We characterized the frequency and genomic characteristics of DOT1L mutations in a cohort of 393 treatment-naïve stage III/IV NSCLC patients using targeted next-generation sequencing....The median progression-free survival of DOT1L-mutated patients receiving ICIs was significantly longer than that of DOT1L-wildtype patients on ICIs (21.1 vs. 3.9 months, P=0.006).