CD8A and neoplasm: Key resistance mechanisms included the following: (1) impaired antigen presentation (downregulation of MHC-I and TAP1) that hindered tumor antigen recognition and (2) immunosuppressive TME remodeling characterized by reduced CD8+ T-cell infiltration, elevated Treg proportions, and diminished expression of cytotoxic markers IFN-γ and GZMB.