We found that, in all three cohorts, ARRB1 expression was significantly higher in the non-responder group than in the responder group of the PD1 blockade cohort in metastatic melanoma; however, no significant difference in ARRB1 expression was detected between the responder and non-responder groups of the nivolumab treatment of renal cell carcinoma and atezolizumab intervention in advanced urothelial carcinoma cohorts (Figure 8B). This evidence concerns the gene PDCD1 and metastatic melanoma.