CD8A and melanoma: In addition, we analyzed Treg levels in the tumor as the effector CD8/regulatory T cell ratios are known to be a potent prognostic factor for the efficacy of immunotherapies in melanoma.25, 26, 42, 43, 44 Notably, the DCVacc/VSV‐GP treatment did not influence the numbers of Tregs in the tumor, but the VSV‐GP related lymphocyte infiltration, mainly with activated virus‐specific CD8 T cells, drastically increased the effector T cell/Treg ratios.