CB307 + pembrolizumab

CB307 + pembrolizumab is an investigational combination immunotherapy for the treatment of advanced or metastatic PSMA-positive solid tumors, including metastatic castration-resistant prostate cancer. **CB307** is a trispecific variable heavy-chain antibody fragment that targets prostate-specific membrane antigen (PSMA), provides CD137 (4-1BB) co-stimulation to T cells, and binds to human serum albumin to extend its half-life. It is designed to activate T cells only in the presence of PSMA-expressing tumor cells, reducing off-tumor toxicity by localizing immune activation to the tumor microenvironment. **Pembrolizumab** is a monoclonal antibody targeting the programmed cell death protein 1 (PD-1), blocking its interaction with PD-L1 and thereby enhancing T-cell–mediated immune responses against cancer. The combination aims to provide additive or supra-additive immune activation, showing enhanced antitumor effects in preclinical and early clinical studies, especially for patients with PSMA-positive metastatic castration-resistant prostate cancer[1][2][3][4][5][6][7].