REGN3048 + REGN3051

REGN3048 + REGN3051 is an investigational cocktail of two fully human IgG1 monoclonal antibodies developed by Regeneron Pharmaceuticals that target non‑overlapping epitopes on the spike glycoprotein receptor‑binding domain of Middle East respiratory syndrome coronavirus (MERS‑CoV). These antibodies neutralize MERS‑CoV by blocking spike interaction with the host receptor dipeptidyl peptidase 4 (DPP4), thereby preventing viral entry into target cells.[1][3][4] In huDPP4 transgenic mouse models, prophylactic or therapeutic co‑administration produced greater reductions in viral titers, lung inflammation, and pathology than either antibody alone, and achieved undetectable virus levels at substantially lower doses.[1][4] A first‑in‑human Phase 1 trial in healthy adults using single ascending intravenous doses up to 150 mg/kg total showed that the combination was generally well tolerated, with no dose‑limiting toxicities, serious adverse events, infusion reactions, or treatment‑emergent anti‑drug antibodies, and pharmacokinetics consistent with human IgG1 antibodies.[1][4][6][9][12] The cocktail has been developed primarily for prophylaxis and treatment of MERS, but development for this indication appears to have been discontinued.[11][13]