silevimig

**Silevimig (GR1801)** is a recombinant, fully human bispecific antibody developed by Chongqing Genrix Biopharmaceutical Co., Ltd. for passive immunization against rabies virus (RABV). It simultaneously binds to antigenic epitopes I and III on the RABV glycoprotein (G protein), blocking viral interaction with host receptors and preventing neural invasion prior to active vaccination-induced immunity. Engineered as an asymmetric IgG1 heterodimer using Knob-into-Hole technology—with a Fab arm (A2) targeting epitope III fused to the Knob Fc and an scFv arm (B353) targeting epitope I fused to the Hole Fc—it demonstrates broad neutralization against diverse RABV strains, low immunogenicity, minimal vaccine interference, and scalable manufacturing. Its Phase 3 trial met the primary efficacy endpoint of non-inferiority to human rabies immunoglobulin (HRIG) for post-exposure prophylaxis (PEP) in WHO Category III exposures, with NDA accepted by China's CDE in January 2025 for adults and ongoing Phase 3 in children/adolescents.[1][5][7]

Other names

GR1801GR-1801GR 1801