Ready N, et al. - Researchers assessed the outcomes of nivolumab plus low-dose ipilimumab and if they were impacted by programmed death ligand 1 (PD-L1) expression and tumor mutational burden (TMB) in first-line treatment of advanced/metastatic non-small-cell lung cancer (NSCLC) in the CheckMate 568, an open-label phase 2 trial. Nivolumab 3 mg/kg every 2 weeks plus ipilimumab 1 mg/kg every 6 weeks were administered to 288 patients with previously untreated, recurrent stage IIIB/IV NSCLC, with a focus on objective response rate in patients with 1% or more and less than 1% tumor PD-L1 expression (primary end point) and on effectiveness on the basis of TMB (FoundationOne CDx assay) (secondary end point). Findings revealed efficacy as well as tolerability of nivolumab plus low-dose ipilimumab as a first-line treatment of advanced/metastatic NSCLC. In both tumor PD-L1 expression 1% or greater and less than 1% subgroups, improved response and prolonged progression-free survival were observed in relation to TMB of 10 or more mutations/megabase and, it was, therefore, found to be a possibly pertinent cutoff in evaluating TMB as a biomarker for first-line nivolumab plus ipilimumab.