Successes and failures: what did we learn from recent first-line treatment immunotherapy trials in non-small cell lung cancer?

The immune checkpoint inhibitors have significantly modified the therapeutic landscape of advanced non-small cell lung cancer in second-line and, more recently, first-line settings. Because of the superior outcome with pembrolizumab as an upfront strategy, PD-L1 status should now be considered a new reflex biomarker for guiding first-line treatment in patients with advanced non-small cell lung cancer. Improved responses have also been reported with the combination of immune checkpoint inhibitors and chemotherapy as the first-line treatment; however, this strategy has not yet been validated by phase III trial data and its interplay with PD-L1 status still requires clarification. In this manuscript we review the contradictory results of recent phase III trials with immune checkpoint inhibitors in the first-line setting, the potential reasons for discrepancies, and some of the remaining open questions related to the positioning of immune checkpoint inhibitors in the first-line setting of non-small cell lung cancer.