FDA Approves IDH2 Inhibitor for AML

— Also OK's companion diagnostic for IDH2 mutations

MedicalToday

The FDA today for adults with relapsed or refractory acute myeloid leukemia (AML) associated with isocitrate dehydrogenase-2 (IDH2) mutations.

At the same time, the agency approved the RealTime IDH2 companion assay, which detects IDH2 mutations.

"Idhifa is a targeted therapy that fills an unmet need for patients with relapsed or refractory AML who have an IDH2 mutation," Richard Pazdur, MD, of the FDA Office of Hematology and Oncology Products, said in a statement. "The use of Idhifa was associated with a complete remission in some patients and a reduction in the need for both red-cell and platelet transfusion."

An IDH2 inhibitor, enasidenib blocks the activity of several enzymes involved in promotion of cell growth. Primary supporting evidence for the drug's approval application came from a single-arm trial involving 199 patients with IDH2-positive relapsed/refractory AML. The primary outcome was no evidence of disease and complete recovery of blood counts after treatment (complete remission, CR) or no evidence of disease and partial recovery (CRh).

The results showed that 19% of patients treated with enasidenib achieved CR, persisting for a median duration of 8.2 months, and 4% of patients attained CRh, with a median duration of 9.6 months. A third of 157 patients who required transfusions prior to treatment with enasidenib no longer needed transfusions after treatment with the IDH2 inhibitor.

Common side effects of enasidenib included nausea, vomiting, diarrhea, increased bilirubin levels, and decreased appetite. The drug is contraindicated for women who are pregnant or breastfeeding.

Approval of enasidenib came with a boxed warning about a risk of differentiation syndrome, which can prove fatal if not treated. Signs and symptoms include fever; dyspnea; acute respiratory distress; radiographic evidence of pulmonary infiltrates; pleural or pericardial effusion; rapid weight gain; peripheral edema; and liver, kidney, or multiorgan dysfunction.

The FDA granted approval of enasidenib to Celgene, following prior designation of the drug for priority review and orphan drug status. The companion diagnostic test is marketed by Abbott Laboratories.

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    Charles Bankhead is senior editor for oncology and also covers urology, dermatology, and ophthalmology. He joined in 2007.