FDA approves atezolizumab plus chemo as adjuvant therapy for Stage III dMMR colon cancer

On 8 October 2026, the US FDA approved atezolizumab (Tecentriq, Genentech) with fluoropyrimidine and oxaliplatin as adjuvant treatment for adults and children aged 2 years and older with Stage III mismatch repair–deficient (dMMR) colon cancer. It also approved atezolizumab/hyaluronidase-tqjs (Tecentriq Hybreza) with chemo for patients aged 12 years and older weighing at least 40 kg.

The ATOMIC trial

• Approval rests on ATOMIC/ML39057 (NCT02912559): a multicentre, randomised, open-label phase 3 study.
• 711 adults and 1 paediatric patient after complete resection without residual lymph-node or metastatic disease were assigned 1:1 to atezolizumab plus mFOLFOX6 (12 cycles) then atezolizumab alone for 6 months, versus mFOLFOX6 alone for 12 cycles.
• Primary endpoint: investigator-assessed disease-free survival (DFS); hazard ratio 0.50 (95% CI 0.35–0.73; p=0.0001); median DFS was not reached in either arm.
• Peer-reviewed follow-up: 3-year DFS 86.3% versus 76.2% at median follow-up 40.9 months. Overall survival was not significantly different (HR 0.90; 95% CI 0.55–1.47).

Limitations

• The trial was open-label; OS did not improve significantly; the indication is adjuvant Stage III dMMR after resection only.
• This is not personal medical advice — patients should talk with their oncologist.