Epacadostat (INCB 024360) is an oral, potent and selective IDO1 inhibitor with IC50 value of 71.8 nM.

IDO1 (HEK293 cells):52.4 nM ± 15.7 nM, IDO1 (HeLa cells):7.4 nM, IDO1 (P1.HTR cells):54.46 nM ± 11.18 nM, IDO1:10 nM

METHODS: Epacadostat (INCB 024360) (0.0001, 0.01, 1, 100, 10000nM) was used to treat SKOV-3 cells and the release of kynurenine was measured.
RESULTS Epacadostat (INCB 024360) inhibited the catalytic activity of IDO1 with an IC50 value of 17.63 nM ± 2.26 (pIC50 = 7.76 ± 0.06). [2]

METHODS: Mice were injected subcutaneously with 200 μl TC-1 cells on the back. After the tumor was palpable, Epacadostat (INCB 024360) (50 mg/kg), IFN-γ (100 ng/mouse), and kynurenine (100 mg/kg) were injected intraperitoneally every day. Tumor volume was measured every 3 days.
RESULTS Intraperitoneal injection of Epacadostat (INCB 024360) caused a significant increase in tumor volume and tumor weight, and inhibited the expression of CD80 on macrophages in tumor tissues. [3]

INCB 024360 (INCB024360) is dissolved in DMSO and stored, and then diluted with appropriate media before use[1]. To determine INCB 024360 activity against IDO in recombinant cells, HEK293/MSR cells are transiently transfected with full-length human or mouse IDO1, or mouse IDO2 cDNA, with Transit-293 transfection reagent or Lipofectamine 2000 reagents. INCB 024360 at different concentrations is added to the recovered transfected cells seeded at 2×104 cells per well in a 96-well plate (200 μL/well). The cells are incubated for 2 days, and kyn in the supernatants is measured as described in the HeLa cell assay. The tryptophan 2,3-dioxygenase (TDO) assay is performed similarly with HEK293/MSR cells transfected with a human TDO expression vector[1].