Neoadjuvant Immunotherapy for Microsatellite Instability–High, Locally Advanced Colon Cancer?

In small series of patients with locally advanced microsatellite instability–high (MSI-high) colorectal cancers treated with immune checkpoint inhibitors, whether single agents or combinations, high rates of clinical and pathologic complete response have been reported. Investigators now report results of the large NICHE-2 trial, an industry-supported, phase 2 trial treating 115 patients with MSI-high colon cancer, clinical stage II or III.

Patients received one dose of ipilimumab (1 mg/kg) and two doses of nivolumab (3 mg/kg; days 1 and 15), followed by surgical resection. Thirty-seven patients had hereditary Lynch syndrome. Most patients (68%) had right-sided primary tumors; disease was clinical stage T3/4a in 21%, stage T4a/T4b in 65%, and…