PDCD1 and cancer: It was the first anti-PD-1 agent to be approved by the FDA, being nowadays used to treat some cancer types where cells express PD-L1, including advanced melanoma, advanced non-small cell lung cancer (NSCLC), recurrent or metastatic head and neck squamous cell carcinoma, classical Hodgkin lymphoma (cHL), and counting, the list being increasing with the release of new clinical trials24.