Drug Interaction Report

MONITOR: Coadministration with inhibitors of CYP450 3A4 may increase the plasma concentrations of unconjugated monomethyl auristatin E (MMAE), the anti-mitotic and cytotoxic component of telisotuzumab vedotin. Telisotuzumab vedotin is an antibody-drug conjugate (ADC) that releases MMAE via proteolytic cleavage, and MMAE has been shown in vitro to be primarily metabolized by CYP450 3A4. MMAE systemic exposure (AUC) is predicted to increase by 1.4-fold following concomitant administration of telisotuzumab vedotin with the potent CYP450 3A4 inhibitor ketoconazole. It is not known if, and to what extent, MMAE may interact with less potent CYP450 3A4 inhibitors.

MANAGEMENT: Caution is advised when telisotuzumab vedotin is used concomitantly with CYP450 3A4 inhibitors. Patients should be closely monitored for development or exacerbation of toxicities such as ocular surface disorders (e.g., dry eyes, keratitis, blurred vision), peripheral neuropathy, interstitial lung disease/pneumonitis, and peripheral edema. If serious adverse reactions occur, the dosing of telisotuzumab vedotin should be adjusted or withheld as necessary in accordance with the product labeling.

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of selpercatinib. 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. The interaction has not been studied with grapefruit juice, but has been reported for other CYP450 3A4 inhibitors. When a single dose of selpercatinib (160 mg) was coadministered with multiple doses of itraconazole (200 mg once daily), a potent CYP450 3A4 inhibitor, selpercatinib peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 30% and 133%, respectively. Based on pharmacokinetic modeling, administration of multiple doses of selpercatinib (160 mg twice daily) with multiple doses of the moderate CYP450 3A4 inhibitors diltiazem (60 mg three times daily), fluconazole (200 mg once daily), or verapamil (80 mg three times daily) is predicted to increase selpercatinib Cmax by 46% to 76% and AUC by 60% to 99%. 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 selpercatinib may increase the risk of serious adverse effects such as QT interval prolongation, liver transaminase and bilirubin elevations, hypertension, hemorrhage, edema, and hypersensitivity reactions (e.g., fever, rash, arthralgias/myalgias with concurrent decreased platelets or transaminitis).

MANAGEMENT: Until further information is available, it may be advisable for patients to limit or avoid consumption of grapefruit and grapefruit juice during treatment with selpercatinib.