PDCD1 and non-small cell lung carcinoma: Recently, the US Food and Drug Administration (FDA) approved the use of four anti-PD-1/PD-L1 drugs, including pembrolizumab, nivolumab, atezolizumab, and durvalumab, for the treatment of NSCLC, according to different corresponding immunohistochemical assays as companion or complementary diagnostic tests.