Correlations of the prevalence of immune cell subsets with disease outcomes in metastatic melanoma patients after anti-PD-1 therapy have been consistently reported for CD8+ T cells [4,13,15,16,17,18] and found in some studies for other immune cell markers, including CD45RO and FOXP3 [13], PD-1, PD-L1 [4,13], and CD103 [37]. The gene discussed is FOXP3; the disease is metastatic melanoma.