Pembrolizumab in the treatment of metastatic non-small cell lung cancer: a review of current evidence:

Immune checkpoint inhibitors (ICPIs) are considered one of the most important breakthroughs in cancer treatment of the past decade; notably, different studies of programmed cell death protein 1 (PD-1) and programmed death-ligand 1 (PD-L1) inhibitors have reported impressive clinical activity and durable responses in patients with advanced non-small cell lung cancer (NSCLC). These findings have led to the changing of the current therapeutic algorithm of advanced NSCLC, adding a new standard first-line treatment option for patients with PD-L1-positive tumors. Pembrolizumab, a highly selective anti-PD-1 humanized monoclonal antibody, was approved by the United States Food and Drug Administration (US FDA) in October 2016 for previously untreated metastatic NSCLC patients whose tumors have high PD-L1 expression, tumor proportion score (TPS) ⩾ 50%, as well as for metastatic NSCLC patients whose tumors express PD-L1 with TPS ⩾ 1% progressing on or after platinum-based chemotherapy. However, many issues remain ou...