TMC353121

TMC353121 is an investigational small-molecule fusion inhibitor developed by Tibotec Pharmaceuticals (a subsidiary of Johnson & Johnson) for the treatment of respiratory syncytial virus (RSV) infection. It is a substituted benzimidazole derivative, specifically a morpholinopropylaminobenzimidazole, designed through molecular modeling of the precursor JNJ-2408068. The compound targets the RSV fusion (F) protein by binding to an intermediate conformation and stabilizing the interaction of heptad-repeat regions (HR1 and HR2) into an alternate six-helix bundle (6HB) conformation. This mechanism effectively inhibits viral fusion and subsequent entry into host cells. TMC353121 has been evaluated in Phase 2 clinical trials as an intravenous treatment for RSV-confirmed upper respiratory tract infections in hematopoietic stem cell transplant recipients.