This is a human IgG4 antibody using the same sequences as the therapeutic antibody pozelimab. It has been shown to bind with high affinity to wild-type and variant (R885H/C) human complement factor C5. C5 is a precursor protein synthesized in the liver. During complement activation, C5 is cleaved, producing two disulfide linked glycoproteins C5α and C5β. C5α is further cleaved by C5 convertase into C5a and C5α’, the latter binds to C5β to form C5b, which in turn sequentially recruits C6-C9 to form the membrane attack complex (MAC). MAC destroys pathogens by forming a lytic pore in their membrane. Pozelimab blocks the pathway leading to red blood cell hemolysis,  thus reduces LDH levels and the occurrence of breakthrough hemolysis. It was invented using Regeneron’s proprietary VelocImmune technology, which uses a unique genetically-humanized mouse to produce optimized fully-human antibodies.