CheckMate 451, a double-blind phase III trial, evaluated nivolumab plus ipilimumab and nivolumab monotherapy as maintenance therapy following first-line chemotherapy for ED-SCLC....A trend toward OS benefit with nivolumab versus placebo was seen in patients with TMB ≥13 mut/Mb (HR, 0.67; 95% CI, 0.45 to 1.01; Fig 3A), but not in those with TMB <13 mut/Mb (HR, 0.92; 95% CI, 0.70 to 1.22; Fig 3B).