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Soo Park, MD
Soo Park, MD
Posted: Thursday, July 24, 2025
In the phase I/II CheckMate 358 trial, both nivolumab alone and in combination with ipilimumab showed frequent and durable responses in patients with immune checkpoint inhibitor (ICI)–naive recurrent or metastatic Merkel cell carcinoma (MCC). However, with a median duration of response of 25.9 months in the nivolumab plus ipilimumab cohort vs 60.6 months with nivolumab alone, the combination did not demonstrate improved efficacy, contradicting previous reports. Shailender Bhatia, MD, and colleagues reported these results in the Journal of Clinical Oncology,
The 68 patients enrolled in the study received either nivolumab monotherapy (n = 25) or nivolumab plus ipilimumab (n = 43). Patients in both cohorts were ICI-naive and had received up to two prior systemic therapies. The median progression-free survival was 21.3 months with nivolumab alone vs 8.4 months with the combination. The median overall survival was also longer in the nivolumab arm than the combination arm (80.7 vs 29.8 months). Adverse events were more frequent and severe with nivolumab plus ipilimumab, with grade 3 or 4 treatment-related adverse events occurring in 47% of patients in the combination arm vs 28% of those treated with nivolumab alone.
The authors concluded: “In summary, our nonrandomized CheckMate 358 study shows that both nivolumab monotherapy and the combination of nivolumab and ipilimumab are associated with frequent and durable responses in patients with ICI-naive recurrent/metastatic MCC. However, the results do not suggest additional efficacy from combining ipilimumab with nivolumab in treating advanced MCC.”
For more definitive results, the authors argue that a randomized trial of nivolumab plus ipilimumab vs nivolumab monotherapy is warranted.
Disclosure: For full disclosures of the study authors, visit ascopubs.org.
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