A recent clinical trial is offering hope for people living with a specific type of metastatic colorectal cancer (mCRC). Researchers found that combining immunotherapy with chemotherapy and targeted therapy may help patients live longer without their cancer growing or spreading compared to immunotherapy alone.
The findings come from the phase III COMMIT trial, which was presented at the 2026 American Society of Clinical Oncology Gastrointestinal Cancers Symposium and co-led by researchers at the University of Texas MD Anderson Cancer Center.
What is dMMR/MSI-H colorectal cancer?
Not all colorectal cancers (CRCs) behave the same way. Some tumors are classified as deficient mismatch repair (dMMR) or microsatellite instability-high (MSI-H). These cancers have trouble repairing damaged DNA, which leads to a high number of mutations.
Because of these mutations, dMMR/MSI-H tumors are often easier for the immune system to recognize. This is one reason why immunotherapy has become an important treatment option for these patients.
What was the COMMIT trial?
The COMMIT trial was a phase III clinical study designed to test better first-line treatment options for patients with previously untreated dMMR/MSI-H mCRC.
Researchers compared different treatment approaches using the immunotherapy drug atezolizumab, which works by blocking the PD-L1 protein and helping the immune system attack cancer cells.
Participants in the study were initially assigned to one of three treatment groups:
- Atezolizumab alone
- Atezolizumab combined with chemotherapy (mFOLFOX6) and the targeted therapy bevacizumab
- Chemotherapy (mFOLFOX6) plus bevacizumab alone
The chemotherapy-only arm was stopped early, and researchers focused primarily on comparing immunotherapy alone versus the combination approach.
What did the study find?
The results were encouraging for patients who received the combination treatment.
Patients treated with atezolizumab plus chemotherapy and bevacizumab had a median progression-free survival of 30 months. In comparison, patients who received atezolizumab alone had a median progression-free survival of 4.3 months.
Progression-free survival refers to how long patients live without their cancer worsening.
Researchers also found that the combination therapy reduced the risk of disease progression or death by more than half compared to immunotherapy alone.
In addition:
- The overall response rate was 80.6% with combination therapy compared to 46% with atezolizumab alone
- At 12 months, disease control rates were 62.9% for the combination group compared to 32.4% for immunotherapy alone
According to senior study author Michael Overman, “These trial results suggest this treatment strategy could be an important advance in first-line care for dMMR metastatic colorectal cancer. It reinforces the value of exploring combination approaches to unlock deeper and more durable responses.”
Why are these findings important?
Immunotherapy alone has already changed treatment for many patients with dMMR/MSI-H CRC. However, researchers have continued exploring whether combining immunotherapy with other treatments could improve outcomes even further.
This study suggests that adding chemotherapy and bevacizumab to immunotherapy may help some patients achieve longer-lasting disease control.
While the results are promising, researchers will continue following patients to better understand long-term outcomes, including:
- Overall survival
- Quality of life
- Side effects and treatment tolerability
These additional findings will help doctors better understand which patients may benefit most from combination therapy.
What should patients know?
If you or a loved one has mCRC, biomarker testing is important. Testing for dMMR or MSI-H status can help determine whether immunotherapy may be an effective treatment option.
The COMMIT trial highlights how treatment for CRC continues to evolve toward more personalized care based on the biology of each patient’s tumor.
Patients interested in learning more about treatment options or clinical trials should speak with their oncology care team.
Connect with an Outcomes4Me oncology nurse practitioner at no charge through the Outcomes4Me app, using the “Ask Outcomes4Me” button.
