PDCD1 and melanoma: In light of these observations, new therapeutic strategies targeting ADO-mediated immunosuppression via CD73 and A2a receptor have been designed and entered phase I clinical trials as monotherapy or in combination with PD-1/PD-L1 inhibition in several solid tumors, including Nonsmall-cell lung carcinoma (NSCLC), melanoma, renal cell carcinoma [89,90].