A phase Ib multicohort study of MK-3475 in patients with advanced solid tumors.

TPS3119 Background: Immune surveillance is one of the primary mechanisms to prevent neoplastic growth. The PD-1 receptor-ligand pathway can be used by tumors to evade immune surveillance. MK-3475 is a potent, highly selective, humanized IgG4/kappa isotype mAb designed to block PD-1 interaction with its ligands PD-L1 and PD-L2, and can reactivate the immune system to eradicate the host tumor. Methods: This is a multi-center, non-randomized, multi-cohort trial of single agent MK-3475 in over 130 patients diagnosed with locally recurrent and/or distant metastatic 1) triple negative breast cancer, 2) head and neck cancer (both HPV and non-HPV associated), 3) urinary tract cancer or 4) gastric cancer. All enrolled patients must express PD-L1 within their tumor microenvironment. MK-3475 is given intravenously at 10 mg/kg every 2 weeks. Primary objectives are to determine (1) safety and tolerability and (2) anti-tumor activity of MK-3475 in patients with PD-L1 positive, advanced solid tumors. Secondary objective...