A retrospective analysis from the phase 3 ATOMIC trial suggests that patients with stage III dMMR colon cancer may benefit most from adding Atezolizumab to standard FOLFOX chemotherapy when they are able to complete more than six cycles of treatment.
Patients who received more than six cycles of FOLFOX plus atezolizumab had a significantly lower risk of disease recurrence or death compared with those receiving FOLFOX alone. This benefit was not seen in patients who completed six or fewer cycles. The analysis also found that the disease-free survival benefit increased with each additional cycle of FOLFOX given alongside atezolizumab.
Completing 12 or more cycles of atezolizumab, including combination therapy and later monotherapy, was also associated with a significant disease-free survival benefit.
The findings come as the FDA is reviewing atezolizumab for adjuvant treatment of stage III dMMR or MSI-H colon cancer, with a decision expected on October 9, 2026. Researchers emphasized that patients should continue treatment as long as it is tolerated to maximize protection against recurrence.