CD274 and neoplasm: Several biomarkers have been studied in metastatic melanoma such as clinical endpoints (tumor burden and metastatic sites), blood markers (serum lactate dehydrogenase (LDH), neutrophils, monocytes, and lymphocytes levels), stool (gut microbiome), tumor tissue markers (mutational analysis, tumor infiltrating lymphocytes, PD-L1, interferon-γ), and imaging biomarkers [59].