Indoleamine 2,3-dioxygenase 1 inhibition targets anti-PD1-resistant lung tumors by blocking myeloid-derived suppressor cells.

ABSTRACT: Indoleamine 2,3-dioxygenase 1 (IDO1), involved in the catabolism of tryptophan (Trp) to kynurenine (Kyn) is an important regulator of tumor-mediated immunosuppression implicated in resistance to anti-PD1 immunotherapy. We investigated the role of IDO1 in an anti-PD1-resistant lung cancer model (344SQ_R) compared to the parental 344SQ tumors (344SQ_P). IDO1 was overexpressed in tumor-infiltrating leukocytes, and plasma Kyn levels were increased, in 344SQ_R vs. 344SQ_P. The IDO1 inhibitor INCB023843 retarded tumor growth and reduced lung metastases in 344SQ_R. IDO1 was expressed at higher levels in F4/80⁺Gr1^intCD11b⁺ myeloid-derived suppressor cells (MDSCs) that were prominent in 344SQ_R. The INCB023843 reduced IDO1 expression and percentages of these MDSCs w

SUBMITTER: Li A 

PROVIDER: S-EPMC6027590 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature