Relevant electronic literature search was conducted in academic databases PubMed, MEDLINE and Google scholar by the author using the search terms “anti-PD-1”, “anti-PD-L1”, “immune checkpoint inhibitor”, “response”, “predicators”, “colorectal cancer”, “metastasis”, “dMMR”, “pMMR” and “MSI” from inception to September 2020. Here, CD274 is linked to colorectal cancer.