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The CHECKMATE-227 trial of nivolumab and ipilimumab presents a potential new frontline chemotherapy-sparing treatment option for patients with PD-L1-positive non-small-cell lung cancer and perhaps, in the future, also for those with PD-L1-negative disease. Indeed, the true predictive value of PD-L1 as well as tumour mutational burden remains to be determined, as neither biomarker segregates clearly with responsiveness.