Indoleamine 2,3-dioxygenase 1 (IDO1)

Indoleamine 2,3-dioxygenase 1 is a heme-containing enzyme that catalyzes the first and rate-limiting step in the degradation of tryptophan along the kynurenine pathway, converting L‑tryptophan into N-formylkynurenine. It is physiologically expressed in various tissues including the small intestine, lungs, female genital tract, and placenta. IDO1 plays a crucial role in modulating immune responses by depleting local tryptophan concentrations and generating immunosuppressive metabolites that inhibit effector T-cell function while promoting regulatory T cell differentiation. This mechanism contributes to peripheral tolerance but can be hijacked by tumors to evade immune surveillance; thus, IDO inhibitors are being explored as cancer therapeutics—especially as adjuncts to other forms of immunotherapy or chemotherapy. Elevated expression has been observed across several cancers such as acute myeloid leukemia, ovarian cancer, and colorectal cancer[1][6][8].

Other names

Indoleamine-pyrrole 2,3-dioxygenaseIDOINDOEC 1.13.11.52

Inhibition of enzymatic activity to restore anti-tumor immunity by preventing tryptophan depletion and reducing immunosuppressive kynurenine metabolites[1]