a, LLC tumor volumes (at day 18 after implantation) in mice treated with anti-PD-1 (days 7, 11 and 15; n = 8 mice), STS (days 6–8, 10–12 and 14–15; n = 5 mice), their combination (n = 7 mice) or vehicle (control; n = 8 mice). b, Flow cytometric quantification of tumor-infiltrating CD8 (left) and Treg cells (middle) and their ratio (right) from the experiment shown in a. Data are expressed as the percentage of total leukocytes (CD45), except for Treg cells, which are expressed as the percentage of total CD4 T cells. c, Flow cytometric analysis of the expression of PD-1, expressed as the mean fluorescence intensity (MFI), in tumor-infiltrating CD8 T cells in all tumors from the experiment shown in a, except for a tumor from a mouse in the STS group that was lost during sample processing. Data are expressed as means ± s.e.m. Statistical significance was determined by two-sided Kruskal–Wallis test with post hoc Mann–Whitney U-test. Numerical source data are provided as a source data file.