Reversal of tumoral immune resistance by inhibition of tryptophan 2,3-dioxygenase

L. Pilotte, P. Larrieu, V. Stroobant, D. Colau, E. Dolušić, R. Frédérick, E. De Plaen, C. Uyttenhove, J. Wouters, B. Masereel, B.J. Van Den Eynde

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Tryptophan catabolism mediated by indoleamine 2,3-dioxygenase (IDO1) is an important mechanism of peripheral immune tolerance contributing to tumoral immune resistance, and IDO1 inhibition is an active area of drug development. Tryptophan 2,3-dioxygenase (TDO) is an unrelated hepatic enzyme that also degrades tryptophan along the kynurenine pathway. Here, we show that enzymatically active TDO is expressed in a significant proportion of human tumors. In a preclinical model, TDO expression by tumors prevented their rejection by immunized mice. We developed a TDO inhibitor, which, upon systemic treatment, restored the ability of mice to reject TDO-expressing tumors. Our results describe a mechanism of tumoral immune resistance based on TDO expression and establish proof-of-concept for the use of TDO inhibitors in cancer therapy.
Original languageEnglish
Pages (from-to)2497-2502
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number7
Publication statusPublished - 14 Feb 2012


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