PD-1 antibodies (pembrolizumab and nivolumab) were approved by the Food and Drug Administration (FDA) for second-line treatment of dMMR/MSI-H CRC in 2017.4 Nevertheless, the prevailing view was that the monotherapy (eg, pembrolizumab) was ineffective for pMMR/MSS CRC patients before 2020.5 In these tumors, lack of immune cell infiltration and low tumor mutation burden (TMB) have been suggested as mechanisms of immune resistance.4 Therefore, to overcome these problems, several new combinatorial regimens in pMMR/MSS CRC are ongoing. The gene discussed is PDCD1; the disease is neoplasm.