On October 8, 2026, the U.S. Food and Drug Administration (FDA) approved adjuvant atezolizumab (Tecentriq, Genentech, Inc.) in combination with a fluoropyrimidine and oxaliplatin among patients two years of age and older with completely resected Stage III mismatch repair deficient (dMMR) colon cancer. The FDA simultaneously approved the subcutaneous (SC) formulation, atezolizumab and hyaluronidase-tqjs (Tecentriq Hybreza, Genentech, Inc.), for the same indication in adult and pediatric patients 12 years of age and older, weighing at least 40 kg.
The approvals were supported by data from the ATOMIC trial, in which the addition of atezolizumab to mFOLFOX6 chemotherapy reduced the risk for disease recurrence or death by half compared with chemotherapy alone in patients with Stage III dMMR colon cancer. Median disease-free survival (DFS) was not reached (NR) in either treatment arm, limiting the ability to characterize the absolute magnitude of benefit at this stage of follow-up.
Key finding
In the ATOMIC trial, adjuvant atezolizumab plus mFOLFOX6 reduced the risk for disease recurrence or death by 50% versus mFOLFOX6 alone in Stage III dMMR colon cancer (HR 0.50; 95% CI: 0.35–0.73; p=0.0001). However, median DFS was NR in either arm, indicating that longer-term follow-up is needed to define the absolute DFS benefit of adjuvant atezolizumab.
Study Design
| Trial | ATOMIC/ML39057 (NCT02912559); multicenter, randomized, open-label, active-controlled |
|---|---|
| Population | 711 adults and one 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 |
| Treatment | Atezolizumab plus mFOLFOX6 (oxaliplatin, leucovorin, and fluorouracil) for 12 cycles followed by atezolizumab monotherapy for 6 months vs. mFOLFOX6 alone for 12 cycles (1:1 randomization) |
| Primary endpoint | Investigator-assessed DFS |
The trial enrolled patients following complete surgical resection, reflecting a purely adjuvant setting. The FDA announcement did not report key secondary trial endpoints.
Results and Safety
The primary endpoint of investigator-assessed DFS favored the atezolizumab combination arm, with a HR of 0.50 (95% CI: 0.35, 0.73; p=0.0001). Median DFS was NR in either treatment arm. No additional efficacy data, including overall survival (OS) results or subgroup analyses, were reported.
The atezolizumab 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. Specific rates of individual adverse events from the ATOMIC trial were not reported in the approval announcement.
Clinical Context
This approval establishes atezolizumab plus fluoropyrimidine-oxaliplatin chemotherapy as an adjuvant option specifically for the dMMR subset of Stage III colon cancer, a molecularly defined population known to derive benefit from immune checkpoint inhibition. The indication extends to pediatric patients as young as two years of age for the intravenous formulation, an inclusion that is uncommon in checkpoint inhibitor approvals, and in this case, was based off of a single pediatric patient enrolled in ATOMIC.
The review was conducted under FDA’s Project Orbis framework in collaboration with the Australian Therapeutic Goods Administration, Health Canada, Israel’s Ministry of Health, and Switzerland’s Swissmedic, with reviews ongoing at those agencies at the time of the FDA action. Because median DFS has not been reached in either arm, the durability of the observed benefit and its translation into any OS advantage must be established with longer follow-up.
Sources
- U.S. Food and Drug Administration. “FDA Approves Atezolizumab in Combination with Chemotherapy for Stage III Mismatch Repair Deficient Colon Cancer.” Drug approval announcement. October 8, 2026. View source.
