Checkpoint blockade provided new hope for patients with cancer refractory to classical strategies of treatment, since monotherapy with PD-1:PD-L1 inhibitors or in combination with anti-CTLA-4 had high response rates ranging 50–90% of patients with Hodgkin’s lymphoma and Merkel cell carcinoma, and ~40% for melanoma [101,102,103]. This evidence concerns the gene CTLA4 and cancer.