PD-L1 expression and immune infiltrates in sarcoma.

Abstract

10522 Background: Programmed death-1 (PD-1) is a member of the CD28 family of T-cell costimulatory receptors that attenuates immune responses by negatively regulating T-cell proliferation and function. The prognostic and predictive implications of programmed death-ligand 1 (PD-L1) has been described in multiple malignancies but are unknown in sarcoma. We previously demonstrated PD-L1 expression by western blot and flow cytometry in 65% of sarcoma cell lines. We now examined PD-L1 expression by IHC in sarcoma specimens and tumor-associated immune cells and correlated expression with clinical parameters and outcomes. Methods: 50 sarcoma patients treated at Memorial Sloan Kettering Cancer Center who were consented to our IRB approved tissue procurement protocol were selected. Correlative clinical information was collected.Using the DAKO PD-L1 IHC assay and archival formalin-fixed paraffin embedded tissue specimens; PD-L1 expression was examined. Positive was defined as >1% of tumor cells (minimum of 100 eval...