Epacadostat (INCB024360)

In IFN-γ–treated human HeLa cells, INCB024360 potently inhibits kynurenine production. INCB024360 also promotes T and natural killer (NK)-cell growth, increases IFN-gamma production, and reduces conversion to regulatory T (T(reg))-like cells. ^[1]

INCB024360 (100 mg/kg, p.o.), via IDO1 inhibition, suppresses kyn generation and tumor growth in immunocompetent, but not immunodeficient, mice. ^[1]

In mice bearing CT26 colon carcinoma, INCB024360 (100 mg/kg, p.o.) also inhibits the growth of IDO-expressing tumors by reducing kynurenine. ^[2]

• IDO enzyme assays

  Human IDO with an N-terminal His tag is expressed in E.coli and purified to homogeneity. IDO catalyzes the oxidative cleavage of the pyrrole ring of the indole nucleus of tryptophan to yield N’-formylkynurenine. The assays are performed at room temperature using 20 nM IDO and 2 mM D-Trp in the presence of 20 mM ascorbate, 3.5 µM methylene blue and 0.2 mg/mL catalase in 50 mM potassium phosphate buffer (pH 6.5). The initial reaction rates are recorded by continuously following the absorbance increase at 321 nm due to the formation of N’-formlylkynurenine.

• Cell lines

  Jurkat cells

• Concentrations

  50 μM

• Incubation Time

  72 h

• Method

  Jurkat cells were incubated with serially diluted epacadostat for 72 h. Their viability was measured and analyzed as percentage of the non-treated control.

• Animal Models

  Female C57BL/6 or Balb/c nu/nu mice bearing PAN02 pancreatic tumors

• Dosages

  ~100 mg/kg, twice a day

• Administration

  p.o.