REGN15505 + cemiplimab

REGN15505 + cemiplimab is an investigational combination therapy being developed by Regeneron Pharmaceuticals for the treatment of advanced solid tumors, specifically metastatic castration-resistant prostate cancer (mCRPC) and clear cell renal cell carcinoma (ccRCC). REGN15505 is a bispecific antibody designed to target Prostate-Specific Membrane Antigen (PSMA) on tumor cells and the costimulatory receptor 4-1BB (CD137) on T cells. By bridging these two targets, REGN15505 provides localized T-cell costimulation within the tumor microenvironment. Cemiplimab (Libtayo) is a fully human monoclonal antibody that inhibits the programmed cell death protein-1 (PD-1) checkpoint, thereby restoring T-cell activity against cancer cells. The combination aims to synergistically enhance anti-tumor immune responses by simultaneously blocking immune checkpoints and providing targeted costimulatory signals.