Idhifa Drug Information

Acute Myeloid Leukemia IDHIFA is 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.

Patient Selection

Select patients for the treatment of AML with IDHIFA based on the presence of IDH2 mutations in the blood or bone marrow. Information on FDA-approved tests for the detection of IDH2 mutations in AML is available at http://www.fda.gov/CompanionDiagnostics.

Recommended Dosage

The recommended dosage 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. Swallow tablets whole.

Do not chew, 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.

Monitoring and Dosage Modifications for Toxicities

Assess blood counts and blood chemistries for leukocytosis and tumor lysis syndrome prior to the initiation of IDHIFA and monitor at a minimum of every 2 weeks for at least the first 3 months during treatment. Manage any abnormalities promptly. Interrupt dosing or reduce dose for toxicities.

See Table 1 for dosage modification guidelines. Adverse Reaction Recommended Action • Differentiation syndrome • If differentiation syndrome is suspected, administer systemic corticosteroids and initiate hemodynamic monitoring. • Interrupt IDHIFA if severe pulmonary symptoms requiring intubation or ventilator support, and/or renal dysfunction persist for more than 48 hours after initiation of corticosteroids. • Resume IDHIFA when signs and symptoms improve to Grade 2* or lower. • Noninfectious leukocytosis (white blood cell count greater than 30 × 10 9 /L) • Initiate treatment with hydroxyurea, as per standard institutional practices. • Interrupt IDHIFA if leukocytosis is not improved with hydroxyurea, and then resume IDHIFA at 100 mg daily when WBC is less than 30 × 10 9 /L. • Elevation of bilirubin greater than 3 times the upper limit of normal (ULN) sustained for ≥2 weeks without elevated transaminases or other hepatic disorders • Reduce IDHIFA dose to 50 mg daily. • Resume IDHIFA at 100 mg daily if bilirubin elevation resolves to less than 2 × ULN. • Other Grade 3* or higher toxicity considered related to treatment including tumor lysis syndrome • Interrupt IDHIFA until toxicity resolves to Grade 2* or lower. • Resume IDHIFA at 50 mg daily; may increase to 100 mg daily if toxicities resolve to Grade 1* or lower. • If Grade 3* or higher toxicity recurs, discontinue IDHIFA.

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The safety evaluation of single-agent IDHIFA is based on 214 patients with relapsed or refractory AML who were assigned to receive 100 mg daily. The median duration of exposure to IDHIFA was 4.3 months (range 0.3 to 23.6).

The 30-day and 60-day mortality rates observed with IDHIFA were respectively. Serious adverse reactions were reported in 77.1% of patients. Differentiation syndrome events characterized as serious included pyrexia, renal failure acute, hypoxia, respiratory failure, and multi-organ failure.

Ten of 214 patients (5%) required a dose reduction due to an adverse reaction; no adverse reaction required dose reduction in more than 2 patients. Thirty-six of 214 patients (17%) permanently discontinued IDHIFA due to an adverse reaction; the most frequent adverse reaction leading to permanent discontinuation was leukocytosis (1%). The most common adverse reactions (≥20%) of any grade were nausea, vomiting, diarrhea, elevated bilirubin and decreased appetite.

Adverse reactions reported in the trial are shown in Table 2. Table 3: Most Common (≥20%) New or Worsening Laboratory Abnormalities Reported in Patients with Relapsed or Refractory AML 8 Elevated Bilirubin IDHIFA may interfere with bilirubin metabolism through inhibition of UGT1A1. Thirty-seven percent of patients (80/214) experienced total bilirubin elevations ≥2 x ULN at least one time.

Of those patients who experienced total bilirubin elevations ≥2 x ULN, 35% had elevations within the first month of treatment, and 89% had no concomitant elevation of transaminases or other severe adverse events related to liver disorders. No patients required a dose reduction for hyperbilirubinemia; treatment was interrupted in 3.7% of patients, for a median of 6 days. Three patients (1.4%) discontinued IDHIFA permanently due to hyperbilirubinemia.

Noninfectious Leukocytosis IDHIFA can induce myeloid proliferation resulting in a rapid increase in white blood cell count. Tumor Lysis Syndrome IDHIFA can induce myeloid proliferation resulting in a rapid reduction in tumor cells which may pose a risk for tumor lysis syndrome. Other Clinical Trials Experience The following adverse reactions occurred in other clinical trials of IDHIFA at the recommended dosage: neutropenia, thrombocytopenia, anemia, stomatitis, renal failure, fatigue, dyspnea, and QT prolongation.

Effect of IDHIFA on Other Drugs Certain CYP1A2 Substrates

Avoid concomitant use with IDHIFA unless otherwise recommended in the Prescribing Information for CYP1A2 substrates where minimal concentration changes may lead to serious adverse reactions. Consider reducing the frequency of caffeine intake from various food and beverages in a 24 hour period while taking IDHIFA because IDHIFA may increase the effect of caffeine in patients who are sensitive to it. Enasidenib is a CYP1A2 inhibitor.

Concomitant use of IDHIFA increases the exposure of CYP1A2 substrates, which may increase the risk of adverse reactions related to the substrates. Enasidenib is a CYP2C19 inhibitor. Certain CYP3A substrates Avoid concomitant use with IDHIFA unless otherwise recommended in the Prescribing Information for CYP3A substrates where minimal concentration changes may lead to reduced efficacy.

Do not administer IDHIFA with anti-fungal agents that are substrates of CYP3A due to expected loss of antifungal efficacy. Co-administration of IDHIFA may decrease the concentrations of hormonal contraceptives. Consider alternative methods of contraception in patients receiving IDHIFA.

Enasidenib is a CYP3A inducer. Concomitant use of IDHIFA decreases the exposure of CYP3A substrates, which may reduce the efficacy of the substrates. Certain OATP1B1, OATP1B3, and BCRP Substrates Avoid coadministration of IDHIFA with OATP1B1, OATP1B3, and BCRP substrates, for which minimal concentration changes may lead to serious toxicities.

If coadministration cannot be avoided, decrease the OATP1B1, OATP1B3, and BCRP substrates dosage(s) in accordance with the respective Prescribing Information. Enasidenib is an OATP1B1, OATP1B3, and BCRP transporter inhibitor. Certain P-glycoprotein (P-gp) Substrates When coadministered with IDHIFA, follow recommended P-gp substrates Prescribing Information and monitor more frequently for adverse reactions related to these substrates.

Enasidenib is a P-gp transporter inhibitor.

Pregnancy Risk Summary Based on animal embryo-fetal toxicity studies, IDHIFA can cause fetal harm when administered to a pregnant woman. There are no available data on IDHIFA use in pregnant women to inform a drug-associated risk of major birth defects and miscarriage. In animal embryo-fetal toxicity studies, oral administration of enasidenib to pregnant rats and rabbits during organogenesis was associated with embryo-fetal mortality and alterations to growth starting at 0.1 times the steady state clinical exposure based on the AUC at the recommended human dose (see Data).

Advise pregnant women of the potential risk to a fetus. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2%-4% and 15%-20%, respectively. Data Animal Data Enasidenib administered to pregnant rats at a dose of 30 mg/kg twice daily during organogenesis (gestation days 6-17) was associated with maternal toxicity and adverse embryo-fetal effects including post-implantation loss, resorptions, decreased viable fetuses, lower fetal birth weights, and skeletal variations.

These effects occurred in rats at approximately 1.6 times the clinical exposure at the recommended human daily dose of 100 mg/day. In pregnant rabbits treated during organogenesis (gestation days 7-19), enasidenib was maternally toxic at doses equal to 5 mg/kg/day or higher (exposure approximately 0.1 to 0.6 times the steady state clinical exposure at the recommended daily dose) and caused spontaneous abortions at 5 mg/kg/day (exposure approximately 0.1 times the steady state clinical exposure at the recommended daily dose).

Pediatric Use Safety and effectiveness of IDHIFA in pediatric patients have not been established.