PDCD1 and melanoma: They also reported that (1) regulatory T cell depletion enhances the capability of cDC2s to differentiate CD4+ T cells, ensuring the anti-tumor activities; and (2) intratumor cDC2s density positively correlates with abundant fully functional CD4+ T cells and with responsiveness to anti-PD-1 (programmed cell death protein-1) therapy in treating melanoma patients with low regulatory T cell abundance [62].