A phase Ib study of MK-3475 in patients with human papillomavirus (HPV)-associated and non-HPV–associated head and neck (H/N) cancer.

6011 Background: The PD-1 receptor-ligand pathway can be used by tumors to evade immune surveillance, thereby allowing neoplastic growth. MK-3475 is a highly selective, humanized IgG4/kappa isotype mAb designed to block PD-1 interaction with its ligands PD-L1 and PD-L2, to reactivate the immune system to eradicate the host tumor. Methods: Pts with recurrent/metastatic H/N cancer were enrolled in this multi-center, non-randomized trial in two cohorts (HPV and non-HPV associated). Pts were prescreened for PD-L1 expression by immunohistochemistry (22C3), and if positive allowed to proceed with treatment of single agent MK-3475 given intravenously at 10 mg/kg every 2 wks. Primary objectives are to determine (1) safety and tolerability and (2) anti-tumor activity of MK-3475 assessed by RECIST 1.1. Secondary objectives include progression-free survival, overall survival and response duration. Results: All results are based on preliminary, unaudited data as of Jan. 27, 2014. 77.9% of patients expressed PD-L1, de...