A phase 2 trial at MD Anderson Cancer Center (Houston, TX) evaluated neoadjuvant pembrolizumab for localized unresectable or high-risk resectable MSI-H/dMMR solid tumors. The trial included 35 patients (27 with colorectal cancer). Among 33 evaluable patients, the best overall response rate was 82%. Among 17 (49%) of patients who underwent surgery, the pathologic complete response rate was 65%. The remaining 18 patients (51%) pursued nonoperative management with durable responses in the majority, suggesting that definitive nonsurgical management with the use of immunotherapy for MSI-H/dMMR tumors is a promising approach.
