Epacadostat

Epacadostat (INCB 024360) is a potent and selective indoleamine 2,3-dioxigenase 1 (IDO1) inhibitor with an IC₅₀ of 71.8 nM^[1]. IC50 & Target: IC50: 71.8 nM±17.5 nM (IDO1), 7.1 nM±0.6 nM (IDO1, in HeLa cells)^[1] In Vitro: In cellular assays, Epacadostat (INCB 024360) selectively inhibits human IDO1 with IC₅₀ values of approximately 10 nM, demonstrating little activity against other related enzymes such as IDO2 or tryptophan 2,3-dioxygenase (TDO). Epacadostat (INCB 024360) also exhibits significant activity toward mouse IDO1, with an IC₅₀ value of 52.4 nM±15.7 nM, in a similar assay using mouse IDO1-transfected HEK293/MSR cells^[1]. In Vivo: Female Balb/c mice bearing CT26 tumors are treated orally twice daily for 12 d with Epacadostat at 100 mg/kg. Epacadostat (INCB 024360) suppresses kynurenine equivalently in plasma, tumors, and lymph nodes. In naïve C57BL/6 mice, 50 mg/kg Epacadostat (INCB 024360) decreases plasma kynurenine levels within 1 hour and those levels stay at least 50% suppressed through the 8-hour time course^[2].