PDCD1LG2 and neoplasm: Currently, many candidate biomarkers, including the platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR), PD-L1 and PD-L2 expression, human papilloma virus (HPV) expression, tumor-infiltrating lymphocyte (TIL) count, and tumor mutational burden (TMB), are being investigated in HNSCC patients [8–10].