FDA has approved atezolizumab with chemotherapy for adjuvant treatment of stage III dMMR colon cancer following the phase 3 ATOMIC trial, delivering a 50% reduction in the risk of recurrence or death. The decision positions checkpoint blockade as a new standard option for a molecularly defined patient group in the adjuvant setting. The approval underscores the FDA’s continued emphasis on tumor biomarker status in selecting therapy strategies. For biotech and translational teams, the dataset and endpoints from ATOMIC will likely shape how new combinations are benchmarked in next-generation adjuvant trials, particularly in dMMR populations.