CD8A and neoplasm: Currently, multiple potential factors have been identified for predicting the clinical outcome of immunotherapy, including the tumor mutation burden (TMB) [51], MSI status [7], neoepitope load [52–55], PD-L1 level [55], CD8+ T-cell density [56], interferon-γ gene signature [57], and MHC and T-cell receptor repertoire [58, 59].