Nivolumab and pembrolizumab of PD-1 inhibitors, and ipilimumab of CTLA-4 inhibitors are approved by FDA in 2014 as cancer immunotherapeutic agents 14, 15; and nivolumab and ipilimumab are the most widely used ICIs in the treatment of advanced MM, either alone or in combination 16. This evidence concerns the gene PDCD1 and cancer.