Sarc 028: A Phase Ii Study Of The Anti-Pd1 Antibody Pembrolizumab (P) In Patients (Pts) With Advanced Sarcomas.

TPS10578 Background: Immune checkpoint inhibition with antibodies (abs) to cytotoxic T-lymphocyte antigen-4 (CTLA-4), programmed death 1 (PD-1), and programmed death ligand 1 (PD-L1) have made a significant therapeutic impact in metastatic melanoma. Abs targeting the PD-1/PD-L1 axis also exhibited clinical activity in solid tumors that are not considered “immunogenic”, e.g., lung and bladder cancer. The significance of the PD-1/PD-L1 axis is currently being elucidated in sarcoma. Over 150 sarcomas of various histologic subtypes have been analyzed for PD-L1 tumor expression and the presence of PD-1+ tumor infiltrating lymphocytes (TIL): up to 65% of sarcomas expressed PD-L1 which, along with PD-1 TIL positivity, correlated with poorer overall survival and aggressive tumor features. We seek to determine the efficacy of PD-1 blockade with the anti-PD-1 ab pembrolizumab in pts with advanced soft tissue (STS) and bone sarcomas. Methods: This is an open label, multicenter, single stage, phase II study of P in p...