Is first-line pembrolizumab appropriate for all patients with metastatic non-squamous histology non-small cell lung cancer patients?

Immune checkpoint inhibitors have emerged as a new frontier of modern cancer treatment. Prior to recent research in oncogenesis and the immune system, lung cancer treatment was mostly limited to platinum-based chemotherapy, radiation therapy, and surgical resection. Platinum-based chemotherapy has remained the standard of care for stage IV or metastatic non-small cell lung cancer (NSCLC) patients since a landmark meta-analysis in 1995, despite a relatively poor increase in median overall survival (OS) of 1.5 months (1). Incremental progress was seen with the addition of maintenance pemetrexed, but since 2009 the outcomes for patients with metastatic NSCLC without targetable driver mutations had stalled (2).