General Information

IDHIFA (enasidenib) is a small molecule inhibitor of the isocitrate dehydrogenase 2 (IDH2) enzyme that works by blocking several enzymes that promote cell growth.

IDHIFA is specifically indicated for the treatment of adult patients with relapsed or refractory acute myeloid leukemia (AML) with an isocitrate dehydrogenase-2 (IDH2) mutation as detected by an FDA-approved test.

IDHIFA is supplied as tablets for oral administration. The recommended starting dose of IDHIFA is 100 mg taken orally once daily with or without food until disease progression or unacceptable toxicity. For patients without disease progression or unacceptable toxicity, treat for a minimum of 6 months to allow time for clinical response.

Do not split or crush IDHIFA tablets.

Administer IDHIFA tablets orally about the same time each day. If a dose of IDHIFA is vomited, missed, or not taken at the usual time, administer the dose as soon as possible on the same day, and return to the normal schedule the following day.

Clinical Results

FDA Approval

The FDA approval of IDHIFA was based on a single-arm trial of 199 patients with relapsed or refractory AML who had IDH2 mutations as detected by the RealTime IDH2 Assay. The trial measured the percentage of patients with no evidence of disease and full recovery of blood counts after treatment (complete remission or CR), as well as patients with no evidence of disease and partial recovery of blood counts after treatment (complete remission with partial hematologic recovery or CRh). With a minimum of six months of treatment, 19 percent of patients experienced CR for a median 8.2 months, and 4 percent of patients experienced CRh for a median 9.6 months. Of the 157 patients who required transfusions of blood or platelets due to AML at the start of the study, 34 percent no longer required transfusions after treatment with IDHIFA.

Side Effects

Adverse effects associated with the use of IDHIFA may include, but are not limited to, the following:

nausea

vomiting

diarrhea

increased levels of bilirubin

decreased appetite

The IDHIFA drug label comes with a Black Box Warning that an adverse reaction known as differentiation syndrome can occur and can be fatal if not treated.

Mechanism of Action

IDHIFA (enasidenib) is a small molecule inhibitor of the isocitrate dehydrogenase 2 (IDH2) enzyme. Enasidenib targets the mutant IDH2 variants R140Q, R172S, and R172K at approximately 40-fold lower concentrations than the wild-type enzyme in vitro. Inhibition of the mutant IDH2 enzyme by enasidenib led to decreased 2-hydroxyglutarate (2-HG) levels and induced myeloid differentiation in vitro and in vivo in mouse xenograft models of IDH2 mutated AML. In blood samples from patients with AML with mutated IDH2, enasidenib decreased 2-HG levels, reduced blast counts and increased percentages of mature myeloid cells.