Immune checkpoint inhibitors are currently considered to provide clinical benefits to cancer patients with DNA mismatch repair-deficient (dMMR) or microsatellite instability-high (MSI-H). In a phase 2 trial (CheckMate 142), 74 recurrent or metastatic colorectal cancer patients were enrolled from 31 sites. The cancers were histologically confirmed and dMMR/MSI-H were locally assessed. Patients received 3 mg/kg nivolumab every two weeks until disease progression or experiencing unacceptable toxicity. Upon data collection, 23 (31.1%) achieved an investigator-assessed objective response and 51 (69%) patients had disease control for 12 weeks or longer. Median progression-free survival was 14.3 months, and median overall survival has not yet reached. Further analyses showed that biomarkers of colorectal cancer (BRAF or KRAS mutation), PD-L1 expression or the history of Lynch syndrome did not predict response to nivolumab. 15 patients (20%) experienced grade 3 or 4 drug-related adverse events, the most common events were increased concentrations of lipase (6 patients [8%]) and amylase (2 patients [3%]). Based on these results, FDA approved nivolumab for metastatic colorectal cancers with dMMR/MSI-H.
Overman MJ, McDermott R, Leach JL, et al., Lancet Oncol. 2017