The SILhigh ICI-resistant melanomas also had similar densities of intratumoral CD3+CD8+ cytotoxic T cells and higher densities of peritumoral CD3+CD8+ T cells (median = 1250 vs 623 cells/mm2, P = 0.20) and CD3+PD1+ T cells (median = 508 vs 88.4 cells/mm2, P = 0.036) compared to the ICI non-resistant group (Fig. 3h, Supplementary Fig. 5a, b), indicating potential antitumor immune response that was hindered by suppressive Treg enrichment. Here, PDCD1 is linked to melanoma.