Drug Interactions between ibrutinib and ivosidenib

GENERALLY AVOID: Coadministration with grapefruit, grapefruit juice, or Seville oranges may significantly increase the plasma concentrations of ibrutinib. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Pharmacokinetic modeling suggests that other moderate CYP450 3A4 inhibitors such as diltiazem and erythromycin may increase ibrutinib systemic exposure (AUC) by 6- to 9-fold under fasting condition. The safety and efficacy of these exposures are unknown. The highest ibrutinib dose evaluated in clinical trials was 12.5 mg/kg (actual doses of 840 to 1400 mg) given for 28 days, which yielded single dose AUC values that were approximately 50% greater than steady-state exposures seen at the highest indicated dose of 560 mg.

ADJUST DOSING INTERVAL: Food increases the oral bioavailability of ibrutinib. The mechanism of interaction is unknown. According to the product labeling, administration with food increases ibrutinib exposure approximately 2-fold compared to administration after overnight fasting.

MANAGEMENT: Patients treated with ibrutinib should avoid consumption of Seville oranges, grapefruit, grapefruit juice, and any supplement containing grapefruit extract. Ibrutinib should be taken once daily at approximately the same time each day.

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GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of ivosidenib. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Inhibition of hepatic CYP450 3A4 may also contribute. Pharmacokinetic data are available for the potent CYP450 3A4 inhibitor, itraconazole, and the moderate inhibitor, fluconazole. When a single 250 mg dose of ivosidenib was administered with itraconazole 200 mg once daily for 18 days, ivosidenib systemic exposure (AUC) increased to 269% of control, with no change in peak plasma concentration (Cmax). Based on physiologically-based pharmacokinetic modeling, coadministration of a 500 mg dose of ivosidenib with fluconazole (dosed to steady-state) is predicted to increase ivosidenib single-dose AUC to 173% of control, while multiple-dosing of both is predicted to increase ivosidenib steady-state Cmax and AUC to 152% and 190% of control, respectively. In general, the effect of grapefruit juice is concentration-, dose- and preparation-dependent, and can vary widely among brands. Certain preparations of grapefruit juice (e.g., high dose, double strength) have sometimes demonstrated potent inhibition of CYP450 3A4, while other preparations (e.g., low dose, single strength) have typically demonstrated moderate inhibition. Increased exposure to ivosidenib may increase the risk of QT interval prolongation, which has been associated with ventricular arrhythmias including torsade de pointes and sudden death.

GENERALLY AVOID: Coadministration with a high-fat meal may increase the plasma concentrations of ivosidenib. According to the product labeling, administration of a single dose with a high-fat meal (approximately 900 to 1000 calories; 500 to 600 calories in fat, 250 calories in carbohydrate, 150 calories in protein) increased ivosidenib Cmax and AUC by 98% and 25%, respectively, in healthy study subjects.

MANAGEMENT: Ivosidenib may be administered with or without food, but should not be administered with a high-fat meal. Patients should avoid consumption of grapefruit and grapefruit juice during treatment with ivosidenib.

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