CD4 and neoplasm: To understand which pathways drive immune suppression and limit T cell activity beyond CTLA-4, we examined expression of the inhibitory markers PD-1, Tim-3, Lag-3, KLRG-1, and CTLA-4 in spleen- (Supplemental Figure 7A) and tumor-infiltrating CD8+ and CD4+ (Supplemental Figure 7B) Teffs at day 21.