Pathological Complete Response to Liver Metastasis With Pembrolizumab in a Previously Treated Patient With Microsatellite Instability-high Colorectal Cancer

Immune checkpoint inhibitors are effective in treating microsatellite instability-high (MSI-H) metastatic colorectal cancer (CRC). Pathological complete response to immune checkpoint inhibitors for MSI-H metastatic CRC have been described in several reports. Liver metastasis is known to predict resistance to ani-programmed death 1 (PD-1)/PD-1 ligand 1 (PD-L1) therapy in several cancers, including CRC.