Trial results for a Phase 3 study (NCT04008030) evaluating nivolumab, alone or in combination with ipilimumab, for deficient mismatch repair (dMMR)/microsatellite instability high (MSI-H) metastatic colorectal cancer (mCRC) were posted on ClinicalTrials.gov on 2025-09-22. The study demonstrated that nivolumab plus ipilimumab significantly improved progression-free survival (PFS) compared to investigator's choice chemotherapy in first-line participants, with a hazard ratio of 0.21 (p=0.0001).
Background
The study investigated treatment options for participants with deficient mismatch repair (dMMR) or microsatellite instability high (MSI-H) metastatic colorectal cancer (mCRC). The main purpose was to compare the clinical benefit of nivolumab in combination with ipilimumab or nivolumab monotherapy against each other and against chemotherapy in this patient population.
Trial design
The study (NCT04008030) was a Phase 3 trial that enrolled 839 participants with Metastatic Colorectal Cancer, specifically those with dMMR/MSI-H status. The study arms included nivolumab monotherapy (Arm A), nivolumab plus ipilimumab (Arm B), and investigator's choice chemotherapy (Arm C). Chemotherapy options included oxaliplatin, leucovorin, fluorouracil, and irinotecan. The study's main purpose was to compare Progression-Free Survival (PFS), Objective Response Rate (ORR), and Overall Survival (OS) among these treatment groups.
Key results
The trial results, as measured by Progression-free Survival (PFS) by Blinded Independent Review Center (BICR), showed notable differences across the treatment arms:
- For all randomized participants, the median PFS for nivolumab plus ipilimumab (Arm B) was 54.08 Months, compared to 18.43 Months for nivolumab monotherapy (Arm A). The hazard ratio (HR) for this comparison was 0.64 (95% Confidence Interval: 0.52 to 0.79).
- In first-line (1L) participants centrally confirmed MSI-H/dMMR, nivolumab plus ipilimumab (Arm B) demonstrated a significant PFS benefit compared to investigator's choice chemotherapy (Arm C). The median PFS for Arm C was 5.85 Months. The hazard ratio for Arm B versus Arm C was 0.21 (95% Confidence Interval: 0.14 to 0.32), with a p-value of 0.0001.
- For 1L randomized participants, nivolumab monotherapy (Arm A) showed a median PFS of 44.85 Months, while investigator's choice chemotherapy (Arm C) had a median PFS of 6.21 Months. The hazard ratio for Arm A versus Arm C was 0.6 (95% Confidence Interval: 0.45 to 0.8).
Further analyses included:
- A comparison of nivolumab plus ipilimumab (Arm B) versus nivolumab monotherapy (Arm A) for all lines centrally confirmed MSI-H/dMMR yielded a hazard ratio of 0.62 (95% Confidence Interval: 0.48 to 0.81) with a p-value of 0.0003. The median PFS for Arm A in this group was 39.26 Months.
What this means
The results from this Phase 3 study indicate that combination therapy with nivolumab plus ipilimumab significantly improves progression-free survival in patients with dMMR/MSI-H metastatic colorectal cancer, particularly when compared to standard chemotherapy in the first-line setting. The substantial hazard ratios and low p-values suggest a clinically meaningful benefit. Furthermore, nivolumab monotherapy also demonstrated an improvement over chemotherapy. These findings support the use of immunotherapy, especially the combination of nivolumab and ipilimumab, as an effective treatment strategy for this specific subtype of metastatic colorectal cancer.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for study NCT04008030, titled "A Study of Nivolumab, Nivolumab Plus Ipilimumab, or Investigator's Choice Chemotherapy for the Treatment of Participants With Deficient Mism," were posted on 2025-09-22 on clinicaltrials.gov.