Frank A. Sinicrope, MD, on Adjuvant Treatment Strategies for Stage III dMMR Colon Cancer

ATOMIC was for patients with deficient mismatch repair stage 3 colon cancer. All of these patients had undergone a surgical resection with curative intent and all were found to have deficient mismatch repair tumors by immunohistochemistry. Patients were randomized 1 to 1 to FOLFOX chemotherapy plus atezolizumab given for six months, with the atezolizumab continued for an additional six months. This was compared to FOLFOX alone for six months. Atezolizumab, as we know, is an anti–PD-L1 antibody. The objective of this study was to see whether or not the immunotherapy would improve outcomes compared to chemotherapy alone. At the second interim analysis of this trial, with 75% of events, the trial was stopped. The results were reported out at a median follow-up of 37.2 months. The chemoimmunotherapy was associated with a hazard ratio of 0.5, indicating that there was a reduction in recurrence or death by 50% compared to the FOLFOX arm. So these are impressive results we regard as practice-changing, and I would comment that the treatments were well tolerated and not associated with really any adverse events that would not be expected with each of the agents. So we regard this treatment as a new standard of care for this patient population, and it really demonstrates that taking immunotherapy that we're commonly using in this population in the metastatic setting now can be moved to earlier-stage or stage 3 disease to benefit these patients also. So we think this is a very clinically meaningful result for patients, and we're very excited to continue to see if the guidelines will now be adopting this new regimen for our patients.