Double regimen therapy does not result in substantially increased frequency of tumor-reactive T cells at early time points in the periphery. A-B. Peptide/Kb pentamer staining was performed on gated CD3+CD8+ T cells, isolated from TdLN (A) or spleen (B) on day 7. Shown are means +/− SEM of a total of 10 mice collected from two experiments. For statistical analysis, Mann–Whitney-U test was performed comparing single treatments to double treatments (* = 0.0317 αCTLA-4 to αCTLA-4 + αPD-L1 in spleen). None of the other treatments was significantly different to the no treatment control. C. IFN-γ ELISpot was performed on splenocytes collected on day 7. Data are shown as mean +/− SEM from 10 mice out of two experiments with no stimulation as open bar and SIY-specific stimulation as filled bar. The Mann–Whitney-U test was used to assess significant differences between the no treatment group and treatment regimens with * in the figure indicating significant difference compared to no treatment. Results with αCTLA-4 were significantly different to αCTLA-4 + IDOi (p = 0.0185) and αPD-L1 was significantly different to αCTLA-4 + αPD-L1 (p = 0.0172).