Combination or Single-Agent Immune Checkpoint Inhibition in MSI-High/dMMR Metastatic Colorectal Cancer?

For patients with microsatellite instability (MSI)-high/mismatch repair protein-deficient (dMMR) metastatic colorectal cancer, first-line treatment with the immune checkpoint inhibitors pembrolizumab or nivolumab is superior to chemotherapy (NEJM JW Oncol Hematol Dec 3 2020 and N Engl J Med 2020; 383:2207). The role of dual-targeted versus single-agent immune checkpoint inhibition in these patients, however, remained an unanswered question.

Investigators now report results of the industry-sponsored, open-label, randomized CheckMate 8HW trial comparing single-agent nivolumab with the combination of ipilimumab and nivolumab. The primary endpoint was progression-free survival (PFS) in patients who had centrally confirmed dMMR/MSI-high metastati…