CTLA4 and neoplasm: Low peripheral lymphocyte counts, as captured by a reduced PNI, may reflect systemic immunosuppression or immune exhaustion—both of which are associated with poor infiltration of tumor-infiltrating lymphocytes (TILs), reduced effector cytokine production, and increased expression of inhibitory receptors such as PD-1 and CTLA-4 (40, 53, 55).