Figure 3.

Major histocompatibility complex (MHC) class I-directed and II-directed indoleamine 2,3-dioxygenase 1 (IDO1) peptides cooperate together but not with IDO1 enzyme inhibition. (A) Growth curves of CT26 tumors in wild-type (WT) mice immunized with the MHC class I-directed and II-directed peptides EP2 and EP6 either separately or together beginning 7 days after tumor engraftment. Responses to adjuvant alone, individual peptides (gray lines) and combined peptides (black lines) are plotted as means±SEM (n=8 tumors/cohort). (B) Evaluation of EP2 and EP6 both separately and in combination in Ido1^-/- mice as described in A (n=8 tumors/cohort). (C) Growth curves of CT26 tumors in WT mice treated with EP2 and epacadostat either separately or together beginning 7 days after tumor engraftment. Responses to adjuvant alone, EP2 and epacadostat individually (gray lines), and combined treatment (black lines) are plotted as means±SEM (n=10 tumors/cohort). (D) Evaluation of EP6 and epacadostat both separately and in combination as described in B (n≥9 tumors/cohort). P values for longitudinal tumor growth comparisons between combined and individual peptide vaccine-treated groups are included on each graph.