Neoadjuvant immunotherapy in primary and metastatic colorectal cancer.

Immunotherapy has proven to be highly effective as first-line treatment of metastatic colorectal cancer (CRC). Further, immune checkpoint blockade by the programmed cell death 1 (PD-1) receptor inhibitors nivolumab and pembrolizumab and the cytotoxic T cell-associated protein 4 (CTLA-4) inhibitor ipilimumab has provided very good results in both early-stage and advanced CRC. The high response rate in dMMR in operable colon cancers by preoperative use of double nivolumab and ipilimumab therapy warrants further investigation into its impact on long-term overall survival. Hence, immunotherapy has emerged as a neoadjuvant approach, possibly changing treatment strategy for both primary resectable and metastatic CRC. Larger phase III trials are needed to evaluate overall effects on survival.