CG001, a C3b-targeted complement inhibitor blocks three complement pathways: development and preclinical evaluation

• The human-derived and antibody-like C3b-targeted fusion protein CG001 may simultaneously and effectively block three complement pathways.

• CG001 holds high potential of further development for clinical study based on the preclinical evaluation.

Excessively activated or dysregulated complement activation may contribute to the pathogenesis of a wide range of human diseases, thus leading to a surge in complement inhibitors. Herein, we developed a human-derived and antibody-like C3b-targeted fusion protein (CRIg-FH-Fc) *2, termed CG001, that could potently block all three complement pathways. CRIg and FH bind to distinct sites in C3b and synergistically inhibit complement activation. CRIg occupancy in C3b prevents the recruitment of C3 and C5 substrates, while FH occupancy in C3b accelerates the decay of C3/C5 convertases and promotes the Factor I-mediated degradation and inactivation of C3b. CG001 also showed therapeutic effects in AP-induced hemolytic mouse and CP-induced MsPGN rat models. In the pharmacological/toxicological evaluation in rats and cynomolgus monkeys, CG001 displayed an antibody-like pharmacokinetic profile, a convincing complement inhibitory effect, and no observable toxic effects. Therefore, CG001 holds substantial potential for human clinical studies.