FDA approves Tecentriq, first adjuvant immunotherapy for stage III dMMR colon cancer

On October 8, 2026, FDA approved Tecentriq (atezolizumab) in combination with a fluoropyrimidine and oxaliplatin for the adjuvant treatment of adults and pediatric patients aged 2 years and older with stage III deficient DNA mismatch repair (dMMR) colon cancer. FDA also approved the subcutaneous formulation, Tecentriq Hybreza (atezolizumab and hyaluronidase-tqjs), for eligible patients aged 12 years and older who weigh at least 40 kg.

Checkpoint inhibitors are already approved for unresectable or metastatic dMMR or microsatellite instability-high colorectal cancer, but this is the first approval in the adjuvant setting, where the goal is to prevent recurrence after surgery. Despite surgery and adjuvant chemotherapy, nearly 30% of patients with stage III disease experience recurrence within five years.

The decision was supported by the phase 3 ATOMIC trial, which evaluated the addition of atezolizumab to modified fluorouracil, leucovorin, and oxaliplatin (mFOLFOX6) after surgical resection. Patients who received atezolizumab plus chemotherapy experienced a 50% reduction in the risk of disease recurrence or death compared with chemotherapy alone. At 36 months, 86% of patients treated with the combination were alive and disease-free, compared with 76% of those receiving chemotherapy alone. The trial population was almost entirely adult, with only one pediatric participant enrolled, limiting direct evidence in younger patients.

The safety profile was consistent with the known risks of atezolizumab and oxaliplatin-based chemotherapy. Common adverse reactions included fatigue, nausea, peripheral neuropathy, constipation, cough, dyspnea, fever, abdominal pain, diarrhea, decreased appetite, stomatitis, and altered taste. Important warnings include immune-mediated adverse reactions, infusion-related reactions, complications following allogeneic hematopoietic stem cell transplantation, and embryo-fetal toxicity.

“Until now, the adjuvant standard of care for stage III colon cancer has not differed based on mismatch repair status,” said Frank A. Sinicrope, MD, professor of oncology at the Mayo Clinic and US principal investigator for the Alliance ATOMIC trial. “This milestone represents an important therapeutic advance that leverages immunotherapy to target the specific biology of dMMR stage III colon cancer after surgical resection. By reducing the risk of disease recurrence or death by 50%, atezolizumab plus chemotherapy is a practice-changing regimen that can improve clinical outcomes of this group of patients living with colon cancer, one of the most common cancers and a leading cause of cancer-related death.”

Sources: FDA. (2026 Oct 08). FDA approves atezolizumab in combination with chemotherapy for Stage III mismatch repair deficient colon cancer; Genentech. (2026 Oct 08). 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