The phase 2 trial KEYNOTE-158 ( NCT02628067 ) evaluated pembrolizumab in microsatellite-instability-high and mismatch-repair-deficient (MSI-H/dMMR) noncolorectal tumors. With 373 participants (95% with baseline MSI/dMMR documentation) and 4.5 years of follow-up, the primary endpoint of overall response rate was 33.8%. Secondary endpoints of duration of response, overall survival and progression-free survival were 63.2, 19.8 and 4.0 months, respectively. Grade ≥3 treatment-related adverse events occurred in 50 (13%) participants. These results further support pembrolizumab use in MSI-H/dMMR tumors.