COMMIT Phase 3: While Atezolizumab and Bevacizumab Combination Improved PFS by 4.6-Fold, No OS Benefit Observed
Background and Design of the COMMIT Study
The COMMIT (NRG-GI004/SWOG-S1610) study was a Phase 3, randomized controlled trial evaluating the efficacy of atezolizumab (Tecentriq, anti-PD-L1) and bevacizumab (Avastin, anti-VEGF) in combination with mFOLFOX6 chemotherapy as a first-line treatment for patients with metastatic colorectal cancer (mCRC) with DNA mismatch repair deficiency (dMMR) or high microsatellite instability (MSI-H). The study compared the combination arm to an atezolizumab monotherapy arm. Originally, the study aimed to enroll 211 patients; however, due to slow enrollment, the target was reduced to 100 patients, and ultimately, 82 patients (41 in each arm) were randomized. Following the release of the Merck (MRK) KEYNOTE-177 results, the third arm, consisting of mFOLFOX6/bevacizumab monotherapy, was discontinued after 20 patients were enrolled.
Key Efficacy Data
With a median follow-up of 3.5 years, the median progression-free survival (PFS) was 24.5 months in the combination arm compared to 5.3 months in the monotherapy arm, resulting in a hazard ratio (HR) of 0.439 (95% CI 0.23-0.84, P=0.0103). This indicates that the combination therapy reduced the risk of progression or death by 56.1%. The objective response rate (ORR) was 86.1% (36.1% complete response rate) in the combination arm and 46.0% (18.9% complete response rate) in the monotherapy arm, representing a difference of approximately 2-fold. The 12-month disease control rate (DCR) was also higher in the combination arm (64.7%) compared to the monotherapy arm (32.4%). These results demonstrate that the combination of chemotherapy and anti-angiogenic therapy significantly enhances the initial efficacy of immune checkpoint inhibitors in terms of PFS and response rate.
Overall Survival and Safety Profile
The 24-month overall survival (OS) was 67% in both arms, with an HR of 1.04 (P=0.90), indicating no significant difference in OS between the two groups. In terms of safety, the incidence of Grade 3 or higher adverse events was approximately 2-fold higher in the combination arm (82.9%) compared to the monotherapy arm (43.9%). The most common Grade 3-4 adverse events in the combination arm were neutropenia (26.8%), infection (26.8%), and hypertension (19.5%). Grade 5 (fatal) adverse events occurred in 4 patients in the combination arm (including 2 cases of sudden death and 1 case of hepatic hemorrhage) and 1 patient in the monotherapy arm. While the combination therapy showed improved PFS, the lack of OS benefit and increased toxicity raise concerns about the risk-benefit profile.
Trial Termination and Shifting Competitive Landscape
The study was discontinued on March 31, 2025, and following the release of the Bristol-Myers Squibb (BMY) CheckMate 8HW results – nivolumab (Opdivo) and ipilimumab (Yervoy) combination with a median PFS of 54.1 months and an HR of 0.21 compared to chemotherapy – the Data Monitoring Committee decided to permanently terminate the study on July 2025. Currently, the standard of care for first-line treatment of dMMR/MSI-H mCRC is Merck's pembrolizumab (Keytruda, based on KEYNOTE-177, with a 5-year OS rate of 55%, FDA approved in June 2020) and BMS's nivolumab and ipilimumab (FDA approved in April 2025). The small cohort size of 82 patients in the COMMIT study and the lack of OS benefit make it unlikely that the results will be used to support regulatory approval or establish a standard of care for Roche's atezolizumab combination in this indication. Furthermore, the study failed to differentiate from competitors that have demonstrated superior outcomes with immune checkpoint inhibitors alone or in combination without the added toxicity of chemotherapy. However, Roche has secured FDA priority review for the ATOMIC trial in the adjuvant setting (Stage III dMMR colorectal cancer, 3-year DFS of 86.4% vs. 76.6%, HR 0.50), with a PDUFA date of October 9, 2026. In the colorectal cancer treatment market (USD 9.38 billion in 2025, projected to reach USD 12.8 billion in 2032), the dMMR/MSI-H segment (5-10% of all colorectal cancers), the growth driver for Tecentriq (CHF 1.7 billion in sales in the first half of 2025) will depend more on expansion in the adjuvant setting and subcutaneous administration (Tecentriq Hybreza) than on first-line treatment of metastatic disease.
In the first-line treatment market for dMMR/MSI-H mCRC, Roche's (RHHBY) atezolizumab triple combination faces limitations in regulatory approval and establishing a standard of care due to the lack of OS benefit (24-month OS of 67% in both arms) and high toxicity (Grade 3+ adverse events in 82.9%), despite a PFS HR of 0.439. With BMS's CheckMate 8HW (nivolumab + ipilimumab, median PFS of 54.1 months) and Merck's KEYNOTE-177 (pembrolizumab, 5-year OS rate of 55%, median OS of 77.5 months) establishing themselves as the standard of care without chemotherapy, the COMMIT study, with its small cohort of 82 patients, has effectively closed the door on the possibility of expanding atezolizumab in this indication. However, Roche has secured FDA priority review for the ATOMIC trial in the adjuvant setting (Stage III dMMR colorectal cancer, 3-year DFS of 86.4% vs. 76.6%, HR 0.50), with a PDUFA date of October 9, 2026. In the colorectal cancer treatment market (USD 9.38 billion in 2025, projected to reach USD 12.8 billion in 2032), the dMMR/MSI-H segment (5-10% of all colorectal cancers), the growth driver for Tecentriq (CHF 1.7 billion in sales in the first half of 2025) will depend more on expansion in the adjuvant setting and subcutaneous administration (Tecentriq Hybreza) than on first-line treatment of metastatic disease.
Source: ClinicalTrials.gov (api_ct)