Searching for Synergy: Chemotherapy and Checkpoint Inhibitors.

Continuation of programmed cell death protein 1 (PD-1) inhibitors in combination with chemotherapy did not improve clinical outcomes for patients with non-small cell lung cancer who progressed on prior PD-1/programmed death ligand 1 inhibitor monotherapy. This highlights the need to evaluate the precise mechanisms of resistance to PD-1 axis inhibitors and explore alternative therapeutic strategies to overcome resistance. See related article by Jung et al., p. 2321.