Results from the phase 3 ATOMIC trial are practice changing for colorectal cancer care and raise broader questions about immunotherapy use in patients with mismatch repair deficiencies across tumor types. Frank A. Sinicrope, MD, a professor of oncology and medicine at the Mayo Clinic Comprehensive Cancer Center in Rochester, Minnesota, presented the findings at the 2025 American Society of Clinical Oncology Annual Meeting. He discussed the significance of the ATOMIC results and next steps with Robert A. Figlin, MD, the interim director of Cedars-Sinai Cancer in Los Angeles and Steven Spielberg Family Chair in Hematology-Oncology. “I think that microsatellite instability is a terrific predictive biomarker for immunotherapy, and all of these patients should get immunotherapy in some form or another,” Dr. Sinicrope noted.