Pembrolizumab for the treatment of non-small cell lung cancer

Introduction: Immune checkpoint inhibitors targeting programmed death protein 1 (PD-1) receptor and its ligand, PD-L1, have recently led to significant and durable improvements in the clinical outcomes of some types of cancers including lung cancer.Areas covered: Pembrolizumab was approved by the US FDA for the treatment of advanced or metastatic NSCLC whose disease has progressed after other treatments and with tumors that express PD-L1. In the phase I KEYNOTE-001 trial, the overall response rate (ORR) was 19.4%, the median progression-free survival (PFS) and overall survival (OS) were 3.7 months and 12.0 months for 495 unselected NSCLC patients. Strong PD-L1 expression (≥ 50%) was associated with higher ORR, longer PFS, and longer OS. The phase II/III randomized KEYNOTE-010 trial demonstrated that pembrolizumab improved OS versus docetaxel in patients with previously treated NSCLC.Expert opinion: Pembrolizumab, demonstrated durable response and prolonged OS especially in NSCLC patients with high expression of PD-1, thereby suggests a new treatment paradigm. However, many issues remain to be explored, including the identification of other robust biomarkers that can accurately predict the immune-responsiveness of tumors. Along with the identification of predictive biomarkers, further understanding of the tumor microenvironment is necessary to improve treatment outcomes through combinations of immunotherapy or combined with other targeted therapies.