A. The pentatherapy combination treatment schedule wherein tumor-bearing mice were administered with: (1) the vaccine Ad-CEA on days 7, 14, and 21 post-tumor inoculation, subcutaneous (s.c.); (2) the superagonist N-803 on days 14, and 21, s.c.; (3) the costimulatory agonist OX40 on days 7, 14, and 21, intraperitoneally (i.p.); (4) the costimulatory agonist GITR on day 5, i.p.; and (5) the IDO inhibitor (IDOi) epacadostat feed starting at day 7. B-Q. Female C57BL/6-CEA-Tg mice (8–16 weeks old; n=10/group) were inoculated with 3×105 MC38-CEA cells on the flank, s.c. Sixteen different IO agent combinations were employed by following the treatment schedule described in (A). Tumor volume was monitored. Inset values represent fraction of mice with <300mm3 tumor volume at the endpoint for each group. Two-way or one-way ANOVA with Tukey’s post hoc test. Error bars represent mean±SEM. These studies were repeated 3–4 times with similar results.