Recently, the effectiveness of the PD-1 drug pembrolizumab was tested in patients with advanced metastasis in a phase II clinical trial; the objective response rate and non-progressive stage in the MMR colorectal cancer group were as high as 40 and 78%, while in the control group, they were 0 and 11%, respectively (Lee and Le, 2015). This evidence concerns the gene PDCD1 and colorectal cancer.