PDCD1 and metastatic melanoma: Immune checkpoints blockades targeting the interaction between programmed cell death protein 1 (PD‐1) and its ligand programmed death ligand 1 (PD‐L1; also known as B7‐H1 and CD274) have shown promising clinical effects in various malignancies including metastatic melanoma and nonsmall cell lung cancer (NSCLC).[1, 2, 3, 4, 5, 6] However, the overall response rate is less than 40% in general.[7, 8, 9] Recent studies have shown that the tumor PD‐L1 level was regarded as a predicting biomarker for assessing the clinical response to anti‐PD‐1/PD‐L1 therapy.