Our data suggest a functionallink between the third branch of the AA cascade and the Kyn pathway.Since the direct IDO1 inhibitor epacadostat recently failed clinicaltrials, alternative approaches to reduce Kyn levels are coveted, andinhibition of the Kyn pathway by modulating sEH may open up novelopportunities to revert cancer-related immune suppression. Here, IDO1 is linked to cancer.