PD-L1 expression in cancer patients receiving anti PD-1/PD-L1 antibodies: A systematic review and meta-analysis.

Despite the success of immunotherapy directed at inhibiting of programmed death-1 (PD-1)/PD-ligand (L)1 signaling, it is not established whether PD-L1 expression correlates with the clinical response and outcome in different tumors. The present meta-analysis investigates whether the PD-L1 status, detected by immunohistochemistry, is associated with clinical response and mortality in patients treated with anti-PD-1/PD-L1 therapy.