FDA Approves Atezolizumab Plus Chemotherapy for Adjuvant Treatment of Stage III dMMR Colon Cancer

The FDA has approved atezolizumab (Tecentriq, Genentech) with a fluoropyrimidine and oxaliplatin for the adjuvant treatment of adult and pediatric patients aged 2 years and older with stage III mismatch repair–deficient (dMMR) colon cancer. The agency also approved subcutaneous atezolizumab and hyaluronidase-tqjs (Tecentriq Hybreza, Genentech) for the same use in patients aged 12 years and older who weigh at least 40 kg.

In a press release, Genentech called the combination the “first approved adjuvant immunotherapy regimen” for stage III dMMR colon cancer and said the approval is the twelfth US indication for Tecentriq. The FDA granted the applications priority review.

Approval was based on the phase 3 ATOMIC trial (NCT02912559), which Genentech said was published in the New England Journal of Medicine. The multicenter, open-label trial included 711 adults and 1 pediatric patient with stage III dMMR colon cancer after complete resection of the primary tumor, with no evidence of residual lymph node involvement or metastatic disease. Patients were randomized 1:1 to atezolizumab plus mFOLFOX6 (oxaliplatin, leucovorin, and fluorouracil) for 12 cycles followed by 6 months of atezolizumab monotherapy, or to mFOLFOX6 alone for 12 cycles.

The hazard ratio for investigator-assessed disease-free survival (DFS), the major efficacy outcome, was 0.50 (95% CI, 0.35-0.73), and median DFS was not reached in either arm, according to the FDA. Genentech reported 36-month DFS rates of 86% with the combination and 76% with mFOLFOX6 alone. The company said safety findings aligned with those of earlier atezolizumab and mFOLFOX6 studies. The prescribing information includes warnings and precautions for immune-mediated adverse reactions, infusion-related reactions, complications of allogeneic hematopoietic stem cell transplantation, and embryo-fetal toxicity.

The recommended adult intravenous dose of atezolizumab is 840mg every 2 weeks, 1200mg every 3 weeks, or 1680mg every 4 weeks with chemotherapy for 6 months, followed by single-agent atezolizumab for 6 months or until disease recurrence or unacceptable toxicity. Atezolizumab and hyaluronidase-tqjs is given as one 15mL subcutaneous injection (1875mg atezolizumab and 30,000 units hyaluronidase) every 3 weeks, with the same 6-month combination and monotherapy phases.

Sources: US Food and Drug Administration. FDA approves atezolizumab in combination with chemotherapy for stage III mismatch repair deficient colon cancer. US Food and Drug Administration; October 8, 2026. Accessed October 9, 2026.

Genentech. FDA approves Genentech’s Tecentriq in combination with a fluoropyrimidine and oxaliplatin for the adjuvant treatment of a certain type of stage III colon cancer. Press release. Genentech; October 8, 2026. Accessed October 9, 2026.