Pharmacokinetics and pharmacodynamics of pozelimab alone or in combination with cemdisiran in non-human primates.

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare disease caused by uncontrolled complement activation; effective and approved treatments include terminal complement inhibition. This study assessed whether combination cemdisiran (an investigational N-acetylgalactosamine-conjugated RNAi therapeutic that suppresses liver production of complement component C5) and pozelimab (an investigational fully human monoclonal antibody against C5) results in more effective and durable complement activity inhibition than the individual agents alone in non-human primates. Cynomolgus monkeys received a single subcutaneous injection of cemdisiran (5 or 25 mg/kg), pozelimab (5 or 10 mg/kg), or combination cemdisiran and pozelimab (5+5 mg/kg, 5+10 mg/kg, or 25+10 mg/kg, respectively). When given in combination, pozelimab was administered 2 weeks after cemdisiran dosing. Pharmacokinetics and ex vivo pharmacodynamic properties were assessed. The half-life of pozelimab alone was 12.9-13.3 days; this increased to 19.6-21.1 days for pozelimab administered in combination with cemdisiran. In ex vivo classical pathway hemolysis assays (CH50), pozelimab + cemdisiran combinations achieved durable and more complete suppression of complement activity (8-13 weeks) vs monotherapy of either agent. Cemdisiran monotherapy demonstrated dose-dependent suppression of total C5 concentrations, with the higher dose (25 mg/kg) achieving >90% maximum suppression. Total C5 concentrations after administration of pozelimab + cemdisiran combinations were similar compared with administration of cemdisiran alone. The combination of pozelimab + cemdisiran mediates complement activity inhibition more efficiently than either pozelimab or cemdisiran administered alone. The pharmacokinetic/pharmacodynamic profile of combination pozelimab + cemdisiran in non-human primates appears suitable for further clinical investigation as a potential long-acting treatment for PNH and other complement-mediated diseases.

Inhibition of complement pathway activation with Pozelimab, a fully human antibody to complement component C5.

Complement is a key component of the innate immune system. Inappropriate complement activation underlies the pathophysiology of a variety of diseases. Complement component 5 (C5) is a validated therapeutic target for complement-mediated diseases, but the development of new therapeutics has been limited by a paucity of preclinical models to evaluate the pharmacokinetic (PK) and pharmacodynamic (PD) properties of candidate therapies. The present report describes a novel humanized C5 mouse and its utility in evaluating a panel of fully human anti-C5 antibodies. Surprisingly, humanized C5 mice revealed marked differences in clearance rates amongst a panel of anti-C5 antibodies. One antibody, pozelimab (REGN3918), bound C5 and C5 variants with high affinity and potently blocked complement-mediated hemolysis in vitro. In studies conducted in both humanized C5 mice and cynomolgus monkeys, pozelimab demonstrated prolonged PK and durable suppression of hemolytic activity ex vivo. In humanized C5 mice, a switch in dosing from in-house eculizumab to pozelimab was associated with normalization of serum C5 concentrations, sustained suppression of hemolytic activity ex vivo, and no overt toxicity. Our findings demonstrate the value of humanized C5 mice in identifying new therapeutic candidates and treatment options for complement-mediated diseases.