Figure 6: IDO1 inhibition slows secondary CRC growth.

A, Experimental setup. C57Bl/6 mice received 1×10⁶ MC38 cells (primary tumor) on Day 0 in the right hind leg. Two doses of focal XRT (6 Gy) was delivered as indicated and epacadostat (Epa, 6 mg) was administered by gavage daily. A secondary MC38 injection was placed in the contralateral leg on day 19. The mice then received a high dose focal RT (20 Gy) to the primary tumor. Both tumors were measured until 35 days post primary tumor implantation. B, Change in tumor volume over time in secondary tumors. Mean+SEM. #p<0.05 of secondary tumor growth by mixed-effect model accounting for interaction with the primary tumors. C, Comparison of endpoint secondary tumor volume at day 35. Mean+SEM. *P<0.05 by Student’s t-test. n=6–7/group.