We then observed, through multivariate analyses performed on eight pooled cohorts including 190 samples of unresectable stage III and IV melanoma, that PD-L1 expression on peripheral blood CD4+ and CD8+ T cells is prognostic on overall survival (OS) and on progression-free survival (PFS), while in resected stage III melanoma, detectable CD137+CD8+ peripheral blood T cells predicted a lack of relapse with ipilimumab + nivolumab combination therapy. The gene discussed is CD8A; the disease is melanoma.