In line with this latter study, and clinical observations showing that anti-CTLA-4 treatment expands immunosuppressive Tregs in blood and tumors of prostate, melanoma, and bladder cancer patients30,31, we did not observe Treg-depletion upon anti-PD-1/anti-CTLA-4 therapy but rather found strong accumulation and increased proliferation of Tregs. Here, CTLA4 is linked to melanoma.