Primary completion for a Phase 3 study evaluating atezolizumab in combination with chemotherapy for Stage III colon cancer with deficient DNA mismatch repair was reported on 2025-02-04. The trial showed that the atezolizumab combination arm achieved a disease-free survival (DFS) of 86.3%, compared to 76.2% for chemotherapy alone, with a hazard ratio of 0.5.
Background
The study investigated atezolizumab in patients with Stage III colon cancer and deficient DNA mismatch repair (dMMR), including those with Lynch Syndrome or Colon Adenocarcinoma. The trial aimed to assess the benefit of adding atezolizumab to standard combination chemotherapy.
Trial design
The Phase 3 study (NCT02912559) enrolled 712 participants with Stage III colon cancer and deficient DNA mismatch repair. The trial compared combination chemotherapy with or without atezolizumab. The chemotherapy regimen included fluorouracil, leucovorin calcium, and oxaliplatin, with the aim of evaluating if adding atezolizumab improved outcomes compared to chemotherapy alone.
Key results
The trial reported the following key results:
- Disease Free Survival (DFS) in the Arm I (Combination Chemotherapy, Atezolizumab) group was 86.3% of participants.
- Disease Free Survival (DFS) in the Arm II (Combination Chemotherapy) group was 76.2% of participants.
An analysis for Disease Free Survival showed a Hazard Ratio (HR) of 0.5 (95% Confidence Interval: 0.35-0.73) with a p-value of 0.0002, using the Stratified Log Rank method.
- Overall Survival in the Arm I (Combination Chemotherapy, Atezolizumab) group was 89.7% of participants.
- Overall Survival in the Arm II (Combination Chemotherapy) group was 87.9% of participants.
An analysis for Overall Survival showed a Hazard Ratio (HR) of 0.9 (95% Confidence Interval: 0.55-1.47) with a p-value of 0.6787, using the Stratified Log Rank method.
- 291 participants in the Arm I (Combination Chemotherapy, Atezolizumab) group experienced adverse events.
- 240 participants in the Arm II (Combination Chemotherapy) group experienced adverse events.
What this means
The primary completion of this Phase 3 study suggests that adding atezolizumab to combination chemotherapy significantly improves disease-free survival in patients with Stage III colon cancer and deficient DNA mismatch repair. With a DFS of 86.3% in the atezolizumab arm compared to 76.2% in the chemotherapy-alone arm, and a statistically significant Hazard Ratio of 0.5 (p=0.0002), these results indicate a substantial benefit. While overall survival showed a numerical increase in the atezolizumab arm (89.7% vs 87.9%), this difference was not statistically significant (p=0.6787). The safety profile indicates a higher number of participants experiencing adverse events in the combination arm (291 vs 240), which warrants further detailed analysis of specific adverse event types and severity.
Source
The information regarding this trial's primary completion and results was obtained from ClinicalTrials.gov, a public database of clinical studies. The data for the study NCT02912559, titled "Combination Chemotherapy With or Without Atezolizumab in Treating Patients With Stage III Colon Cancer and Deficient DNA Mismatch Repair", was updated on 2025-02-04 on clinicaltrials.gov.