Trial results for atezolizumab in combination with chemotherapy for patients with Stage III Colon Cancer and deficient DNA mismatch repair (dMMR) were posted on ClinicalTrials.gov on 2026-04-14. The study demonstrated that the combination arm achieved 86.3% disease-free survival compared to 76.2% for chemotherapy alone, with a hazard ratio of 0.5.
Background
The Phase 3 trial investigated atezolizumab in combination with standard chemotherapy for patients diagnosed with Stage III Colon Cancer and deficient DNA mismatch repair (dMMR). Atezolizumab is an immunotherapy, while the chemotherapy regimen included oxaliplatin, leucovorin calcium, and fluorouracil. This specific patient population often involves conditions like Colon Adenocarcinoma and Lynch Syndrome, which are associated with DNA Repair Disorder.
Trial design
The study, NCT02912559, was a Phase 3 trial that enrolled 712 participants. It evaluated the efficacy of combination chemotherapy with or without atezolizumab in treating patients with Stage III Colon Cancer and deficient DNA mismatch repair. The conditions studied included Colon Adenocarcinoma, DNA Repair Disorder, and Lynch Syndrome. Participants were randomized into two arms: Arm I received combination chemotherapy with atezolizumab, and Arm II received combination chemotherapy alone.
Key results
The trial results showed differences between the treatment arms for disease-free survival and overall survival, as well as adverse events:
- For Disease Free Survival (DFS), the percentage of participants in Arm I (Combination Chemotherapy, Atezolizumab) was 86.3%. In comparison, Arm II (Combination Chemotherapy) showed 76.2%.
- An analysis using the Stratified Log Rank method yielded a Hazard Ratio (HR) of 0.5 (95.0% CI: 0.35 to 0.73) with a p-value of 0.0002.
- For Overall Survival, Arm I (Combination Chemotherapy, Atezolizumab) reported 89.7% of participants, while Arm II (Combination Chemotherapy) reported 87.9%.
- The Hazard Ratio (HR) for Overall Survival was 0.9 (95.0% CI: 0.55 to 1.47) with a p-value of 0.6787.
- Regarding Adverse Events, 291 participants in Arm I (Combination Chemotherapy, Atezolizumab) experienced adverse events, compared to 240 participants in Arm II (Combination Chemotherapy).
What this means
The results suggest that adding atezolizumab to combination chemotherapy significantly improves disease-free survival for patients with Stage III Colon Cancer and deficient DNA mismatch repair. The notable difference in DFS percentages and the statistically significant hazard ratio for DFS indicate a potential benefit for this patient population. While overall survival showed a numerical difference, it was not statistically significant. The observed increase in the number of patients experiencing adverse events in the atezolizumab arm warrants consideration in clinical decision-making.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for study NCT02912559, titled "Combination Chemotherapy With or Without Atezolizumab in Treating Patients With Stage III Colon Cancer and Deficient DNA Mismatch Repair," were posted on 2026-04-14 on clinicaltrials.gov.