Several biomarkers have been investigated including PD-L1 tumor expression, tumor mutational burden (TMB), human leukocyte antigen (HLA) class I and II expression, β2-microglobulin (β2m) mutations, tumor microenvironment (TME) composition, gene expression profiles (GEPs) and gut microbiome composition [28–31]. The gene discussed is B2M; the disease is neoplasm.