Fig. 1: Effective immune checkpoint inhibitor therapy correlates with the increased frequency of circulating CX3CR1⁺ CD8⁺ T cells.

a Experimental scheme of treatment with immune checkpoint inhibitors (ICI). b Individual tumor growth and survival curves in MC38 and CT26 tumor-bearing mice treated with isotype antibody (Ab) (NT) or anti-PD-L1 Ab and anti-CTLA-4 Ab (ICI). c, d Representative flow cytometry plots and data panel showing the frequency of CX3CR1⁺ cells among CD8⁺ T cells (c) and tetramer (Tet)⁺ CD8⁺ T cells (d) in peripheral blood (PB) of MC38 and CT26 tumor-bearing mice in different treatments as indicated. Numbers denote percent CX3CR1⁺ cells. The gating strategy is presented in Supplementary Fig. 1. PB was harvested 2 weeks after initiation of the treatment. n = 5 mice in all groups (b–d). e, f Frequency of the PB CX3CR1⁺ subset among CD8⁺ T cells (e), tumor growth curves (mean) and survival curves (f) in CT26-bearing mice in different treatment groups as indicated. n = 9 mice (NT), 6 mice (anti-CTLA-4 Ab), 6 mice (anti-PD-L1 Ab), and 5 mice (combo). g Frequency of the PB CX3CR1⁺ subset among CD8⁺ T cells in MC38 tumor-bearing mice treated with isotype control Ab (NT) or anti-PD-L1 Ab. n = 7 mice (NT) and 6 mice (anti-PD-L1 Ab). h Tumor growth curves (mean) and survival curves in MC38-bearing mice in different treatment groups as indicated. n = 5 mice in all groups. Data shown in b–h are representative of two independent experiments. PB was harvested 1 week after initiation of the treatment (e, g). Arrows indicate initiation of treatment (b, f, h). P-values were determined by a log-rank (Mantel–Cox) test (b, f, h), a two-tailed Mann–Whitney U-test (c, d, g) or Kruskal–Wallis with Dunn’s multiple comparisons (e). Data in f, h are presented as mean ± SEM. Box plots: dot, single PB; hinges, 25th and 75th percentiles; middle line, median; whiskers, minimum to maximum value (c–e, g). Source data are provided as a Source Data file.