Early studies showed that ICIs exhibit limited anticancer activity.347,348 It is currently accepted that the selection of patients with deficiency in MMR genes is important, because this subset of patients is potentially responsive to ICIs.345 The anti-PD1 antibody pembrolizumab is approved by the FDA to treat cancers, including PCa with MMR mutations or MSI.349 The responses of ICIs in MMR mutations or MSI PCa are not universal. Here, MRC1 is linked to cancer.