ECM2 mutation has a strong connection with better outcomes to immune checkpoint inhibitors only in melanoma cancer. ECM2-mutated group was significantly associated with higher ORR (75.0% vs 13.9%, P = 0.013), longer OS (35.9 months vs 8.5 months, 95% CI, 0.02-1.09, P = 0.032) than ECM2-wide-type group....ECM2 mutation can serve as a potential predictor for a favorable response to ICIs in melanoma patients.