Immune checkpoint modulation for non-small cell lung cancer

Therapies targeting immune checkpoints have recently shown encouraging activity in patients with heavily pretreated advanced non-small cell lung cancer (NSCLC), independently of NSCLC histology or mutational status, with low toxicity profiles when used as monotherapy. Objective response rates of approximately 20% have been reported in patients with advanced NSCLC treated with antagonist antibodies targeting the immune checkpoint, programmed death 1 (PD-1) on activated T cells, or its primary ligand, programmed death ligand 1 (PD-L1) expressed within the tumor microenvironment. Response rates appear to be higher in patients with tumor PD-L1 expression documented by immunohistochemistry, although responses have been appreciated in patients with reportedly PD-L1-negative tumor specimens. Antibodies directed against cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), another immunosuppressive T-cell signaling molecule, are also being evaluated in clinical trials, with one randomized phase II trial demonstrating improved immune-related progression-free survival in lung cancer patients when added to standard chemotherapy. Additional clinical trials are combining anti-CTLA-4 antibodies with either anti-PD-1 or anti-PD-L1 antibodies. Combinations of other immune checkpoint antagonists or agonist antibodies with anti-PD-1 or anti-PD-L1 antibodies are also being pursued.