CTLA4 and colon adenocarcinoma: To further elucidate this mechanism, we evaluated CX3CR1 expression, a marker of T-cell differentiation in combination with CD27 29–31, on PB CD8+ T cells before and during treatment with anti-PD-L1 and anti-CTLA-4 Ab or isotype Ab (NT: no-treatment) in two mouse tumor models, MC38 and CT26 colon adenocarcinoma (Fig. 1a and Supplementary Fig. 1).