RCT: Nivolumab Plus Ipilimumab Extends Progression-Free Survival in MSI-H or dMMR Metastatic Colorectal Cancer
4 Dec, 2024 | 11:51h | UTCBackground: Patients with microsatellite-instability–high (MSI-H) or mismatch-repair–deficient (dMMR) metastatic colorectal cancer typically experience poor outcomes with standard chemotherapy. Previous nonrandomized studies suggested that combining nivolumab with ipilimumab may offer clinical benefits in this population.
Objective: To evaluate the efficacy and safety of nivolumab plus ipilimumab compared with chemotherapy in patients with MSI-H or dMMR metastatic colorectal cancer who had not received prior systemic treatment for metastatic disease.
Methods: In this phase 3, open-label, randomized trial, 303 patients with unresectable or metastatic MSI-H or dMMR colorectal cancer were assigned in a 2:2:1 ratio to receive nivolumab plus ipilimumab, nivolumab alone, or chemotherapy with or without targeted therapies. The primary endpoint assessed in this interim analysis was progression-free survival (PFS) of nivolumab plus ipilimumab versus chemotherapy in patients with centrally confirmed MSI-H or dMMR status.
Results: At a median follow-up of 31.5 months, nivolumab plus ipilimumab significantly improved PFS compared to chemotherapy (P<0.001). The 24-month PFS was 72% (95% CI, 64–79) with nivolumab plus ipilimumab versus 14% (95% CI, 6–25) with chemotherapy. The restricted mean survival time at 24 months was 10.6 months longer with the combination therapy. Grade 3 or 4 treatment-related adverse events occurred in 23% of patients receiving nivolumab plus ipilimumab and 48% of those receiving chemotherapy.
Conclusions: First-line treatment with nivolumab plus ipilimumab significantly prolonged progression-free survival compared to chemotherapy in patients with MSI-H or dMMR metastatic colorectal cancer, with a lower incidence of high-grade treatment-related adverse events.
Implications for Practice: The combination of nivolumab and ipilimumab may represent a new standard of care for first-line treatment in MSI-H or dMMR metastatic colorectal cancer. However, clinicians should weigh the benefits against potential immune-related adverse events, and long-term survival benefits remain to be fully established.
Study Strengths and Limitations: Strengths include the randomized, phase 3 design and central confirmation of MSI-H or dMMR status. Limitations involve the open-label design, potential bias in patient-reported outcomes, underrepresentation of certain populations, and immature overall survival data.
Future Research: Further studies are needed to compare nivolumab plus ipilimumab directly with nivolumab monotherapy and to assess long-term overall survival benefits and quality of life in diverse patient populations.