Pairwise combinations of αCTLA-4, αPD-L1 or IDOi blockade results in retarded tumor outgrowth. A. Schema of experimental design illustrating the time points of drug administration throughout the experiment. αCTLA-4 was administered on day 4, 7, 10 i.p., αPD-L1 on days 4, 6, 8, 10, 12, 14, 16 i.p. and IDOi was given on a 5 day/2 day off regimen via oral gavage Monday-Friday. B-D. Tumor outgrowth measured in mm2 comparing the single treatment to the respective combined double treatment of B. αCTLA-4 and αPD-L1 C. αCTLA-4 and IDOi and D. αPD-L1 and IDOi (pool of 3 experiments). Depicted are means +/− SEM of 6 mice from one representative experiment. All experiments were at least done three times with the same overall result. Numbers next to curves indicate # of survivors/total number of mice for all experiments done. Significance to the single treatments was tested using a two-way-Anova with Bonferroni post-test and is shown in the figure while all treatments regimens were significantly different to the no treatment control (**** <0.0001, ** <0.01).