'). This occurs by the spontaneous hydrolysis of the thioester bond in C3 to form C3(H2O) with an altered conformation, allowing the binding of the plasma protein factor B. The binding of C3(H2O) to B then allows the plasma protease, called factor D, to cleave factor B into Ba and Bb, the latter remaining associated with C3(H2O) to form the C3(H2O)Bb complex. This complex is the alternative pathway C3 convertase and although the complex is formed in only small amounts, it can cleave many molecules of C3 into C3a and C3b. Although most of this C3b is inactivated by hydrolysis, some becomes covalently attached to the surface of host cells or pathogens through its reactive thioester group. C3b bound in this way is able to bind factor B, allowing it to be cleaved by factor D to produce the small fragment Ba and the active protease Bb. This allows the formation of the alternative pathway C3 convertase C3b,Bb.

[0092] When C3b binds to host cells, a number of complement regulatory proteins present in plasma and on the host cell membrane combine to prevent complement activation from proceeding. These proteins interact with C3b and prevent convertase formation or promote its rapid dissociation. Thus, complement receptor 1 (CR1) and the membrane-attached protein called decay-accelerating factor (DAF or CD55) compete with factor B for binding to C3b on the cell surface and can displace Bb from already formed convertases. Convertase formation can also be prevented by cleaving C3b into its inactive derivative iC3b. This is achieved by the plasma protease factor I binding to C3b-binding proteins (another host cell membrane protein) that can act as cofactors (such as CR1) and proteolytic membrane cofactor (MCP or CD46). Factor H is another complement regulatory protein in plasma that binds to C3b and, like CR1, in addition to acting as a cofactor for factor I, it is also able to compete with factor B and displace Bb from convertases. Factor H preferentially binds to C3b bound to vertebrate cells because it has an affinity for sialic acid residues present on these cells.

[0093] In contrast, since these regulatory proteins and sialic acid residues are lacking on the surface of pathogens, C3bBb convertase can form and persist. In fact, this process can be facilitated by a positive regulator of properdin or factor P, which binds to many microbial surfaces and stabilizes the convertase. Lack of factor P is associated with increased susceptibility to infection with Neisseria. Once formed, C3b,Bb convertase rapidly cleaves even more C3 into C3b, which can bind to the pathogen and either act as an opsonin or restart the pathway to form another C3bBb convertase molecule. Thus, the alternative pathway is activated by an amplification loop, which can occur on the surface of pathogens but not on host cells. This same amplification loop enables the alternative pathway to contribute to complement activation initially triggered by the classical or MB-lectin pathways.

[0094] The C3 convertases generated by activation of the classical and MB-lectin pathways (C4b,2b) and the alternative pathway (C3b,Bb) are significantly different. Only one component of the alternative pathway seems to be completely unrelated to its functional equivalent in the classical and MB-lectin pathways; this is the initiating serine protease factor D. Factor D can also be singled out as the only activating protease of the complement system to circulate as an active enzyme rather than a zymogen. This is necessary for initiating the alternative pathway by spontaneous C3 cleavage and is safe for the host because factor D has no other substrates except factor B when bound to C3b. This means that factor D finds its substrate only at very low levels in plasma and on the surfaces of pathogens that permit the alternative pathway of complement activation to proceed.

[0095] The formation of C3 convertase is the point at which the three complement activation pathways converge because both the classical and MB-lectin pathway convertases C4b,2b and the alternative pathway convertase C3bBb have the same activity and they initiate the same subsequent events. Both of them cleave C3 into C3b and C3a. C3b covalently binds to adjacent molecules on the pathogen surface through its thioester bond; otherwise C3b is inactivated by hydrolysis. C3 is the most abundant complement protein in plasma, present at a concentration of 1.2 mg ml-1, and up to 1000 C3b molecules can bind near a single active C3 convertase. Thus, the main effect of complement activation is the deposition of large amounts of C3b on the surface of infecting pathogens, which forms a covalently bonded coat on the surface that can signal the ultimate destruction of the pathogen by phagocytes.

[0096] The next step in the cascade is the generation of C5 convertase. In the classical and MB-lectin pathways, C5 convertase is formed by the binding of C3b to C4b,2b to produce C4b,2b,3b. Similarly, the C5 convertase of the alternative pathway is formed by binding C3b to the C3 convertase to form C3b2Bb. C5 is captured by these C5 convertase complexes by binding to a receptor site on C3b and is then rendered susceptible to cleavage by the serine protease activity of C2b or Bb. This reaction to produce C5b and C5a is more restricted than the cleavage of C3 because C5 can only be cleaved when bound to C3b as part of the C5 convertase complex. Thus, complement activation in both the alternative, MB-lectin, and classical pathways results in the binding of a large number of C3b molecules on the pathogen surface, the production of a more limited number of C5b molecules, and the release of C3a and C5a.

[0097] C3b antagonists and anti-C3b antibodies

[0098] C3b antagonists suitable for the present invention include therapeutic agents that can reduce, inhibit, or eliminate one or more C3b-mediated signalings, including those described herein. For example, suitable C3b antagonists according to the present invention include, but are not limited to, anti-C3b antibodies or fragments thereof, anti-C3b VHH-Fc, soluble C3b-binding proteins, soluble C3b-binding protein-Fc fusion proteins or fragments thereof, to name a few.

[0099] Anti-C3b antibodies and fragments

[0100] Conventional antibodies, also known as immunoglobulins, are Y-shaped structures composed of four polypeptides - two heavy chains and two light chains. This structure allows antibody molecules to perform their dual functions: antigen binding and bioactivity mediation. Each function is carried out by different parts of the antibody: the fragment antigen binding (Fab fragment) and the fragment crystallizable region (Fc region). The Fab fragment is the region on the antibody that binds to the antigen. It consists of one constant domain and one variable domain from each of the heavy and light chains. These domains form a paratope - the antigen-binding site - at the amino terminus of the monomer. The Fc region is the tail region of the antibody that interacts with cell surface receptors called Fc receptors and some proteins of the complement system. This property allows antibodies to activate the immune system. The Fc region of immunoglobulin Gs has a highly conserved N-glycosylation site.

[0101] There are three CDRs in the VH and VL regions, namely hypervariable amino acid sequences, which form the antigen-binding site of each Fab. The interface between each heavy and light chain CDR and the constant segment generates a three-dimensional binding structure with high specificity for different antigenic determinants or epitopes.

[0102] Single domain antibody (VHH)

[0103] Single domain antibodies (VHHs) are fragments that represent the smallest antigen-binding domains of antibodies. Although the molecular weight is usually less than 12 - 15 KDa of their parental antibodies, this type of antibody retains its binding specificity and affinity. This type of single domain antibody is characterized by its high physical and thermal stability as well as the production process.

[0104] In some embodiments, the VHH is fused to the Fc domain. In some embodiments, the VHH is fused to the CH2 domain. In some embodiments, the VHH is fused to the CH3 domain. In some embodiments, the VHH is fused to the CH2 and CH3 domains.

[0105] Constant region (Fc)

[0106] The Fc region of an antibody interacts with a number of Fc receptors and ligands, conferring a range of important functional capabilities known as effector functions. For IgG, the Fc region contains the Ig domains Cγ2 and Cγ3 and the N-terminal hinge leading to Cγ2. An important family of Fc receptors for the IgG class is the Fcγ receptors (FcγRs). These receptors mediate communication between antibodies and the cellular arm of the immune system (Raghavan et al., 1996, Annu Rev Cell Dev Biol 12:181-220; Ravetch et al., 2001, Annu Rev Immunol 19:275-290). In humans, this protein family includes: FcγRI (CD64), which includes the isotypes FcγRIa, FcγRIb, and FcγRIc; FcγRII (CD32), which includes the isotypes FcγRIIa (including the allotypes H131 and R131), FcγRIIb (including FcγRIIb-1 and FcγRIIb-2), and FcγRIIc; and FcγRIII (CD16), which includes the isotypes FcγRIIIa (including the allotypes V158 and F158) and FcγRIIIb (including the allotypes FcγRIIIb-NA1 and FcγRIIIb-NA2) (Jefferis et al., 2002, Immunol Lett 82:57-65, which is incorporated by reference). These receptors typically have an extracellular domain that mediates binding to Fc, a transmembrane region, and an intracellular domain that can mediate some signal transduction events within the cell. These receptors are expressed on a variety of immune cells, including monocytes, macrophages, neutrophils, dendritic cells, eosinophils, mast cells, platelets, B cells, large granular lymphocytes, Langerhans cells, natural killer (NK) cells, and γδ T cells. Formation of the Fc / FcγR complex recruits these effector cells to the site of antigen binding, typically leading to signal transduction events within the cell and important subsequent immune responses, such as the release of inflammatory mediators, B cell activation, endocytosis, phagocytosis, and cytotoxic attack. The ability to mediate cytotoxic and phagocytic effector functions is a potential mechanism by which antibodies destroy target cells.A cell-mediated reaction in which non-specific cytotoxic cells expressing FcγR recognize bound antibody on a target cell and subsequently cause lysis of the target cell is referred to as antibody-dependent cell-mediated cytotoxicity (ADCC) (Raghavan et al., 1996, Annual Review of Cell and Developmental Biology 12:181-220; Ghetie et al., 2000, Annual Review of Immunology 18:739-766; Ravetch et al., 2001, Annual Review of Immunology 19:275-290, which are incorporated by reference). A cell-mediated reaction in which non-specific cytotoxic cells expressing FcγR recognize bound antibody on a target cell and subsequently cause phagocytosis of the target cell is referred to as antibody-dependent cell-mediated phagocytosis (ADCP). The extracellular domains of human FcγR have been solved for many structures, including FcγRIIa (pdb accession code 1H9V) (Sondermann et al., 2001, Journal of Molecular Biology 309:737-749) (pdb accession code 1FCG) (Maxwell et al., 1999, Nature Structural Biology 6:437-442), FcγRIIb (pdb accession code 2FCB) (Sondermann et al., 1999, EMBO Journal 18:1095-1103); and FcγRIIIb (pdb accession code 1E4J) (Sondermann et al., 2000, Nature 406:267-273, which is incorporated by reference). All FcγR bind to the same region on Fc at the N-terminus of the Cγ2 domain and the preceding hinge. This interaction has been well characterized structurally (Sondermann et al., 2001, Journal of Biological Chemistry 309:737-749, which is incorporated by reference), and several structures of human Fc bound to the extracellular domain of human FcγRIIIb have been solved (pdb accession code 1E4K) (Sondermann et al., 2000, Nature 406:267-273) (pdb accession codes 1IIS and 1IIX) (Radaev et al., 2001, Journal of Biological Chemistry 276:16469-16477, which is incorporated by reference), as well as the structure of the human IgE Fd / FcεRIa complex (pdb accession code 1F6A) (Garman et al., 2000, Nature 406:259-266, which is incorporated by reference).

[0107] Overlapping but distinct sites on Fc serve as the interface for the complement protein C1q. In a manner analogous to how Fc / FcγR binding mediates ADCC, Fc / C1q binding mediates complement-dependent cytotoxicity (CDC). C1q forms a complex with the serine proteases C1r and C1s to form the C1 complex. C1q is capable of binding six antibodies, but binding to two IgGs is sufficient to activate the complement cascade. Similar to the Fc interactions with FcγRs, different IgG subclasses have different affinities for C1q, where the binding of IgG1 and IgG3 to FcγRs is generally significantly better than that of IgG2 and IgG4 to FcγRs.

[0108] Sites on Fc between the Cγ2 and Cγ3 domains mediate the interaction with the neonatal receptor FcRn, whose binding recycles endocytosed antibodies from endosomes back to the bloodstream (Raghavan et al., 1996, Annual Review of Cell and Developmental Biology 12:181 - 220; Ghetie et al., 2000, Annual Review of Immunology 18:739 - 766, which are incorporated by reference). This process, coupled with the exclusion of renal filtration due to the large size of the full-length molecule, results in a favorable antibody serum half-life ranging from one to three weeks. The binding of Fc to FcRn also plays a key role in antibody transport. The binding site for FcRn on Fc is also the site where the bacterial proteins A and G bind. The tight binding of these proteins is commonly used as a method for purifying antibodies by employing protein A or protein G affinity chromatography during protein purification. Thus, the fidelity of this region on Fc is important for both the clinical properties of the antibody and its purification. The available structures of the rat Fc / FcRn complex (Martin et al., 2001, Molecular Cell 7:867 - 877, which is incorporated by reference) and the complexes of Fc with proteins A and G (Deisenhofer, 1981, Biochemistry 20:2361 - 2370; Sauer-Eriksson et al., 1995, Structure 3:265 - 278; Tashiro et al., 1995, Current Opinion in Structural Biology 5:471 - 481, which are incorporated by reference) provide insights into the interactions of Fc with these proteins.

[0109] In some embodiments, the antibody or its fragment comprises an optimized Fc variant for various contexts. As outlined above, current antibody therapies face various problems. The present invention provides a promising method for enhancing the therapeutic efficacy of an antibody by eliminating its ability to mediate cytotoxic effector functions such as ADCC, ADCP, and CDC.

[0110] Fc variants

[0111] Fc polypeptides comprising the Fc variants described herein are referred to as "Fc polypeptides". The Fc polypeptides of the present invention include polypeptides comprising Fc variants in the context of larger polypeptides such as antibodies or Fc fusions, such as antibodies or Fc fusions. That is, Fc polypeptides include antibodies and Fc fusions comprising the Fc variants of the present invention. The Fc polypeptides of the present invention also include polypeptides that, in addition to the Fc region, contain little or no additional polypeptide sequence, referred to as isolated Fc. The Fc polypeptides described in the present invention also include fragments of the Fc region. As described below, any of the foregoing Fc polypeptides can be fused to one or more fusion partners or conjugation partners to provide the desired functional properties.

[0112] The parent Fc polypeptides described herein can be derived from a wide range of sources and can be encoded substantially by one or more Fc genes from any organism, including but not limited to humans, rodents, including but not limited to mice and rats, lagomorphs such as rabbits and hares, camelids such as camels, llamas and dromedaries, and non-human primates, including but not limited to prosimians, platyrrhines (New World monkeys), cercopithecines (Old World monkeys) and the hominoid superfamily most preferred by humans, including gibbons, small apes and great apes. The parent Fc polypeptides of the present invention can be encoded substantially by immunoglobulin genes belonging to any of the antibody classes, including but not limited to sequences belonging to the IgG (including human subclasses IgG1, IgG2, IgG3 or IgG4), IgA (including human subclasses IgA1 and IgA2), IgD, IgE, IgG or IgM classes of antibodies. The parent Fc polypeptides of the present invention contain sequences belonging to the human IgG class of antibodies. For example, the parent Fc polypeptide can be a parent antibody, such as a human IgG1 antibody, a human IgA antibody or a mouse IgG2a or IgG2b antibody. The parent antibody can be non-human, chimeric, humanized or fully human as described in detail below. The parent Fc polypeptide can be modified or engineered in some way, for example the parent antibody can be affinity matured or can have an engineered glycoform, all of which are described more fully below. Alternatively, the parent Fc polypeptide can be an Fc fusion, such as an Fc fusion in which the fusion partner targets a cell surface receptor. Alternatively, the parent Fc polypeptide can be an isolated Fc region that contains little or no other polypeptide sequence outside the Fc region. The parent Fc polypeptide can be a naturally occurring Fc region or can be an existing engineered variant of the Fc polypeptide. Importantly, the parent Fc polypeptide contains an Fc region, which can then be mutated to produce an Fc variant.

[0113] Optimized properties

[0114] The Fc variants described herein are optimized for a number of therapeutically relevant properties. Relative to the parental Fc polypeptide, the Fc variant comprises one or more amino acid modifications, wherein the amino acid modification provides one or more optimized properties. The amino acid sequence of the Fc variant of the present invention differs from that of its parental Fc polypeptide by at least one amino acid modification. In some embodiments, the Fc variant has at least one amino acid modification compared to the parental. Alternatively, in some embodiments, the Fc variant can have more than one amino acid modification compared to the parental, such as about one to fifty amino acid modifications, about one to ten amino acid modifications, or about one to about five amino acid modifications compared to the parental. Thus, the sequence of the Fc variant and the sequence of the parental Fc polypeptide are substantially homologous. For example, the variant Fc variant sequences herein will have about 80% homology with the parental Fc variant sequences, preferably at least about 90% homology, and most preferably at least about 95% homology.

[0115] Fc variants can be optimized for various properties. Fc variants engineered or predicted to display one or more optimized properties are referred to herein as "optimized Fc variants". Properties that can be optimized include, but are not limited to, enhancing or reducing the affinity for FcγR. In some embodiments, the Fc variant is optimized to have a reduced or ablated affinity for human FcγR, including but not limited to FcγRI, FcγRIIa, FcγRIIb, FcγRIIc, FcγRIIIa, and FcγRIIIb. These embodiments are expected to provide Fc polypeptides with enhanced therapeutic properties in humans, such as reduced effector function and reduced toxicity. In other embodiments, the Fc variant provides enhanced affinity for one or more FcγR, but reduced affinity for one or more other FcγR. For example, the Fc variant can have enhanced binding to FcγRIIIa, but reduced binding to FcγRIIb. Alternatively, the Fc variant can have enhanced binding to FcγRIIa and FcγRI, but reduced binding to FcγRIIb. In yet another embodiment, the Fc variant can have enhanced affinity for FcγRIIb, but reduced affinity for one or more activating FcγR.

[0116] In some embodiments, the Fc variant has a reduced or ablated affinity for FcγRI. In some embodiments, the Fc variant has a reduced or ablated affinity for FcγRIIa. In some embodiments, the Fc variant has a reduced or ablated affinity for FcγRIIb. In some embodiments, the Fc variant has a reduced or ablated affinity for FcγRIIc. In some embodiments, the Fc variant has a reduced or ablated affinity for FcγRIIIa. In some embodiments, the Fc variant has a reduced or ablated affinity for FcγRIIIb. In some embodiments, the Fc variant has a reduced or ablated affinity for C1q. In some embodiments, the Fc variant has an enhanced affinity for FcRn. In some embodiments, the Fc variant maintains an affinity for FcRn. In some embodiments, the Fc variant has a reduced or ablated affinity for FcγRI, FcγRIIa, FcγRIIb, FcγRIIIa, FcγRIIIb, and C1q. In some embodiments, the Fc variant has a reduced or ablated affinity for FcγRI, FcγRIIa, FcγRIIb, FcγRIIIa, FcγRIIIb, and C1q and retains binding to FcRn.

[0117] The Fc variant can also be optimized to enhance the functionality and / or solution properties of the deglycosylated form. In a preferred embodiment, the deglycosylated Fc variant binds to the Fc ligand with a reduced affinity compared to the deglycosylated form of the parental Fc variant. The Fc ligands include, but are not limited to, FcγR, C1q, FcRn, and Protein A and G, and can be from any source, including but not limited to human, mouse, rat, rabbit, or monkey, preferably human. In an alternatively preferred embodiment, the Fc variant is optimized to be more stable and / or more soluble than the deglycosylated form of the parental Fc variant.

[0118] In some embodiments, the antibody or fragment thereof comprises an Fc variant that comprises an L235E mutation. In some embodiments, the antibody or fragment thereof comprises an Fc variant that comprises a D265G mutation. In some embodiments, the antibody or fragment thereof comprises an Fc variant that comprises an F234V mutation. In some embodiments, the antibody or fragment thereof comprises an Fc variant that comprises F234V, L235E, D265G mutations.

[0119] Engineered Fc mutations

[0120] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG1 Fc region that comprises the amino acid substitutions L234F / L235E / D265G, wherein the residues are numbered according to the EU index.

[0121] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG1 Fc region, the Fc variant comprising the amino acid substitutions T307Q / Q311V / A378V, wherein the residues are numbered according to the EU index.

[0122] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG1 Fc region, the Fc variant comprising the amino acid substitutions L234F / L235E / D265G / S228P / T307Q / Q311V / A378V, wherein the residues are numbered according to the EU index.

[0123] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG1 Fc region, the Fc variant comprising the amino acid substitutions L234F / L235E / G237A / D265G, wherein the residues are numbered according to the EU index.

[0124] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG1 Fc region, the Fc variant comprising the amino acid substitutions L234V / L235E / G237A / D265G, wherein the residues are numbered according to the EU index.

[0125] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG1 Fc region, the Fc variant comprising the amino acid substitutions L234F / L235E / D265G / A330S / P331S, wherein the residues are numbered according to the EU index.

[0126] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG1 Fc region, the Fc variant comprising the amino acid substitutions L234V / L235A / G237A / D265G, wherein the residues are numbered according to the EU index.

[0127] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG1 Fc region, the Fc variant comprising the amino acid substitutions L234V / L235A / G237A / D265G / A330S / P331S, wherein the residues are numbered according to the EU index.

[0128] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG1 Fc region, the Fc variant comprising the amino acid substitution D265G, wherein the residues are numbered according to the EU index.

[0129] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG4 Fc region, the Fc variant comprising the amino acid substitutions L235E / D265G / S228P, wherein the residues are numbered according to the EU index.

[0130] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG4 Fc region, the Fc variant comprising the amino acid substitutions F234V / L235E / D265G / S228P, wherein the residues are numbered according to the EU index.

[0131] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG4 Fc region, the Fc variant comprising the amino acid substitutions F234V / L235A / G237A / D265G / S228P, wherein the residues are numbered according to the EU index.

[0132] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG4 Fc region, the Fc variant comprising the amino acid substitutions L235E / G237A / D265G / S228P, wherein the residues are numbered according to the EU index.

[0133] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG4 Fc region, the Fc variant comprising the amino acid substitutions L235E / G237A / P329G / S228P, wherein the residues are numbered according to the EU index.

[0134] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG4 Fc region, the Fc variant comprising the amino acid substitutions L235E / G237A / L328R / S228P, wherein the residues are numbered according to the EU index.

[0135] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG2 Fc region, the Fc variant comprising the amino acid substitutions D265G / A330S / P331S, wherein the residues are numbered according to the EU index.

[0136] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG2 Fc region, the Fc variant comprising the amino acid substitutions A235E / D265G / A330S / P331S, wherein the residues are numbered according to the EU index.

[0137] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG2 Fc region, the Fc variant comprising the amino acid substitutions A235E / D265G / P329G, wherein the residues are numbered according to the EU index.

[0138] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG Fc region, the Fc variant comprising amino acid substitutions at positions 235 and 265, wherein the amino acid at 265 is replaced with Gly, wherein the residues are numbered according to the EU index.

[0139] In some embodiments, the Fc variant further comprises one or more amino acid substitutions at 234, 237, 329, 330, or 331. In some embodiments, the Fc variant further comprises an amino acid substitution at 234. In some embodiments, the Fc variant further comprises amino acid substitutions at 234 and 237. In some embodiments, the Fc variant further comprises amino acid substitutions at 234, 330, and 331. In some embodiments, the Fc variant further comprises amino acid substitutions at 234, 237, 330, and 331. In some embodiments, the Fc variant further comprises an amino acid substitution at 237. In some embodiments, the Fc variant further comprises amino acid substitutions at 330 and 331. In some embodiments, the Fc variant further comprises an amino acid substitution at 329.

[0140] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG Fc region, the Fc variant comprising amino acid substitutions at positions 234 and 265, wherein the amino acid at 234 is replaced with Val, and wherein the residues are numbered according to the EU index.

[0141] In some embodiments, the Fc variant further comprises amino acid substitutions at 235 and 237. In some embodiments, the Fc variant further comprises amino acid substitutions at 235, 237, 330, and 331. In some embodiments, the Fc variant further comprises an amino acid substitution at 235.

[0142] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG4 Fc region, the Fc variant comprising amino acid substitutions at positions F234, L235, and D265, wherein the residues are numbered according to the EU index.

[0143] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG Fc region, the Fc variant comprising amino acid substitutions of 234V, L235E, and D265G, wherein the residues are numbered according to the EU index.

[0144] In some embodiments, the Fc variant is an IgG4 Fc region. In some embodiments, the Fc variant comprises amino acid substitutions of S228P, F234V, L235E, and D265G. In some embodiments, the Fc variant is an IgG4 Fc region and comprises amino acid substitutions of S228P, F234V, L235E, and D265G.

[0145] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG Fc region, the Fc variant comprising amino acid substitutions of 234F, L235E, and D265G, wherein the residues are numbered according to the EU index.

[0146] In some embodiments, the Fc variant is the IgG1 Fc region. In some embodiments, the Fc variant comprises amino acid substitutions of L234F, L235E, and D265G. In some embodiments, the Fc variant is the IgG1 Fc region and comprises amino acid substitutions of L234F, L235E, and D265G.

[0147] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG Fc region, the Fc variant comprising amino acid substitutions of 234F, L235E, G237A, and D265G, wherein the residues are numbered according to the EU index.

[0148] In some embodiments, the Fc variant is the IgG1 Fc region. In some embodiments, the Fc variant comprises amino acid substitutions of L234F, L235E, G237A, and D265G. In some embodiments, the Fc variant is the IgG1 Fc region and comprises amino acid substitutions of L234F, L235E, G237A, and D265G.

[0149] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG Fc region, the Fc variant comprising amino acid substitutions of 234V, L235E, G237A, and D265G, wherein the residues are numbered according to the EU index.

[0150] In some embodiments, the Fc variant is the IgG1 Fc region. In some embodiments, the Fc variant comprises amino acid substitutions of L234V, L235E, G237A, and D265G. In some embodiments, the Fc variant is the IgG1 Fc region and comprises amino acid substitutions of L234V, L235E, G237A, and D265G.

[0151] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG Fc region, the Fc variant comprising amino acid substitutions of 234F, L235E, D265D, A330S, and P331S, wherein the residues are numbered according to the EU index.

[0152] In some embodiments, the Fc variant is the IgG1 Fc region. In some embodiments, the Fc variant comprises the amino acid substitutions of L234F, L235E, D265D, A330S, and P331S. In some embodiments, the Fc variant is the IgG1 Fc region and comprises the amino acid substitutions of L234F, L235E, D265D, A330S, and P331S.

[0153] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG Fc region, the Fc variant comprising the amino acid substitutions of 234V, L235A, G237A, and D265G, wherein the residues are numbered according to the EU index.

[0154] In some embodiments, the Fc variant is the IgG1 Fc region. In some embodiments, the Fc variant comprises the amino acid substitutions of L234V, L235A, G237A, and D265G. In some embodiments, the Fc variant is the IgG1 Fc region and comprises the amino acid substitutions of 234F, L234V, L235A, G237A, and D265G. In some embodiments, the Fc variant is the IgG4 Fc region. In some embodiments, the Fc variant comprises the amino acid substitutions of S228P, L234V, L235A, G237A, and D265G. In some embodiments, the Fc variant is the IgG4 Fc region and comprises the amino acid substitutions of S228P, L234V, L235A, G237A, and D265G.

[0155] . In some embodiments, the Fc variant comprises the amino acid substitutions of S228P, L234V, L235A, G237A, D265G, T307Q, Q311V, and A378V. In some embodiments, the Fc variant is the IgG4 Fc region and comprises the amino acid substitutions of L234V, L235A, G237A, D265G, T307Q, Q311V, and A378V.

[0156] In some embodiments, the antibody or fragment thereof comprises an Fc variant of the wild-type human IgG Fc region, the Fc variant comprising the amino acid substitutions of 234V, L235A, G237A, D265G, A330S, and P331S, wherein the residues are numbered according to the EU index.

[0157] In some embodiments, the Fc variant is the IgG1 Fc region. In some embodiments, the Fc variant comprises the amino acid substitutions of L234V, L235A, G237A, D265G, A330S, and P331S. In some embodiments, the Fc variant is the IgG1 Fc region and comprises the amino acid substitutions of L234V, L235A, G237A, D265G, A330S, and P331S.

[0158] In some embodiments, the antibody or fragment thereof comprises an Fc variant of a wild-type human IgG Fc region, the Fc variant comprising amino acid substitutions of L235E and D265G, wherein the residues are numbered according to the EU index.

[0159] In some embodiments, the Fc variant is an IgG4 Fc region. In some embodiments, the Fc variant comprises amino acid substitutions of S228P, L235E and D265G. In some embodiments, the Fc variant is an IgG4 Fc region and comprises amino acid substitutions of S228P, L235E and D265G.

[0160] In some embodiments, the antibody or fragment thereof comprises an Fc variant of a wild-type human IgG Fc region, the Fc variant comprising amino acid substitutions of L235E, G237A and D265G, wherein the residues are numbered according to the EU index.

[0161] In some embodiments, the Fc variant is an IgG4 Fc region. In some embodiments, the Fc variant comprises amino acid substitutions of S228P, L235E, G237A and D265G. In some embodiments, the Fc variant is an IgG4 Fc region and comprises amino acid substitutions of S228P, L235E, G237A and D265G.

[0162] In some embodiments, the antibody or fragment thereof comprises an Fc variant of a wild-type human IgG Fc region, the Fc variant comprising amino acid substitutions of L235E, G237A and P329G, wherein the residues are numbered according to the EU index.

[0163] In some embodiments, the Fc variant is an IgG4 Fc region. In some embodiments, the Fc variant comprises amino acid substitutions of S228P, L235E, G237A and P329G. In some embodiments, the Fc variant is an IgG4 Fc region and comprises amino acid substitutions of S228P, L235E, G237A and P329G.

[0164] In some embodiments, the antibody or fragment thereof comprises an Fc variant of a wild-type human IgG Fc region, the Fc variant comprising amino acid substitutions of L235E, G237A and L328R, wherein the residues are numbered according to the EU index.

[0165] In some embodiments, the Fc variant is an IgG4 Fc region. In some embodiments, the Fc variant comprises amino acid substitutions of S228P, L235E, G237A and L328R. In some embodiments, the Fc variant is an IgG4 Fc region and comprises amino acid substitutions of S228P, L235E, G237A and L328R.

[0166] In some embodiments, the antibody or fragment thereof comprises an Fc variant of a wild-type human IgG Fc region, the Fc variant comprising amino acid substitutions of D265G, A330S, and P331S, wherein the residues are numbered according to the EU index.

[0167] In some embodiments, the Fc variant is an IgG2 Fc region. In some embodiments, the Fc variant comprises amino acid substitutions of D265G, A330S, and P331S. In some embodiments, the Fc variant is an IgG2 Fc region and comprises amino acid substitutions of D265G, A330S, and P331S.

[0168] In some embodiments, the antibody or fragment thereof comprises an Fc variant of a wild-type human IgG Fc region, the Fc variant comprising amino acid substitutions of 235E, D265G, A330S, and P331S, wherein the residues are numbered according to the EU index.

[0169] In some embodiments, the Fc variant is an IgG2 Fc region. In some embodiments, the Fc variant comprises amino acid substitutions of A235E, D265G, A330S, and P331S. In some embodiments, the Fc variant is an IgG2 Fc region and comprises amino acid substitutions of A235E, D265G, A330S, and P331S.

[0170] In some embodiments, the antibody or fragment thereof comprises an Fc variant of a wild-type human IgG Fc region, the Fc variant comprising amino acid substitutions of 235E, D265G, and P329G, wherein the residues are numbered according to the EU index.

[0171] In some embodiments, the Fc variant is an IgG2 Fc region. In some embodiments, the Fc variant comprises amino acid substitutions of A235E, D265G, and P329G. In some embodiments, the Fc variant is an IgG2 Fc region and comprises amino acid substitutions of A235E, D265G, and P329G.

[0172] In some embodiments, the Fc variant comprises SEQ ID NO:14.

[0173] ESKYGPPCPPCPAPEVEGGPSVFLFPPKPKDTLMISRTPEVTCVVVGVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLQVLHVDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIVVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK(SEQ ID NO:14)

[0174] In some embodiments, the Fc variant comprises an amino acid sequence that is 85% identical to SEQ ID NO:14. In some embodiments, the Fc variant comprises an amino acid sequence that is 90% identical to SEQ ID NO:14. In some embodiments, the Fc variant comprises an amino acid sequence that is 92% identical to SEQ ID NO:14. In some embodiments, the Fc variant comprises an amino acid sequence that is 95% identical to SEQ ID NO:14. In some embodiments, the Fc variant comprises an amino acid sequence that is 96% identical to SEQ ID NO:14. In some embodiments, the Fc variant comprises an amino acid sequence that is 97% identical to SEQ ID NO:14. In some embodiments, the Fc variant comprises an amino acid sequence that is 98% identical to SEQ ID NO:14. In some embodiments, the Fc variant comprises an amino acid sequence that is 99% identical to SEQ ID NO:14. In some embodiments, the Fc variant comprises an amino acid sequence identical to SEQ ID NO:14.

[0175] Sequence of anti-C3b antibody

[0176] In some embodiments, the antibody is composed of two light chains and two heavy chains. In some embodiments, each of the heavy and light chains comprises complementarity determining regions (CDRs) and framework regions. In some embodiments, the antibody or a fragment thereof is a VHH.

[0177] In some embodiments, the VHH comprises three CDRs: CDR1, CDR2, and CDR3 as identified by the amino acid sequences in Table A and Table B.

[0178] Exemplary anti-C3b antibody sequences are provided below:

[0179] Table A: CDR sequences of exemplary anti-C3b VHHs based on Kabat convention

[0180]

[0181] Table B: CDR Sequences of Exemplary Anti-C3b VHHs Based on Chothia Conventions

[0182]

[0183] In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises the VHH sequence of SEQ ID NO:10.

[0184] EVQLLESGGGLVQPGGSLRLSCAASGRTFSNYHMGWFRQAPGQGREFVATIIRTGETIYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAAATSGWNIKTVTPYEYWGQGTLVTVSS(SEQ ID NO:10)

[0185] In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises the VHH sequence of SEQ ID NO:11.

[0186] EVQLLESGGGLVQPGGSLRLSCAASGRTFSNYHMGWFRQAPGQGREFVATIIRTGKTIYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAAATSGWHIKTVTPYEYWGQGTLVTVSS(SEQ ID NO:11)

[0187] In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises the VHH sequence of SEQ ID NO:12.

[0188] EVQLLESGGGLVQPGGSLRLSCAASGRTFSNYHMGWFRQAPGQGREFVATIIRTGTTIYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAAATSGWHIKTVTPYEYWGQGTLVTVSS(SEQ ID NO:12)

[0189] In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises the VHH sequence of SEQ ID NO:13.

[0190] EVQLLESGGGLVQPGGSLRLSCAASGRTFSNYHMGWFRQAPGQGREFVATIIRHGTTIYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAAATSGWHIKTVTPYEYWGQGTLVTVSS(SEQ ID NO:13)

[0191] In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH fused to an Fc domain.

[0192] In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain fusion of SEQ ID NO:4.

[0193] EVQLLESGGGLVQPGGSLRLSCAASGRTFSNYHMGWFRQAPGQGREFVATIIRTGETIYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAAATSGWNIKTVTPYEYWGQGTLVTVSSESKYGPPCPPCPAPEVEGGPSVFLFPPKPKDTLMISRTPEVTCVVVGVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLQVLHVDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIVVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK(SEQ ID NO:4)

[0194] In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain fusion of SEQ ID NO:5.

[0195] EVQLLESGGGLVQPGGSLRLSCAASGRTFSNYHMGWFRQAPGQGREFVATIIRTGKTIYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAAATSGWHIKTVTPYEYWGQGTLVTVSSESKYGPPCPPCPAPEVEGGPSVFLFPPKPKDTLMISRTPEVTCVVVGVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLQVLHVDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIVVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK(SEQ ID NO:5)

[0196] In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain fusion of SEQ ID NO:6.

[0197] EVQLLESGGGLVQPGGSLRLSCAASGRTFSNYHMGWFRQAPGQGREFVATIIRTGTTIYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAAATSGWHIKTVTPYEYWGQGTLVTVSSESKYGPPCPPCPAPEVEGGPSVFLFPPKPKDTLMISRTPEVTCVVVGVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLQVLHVDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIVVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK(SEQ ID NO:6)

[0198] In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain fusion of SEQ ID NO:7.

[0199] EVQLLESGGGLVQPGGSLRLSCAASGRTFSNYHMGWFRQAPGQGREFVATIIRHGTTIYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAAATSGWHIKTVTPYEYWGQGTLVTVSSESKYGPPCPPCPAPEVEGGPSVFLFPPKPKDTLMISRTPEVTCVVVGVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLQVLHVDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIVVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK(SEQ ID NO:7)

[0200] In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain fusion of SEQ ID NO:8.

[0201] EVQLLESGGGLVQPGGSLRLSCAASGRTFSNYHMGWFRQAPGQGREFVATIIRTGETIYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAAATSGWNIKTVTPYEYWGQGTLVTVSSESKYGPPCPPCPAPEFLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK(SEQ ID NO:8)

[0202] In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain fusion of SEQ ID NO:9.

[0203] EVQLLESGGGLVQPGGSLRLSCAASGRTFSNYHMGWFRQAPGQGREFVATIIRTGTTIYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAAATSGWHIKTVTPYEYWGQGTLVTVSSESKYGPPCPPCPAPEFLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK(SEQ ID NO:9)

[0204] In some embodiments, the anti-C3b antibody according to the invention comprises CDR amino acid sequences having at least 75%, 78%, 80%, 82%, 85%, 87%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more identity to one or more of SEQ ID NOs: 16-27.

[0205] In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 75% identity to SEQ ID NO:16. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 78% identity to SEQ ID NO:16. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 80% identity to SEQ ID NO:16. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 82% identity to SEQ ID NO:16. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 85% identity to SEQ ID NO:16. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 85% identity to SEQ ID NO:16. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 87% identity to SEQ ID NO:16. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 90% identity to SEQ ID NO:16. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 91% identity to SEQ ID NO:16. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 92% identity to SEQ ID NO:16. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 93% identity to SEQ ID NO:16. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 94% identity to SEQ ID NO:16. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 95% identity to SEQ ID NO:16. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 96% identity to SEQ ID NO:16. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 97% identity to SEQ ID NO:16. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 98% identity to SEQ ID NO:16. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 99% identity to SEQ ID NO:16.

[0206] In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 75% identity to SEQ ID NO:17. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 78% identity to SEQ ID NO:17. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 80% identity to SEQ ID NO:17. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 82% identity to SEQ ID NO:17. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 85% identity to SEQ ID NO:17. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 85% identity to SEQ ID NO:17. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 87% identity to SEQ ID NO:17. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 90% identity to SEQ ID NO:17. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 91% identity to SEQ ID NO:17. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 92% identity to SEQ ID NO:17. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 93% identity to SEQ ID NO:17. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 94% identity to SEQ ID NO:17. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 95% identity to SEQ ID NO:17. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 96% identity to SEQ ID NO:17. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 97% identity to SEQ ID NO:17. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 98% identity to SEQ ID NO:17. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 99% identity to SEQ ID NO:17.

[0207] In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 75% identity to SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 78% identity to SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 80% identity to SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 82% identity to SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 85% identity to SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 85% identity to SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 87% identity to SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 90% identity to SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 91% identity to SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 92% identity to SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 93% identity to SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 94% identity to SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 95% identity to SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 96% identity to SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 97% identity to SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 98% identity to SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 99% identity to SEQ ID NO:18.

[0208] In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 75% identity to SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 78% identity to SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 80% identity to SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 82% identity to SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 85% identity to SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 85% identity to SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 87% identity to SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 90% identity to SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 91% identity to SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 92% identity to SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 93% identity to SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 94% identity to SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 95% identity to SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 96% identity to SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 97% identity to SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 98% identity to SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 amino acid sequence having at least 99% identity to SEQ ID NO:19.

[0209] In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 75% identity to SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 78% identity to SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 80% identity to SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 82% identity to SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 85% identity to SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 85% identity to SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 87% identity to SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 90% identity to SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 91% identity to SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 92% identity to SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 93% identity to SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 94% identity to SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 95% identity to SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 96% identity to SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 97% identity to SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 98% identity to SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 99% identity to SEQ ID NO:20.

[0210] In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 75% identity to SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 78% identity to SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 80% identity to SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 82% identity to SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 85% identity to SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 85% identity to SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 87% identity to SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 90% identity to SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 91% identity to SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 92% identity to SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 93% identity to SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 94% identity to SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 95% identity to SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 96% identity to SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 97% identity to SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 98% identity to SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises: a CDR2 amino acid sequence having at least 99% identity to SEQ ID NO:21.

[0211] In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 75% identity to SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 78% identity to SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 80% identity to SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 82% identity to SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 85% identity to SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 85% identity to SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 87% identity to SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 90% identity to SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 91% identity to SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 92% identity to SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 93% identity to SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 94% identity to SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 95% identity to SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 96% identity to SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 97% identity to SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 98% identity to SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR3 amino acid sequence having at least 99% identity to SEQ ID NO:22.

[0212] In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 75% identity to SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 78% identity to SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 80% identity to SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 82% identity to SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 85% identity to SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 85% identity to SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 87% identity to SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 90% identity to SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 91% identity to SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 92% identity to SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 93% identity to SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 94% identity to SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 95% identity to SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 96% identity to SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 97% identity to SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 98% identity to SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 99% identity to SEQ ID NO:23.

[0213] In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 75% identity to SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 78% identity to SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 80% identity to SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 82% identity to SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 85% identity to SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 85% identity to SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 87% identity to SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 90% identity to SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 91% identity to SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 92% identity to SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 93% identity to SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 94% identity to SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 95% identity to SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 96% identity to SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 97% identity to SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 98% identity to SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 99% identity to SEQ ID NO:24.

[0214] In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 75% identity to SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 78% identity to SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 80% identity to SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 82% identity to SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 85% identity to SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 85% identity to SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 87% identity to SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 90% identity to SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 91% identity to SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 92% identity to SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 93% identity to SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 94% identity to SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 95% identity to SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 96% identity to SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 97% identity to SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 98% identity to SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 99% identity to SEQ ID NO:25.

[0215] In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 75% identity to SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 78% identity to SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 80% identity to SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 82% identity to SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 85% identity to SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 85% identity to SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 87% identity to SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 90% identity to SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 91% identity to SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 92% identity to SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 93% identity to SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 94% identity to SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 95% identity to SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 96% identity to SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 97% identity to SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 98% identity to SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 99% identity to SEQ ID NO:26.

[0216] In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 75% identity to SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 78% identity to SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 80% identity to SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 82% identity to SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 85% identity to SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 85% identity to SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 87% identity to SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 90% identity to SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 91% identity to SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 92% identity to SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 93% identity to SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 94% identity to SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 95% identity to SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 96% identity to SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 97% identity to SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 98% identity to SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR2 amino acid sequence having at least 99% identity to SEQ ID NO:27.

[0217] In some embodiments, the anti-C3b antibody according to the invention comprises up to one, two, three or four amino acid substitutions in one or more CDR sequences of SEQ ID NOs: 16-27. In some embodiments, the anti-C3b antibody according to the invention comprises up to one, two, three, four or five amino acid substitutions in one or more CDR sequences selected from SEQ ID NOs: 16-27.

[0218] In some embodiments, the anti-C3b antibody or fragment thereof comprises one amino acid substitution in CDR1 of SEQ ID NO: 16. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in CDR1 of SEQ ID NO: 16. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in CDR1 of SEQ ID NO: 16. In some embodiments, the anti-C3b antibody or fragment thereof comprises three amino acid substitutions in CDR1 of SEQ ID NO: 16. In some embodiments, the anti-C3b antibody or fragment thereof comprises four amino acid substitutions in CDR1 of SEQ ID NO: 16. In some embodiments, the anti-C3b antibody or fragment thereof comprises five amino acid substitutions in CDR1 of SEQ ID NO: 16.

[0219] In some embodiments, the anti-C3b antibody or fragment thereof comprises one amino acid substitution in CDR2 of SEQ ID NO: 17. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in CDR2 of SEQ ID NO: 17. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in CDR2 of SEQ ID NO: 17. In some embodiments, the anti-C3b antibody or fragment thereof comprises three amino acid substitutions in CDR2 of SEQ ID NO: 17. In some embodiments, the anti-C3b antibody or fragment thereof comprises four amino acid substitutions in CDR2 of SEQ ID NO: 17. In some embodiments, the anti-C3b antibody or fragment thereof comprises five amino acid substitutions in CDR2 of SEQ ID NO: 17.

[0220] In some embodiments, the anti-C3b antibody or fragment thereof comprises one amino acid substitution in the CDR3 of SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in the CDR3 of SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in the CDR3 of SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises three amino acid substitutions in the CDR3 of SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises four amino acid substitutions in the CDR3 of SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises five amino acid substitutions in the CDR3 of SEQ ID NO:18.

[0221] In some embodiments, the anti-C3b antibody or fragment thereof comprises one amino acid substitution in the CDR1 of SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in the CDR1 of SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in the CDR1 of SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises three amino acid substitutions in the CDR1 of SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises four amino acid substitutions in the CDR1 of SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises five amino acid substitutions in the CDR1 of SEQ ID NO:19.

[0222] In some embodiments, the anti-C3b antibody or fragment thereof comprises one amino acid substitution in the CDR2 of SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in the CDR2 of SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in the CDR2 of SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises three amino acid substitutions in the CDR2 of SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises four amino acid substitutions in the CDR2 of SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises five amino acid substitutions in the CDR2 of SEQ ID NO:20.

[0223] In some embodiments, the anti-C3b antibody or fragment thereof comprises one amino acid substitution in the CDR2 of SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in the CDR2 of SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in the CDR2 of SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises three amino acid substitutions in the CDR2 of SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises four amino acid substitutions in the CDR2 of SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises five amino acid substitutions in the CDR2 of SEQ ID NO:21.

[0224] In some embodiments, the anti-C3b antibody or fragment thereof comprises one amino acid substitution in the CDR3 of SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in the CDR3 of SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in the CDR3 of SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises three amino acid substitutions in the CDR3 of SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises four amino acid substitutions in the CDR3 of SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises five amino acid substitutions in the CDR3 of SEQ ID NO:22.

[0225] In some embodiments, the anti-C3b antibody or fragment thereof comprises one amino acid substitution in the CDR2 of SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in the CDR2 of SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in the CDR2 of SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises three amino acid substitutions in the CDR2 of SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises four amino acid substitutions in the CDR2 of SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises five amino acid substitutions in the CDR2 of SEQ ID NO:23.

[0226] In some embodiments, the anti-C3b antibody or fragment thereof comprises one amino acid substitution in CDR2 of SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in CDR2 of SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in CDR2 of SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises three amino acid substitutions in CDR2 of SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises four amino acid substitutions in CDR2 of SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises five amino acid substitutions in CDR2 of SEQ ID NO:24.

[0227] In some embodiments, the anti-C3b antibody or fragment thereof comprises one amino acid substitution in CDR2 of SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in CDR2 of SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in CDR2 of SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises three amino acid substitutions in CDR2 of SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises four amino acid substitutions in CDR2 of SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises five amino acid substitutions in CDR2 of SEQ ID NO:25.

[0228] In some embodiments, the anti-C3b antibody or fragment thereof comprises one amino acid substitution in CDR2 of SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in CDR2 of SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in CDR2 of SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises three amino acid substitutions in CDR2 of SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises four amino acid substitutions in CDR2 of SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises five amino acid substitutions in CDR2 of SEQ ID NO:26.

[0229] In some embodiments, the anti-C3b antibody or fragment thereof comprises one amino acid substitution in CDR2 of SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in CDR2 of SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises two amino acid substitutions in CDR2 of SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises three amino acid substitutions in CDR2 of SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises four amino acid substitutions in CDR2 of SEQ ID NO:27. In some embodiments, the anti-C3b antibody or fragment thereof comprises five amino acid substitutions in CDR2 of SEQ ID NO:27.

[0230] In some embodiments, the anti-C3b antibody or fragment thereof comprises CDR1 defined by SEQ ID NO:16. In some embodiments, the anti-C3b antibody or fragment thereof comprises CDR2 defined by SEQ ID NO:17. In some embodiments, the anti-C3b antibody or fragment thereof comprises CDR3 defined by SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises CDR1 defined by SEQ ID NO:19. In some embodiments, the anti-C3b antibody or fragment thereof comprises CDR2 defined by SEQ ID NO:20. In some embodiments, the anti-C3b antibody or fragment thereof comprises CDR2 defined by SEQ ID NO:21. In some embodiments, the anti-C3b antibody or fragment thereof comprises CDR3 defined by SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises CDR2 defined by SEQ ID NO:23. In some embodiments, the anti-C3b antibody or fragment thereof comprises CDR2 defined by SEQ ID NO:24. In some embodiments, the anti-C3b antibody or fragment thereof comprises CDR2 defined by SEQ ID NO:25. In some embodiments, the anti-C3b antibody or fragment thereof comprises CDR2 defined by SEQ ID NO:26. In some embodiments, the anti-C3b antibody or fragment thereof comprises CDR2 defined by SEQ ID NO:27.

[0231] In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 defined by SEQ ID NO:16, a CDR2 defined by SEQ ID NO:17, and a CDR3 defined by SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 defined by SEQ ID NO:19, a CDR2 defined by SEQ ID NO:20, and a CDR3 defined by SEQ ID NO:18. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 defined by SEQ ID NO:16, a CDR2 defined by SEQ ID NO:21, and a CDR3 defined by SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 defined by SEQ ID NO:19, a CDR2 defined by SEQ ID NO:23, and a CDR3 defined by SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 defined by SEQ ID NO:16, a CDR2 defined by SEQ ID NO:24, and a CDR3 defined by SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 defined by SEQ ID NO:19, a CDR2 defined by SEQ ID NO:25, and a CDR3 defined by SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 defined by SEQ ID NO:16, a CDR2 defined by SEQ ID NO:26, and a CDR3 defined by SEQ ID NO:22. In some embodiments, the anti-C3b antibody or fragment thereof comprises a CDR1 defined by SEQ ID NO:19, a CDR2 defined by SEQ ID NO:27, and a CDR3 defined by SEQ ID NO:22.

[0232] In some embodiments of the present invention, the heavy chain constant region of the anti-C3b antibody comprises CH1, hinge and CH2 domains derived from an IgG4 antibody, which domains are fused to a CH3 domain derived from an IgG1 antibody. In some embodiments of the present invention, the heavy chain constant region of the anti-C3b antibody is or is derived from an IgG1, IgG2, IgG3 or IgG4 heavy chain constant region. In some embodiments of the present invention, the light chain constant region of the anti-C3b antibody is or is derived from a λ or κ light chain constant region.

[0233] In some embodiments, the antibody or antigen-binding fragment thereof is a single-chain variable fragment (ScFv) comprising at least any one of the CDR sequences of SEQ ID NOs: 16-27. In some embodiments, the antibody or antigen-binding fragment thereof is a fusion molecule comprising at least any one of the CDR sequences of SEQ ID NOs: 16-27. In some embodiments, the antibody or antigen-binding fragment thereof is a bispecific antibody comprising at least one of the CDR sequences of SEQ ID NOs: 16-27. In some embodiments, the antibody or antigen-binding fragment thereof is a VHH comprising at least one of the CDR sequences of SEQ ID NOs: 16-27.

[0234] In some embodiments, the VHH that binds to Cb3 comprises CDR1 defined by SEQ ID NO: 16, CDR2 defined by SEQ ID NO: 17, and CDR3 defined by SEQ ID NO: 18. In some embodiments, the VHH that binds to Cb3 comprises CDR1 defined by SEQ ID NO: 19, CDR2 defined by SEQ ID NO: 20, and CDR3 defined by SEQ ID NO: 18. In some embodiments, the VHH that binds to Cb3 comprises CDR1 defined by SEQ ID NO: 16, CDR2 defined by SEQ ID NO: 21, and CDR3 defined by SEQ ID NO: 22. In some embodiments, the VHH that binds to Cb3 comprises CDR1 defined by SEQ ID NO: 19, CDR2 defined by SEQ ID NO: 23, and CDR3 defined by SEQ ID NO: 22. In some embodiments, the VHH that binds to Cb3 comprises CDR1 defined by SEQ ID NO: 16, CDR2 defined by SEQ ID NO: 24, and CDR3 defined by SEQ ID NO: 22. In some embodiments, the VHH that binds to Cb3 comprises CDR1 defined by SEQ ID NO: 19, CDR2 defined by SEQ ID NO: 25, and CDR3 defined by SEQ ID NO: 22. In some embodiments, the VHH that binds to Cb3 comprises CDR1 defined by SEQ ID NO: 16, CDR2 defined by SEQ ID NO: 26, and CDR3 defined by SEQ ID NO: 22. In some embodiments, the VHH that binds to Cb3 comprises CDR1 defined by SEQ ID NO: 19, CDR2 defined by SEQ ID NO: 27, and CDR3 defined by SEQ ID NO: 22.

[0235] In some embodiments, the antibody or antigen-binding fragment thereof is a VHH-Fc fusion comprising at least one of the CDR sequences of SEQ ID NOs: 16-27.

[0236] In some embodiments, the VHH-Fc fusion that binds to Cb3 comprises a CDR1 defined by SEQ ID NO:16, a CDR2 defined by SEQ ID NO:17, and a CDR3 defined by SEQ ID NO:18. In some embodiments, the VHH-Fc fusion that binds to Cb3 comprises a CDR1 defined by SEQ ID NO:19, a CDR2 defined by SEQ ID NO:20, and a CDR3 defined by SEQ ID NO:18. In some embodiments, the VHH-Fc fusion that binds to Cb3 comprises a CDR1 defined by SEQ ID NO:16, a CDR2 defined by SEQ ID NO:21, and a CDR3 defined by SEQ ID NO:22. In some embodiments, the VHH-Fc fusion that binds to Cb3 comprises a CDR1 defined by SEQ ID NO:19, a CDR2 defined by SEQ ID NO:23, and a CDR3 defined by SEQ ID NO:22. In some embodiments, the VHH-Fc fusion that binds to Cb3 comprises a CDR1 defined by SEQ ID NO:16, a CDR2 defined by SEQ ID NO:24, and a CDR3 defined by SEQ ID NO:22. In some embodiments, the VHH-Fc fusion that binds to Cb3 comprises a CDR1 defined by SEQ ID NO:19, a CDR2 defined by SEQ ID NO:25, and a CDR3 defined by SEQ ID NO:22. In some embodiments, the VHH-Fc fusion that binds to Cb3 comprises a CDR1 defined by SEQ ID NO:16, a CDR2 defined by SEQ ID NO:26, and a CDR3 defined by SEQ ID NO:22. In some embodiments, the VHH-Fc fusion that binds to Cb3 comprises a CDR1 defined by SEQ ID NO:19, a CDR2 defined by SEQ ID NO:27, and a CDR3 defined by SEQ ID NO:22.

[0237] In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH sequence that is at least 85% identical to SEQ ID NO:10. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH sequence that is at least 88% identical to SEQ ID NO:10. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH sequence that is at least 90% identical to SEQ ID NO:10. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH sequence that is at least 92% identical to SEQ ID NO:10. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH sequence that is at least 95% identical to SEQ ID NO:10. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH sequence that is at least 97% identical to SEQ ID NO:10. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH sequence that is at least 98% identical to SEQ ID NO:10. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH sequence that is at least 99% identical to SEQ ID NO:10.

[0238] In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH sequence that is at least 85% identical to SEQ ID NO:11. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH sequence that is at least 88% identical to SEQ ID NO:11. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH sequence that is at least 90% identical to SEQ ID NO:11. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH sequence that is at least 92% identical to SEQ ID NO:11. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH sequence that is at least 95% identical to SEQ ID NO:11. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH sequence that is at least 97% identical to SEQ ID NO:11. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH sequence that is at least 98% identical to SEQ ID NO:11. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH sequence that is at least 99% identical to SEQ ID NO:11.

[0239] In some embodiments, the anti-C3b antibody or its antigen-binding fragment comprises a VHH sequence that is at least 85% identical to SEQ ID NO:12. In some embodiments, the anti-C3b antibody or its antigen-binding fragment comprises a VHH sequence that is at least 88% identical to SEQ ID NO:12. In some embodiments, the anti-C3b antibody or its antigen-binding fragment comprises a VHH sequence that is at least 90% identical to SEQ ID NO:12. In some embodiments, the anti-C3b antibody or its antigen-binding fragment comprises a VHH sequence that is at least 92% identical to SEQ ID NO:12. In some embodiments, the anti-C3b antibody or its antigen-binding fragment comprises a VHH sequence that is at least 95% identical to SEQ ID NO:12. In some embodiments, the anti-C3b antibody or its antigen-binding fragment comprises a VHH sequence that is at least 97% identical to SEQ ID NO:12. In some embodiments, the anti-C3b antibody or its antigen-binding fragment comprises a VHH sequence that is at least 98% identical to SEQ ID NO:12. In some embodiments, the anti-C3b antibody or its antigen-binding fragment comprises a VHH sequence that is at least 99% identical to SEQ ID NO:12.

[0240] In some embodiments, the anti-C3b antibody or its antigen-binding fragment comprises a VHH sequence that is at least 85% identical to SEQ ID NO:13. In some embodiments, the anti-C3b antibody or its antigen-binding fragment comprises a VHH sequence that is at least 88% identical to SEQ ID NO:13. In some embodiments, the anti-C3b antibody or its antigen-binding fragment comprises a VHH sequence that is at least 90% identical to SEQ ID NO:13. In some embodiments, the anti-C3b antibody or its antigen-binding fragment comprises a VHH sequence that is at least 92% identical to SEQ ID NO:13. In some embodiments, the anti-C3b antibody or its antigen-binding fragment comprises a VHH sequence that is at least 95% identical to SEQ ID NO:13. In some embodiments, the anti-C3b antibody or its antigen-binding fragment comprises a VHH sequence that is at least 97% identical to SEQ ID NO:13. In some embodiments, the anti-C3b antibody or its antigen-binding fragment comprises a VHH sequence that is at least 98% identical to SEQ ID NO:13. In some embodiments, the anti-C3b antibody or its antigen-binding fragment comprises a VHH sequence that is at least 99% identical to SEQ ID NO:13.

[0241] In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 85% identical to SEQ ID NO:4. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 88% identical to SEQ ID NO:4. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 90% identical to SEQ ID NO:4. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 92% identical to SEQ ID NO:4. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 95% identical to SEQ ID NO:4. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 96% identical to SEQ ID NO:4. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 97% identical to SEQ ID NO:4. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 98% identical to SEQ ID NO:4. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 99% identical to SEQ ID NO:4.

[0242] In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 85% identical to SEQ ID NO:5. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 88% identical to SEQ ID NO:5. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 90% identical to SEQ ID NO:5. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 92% identical to SEQ ID NO:5. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 95% identical to SEQ ID NO:5. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 96% identical to SEQ ID NO:5. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 97% identical to SEQ ID NO:5. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 98% identical to SEQ ID NO:5. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 99% identical to SEQ ID NO:5.

[0243] In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 85% identical to SEQ ID NO:6. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 88% identical to SEQ ID NO:6. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 90% identical to SEQ ID NO:6. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 92% identical to SEQ ID NO:6. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 95% identical to SEQ ID NO:6. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 96% identical to SEQ ID NO:6. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 97% identical to SEQ ID NO:6. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 98% identical to SEQ ID NO:6. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 99% identical to SEQ ID NO:6.

[0244] In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 85% identical to SEQ ID NO:7. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 88% identical to SEQ ID NO:7. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 90% identical to SEQ ID NO:7. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 92% identical to SEQ ID NO:7. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 95% identical to SEQ ID NO:7. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 96% identical to SEQ ID NO:7. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 97% identical to SEQ ID NO:7. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 98% identical to SEQ ID NO:7. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 99% identical to SEQ ID NO:7.

[0245] In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 85% identical to SEQ ID NO:8. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 88% identical to SEQ ID NO:8. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 90% identical to SEQ ID NO:8. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 92% identical to SEQ ID NO:8. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 95% identical to SEQ ID NO:8. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 96% identical to SEQ ID NO:8. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 97% identical to SEQ ID NO:8. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 98% identical to SEQ ID NO:8. In some embodiments, the anti-C3b antibody or antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 99% identical to SEQ ID NO:8.

[0246] In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 85% identical to SEQ ID NO:9. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 88% identical to SEQ ID NO:9. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 90% identical to SEQ ID NO:9. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 92% identical to SEQ ID NO:9. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 95% identical to SEQ ID NO:9. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 96% identical to SEQ ID NO:9. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 97% identical to SEQ ID NO:9. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 98% identical to SEQ ID NO:9. In some embodiments, the anti-C3b antibody or an antigen-binding fragment thereof comprises a VHH-Fc domain sequence that is at least 99% identical to SEQ ID NO:9.

[0247] In other embodiments, suitable C3b antagonists are anti-C3b antibodies. The anti-C3b antibodies of the present disclosure can be multispecific, such as bispecific. The antibodies can be mammalian (e.g., human, camelid, or murine), humanized, chimeric, recombinant, synthetically produced, or naturally isolated. Exemplary antibodies of the present disclosure include, but are not limited to, IgG (e.g., IgG1, IgG2, IgG3, and IgG4), IgM, IgA (e.g., IgA1, IgA2, and IgAsec), IgD, IgE, Fab, Fab', Fab'2, F(ab')2, Fd, Fv, Feb, scFv, scFv-Fc, and SMIP binding portions. In certain embodiments, the antibody is an scFv. The scFv can include, for example, a flexible linker, thereby allowing the scFv to be oriented in different directions to enable antigen binding. In various embodiments, the antibody can be a cytosolic-stable scFv or an intracellular antibody that retains its structure and function in the reducing environment inside the cell (see, for example, Fisher and DeLisa, Journal of Molecular Biology (J. Mol. Biol.) 385(1):299-311, 2009; incorporated herein by reference). In specific embodiments, the scFv is converted to IgG or a chimeric antigen receptor according to methods known in the art. In embodiments, the antibody binds to both denatured protein targets and native protein targets. In embodiments, the antibody binds to a denatured protein or a native protein.

[0248] In most mammals, including humans, a complete antibody has at least two heavy chains (H) and two light chains (L) linked by disulfide bonds. Each heavy chain consists of a heavy-chain variable region (VH) and a heavy-chain constant region (CH). The heavy-chain constant region consists of three domains (CH1, CH2, and CH3) and a hinge region between CH1 and CH2. Each light chain consists of a light-chain variable region (VL) and a light-chain constant region (CL). The light-chain constant region consists of one domain CL. The VH region and the VL region can be further subdivided into hypervariable regions called complementarity-determining regions (CDRs), which are interspersed with more conserved regions called framework regions (FRs). Each VH and VL consists of three CDRs and four FRs arranged in the following order from the amino terminus to the carboxy terminus: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4. The variable regions of the heavy and light chains contain binding domains that interact with antigens.

[0249] Antibodies include all known forms of antibodies and other protein scaffolds with antibody-like properties. For example, an anti-C3b antibody can be a monoclonal antibody, a polyclonal antibody, a human antibody, a humanized antibody, a bispecific antibody, a monovalent antibody, a chimeric antibody, or a protein scaffold with antibody-like properties, such as fibronectin or ankyrin repeats. Antibodies can be of any of the following isotypes: IgG (e.g., IgG1, IgG2, IgG3, and IgG4), IgM, IgA (e.g., IgA1, IgA2, and IgAsec), IgD, or IgE.

[0250] Antibody fragments can include one or more segments derived from an antibody. The segments derived from an antibody can retain the ability to specifically bind to a particular antigen. Antibody fragments can be, for example, Fab, Fab', Fab'2, F(ab')2, Fd, Fv, Feb, scFv, or SMIP. Antibody fragments can be, for example, bifunctional antibodies, trifunctional antibodies, affibody molecules, nanobodies (VhH), aptamers, domain antibodies, linear antibodies, single-chain antibodies, or any of the various multispecific antibodies formed from antibody fragments.

[0251] Examples of antibody fragments include: (i) Fab fragments, which are monovalent fragments consisting of the VL, VH, CL, and CH1 domains; (ii) F(ab')2 fragments, which are bivalent fragments containing two Fab fragments linked by a hinge region disulfide bond; (iii) Fd fragments, which are fragments consisting of the VH and CH1 domains; (iv) Fv fragments, which are fragments consisting of the VL and VH domains of a single arm of an antibody; (v) dAb fragments: fragments that include the VH and VL domains; (vi) dAb fragments: fragments that are the VH domain; (vii) dAb fragments: fragments that are the VL domain; (viii) isolated complementarity-determining regions (CDRs); and (ix) combinations of two or more isolated CDRs, which can optionally be joined by one or more synthetic linkers. In addition, although the two domains VL and VH of an Fv fragment are encoded by separate genes, the two domains can be joined using recombinant methods, such as by a synthetic linker that enables the two domains to be expressed as a single protein chain, in which the VL region and the VH region pair to form a monovalent binding moiety (referred to as single-chain Fv (scFv)). Antibody fragments can be obtained using conventional techniques known to those skilled in the art and, in some cases, can be used in the same manner as intact antibodies. Antigen-binding fragments can be produced by recombinant DNA techniques or by enzymatic or chemical cleavage of intact immunoglobulins. Antibody fragments can also include any of the antibody fragments described above, where additional C-terminal amino acids, N-terminal amino acids, or amino acids separating the individual fragments are added.

[0252] An antibody can be called chimeric if it comprises one or more antigen-determining regions or constant regions derived from a first species and one or more antigen-determining regions or constant regions derived from a second species. Chimeric antibodies can be constructed, for example, by genetic engineering. Chimeric antibodies can comprise immunoglobulin gene segments belonging to different species (e.g., from mouse and human).

[0253] An antibody can be a human antibody. A human antibody refers to a binding portion having variable regions, wherein both the framework regions and the CDR regions are derived from human immunoglobulin sequences. Additionally, if the antibody contains a constant region, the constant region is also derived from human immunoglobulin sequences. A human antibody can include amino acid residues not identified in the human immunoglobulin sequence, such as one or more sequence variants, e.g., mutations. Variations or additional amino acids can be introduced, for example, by human manipulation. The human antibodies of the present disclosure are not chimeric.

[0254] An antibody can be humanized, meaning an antibody comprising one or more antigen-determining regions (e.g., at least one CDR) substantially derived from a non-human immunoglobulin or antibody is manipulated to include at least one immunoglobulin domain substantially derived from a human immunoglobulin or antibody. Antibodies can be humanized using the conversion methods described herein, e.g., by inserting the antigen recognition sequences from a non-human antibody encoded by a first vector into a human framework encoded by a second vector. For example, the first vector can include a polynucleotide encoding a non-human antibody (or a fragment thereof) and a site-specific recombination motif, while the second vector can include a polynucleotide encoding a human framework and a site-specific recombination complementary to the site-specific recombination motif on the first vector. The site-specific recombination motifs can be positioned on each vector such that the recombination event results in the insertion of one or more antigen-determining regions from the non-human antibody into the human framework, thereby forming a polynucleotide encoding a humanized antibody.

[0255] In certain embodiments, an antibody is converted from scFv to IgG (e.g., IgG1, IgG2, IgG3, and IgG4). There are various methods in the art for converting scFv fragments to IgG. One such method for converting scFv fragments to IgG is disclosed in U.S. Patent Application Publication No. 20160362476, the content of which is incorporated herein by reference.

[0256] Specificity of anti-C3b antibody

[0257] In some embodiments, the anti-C3b antibody binds to human or cynomolgus monkey C3b with a dissociation constant (K D ) between 0.01 nM and 1000 nM. In some embodiments, K D is determined by surface plasmon resonance (SPR). In some embodiments, K DDetermined by ELISA.

[0258] In some embodiments, the anti-C3b antibody is more selective for C3b than for C3. In some embodiments, the anti-C3b antibody binds to C3b but not to C3. In some embodiments, the anti-C3b antibody described herein binds to C3b with a binding affinity for C3b that is more than 5-fold, more than 6-fold, more than 7-fold, more than 8-fold, more than 9-fold, more than 10-fold, more than 12-fold, more than 15-fold, more than 17-fold, or more than 20-fold that of its binding affinity for C3. In some embodiments, the anti-C3b antibody described herein binds to C3b with a binding affinity for C3b that is more than 7-fold, 10-fold, 15-fold, 20-fold, 25-fold, or 30-fold that of its binding affinity for C3. In some embodiments, the anti-C3b antibody described herein has a selectivity for C3b that is greater than 2-fold, greater than 5-fold, greater than 7-fold, greater than 8-fold, greater than 10-fold, greater than 12-fold, or greater than 15-fold its selectivity for C3.In some embodiments, the anti-C3b antibodies described herein are more than 18-fold selective for C3b over C3. In some embodiments, the anti-C3b antibodies described herein are more than 20-fold selective for C3b over C3. In some embodiments, the anti-C3b antibodies described herein are more than 25-fold selective for C3b over C3. In some embodiments, the anti-C3b antibodies described herein are more than 30-fold selective for C3b over C3.

[0259] In some embodiments, the anti-C3b antibody binds to C3 with a dissociation constant (K D ) greater than 100 nM. In some embodiments, the anti-C3b antibody binds to C3 with a dissociation constant (K D ) greater than 150 nM. In some embodiments, the anti-C3b antibody binds to C3 with a dissociation constant (K D ) greater than 200 nM. In some embodiments, the anti-C3b antibody binds to C3 with a dissociation constant (K D ) greater than 250 nM. In some embodiments, the anti-C3b antibody binds to C3 with a dissociation constant (K D ) greater than 300 nM. In some embodiments, the anti-C3b antibody binds to C3 with a dissociation constant (K D ) greater than 350 nM. In some embodiments, the anti-C3b antibody binds to C3 with a dissociation constant (K D ) greater than 400 nM. In some embodiments, the anti-C3b antibody binds to C3 with a dissociation constant (K D ) greater than 450 nM. In some embodiments, the anti-C3b antibody binds to C3 with a dissociation constant (K D ) greater than 500 nM. In some embodiments, K D is determined by surface plasmon resonance (SPR). In some embodiments, K D is determined by ELISA.

[0260] In some embodiments, the anti-C3b antibody lacks effector function to prevent cytotoxic effects on cells to which C3b binds.

[0261] Potency of anti-C3b antibody

[0262] In some embodiments, the EC50 of the anti-C3b antibody or fragment thereof is between 0.1 ng / mL and 100 ng / mL.

[0263] In some embodiments, the IC50 of the anti-C3b antibody or fragment thereof is between 0.1 nM and 100 nM. In some embodiments, the IC50 is measured by C3 deposition assay. In some embodiments, the IC50 is measured by hemolysis assay.

[0264] Epitope of anti-C3b antibody

[0265] The exemplary anti-C3b antibodies described herein have characteristics based on different epitopes on C3b that bind to the anti-C3b antibodies. The term "epitope" means that when an antibody binds to a target molecule, the amino acids of the target molecule are contacted by the anti-C3b antibody. An epitope can be continuous or discontinuous (e.g., (i) in a single-chain polypeptide, amino acid residues that are not contiguous to each other in the polypeptide sequence but are bound by the antibody within the context of the target molecule, or (ii) in a multimeric protein comprising two or more separate components (e.g., amino acid residues are present on one or more separate components but are still bound by the antibody). An epitope determinant can include the chemical reactive surface grouping of a molecule, such as amino acids, sugar side chains, phosphoryl or sulfonyl groups, and can have specific three-dimensional structural characteristics and / or specific charge characteristics. Generally, an antigen-binding protein specific for a particular target molecule will preferentially recognize an epitope on the target molecule in a complex mixture of proteins and / or macromolecules.

[0266] Methods for characterizing epitopes bound by antigen-binding proteins are well known in the art and include, but are not limited to, binning (cross-competition) (Miller et al., "Epitope binning of murine monoclonal antibody by a Multiplexed pair assay," Journal of Immunological Methods (2011) 365, 118-25), peptide mapping (PEPSPOTTM) (Albert et al., "The B-cell Epitope of the Monoclonal Anti-Factor VIII Antibody ESH8 Characterized by Peptide Array Analysis," 2008, Thromb. Haemost. 99, 634-7), mutagenesis methods such as chimeras (Song et al., "Epitope Mapping of Ibalizumab, a Humanized Anti-CD4 Monoclonal Antibody with Anti-HIV-1 Activity in Infected Patients," Journal of Virology)》(2010)84,6935-6942), alanine scanning (Cunningham and Wells, "High-resolution epitope mapping of HGH-receptor interactions by alanine-scanning mutagenesis" 《Science》(1989) 244, 1081–1085), arginine scanning (Lim et al., "A diversity of antibody epitopes can induce signaling through the erythropoietin receptor" 《Biochemistry》(2010) 49, 3797–3804), HD exchange method (Coates et al., "Epitope mapping by amide hydrogen / deuterium exchange coupled with immobilization of antibody, on-line proteolysis, liquid chromatography and mass spectrometry" 《Rapid Commun. Mass Spectrom.》(2009) 23 639–647), NMR cross-saturation method (Morgan et al., "Precise epitope mapping of malaria parasite inhibitory antibodies by TROSY NMR cross-saturation" 《Biochemistry》(2005) 44, 518-23) and crystallography (Gerhardt et al., "Structure of IL-17A in complex with a potent, fully human neutralizing antibody" 《J. Mol. Biol》(2009) 394, 905-21). The methods vary in the level of detail, the level of detail regarding the amino acids comprising the epitope.

[0267] Antibodies having the same epitope or overlapping epitopes will generally cross-compete for binding to the antigen. Thus, in certain embodiments, the antibodies of the invention cross-compete with any of Ab3-Ab35. "Cross-compete" or "cross-competition" means that antibodies compete for the same epitope or binding site on the target. Such competition can be determined by an assay in which a reference antigen-binding protein (e.g., an antibody or an antigen-binding portion thereof) blocks or inhibits the specific binding of a test antibody, and vice versa. Many types of competitive binding assays can be used to determine whether a test molecule competes with a reference molecule for binding. Examples of assays that can be employed include solid-phase direct or indirect radioimmunoassay (RIA), solid-phase direct or indirect enzyme immunoassay (EIA), sandwich competition assay (see, e.g., Stahli et al. (1983) Methods in Enzymology 9:242-253), solid-phase direct biotin-avidin EIA (see, e.g., Kirkland et al., (1986) J. Immunol. 137:3614-9), solid-phase direct label assay, solid-phase direct label sandwich assay, Luminex (Jia et al. "A novel method of Multiplexed Competitive Antibody Binning for the characterization of monoclonal antibodies" Journal of Immunological Methods (2004) 288, 91-98) and surface plasmon resonance (Song et al. "Epitope mapping of the humanized anti-CD4 monoclonal antibody ibalizumab with anti-HIV-1 activity in infected patients" Journal of Virology (2010) 84, 6935-42). Generally, when the competing antibody is present in excess, it will inhibit the binding of the reference antigen-binding protein to the common antigen by at least 50%, 55%, 60%, 65%, 70% or 75%. In some cases, the binding is inhibited by at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more.

[0268] Nucleic acids encoding C3b antagonists and anti-C3b antibodies

[0269] In some embodiments, the present invention particularly provides nucleic acids encoding C3b antagonists or anti-C3b antibodies. In some embodiments, the nucleic acid encodes the CDRs of the anti-C3b antibody of the present invention. In some embodiments, the nucleic acid encodes a fragment of the anti-C3b antibody of the present invention. In some embodiments, the nucleic acid encodes the variable region of the anti-C3b antibody of the present invention. In some embodiments, the nucleic acid encodes the variable heavy chain and / or variable light chain of the anti-C3b antibody of the present invention. In some embodiments, the nucleic acid encodes the VHH of the anti-C3b antibody of the present invention. In some embodiments, the nucleic acid encodes an anti-C3b VHH fused to an Fc domain.

[0270] In some embodiments, the nucleic acid is DNA. In some embodiments, the nucleic acid is cDNA. In some embodiments, the nucleic acid is RNA. In some embodiments, the nucleic acid is messenger RNA (mRNA).

[0271] In some embodiments, the present invention particularly provides messenger RNA (mRNA) encoding C3b antagonists or anti-C3b antibodies. In some embodiments, the mRNA encodes the CDRs of the anti-C3b antibody of the present invention. In some embodiments, the mRNA encodes a fragment of the anti-C3b antibody of the present invention. In some embodiments, the mRNA encodes the variable region of the anti-C3b antibody of the present invention. In some embodiments, the mRNA encodes the variable heavy chain and / or variable light chain of the anti-C3b antibody of the present invention. In some embodiments, the mRNA encodes the VHH of the anti-C3b antibody of the present invention. In some embodiments, the mRNA encodes an anti-C3b VHH fused to an Fc domain.

[0272] mRNA encoding anti-C3b antibody and mRNA of its antigen-binding fragment

[0273] In some embodiments, the present invention provides mRNA encoding an anti-C3b antibody or an antigen-binding fragment thereof. In some embodiments, the mRNA encoding an anti-C3b antibody or an antigen-binding fragment thereof is codon-optimized. In some embodiments, the present invention provides methods and compositions for delivering codon-optimized mRNA encoding an anti-C3b antibody or an antigen-binding fragment thereof to a subject for treating complement-mediated diseases. Suitable codon-optimized mRNA encodes any full-length, fragment, or portion of an anti-C3b antibody, such as CDRs, variable regions, variable heavy chains, variable light chains, scFv, VHH, or VHH-Fc fusions.

[0274] Synthesis of mRNA

[0275] The mRNA according to the present invention can be synthesized according to any one of a variety of known methods. For example, the mRNA according to the present invention can be synthesized by in vitro transcription (IVT). Briefly, IVT is typically performed using a linear or circular DNA template that contains a promoter, a ribonucleotide triphosphate pool, a buffer system that may include DTT and magnesium ions, and an appropriate RNA polymerase (e.g., T3, T7, or SP6 RNA polymerase), DNase I, pyrophosphatase, and / or an RNase inhibitor. The exact conditions will vary depending on the specific application.

[0276] Exemplary mRNA construct

[0277] Construct design:

[0278] 5'UTR – mRNA encoding an antibody or a fragment thereof – 3'UTR

[0279] Codon optimization

[0280] According to a growing body of research, mRNA contains many layers of information that overlap with the amino acid code. Traditionally, codon optimization has been used to remove rare codons that are thought to be rate-limiting for protein expression. While both rapidly growing bacteria and yeast exhibit strong codon bias in highly expressed genes, higher eukaryotes exhibit much lower codon bias, making it more difficult to discern codons that may be rate-limiting. Additionally, it has been found that codon bias alone does not necessarily result in high expression but rather requires other features.

[0281] For example, rare codons have been implicated in slowing translation and forming pause sites, which may be required for proper protein folding. Thus, variations in codon usage can provide a mechanism for fine-tuning the temporal pattern of elongation and, therefore, increasing the available time for the protein to undergo proper conformation. Codon optimization may disrupt this fine-tuning mechanism, resulting in lower efficiency of protein translation or an increased amount of misfolded protein. Similarly, codon optimization may disrupt the normal pattern of homologous and wobble tRNA usage, thereby affecting protein structure and function, as wobble-dependent elongation slowdown may also be selected as a mechanism for achieving proper protein folding.

[0282] Various methods of codon optimization are known in the art. However, each of these methods has significant drawbacks and limitations from a computational and / or therapeutic perspective. Specifically, known codon optimization methods typically involve, for each amino acid, replacing each codon with the codon having the highest usage for that amino acid, such that the "optimized" sequence contains only one codon encoding each amino acid (and can thus be referred to as a one-to-one sequence). Increased expression is not limited to cell cultures of mammalian cells, but has also been observed in vivo in mouse models. It is expected that the improved expression of the codon-optimized coding sequences observed will lead to improved, more cost-effective mRNA replacement therapies for patients in need, as it does not require the use of modified nucleotides to prepare the mRNA and allows treatment with reduced doses and / or at extended dosing intervals.

[0283] In some embodiments, the codon-optimized mRNA is produced according to methods known in the art.

[0284] Nucleotide

[0285] According to the present invention, various naturally occurring or modified nucleosides can be used to produce mRNA. In some embodiments, the mRNA is or comprises natural nucleosides (e.g., adenosine, guanosine, cytidine, uridine); nucleoside analogs (e.g., 2-aminoadenosine, 2-thiothymidine, inosine, pyrrolopyrimidine, 3-methyladenosine, 5-methylcytidine, C-5 propynylcytidine, C-5 propynyl-uridine, 2-aminoadenosine, C5-bromouridine, C5-fluorouridine, C5-iodouridine, C5-propynyluridine, C5-propynylcytidine, C5-methylcytidine, 2-aminoadenosine, 7-deazaadenosine, 7-deazaguanosine, 8-oxoadenosine, 8-oxoguanosine, O(6)-methylguanine, pseudouridine (e.g., N-1-methyl-pseudouridine), 2-thiouridine and 2-thiocytidine); chemically modified bases; biologically modified bases (e.g., methylated bases); inserted bases; modified sugars (e.g., 2'-fluororibose, ribose, 2'-deoxyribose, arabinose and hexose); and / or modified phosphate groups (e.g., phosphorothioates and 5'-N-phosphoramidite linkages).

[0286] In some embodiments, the mRNA comprises one or more non-standard nucleotide residues. Non-standard nucleotide residues can include, for example, 5-methylcytidine (“5mC”), pseudouridine (“ψU”), and / or 2-thiouridine (“2sU”). See, for example, U.S. Patent No. 8,278,036 or WO2011012316 for a discussion of such residues and their incorporation into mRNA. The mRNA can be an RNA defined as an RNA in which 25% of the U residues are 2-thiouridine and 25% of the C residues are 5-methylcytidine. The teachings of using such RNAs are disclosed in U.S. Patent Publication US20120195936 and International Publication WO2011012316, both of which are hereby incorporated by reference in their entireties. The presence of non-standard nucleotide residues can render the mRNA more stable and / or less immunogenic than a control mRNA having the same sequence but containing only standard residues. In additional embodiments, the mRNA can comprise one or more non-standard nucleotide residues selected from isocytosine, pseudoisocytosine, 5-bromouracil, 5-propynyluracil, 6-aminopurine, 2-aminopurine, inosine, diaminopurine, and 2-chloro-6-aminopurine cytosine, as well as combinations of these modifications and other nucleobase modifications. Some embodiments can further include additional modifications to the furanose ring or the nucleobase. Additional modifications can include, for example, sugar modifications or substitutions (e.g., one or more of 2'-O-alkyl modifications, locked nucleic acids (LNAs)). In some embodiments, the RNA can be complexed or hybridized with additional polynucleotides and / or peptide polynucleotides (PNAs). In some embodiments where the sugar modification is a 2'-O-alkyl modification, such modifications can include, but are not limited to, 2'-deoxy-2'-fluoro modification, 2'-O-methyl modification, 2'-O-methoxyethyl modification, and 2'-deoxy modification. In some embodiments, any of these modifications can be present individually or in combination in 0-100% of the nucleotides, such as in more than 0%, 1%, 10%, 25%, 50%, 75%, 85%, 90%, 95%, or 100% of the constituent nucleotides.

[0287] Post-synthesis processing

[0288] Generally, a 5' cap and / or a 3' tail can be added after synthesis. The presence of the cap is important for providing resistance to nucleases found in most eukaryotic cells. The presence of a “tail” is used to protect the mRNA from exonucleolytic degradation.

[0289] The 5' cap is typically added as follows: First, an RNA terminal phosphatase removes one of the terminal phosphate groups from the 5'-nucleotide, leaving two terminal phosphates; then guanosine triphosphate (GTP) is added to the terminal phosphate by a guanylyltransferase, resulting in a 5'5'5-triphosphate linkage; and then the 7-nitrogen of guanine is methylated by a methyltransferase. Examples of cap structures include, but are not limited to, m7G(5')ppp(5'(A,G(5')ppp(5')A, and G(5')ppp(5')G. Additional cap structures are described in the published U.S. application Ser. No. US2016 / 0032356, filed Feb. 27, 2017, and U.S. Provisional Application 62 / 464,327, which are incorporated herein by reference.

[0290] Typically, the tail structure includes a poly(A) and / or poly(C) tail. The poly-A or poly-C tail on the 3' end of the mRNA typically includes at least 50 adenosine or cytosine nucleotides, at least 150 adenosine or cytosine nucleotides, at least 200 adenosine or cytosine nucleotides, at least 250 adenosine or cytosine nucleotides, at least 300 adenosine or cytosine nucleotides, at least 350 adenosine or cytosine nucleotides, at least 400 adenosine or cytosine nucleotides, at least 450 adenosine or cytosine nucleotides, at least 500 adenosine or cytosine nucleotides, at least 550 adenosine or cytosine nucleotides, at least 600 adenosine or cytosine nucleotides, at least 650 adenosine or cytosine nucleotides, at least 700 adenosine or cytosine nucleotides, at least 750 adenosine or cytosine nucleotides, at least 800 adenosine or cytosine nucleotides, at least 850 adenosine or cytosine nucleotides, at least 900 adenosine or cytosine nucleotides, at least 950 adenosine or cytosine nucleotides, or at least 1 kb adenosine or cytosine nucleotides. In some embodiments, the poly A or poly C tail can be about 10 to 800 adenosine or cytosine nucleotides (e.g., about 10 to 200 adenosine or cytosine nucleotides, about 10 to 300 adenosine or cytosine nucleotides, about 10 to 400 adenosine or cytosine nucleotides, about 10 to 500 adenosine or cytosine nucleotides, about 10 to 550 adenosine or cytosine nucleotides, about 10 to 600 adenosine or cytosine nucleotides, about 50 to 600 adenosine or cytosine nucleotides, about 100 to 600 adenosine or cytosine nucleotides, about 150 to 600 adenosine or cytosine nucleotides, about 200 to 600 adenosine or cytosine nucleotides, about 250 to 600 adenosine or cytosine nucleotides, about 300 to 600 adenosine or cytosine nucleotides, about 350 to 600 adenosine or cytosine nucleotides, about 400 to 600 adenosine or cytosine nucleotides, about 450 to 600 adenosine or cytosine nucleotides, about 500 to 600 adenosine or cytosine nucleotides, about 10 to 150 adenosine or cytosine nucleotides, about 10 to 100 adenosine or cytosine nucleotides, about 20 to 70 adenosine or cytosine nucleotides, or about 20 to 60 adenosine or cytosine nucleotides). In some embodiments, the tail structure includes a combination of poly(A) tails and poly(C) tails having various lengths as described herein. In some embodiments, the tail structure includes at least 50%, 55%, 65%, 70%, 75%, 80%, 85%, 90%, 92%, 94%, 95%, 96%, 97%, 98%, or 99% adenosine nucleotides.In some embodiments, the tail structure comprises at least 50%, 55%, 65%, 70%, 75%, 80%, 85%, 90%, 92%, 94%, 95%, 96%, 97%, 98%, or 99% cytosine nucleotides.

[0291] As described herein, adding a 5' cap and / or a 3' tail facilitates the detection of truncated transcripts generated during in vitro synthesis because, without capping and / or tailing, those prematurely terminated mRNA transcripts may be too small to detect. Thus, in some embodiments, a 5' cap and / or a 3' tail is added to the synthesized mRNA before testing the purity of the mRNA (e.g., the level of truncated transcripts present in the mRNA). In some embodiments, a 5' cap and / or a 3' tail is added to the synthesized mRNA before purifying the mRNA as described herein. In other embodiments, a 5' cap and / or a 3' tail is added to the synthesized mRNA after purifying the mRNA as described herein.

[0292] Delivery vehicle

[0293] According to the invention, the mRNA encoding an anti-C3b antibody or antigen-binding fragment as described herein can be delivered as naked RNA (unencapsulated) or via a delivery vehicle. As used herein, the terms "delivery vehicle", "transfer vehicle", "nanoparticle", or grammatical equivalents thereof are used interchangeably.

[0294] The delivery vehicle can be formulated in combination with one or more additional nucleic acids, carriers, targeting ligands, or stabilizing agents, or formulated in a pharmaceutical composition, wherein it is mixed with suitable excipients. Techniques for formulating and administering drugs can be found in Remington's Pharmaceutical Sciences, Mack Publishing Co., Easton, Pa., latest edition. The delivery vehicle is selected based on its ability to facilitate nucleic acid transfection into target cells.

[0295] Liposomal delivery vehicle

[0296] In some embodiments, a suitable delivery vehicle is a liposomal delivery vehicle, e.g., a lipid nanoparticle (LNP). As used herein, a liposomal delivery vehicle (e.g., a lipid nanoparticle) is generally characterized as a microscopic vesicle having an internal aqueous space that is isolated from the external medium by a membrane of one or more bilayers. The bilayer membrane of a liposome is typically formed from amphiphilic molecules, such as synthetic or naturally-derived lipids (Lasic, Trends Biotechnol., 16:307-321, 1998) that contain spatially separated hydrophilic and hydrophobic domains. The bilayer membrane of a liposome can also be formed from amphiphilic polymers and surfactants (e.g., polymersomes, niosomes, etc.). In the context of the present invention, liposomal delivery vehicles are generally used to transport the desired mRNA to target cells or tissues. In some embodiments, the nanoparticle delivery vehicle is a liposome. In some embodiments, the liposome comprises one or more cationic lipids, one or more non-cationic lipids, one or more cholesterol-based lipids, and / or one or more PEG-modified lipids.

[0297] Therapeutic use of the composition

[0298] In one aspect, the present invention particularly provides a method for inducing the expression of anti-C3b antibodies in vivo by administering a nucleic acid encoding an anti-C3b antibody or a fragment thereof or by administering an anti-C3b antibody. In some embodiments, the composition comprises a nucleic acid encapsulated or complexed with a delivery vehicle. In some embodiments, the delivery vehicle is selected from the group consisting of liposomes, lipid nanoparticles, solid-lipid nanoparticles, polymers, viruses, sol-gels, and nanogels. In some embodiments, the nucleic acid encoding an anti-C3b antibody or a fragment thereof is packaged in a viral particle.

[0299] Gene therapy

[0300] In some embodiments, a pharmaceutical composition comprising a nucleic acid encoding an anti-C3b antibody or a fragment thereof is used to treat a subject in need thereof. In some embodiments, a pharmaceutical composition comprising the rAAV vector described herein is used to treat a subject in need thereof. A pharmaceutical composition containing the rAAV vector or particle of the present invention contains a pharmaceutically acceptable excipient, diluent, or carrier. Examples of suitable pharmaceutical carriers are well known in the art and include phosphate buffered saline solutions, water, emulsions (such as oil / water emulsions), various types of wetting agents, and sterile solutions, etc. The pharmaceutical composition can be in lyophilized form. Such carriers can be formulated by conventional methods and administered to the subject in a therapeutically effective amount.

[0301] The rAAV vector is administered to a subject in need thereof by a suitable route. In some embodiments, the rAAV vector is administered by intravenous, intraperitoneal, subcutaneous, or intradermal routes. In one embodiment, the rAAV vector is administered intravenously. In an embodiment, intradermal administration comprises administration by using a "gene gun" or a gene gun particle delivery system. In some embodiments, the rAAV vector is administered by non-viral lipid nanoparticles. For example, a composition comprising the rAAV vector may comprise one or more diluents, buffers, liposomes, lipids, lipid complexes. In some embodiments, the rAAV vector is encapsulated within microspheres or nanoparticles, such as lipid nanoparticles or inorganic nanoparticles.

[0302] In some embodiments, the rAAV is pseudotyped. A pseudotyped rAAV is an infectious virus comprising any combination of AAV capsid proteins and an rAAV genome. Pseudotyped rAAV can be used to alter the tissue or cell specificity of rAAV and can be used alone or in combination with non-pseudotyped rAAV to transfer one or more genes into cells, such as mammalian cells. For example, pseudotyped rAAV can be administered after non-pseudotyped rAAV in a mammal that has developed an immune response to the non-pseudotyped rAAV. Capsid proteins from any AAV serotype can be used with an rAAV genome that is derived from or obtainable from a wild-type AAV genome of a different serotype, or is a chimeric genome, i.e., formed from AAV DNA from two or more different serotypes, such as a chimeric genome having 2 ITRs, each ITR from a different serotype or a chimeric ITR. The use of chimeric genomes, such as those comprising ITRs from two AAV serotypes or chimeric ITRs, can result in directed recombination, which can further enhance the production of transcriptionally active intermolecular tandems. Thus, the 5' and 3' ITRs within the rAAV vector of the present invention can be homologous, i.e., from the same serotype, heterologous, i.e., from different serotypes, or chimeric, i.e., an ITR having ITR sequences from more than one AAV serotype.

[0303] In some embodiments, the rAAV vector is an AAV1, AAV2, AAV3, AAV4, AAV5, AAV6, AAV7, AAV8, AAV9, AAV10 or AAV11 vector. In some embodiments, the rAAV vector is AAV1. In some embodiments, the rAAV vector is AAV2. In some embodiments, the rAAV vector is AAV3. In some embodiments, the rAAV vector is AAV4. In some embodiments, the rAAV vector is AAV5. In some embodiments, the rAAV vector is AAV6. In some embodiments, the rAAV vector is AAV7. In some embodiments, the rAAV vector is AAV8. In some embodiments, the rAAV vector is AAV9. In some embodiments, the rAAV vector is AAV10. In some embodiments, the rAAV vector is AAV11. In some embodiments, the rAAV vector is sequence-optimized. In some embodiments, the rAAV capsid is modified. For example, in some embodiments, the AAV8 capsid is modified.

[0304] Treatment with a C3b antagonist or anti-C3b antibody

[0305] In some embodiments, the present invention particularly provides a method for treating a complement-mediated disorder (e.g., C3 glomerulopathy) by administering a C3b antagonist or anti-C3b antibody. In some embodiments, the present invention particularly provides a method for treating a complement-mediated disorder in a subject, the method comprising administering to the subject a C3b antagonist or anti-C3b antibody at a therapeutically effective dose and administration interval for a treatment period sufficient to improve, stabilize or alleviate one or more symptoms of the disorder. In some embodiments, the present invention particularly provides a method for treating a complement-mediated disorder in a subject, the method comprising administering to the subject a composition at a therapeutically effective dose and administration interval, the composition comprising a nucleic acid encoding a C3b antagonist or anti-C3b antibody, for a treatment period sufficient to improve, stabilize or alleviate one or more symptoms of the disorder. In some embodiments, the present invention particularly provides a method for treating a complement-mediated disorder in a subject, the method comprising administering to the subject a composition at a therapeutically effective dose and administration interval, the composition comprising an mRNA encoding a C3b antagonist or anti-C3b antibody, for a treatment period sufficient to improve, stabilize or alleviate one or more symptoms of the disorder.

[0306] Complement-mediated disorders

[0307] Many autoimmune diseases are characterized by the production of autoantibodies that bind to host proteins or deposit within tissues as components of immune complexes. Autoantibodies can activate the complement system, which can mediate tissue damage and trigger systemic inflammation. Thus, complement inhibitory drugs may be beneficial in many different autoimmune diseases.

[0308] C3 glomerulopathy (C3G) is a rare disease characterized by the accumulation of complement factors in the glomeruli due to overactivation and dysregulation of the alternative pathway (AP) of complement. It is an ultra-rare disease with an annual incidence of approximately 1 - 3 per million per year. C3 glomerulopathy is an umbrella term for a series of related diseases or conditions characterized by the accumulation of C3 complement component in renal tissue. Aberrant control of the complement AP may be due to acquired or genetic abnormalities of complement regulatory proteins. Deposition of complement factors drives glomerular inflammation, leading to proliferative glomerulonephritis. The most common diseases under the C3G umbrella are C3 glomerulonephritis (C3GN), characterized by mesangial, subendothelial, and intramembranous deposits; and dense deposit disease (DDD), characterized by dense deposits along the glomerular and tubular basement membranes. The presentation of the disease ranges from asymptomatic hematuria and proteinuria to acute presentation with typical symptoms and signs of glomerulonephritis. C3 glomerulopathy is driven by acquired factors (anti-C3 and C5 convertase autoantibodies) and genetic mutations in complement-related genes. These autoantibodies drive complement dysregulation by increasing the half-life of these important but usually short-lived enzymes. Genetic mutations in factor H, complement factor H-related (CFHR) proteins C3 may lead to impaired regulation of the C3 convertase.

[0309] Other diseases associated with overactivation of the AP include paroxysmal nocturnal hemoglobinuria with extravascular hemolysis, a rare acquired blood disorder in which RBCs are targeted by C3b rather than MAC. In patients with paroxysmal nocturnal hemoglobinuria, C5 inhibitors are ineffective, and this remains a major unmet medical need. Geographic atrophy (GA) is another complication associated with overactivation of the AP. Geographic atrophy is an advanced manifestation of age-related macular degeneration (AMD), characterized by the progressive and irreversible loss of the retinal pigment epithelium and photoreceptors, which is a leading cause of legal blindness. 98% of patients with wet AMD develop GA despite anti-VEGF treatment.

[0310] On the one hand, the present invention provides a method for treating a disease or disorder, the method comprising administering to a subject in need thereof a therapeutically effective amount of an anti-C3b antibody or a fragment thereof. In some embodiments, the disease or disorder is a complement-mediated disorder. In some embodiments, the disease or disorder is C3 glomerulopathy. In some embodiments, the disease or disorder is associated with C3 glomerulopathy. In some embodiments, the disease or disorder is dense deposit disease. In some embodiments, the disease or disorder is C3 glomerulonephritis (C3GN). In some embodiments, the disease or disorder is characterized by the accumulation of C3 complement component in renal tissue. In some embodiments, the disease or disorder is hematuria. In some embodiments, the disease or disorder is proteinuria. In some embodiments, the disease or disorder is acute kidney injury (AKI). In some embodiments, the disease or disorder is chronic kidney disease (CKD). In some embodiments, the disease or disorder is associated with overactivation of AP. In some embodiments, the disease or disorder is paroxysmal nocturnal hemoglobinuria. In some embodiments, the disease or disorder is geographic atrophy (GA). In some embodiments, the disease or disorder is autoimmune hemolytic anemia (AIHA). In some embodiments, the disease or disorder is age-related macular degeneration (AMD). In some embodiments, the disease or disorder is wet age-related macular degeneration (wAMD). In some embodiments, the disease or disorder is passive Heymann nephritis (PHN). In some embodiments, the disease or disorder is rheumatoid arthritis (RA). In some embodiments, the disease or disorder is collagen antibody-induced arthritis (CAIA). In some embodiments, the disease or disorder is caused by a genetic mutation in factor H. In some embodiments, the disease or disorder is caused by a genetic mutation in CFHR protein. In some embodiments, the disease or disorder is caused by a genetic mutation in C43. In some embodiments, the disease is driven by an acquired factor. In some embodiments, the acquired factor is an anti-C3 autoantibody. In some embodiments, the acquired factor is a C5 convertase autoantibody.

[0311] Effect of anti-C3b antibody

[0312] In some embodiments, administering the anti-C3b antibody or a fragment thereof inhibits C3 deposition in the subject. In some embodiments, administering the anti-C3b antibody or a fragment thereof inhibits C3 activity or C3 activation.

[0313] In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the alternative pathway (AP). In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the classical pathway (CP). In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits both the alternative pathway (AP) and the classical pathway (CP). In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the alternative pathway (AP) but not the classical pathway (CP). In some embodiments, the level of AP inhibition is higher than the level of CP inhibition. In some embodiments, the level of AP inhibition is about 2-fold or more than the level of CP inhibition. In some embodiments, the level of AP inhibition is about 3-fold or more than the level of CP inhibition. In some embodiments, the level of AP inhibition is about 4-fold or more than the level of CP inhibition. In some embodiments, the level of AP inhibition is about 5-fold or more than the level of CP inhibition. In some embodiments, the level of AP inhibition is about 8-fold or more than the level of CP inhibition. In some embodiments, the level of AP inhibition is about 10-fold or more than the level of CP inhibition.

[0314] In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of complement factor B to C3b. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor B to C3b by about 10% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor B to C3b by about 15% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor B to C3b by about 20% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor B to C3b by about 25% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor B to C3b by about 30% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor B to C3b by about 40% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor B to C3b by about 45% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor B to C3b by about 50% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor B to C3b by about 60% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor B to C3b by about 70% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor B to C3b by about 80% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor B to C3b by about 85% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor B to C3b by about 90% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor B to C3b by about 95% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor B to C3b by about 99% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof completely inhibits the binding of factor B to C3b. In some embodiments, administration of an anti-C3b antibody or fragment thereof partially inhibits the binding of factor B to C3b.

[0315] In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of complement factor P to C3bBb. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor P to C3bBb by about 10% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor P to C3bBb by about 15% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor P to C3bBb by about 20% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor P to C3bBb by about 25% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor P to C3bBb by about 30% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor P to C3bBb by about 40% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor P to C3bBb by about 45% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor P to C3b by about 50% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor P to C3bBb by about 60% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor P to C3bBb by about 70% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor P to C3bBb by about 80% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor P to C3bBb by about 85% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor P to C3bBb by about 90% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor P to C3bBb by about 95% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof inhibits the binding of factor P to C3bBb by about 99% compared to baseline. In some embodiments, administration of an anti-C3b antibody or fragment thereof completely inhibits the binding of complement factor P to C3bBb. In some embodiments, administration of an anti-C3b antibody or fragment thereof partially inhibits the binding of complement factor P to C3bBb.

[0316] Pharmaceutical composition and administration

[0317] The antibodies or agents of the present invention (also referred to herein as "active compounds") and their derivatives, fragments, analogs, and homologs can be incorporated into pharmaceutical compositions suitable for administration. Such compositions generally comprise an antibody or agent and a pharmaceutically acceptable carrier. As used herein, the term "pharmaceutically acceptable carrier" is intended to include any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like that are compatible with pharmaceutical administration. Suitable carriers are described in the latest edition of Remington's Pharmaceutical Sciences, which is a standard reference text in the art and is incorporated herein by reference. Preferred examples of such carriers or diluents include, but are not limited to, water, saline, Ringer's solution, dextrose solution, and 5% human serum albumin. Non-aqueous vehicles such as liposomes and fixed oils can also be used. The use of such media and agents for pharmaceutical active substances is well known in the art. Unless any conventional medium or reagent is incompatible with the active compound, its use in the composition. Supplementary active compounds can also be incorporated into the composition.

[0318] The pharmaceutical compositions of the present invention are formulated to be compatible with their intended route of administration. Examples of routes of administration include parenteral, such as intravenous, intradermal, subcutaneous, oral (e.g., inhalation), transdermal (i.e., topical), transmucosal, intravitreal, and rectal administration. Solutions or suspensions for parenteral, intradermal, or subcutaneous application can include the following components: a sterile diluent, such as water for injection, saline solution, non-volatile oils, polyethylene glycol, glycerol, propylene glycol, or other synthetic solvents; antibacterial agents, such as benzyl alcohol or methylparaben; antioxidants, such as ascorbic acid or sodium bisulfite; chelating agents, such as ethylenediaminetetraacetic acid (EDTA); buffers, such as acetate, citrate, or phosphate; and agents for adjusting tonicity, such as sodium chloride or dextrose. The pH can be adjusted with an acid or base such as hydrochloric acid or sodium hydroxide. Parenteral preparations can be enclosed in ampoules, disposable syringes, or multi-dose vials made of glass or plastic.

[0319] Pharmaceutical compositions suitable for injectable use include sterile aqueous solutions (wherein the same are water-soluble) or dispersions and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersions. For intravenous administration, suitable carriers include physiological saline, bacteriostatic water, polyethylene glycol 40 hydrogenated castor oil (Cremophor EL) (BASF Corporation, Parsippany, NJ TM(BASF, Parsippany, N.J.)) or phosphate buffered saline (PBS). The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyols (such as glycerol, propylene glycol, and liquid polyethylene glycol, etc.) and suitable mixtures thereof. Appropriate fluidity can be maintained, for example, by using coatings such as lecithin, by maintaining the desired particle size in the case of dispersions, and by using surfactants. Prevention of microbial action can be achieved by various antibacterial and antifungal agents such as parabens, chlorobutanol, phenol, ascorbic acid, thimerosal, etc. In many cases, it is preferred that the composition includes isotonic agents such as sugars, polyols such as mannitol, sorbitol, and sodium chloride. Prolonged absorption of the injectable composition can be achieved by including agents that delay absorption such as aluminum monostearate and gelatin in the composition.

[0320] Sterile injectable solutions can be prepared by incorporating the active compound in the required amount with one or a combination of the ingredients listed above in a suitable solvent, and if necessary, subsequently filtering and sterilizing. Generally, dispersions are prepared by incorporating the active compound into a sterile vehicle that contains a basic dispersion medium and the required other ingredients from those listed above. In the case of sterile powders for the preparation of sterile injectable solutions, the preparation method is vacuum drying and freeze-drying of the powder of the active ingredient plus any additional desired ingredients from its previously sterile filtered solution.

[0321] Oral compositions generally include an inert diluent or an edible carrier. They can be enclosed in gelatin capsules or compressed into tablets. For the purpose of oral therapeutic administration, the active compound can be incorporated with excipients and used in the form of tablets, lozenges, or capsules. Oral compositions can also be prepared using a fluid carrier that serves as a mouthwash, where the compound in the fluid carrier is orally administered and then rinsed and spat out or swallowed. Pharmaceutically compatible binders and / or adjuvant materials can be included as part of the composition. Tablets, pills, capsules, lozenges, etc. can contain any one of the following ingredients or compounds with similar properties: binders such as microcrystalline cellulose, tragacanth, or gelatin; excipients such as starch or lactose; disintegrants such as alginic acid, sodium starch glycolate, or corn starch; lubricants such as magnesium stearate or Sterotes; glidants such as colloidal silica; sweeteners such as sucrose or saccharin; or flavoring agents such as peppermint, methyl salicylate, or orange flavoring.

[0322] For administration by inhalation, the compound is delivered in the form of an aerosol spray from a pressurized container or dispenser or nebulizer containing a suitable propellant (such as a gas, such as carbon dioxide).

[0323] Systemic administration can also be effected by transmucosal or transdermal means. For transmucosal or transdermal administration, penetrants appropriate to the barrier to be permeated are used in the formulation. Such penetrants are generally known in the art and include, for example, for transmucosal administration, detergents, bile salts, and fusidic acid derivatives. Transmucosal administration can be effected using a nasal spray or a suppository. For transdermal administration, as is generally known in the art, the active compound is formulated into ointments, pastes, gels, or creams.

[0324] The active compounds can also be prepared in the form of suppositories (e.g., using conventional suppository bases such as cocoa butter and other glycerides) or retention enemas for rectal delivery.

[0325] In one embodiment, the active compounds are prepared with carriers that protect the compounds against rapid elimination from the body, such as controlled-release formulations that include implants and microencapsulation delivery systems. Biodegradable, biocompatible polymers such as ethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen, polyorthoesters, and polylactic acid can be used. Methods for preparing such formulations will be apparent to those skilled in the art. The materials can also be obtained commercially from, for example, Alza Corporation and Nova Pharmaceuticals, Inc. Liposome suspensions, including liposomes targeted to infected cells with monoclonal antibodies to antiviral antigens, can also be used as pharmaceutically acceptable carriers. These can be prepared by methods known to those skilled in the art, for example, as described in U.S. Patent No. 4,522,811.

[0326] It is especially advantageous to formulate oral or parenteral compositions in dosage unit form for ease of administration and uniformity of dosage. As used herein, a dosage unit form refers to a physically discrete unit suitable as a unit dose for the subject to be treated; each unit containing a predetermined quantity of the active compound calculated to produce the desired therapeutic effect in association with the required pharmaceutical carrier. The specification for the dosage unit forms of the invention is dictated by and directly dependent on: the unique characteristics of the active compound and the particular therapeutic effect to be achieved, and the limitations inherent in the art of compounding such active compounds for the treatment of individuals.

[0327] The pharmaceutical compositions can be included in a container, package, or dispenser together with instructions for administration.

[0328] Method of administration

[0329] In certain embodiments, the anti-C3b antibody is administered by any route suitable for administering the anti-C3b antibody, such as intravenously or subcutaneously.

[0330] In some embodiments, a single administration of an anti-C3b antibody is sufficient to improve, stabilize, or alleviate one or more symptoms for more than five days, 1 week, 2 weeks, 4 weeks, 5 weeks, 7 weeks, 12 weeks, or longer.

[0331] In some embodiments, a single administration of an anti-C3b antibody is sufficient to improve, stabilize, or alleviate one or more symptoms such that the subject does not require repeated doses.

[0332] The therapeutically effective amount of the pharmaceutical composition containing the anti-C3b antibody to be employed will depend, for example, on the treatment setting and purpose. Those skilled in the art will understand that the appropriate dosage level for treatment will vary in part depending on the molecule being delivered, the indication for using the anti-C3b antibody, the route of administration, and the size (body weight, body surface, or organ size) and / or condition (age and general health status) of the patient. In certain embodiments, the clinician can titrate the dose and modify the route of administration to obtain the optimal therapeutic effect. Depending on the above factors, typical doses can range from about 0.1 μg / kg to up to about 1000 mg / kg or more.

[0333] In some embodiments, the therapeutically effective dose is between about 1 mg and 1000 mg. In some embodiments, the therapeutically effective dose is between about 10 mg and 500 mg.

[0334] Examples

[0335] Although certain compounds, compositions, and methods of the invention have been specifically described in accordance with certain embodiments, the following examples are for illustrative purposes only and are not intended to limit the invention. Although certain compounds, compositions, and methods of the invention have been specifically described in accordance with certain embodiments, the following examples are for illustrative purposes only and are not intended to limit the invention.

[0336] Example 1. Pharmacokinetic analysis of an anti-C3b antibody.

[0337] In this study, the pharmacokinetics of an anti-C3b antibody in non-human primates were determined. First, Ab1 (anti-C3b VHH fused to a modified IgG4 Fc) and a control Ab (IC12; control antibody) were administered intravenously to cynomolgus monkeys at 10 mg / kg. The characteristics of each antibody are shown in Table 1. Plasma samples were collected before administration and at 30 minutes, 6 hours, 24 hours, 48 hours, 120 hours, 336 hours, 456 hours, 672 hours, and 792 hours after administration, and the remaining antibody % was measured.

[0338] Table 1 – Description of the antibodies used in pharmacokinetics

[0339]

[0340] Figure 1A Shows the levels of Ab1 (in duplicate) and control Ab in plasma levels over 20 days. Ab1 was observed to persist in serum for over 15 days. Figure 1B Shows the percentages of Ab1 (in duplicate) and control Ab in plasma levels over 20 days. The data show that Ab1 retains significantly higher antibody % over time compared to control Ab.

[0341] To confirm that the C3b antibody of the present invention binds to human C3b with high affinity, in addition to cynomolgus monkey C3b, the antibody concentration of human C3b or cynomolgus monkey C3b was also measured. As Figure 1C and Figure 1D shown in, Ab1 binds to human C3b with high affinity, and the affinity is about 100 times that of Ab1 binding to cynomolgus monkey C3b.

[0342] Next, the pharmacodynamic effects of anti-C3b Ab1 and control Ab were evaluated. Ex vivo C3 deposition studies were performed at 3% serum concentration, and the inhibition of C3 deposition over time was measured. Figure 1E Shows the plasma antibody levels, and Figure 1F shows the inhibition of C3 deposition. Under these conditions, the PD effect observed for Ab1 persisted for over 14 days. Additionally, the PK / PD of the control Ab shows the importance of the C3(H2O)-mediated idle mechanism in the inhibition of target-mediated drug disposition (TMDD).

[0343] Example 2. C3 Convertase Inhibition of C3b Antibody in Wet Age-Related Macular Degeneration (AMD)

[0344] Wet age-related macular degeneration (wAMD) is the less common but most severe form of AMD and is one of the leading causes of blindness in the elderly. wAMD is characterized by choroidal neovascularization (CMV) and acute vision loss. The retina is particularly vulnerable to complement activation and oxidative damage to tissue development that trigger AMD. Current treatments involve monthly intravitreal injections of anti-VEGF antibodies.

[0345] This example demonstrates the efficacy of the C3b antibody of the present invention in wAMD using a mouse laser-induced choroidal neovascularization (CNV) model. In mice, wAMD-like disease is triggered by laser-induced damage to the retinal basement membrane (Bruch's membrane) at 4 spots placed around the optic nerve. The damage triggers neovascularization from the underlying capillary layer (choroid) to the retina, resulting in an inflammatory response.

[0346] Table 2: Studies of Different Antibodies in the CNV Model

[0347] Animal group Description / SEQ ID Vehicle control Negative control Eylea (positive control) Positive control (commercially available VEGF inhibitor) Ab2 Anti-C3b VHH (SEQ ID NO:8) fused to IgG4 Fc with S228P Ab3 Anti-C3b VHH SEQ ID NO:9 fused to IgG4 Fc with S228P

[0348] Administer the vehicle or antibody as shown in Table 2 into the vitreous of mice, and perform ocular imaging on days 0, 1, 3, and 7 according to the research design shown in Figure 2 . Specifically, two ocular imaging techniques are used in this example. First, perform frontal imaging by fluorescein angiography (FA), which uses sodium fluorescein to visualize the ocular vasculature. The degree of CNV is determined by the vascular lesion-based scoring system shown below and the size of the CNV frontal area. Second, perform ocular imaging by cross-sectional imaging of optical coherence tomography (OTC). The degree of CNV is determined by the size of the CNV cross-sectional area.

[0349] FA vascular lesion scoring system

[0350] Score Descriptor 1 No hyperfluorescence 2 Hyperfluorescence, no leakage 3 Hyperfluorescence early or mid-passage, late leakage 4 Hyperfluorescence early or mid-passage, late leakage, beyond the boundary of the treated area

[0351] Figure 3A Shows the FA leakage areas after treatment with each antibody on day 7. Figure 3B Shows the OCT areas after treatment with each antibody on day 7. Table 3 shows the percentage reduction of the OCT area and FA leakage relative to the vehicle control. The data show that Ab2 and Ab3 provided at least about 30% protection in mice on day 7. The alternative pathway is only partially responsible for CNV pathology (about 35%). Thus, a 30% reduction in disease indicates that the C3b antibodies of the present invention are highly effective in blocking the role of the AP in disease progression.

[0352] Table 3: Percentage reduction relative to the control on day 7

[0353]

[0354] Example 3. Efficacy of C3b antibody against passive Heymann nephritis (PHN)

[0355] Passive Heymann nephritis (PHN) mimics human idiopathic membranous nephritis (iMN), which is triggered by autoantibodies against the podocyte antigen PLA2-R. PHN is triggered in rats by a nephrotoxic serum (Fx1A) targeting megalin, a nephritis protein found on the surface of podocytes and proximal tubules.

[0356] This experiment evaluated the use of C3b antibody in a PHN mouse model. The research design of this experiment is shown in Figure 4In the PHN model mice, the PHN phenotype was induced by induction with a serum of a renal toxin targeting megalin (Fx1A). On day 2, the PHN mice were treated with the antibodies shown in Table 4 and treated twice a week by intravenous administration. Serum and urinary biomarkers and renal histology were evaluated to assess the efficacy of the treatment groups.

[0357] Table 4: Treatment groups in the PHN study

[0358]

[0359] Figure 5A The albumin-to-creatinine ratio (urinary biomarker) in the PHN mouse model treated with different doses of Ab2 is shown compared to mice treated with a positive control and a negative control. A significantly lower albumin-to-creatinine ratio was observed with treatment with 50 mg / kg Ab2. Next, the ratio of total protein to creatinine was determined as shown in Figure 5B .

[0360] Example 4. Efficacy of C3b antibody in a collagen antibody-induced arthritis (CAIA) mouse model of RA

[0361] This experiment evaluated the use of C3b antibody in type II collagen-specific monoclonal antibody-induced arthritis (CAIA). A schematic diagram of the study design is shown in Figure 6A . On days 6, 9, and 13, anti-C3b VHH fused to Fc (Ab2) was administered at various concentrations. The MVZ antibody was used as a positive control, and dexamethasone was used as a negative control. Figure 6B A dose-dependent decrease in mouse paw volume in response to treatment with Ab2 is shown. Based on the data, it appears that the protection is mainly related to the first dose administered on day 6 of the study.

[0362] Example 5. Efficacy of C3b antibody on C3 convertase activity in patients with C3G

[0363] This experiment evaluated the efficacy of C3b antibody in inhibiting C3 convertase activity in the sera of patients with human complement 3 glomerulopathy (C3G). C3G patient samples were collected, and ex vivo C3 convertase inhibition was measured by C3 deposition assay according to methods known in the art. AMY-101 (C3 inhibitor) and LNP023 were used as controls. The anti-C3b antibody used in this particular assay was Ab4, which contains the VHH of SEQ ID NO: 13 fused to the Fc domain of SEQ ID NO: 14. As shown in Figure 7 , Ab4 was particularly effective in inhibiting C3 deposition compared to the controls.

[0364] Equivalent forms

[0365] Those skilled in the art will recognize or be able to ascertain using only routine experimentation many equivalent forms to the specific embodiments of the invention described herein. The scope of the invention is not intended to be limited to the foregoing description, but rather is as set forth in the following claims:

Claims

1. An antibody or antigen-binding fragment thereof, wherein the antibody or antigen-binding fragment thereof binds to C3b, and the antibody or antigen-binding fragment thereof comprises three complementarity-determining regions (CDR1 to CDR3 respectively), wherein CDR1 comprises NYHMG (SEQ ID NO: 16), CDR2 comprises TIIRTGETIYYADSVKG (SEQ ID NO: 17), and CDR3 comprises ATSGWNIKTVTPYEY (SEQ ID NO: 18).

2. An antibody or antigen-binding fragment thereof, wherein the antibody or antigen-binding fragment thereof binds to C3b, and the antibody or antigen-binding fragment thereof comprises three complementarity-determining regions (CDR1 to CDR3 respectively), wherein CDR1 comprises GRTFSNY (SEQ ID NO: 19), CDR2 comprises IRTGET (SEQ ID NO: 20), and CDR3 comprises ATSGWNIKTVTPYEY (SEQ ID NO: 18).

3. An antibody or antigen-binding fragment thereof, wherein the antibody or antigen-binding fragment thereof binds to C3b, and the antibody or antigen-binding fragment thereof comprises three complementarity-determining regions (CDR1 to CDR3 respectively), wherein CDR1 comprises NYHMG (SEQ ID NO: 16), CDR2 comprises TIIRHGTTIYYADSVKG (SEQ ID NO: 26), and CDR3 comprises ATSGWHIKTVTPYEY (SEQ ID NO: 22).

4. An antibody or antigen-binding fragment thereof, wherein the antibody or antigen-binding fragment thereof binds to C3b, and the binding portion comprises three complementarity-determining regions (CDR1 to CDR3 respectively), wherein CDR1 comprises GRTFSNY (SEQ ID NO: 19), CDR2 comprises IRHGTT (SEQ ID NO: 27), and CDR3 comprises ATSGWHIKTVTPYEY (SEQ ID NO: 22).

5. An antibody or antigen-binding fragment thereof, wherein the antibody or antigen-binding fragment thereof binds to C3b, and the antibody or antigen-binding fragment thereof comprises three complementarity-determining regions (CDR1 to CDR3 respectively), wherein CDR1 comprises NYHMG (SEQ ID NO: 16), CDR2 comprises TIIRTGKTIYYADSVKG (SEQ ID NO: 21), and CDR3 comprises ATSGWHIKTVTPYEY (SEQ ID NO: 22).

6. An antibody or antigen-binding fragment thereof, wherein the antibody or antigen-binding fragment thereof binds to C3b, and the antibody or antigen-binding fragment thereof comprises three complementarity-determining regions (CDR1 to CDR3 respectively), wherein CDR1 comprises GRTFSNY (SEQ ID NO:19), CDR2 comprises IRTGKT (SEQ ID NO:23), and CDR3 comprises ATSGWHIKTVTPYEY (SEQ ID NO:22).

7. An antibody or antigen-binding fragment thereof, wherein the antibody or antigen-binding fragment thereof binds to C3b, and the antibody or antigen-binding fragment thereof comprises three complementarity-determining regions (CDR1 to CDR3 respectively), wherein CDR1 comprises NYHMG (SEQ ID NO:16), CDR2 comprises TIIRTGTTIYYADSVKG (SEQ ID NO:24), and CDR3 comprises ATSGWHIKTVTPYEY (SEQ ID NO:22).

8. An antibody or antigen-binding fragment thereof, wherein the antibody or antigen-binding fragment thereof binds to C3b, and the binding portion comprises three complementarity-determining regions (CDR1 to CDR3 respectively), wherein CDR1 comprises GRTFSNY (SEQ ID NO:19), CDR2 comprises IRTGTT (SEQ ID NO:25), and CDR3 comprises ATSGWHIKTVTPYEY (SEQ ID NO:22).

9. An antibody or antigen-binding fragment thereof, wherein the antibody or antigen-binding fragment thereof binds to complement component 3b (C3b), and the antibody or antigen-binding fragment thereof comprises an amino acid sequence that is at least 90% identical to any one of SEQ ID NOs: 10-13.

10. The antibody or antigen-binding fragment thereof according to any one of the preceding claims, wherein the antibody or antigen-binding fragment thereof is a VHH.

11. The antibody or antigen-binding fragment thereof according to claim 10, wherein the VHH comprises SEQ ID NO:

10.

12. The antibody or antigen-binding fragment thereof according to claim 10, wherein the VHH comprises SEQ ID NO:

11.

13. The antibody or antigen-binding fragment thereof according to claim 10, wherein the VHH comprises SEQ ID NO:

12.

14. The antibody or antigen-binding fragment thereof according to claim 10, wherein the VHH comprises SEQ ID NO:

13.

15. The antibody or antigen-binding fragment thereof according to any one of the preceding claims, wherein the antibody or antigen-binding fragment thereof further comprises an Fc domain, and the Fc domain is derived from IgG1, IgG2, IgG3 or IgG4.

16. The antibody or antigen-binding fragment thereof according to claim 15, wherein the Fc domain is derived from IgG4.

17. The antibody or antigen-binding fragment thereof according to any one of claims 15 to 16, wherein the Fc domain is modified.

18. The antibody or antigen-binding fragment thereof according to claim 17, wherein the Fc domain comprises T307Q, Q311V, and / or A378V mutations, and the Fc domain numbering is according to the EU index.

19. The antibody or antigen-binding fragment thereof according to any one of claims 17 to 18, wherein the Fc domain comprises an S228P mutation, and the Fc domain numbering is according to the EU index.

20. The antibody or antigen-binding fragment thereof according to any one of claims 17 to 19, wherein the Fc domain comprises substitutions at positions F234, L235, and / or D265, and the Fc domain numbering is according to the EU index.

21. The antibody or antigen-binding fragment thereof according to claim 20, wherein the substitution at position F234 is a hydrophobic amino acid selected from the group consisting of alanine, valine, leucine, isoleucine, phenylalanine, and tryptophan, and the Fc domain numbering is according to the EU index.

22. The antibody or antigen-binding fragment thereof according to any one of claims 20 to 21, wherein the substitution at position F234 is valine, and the Fc domain numbering is according to the Kabat EU index.

23. The antibody or antigen-binding fragment thereof according to any one of claims 20 to 22, wherein the substitution at position L235 is an acidic amino acid, and the Fc domain numbering is according to the EU index.

24. The antibody or antigen-binding fragment thereof according to any one of claims 20 to 23, wherein the substitution at position L235 is an acidic amino acid selected from the group consisting of glutamic acid and aspartic acid, and the Fc domain numbering is according to the EU index.

25. The antibody or antigen-binding fragment thereof according to any one of claims 20 to 24, wherein the substitution at position L235 is aspartic acid, and the Fc domain numbering is according to the EU index.

26. The antibody or antigen-binding fragment thereof according to any one of claims 20 to 25, wherein the substitution at position D265 is a nonpolar amino acid, and the Fc domain numbering is according to the EU index.

27. The antibody or antigen-binding fragment thereof according to any one of claims 20 to 26, wherein the substitution at position D265 is a nonpolar amino acid selected from the group consisting of alanine, cysteine, glycine, isoleucine, leucine, methionine, and valine, and the Fc domain numbering is according to the EU index.

28. The antibody or antigen-binding fragment thereof according to any one of claims 20 to 27, wherein the substitution at position D265 is glycine, and the Fc domain numbering is according to the EU index.

29. The antibody or antigen-binding fragment thereof according to any one of claims 20 to 28, wherein the Fc domain comprises S228P, F234V, L235E, D265G, T307Q, Q311V, and A378V mutations.

30. The antibody or antigen-binding fragment thereof according to claim 29, wherein the Fc domain comprises the amino acid sequence of SEQ ID NO:

14.

31. The antibody or antigen-binding fragment thereof according to any one of the preceding claims, wherein the antibody or fragment thereof inhibits the formation of C3 convertase and / or C5 convertase.

32. The antibody or antigen-binding fragment thereof according to any one of the preceding claims, wherein the antibody or fragment thereof does not bind to C3 protein.

33. The antibody or antigen-binding fragment thereof according to any one of the preceding claims, wherein the antibody or fragment thereof inhibits the activity of C3 convertase.

34. The antibody or antigen-binding fragment thereof according to any one of the preceding claims, wherein the antibody or antigen-binding fragment comprises an amino acid sequence that is at least 90% identical to SEQ ID NO:

4.

35. The antibody or antigen-binding fragment thereof according to claim 34, wherein the antibody or antigen-binding fragment comprises SEQ ID NO:

4.

36. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 33, wherein the antibody or antigen-binding fragment comprises an amino acid sequence that is at least 90% identical to SEQ ID NO:

5.

37. The antibody or antigen-binding fragment thereof according to claim 36, wherein the antibody or antigen-binding fragment comprises SEQ ID NO:

5.

38. The antibody or fragment thereof according to any one of claims 1 to 33, wherein the antibody or fragment thereof comprises an amino acid sequence that is at least 90% identical to SEQ ID NO:

6.

39. The antibody or antigen-binding fragment thereof according to claim 38, wherein the antibody or antigen-binding fragment comprises SEQ ID NO:

6.

40. The antibody or fragment thereof according to any one of claims 1 to 33, wherein the antibody or fragment thereof comprises an amino acid sequence that is at least 90% identical to SEQ ID NO:

7.

41. The antibody or antigen-binding fragment thereof according to claim 40, wherein the antibody or antigen-binding fragment comprises SEQ ID NO:

7.

42. The antibody or fragment thereof according to any one of claims 1 to 33, wherein the antibody or fragment thereof comprises an amino acid sequence that is at least 90% identical to SEQ ID NO:

8.

43. The antibody or antigen-binding fragment thereof according to claim 41, wherein the antibody or antigen-binding fragment comprises SEQ ID NO:

8.

44. The antibody or fragment thereof according to any one of claims 1 to 33, wherein the antibody or fragment thereof comprises an amino acid sequence that is at least 90% identical to SEQ ID NO:

9.

45. The antibody or antigen-binding fragment thereof according to claim 40, wherein the antibody or antigen-binding fragment comprises SEQ ID NO:

9.

46. A nucleic acid encoding the antibody or antigen-binding fragment thereof according to any one of the preceding claims.

47. The nucleic acid according to claim 46, wherein the nucleic acid is DNA, cDNA, RNA or messenger RNA (mRNA).

48. The nucleic acid according to claim 47, wherein the nucleic acid is mRNA.

49. A composition comprising the nucleic acid according to any one of claims 46 to 48 and a delivery agent.

50. The composition according to claim 49, wherein the delivery agent is an adeno-associated virus (AAV) vector or a lipid nanoparticle (LNP).

51. The composition according to claim 50, wherein the mRNA is encapsulated in the LNP.

52. A method of treating a complement-mediated disease or disorder, the method comprising administering to a subject in need thereof a therapeutically effective amount of the antibody or antigen-binding fragment thereof according to any one of claims 1 to 45.

53. The method according to claim 52, wherein the complement-mediated disease or disorder is C3 glomerulopathy, or a disease or disorder associated with C3 glomerulopathy.

54. The method according to claim 53, wherein the disease or disorder associated with C3 glomerulopathy is dense deposit disease (DDD).

55. The method according to claim 53, wherein the disease or disorder associated with C3 glomerulopathy is C3 glomerulonephritis (C3GN).

56. The method according to claim 52, wherein the complement-mediated disease or disorder is characterized by the accumulation of C3 complement component in renal tissue.

57. The method according to any one of claims 52 to 56, wherein the subject has symptomatic hematuria, proteinuria, acute kidney injury (AKI) or chronic kidney disease (CKD).

58. The method according to claim 52, wherein the complement-mediated disease or disorder is paroxysmal nocturnal hemoglobinuria, geographic atrophy or autoimmune hemolytic anemia (AIHA).

59. The method according to claim 52, wherein the complement-mediated disease or disorder is age-related macular degeneration (AMD).

60. The method according to claim 52, wherein the complement-mediated disease or disorder is passive Heymann nephritis (PHN).

61. A method of treating a complement-mediated disease or disorder, the method comprising administering to a subject in need thereof a therapeutically effective amount of an anti-C3b antibody or a fragment thereof.

62. The method according to claim 61, wherein the complement-mediated disease or disorder is C3 glomerulopathy, or a disease or disorder associated with C3 glomerulopathy.

63. The method according to claim 62, wherein the disease or disorder associated with C3 glomerulopathy is dense deposit disease (DDD).

64. The method according to claim 62, wherein the disease or disorder associated with C3 glomerulopathy is C3 glomerulonephritis (C3GN).

65. The method according to claim 61, wherein the complement-mediated disease or disorder is age-related macular degeneration (AMD).

66. The method according to claim 61, wherein the complement-mediated disease or disorder is passive Heymann nephritis (PHN).

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