Drug Interaction Report

MONITOR: Coadministration with mosunetuzumab may increase the plasma concentrations of drugs that are substrates of CYP450 isoenzymes. Initiation of mosunetuzumab treatment causes transient release of cytokines that may suppress CYP450 isoenzymes, although the potential for interaction has not been studied. According to the manufacturer, the highest drug-drug interaction risk would be after the first dose of the first cycle, up to 14 days after the second 60 mg dose on the first day of the second cycle, as well as during and after cytokine release syndrome.

MANAGEMENT: Caution is advised when mosunetuzumab is prescribed to patients receiving drugs that are metabolized by CYP450 isoenzymes, particularly those with a narrow therapeutic index such as carbamazepine, colchicine, cyclosporine, disopyramide, phenytoin, quinidine, theophylline, warfarin, macrolide immunosuppressants, vinca alkaloids, and some narcotic analgesics. Clinical laboratory monitoring are recommended following the initiation of mosunetuzumab, and the individual dosage of the concomitant agents adjusted as needed.

GENERALLY AVOID: Grapefruit juice may significantly increase the systemic exposure to eliglustat. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Because eliglustat is predicted to cause prolongation of the PR, QTc, and QRS cardiac intervals at substantially elevated plasma concentrations, consumption of grapefruit juice during treatment may increase the risk of bradycardia, atrioventricular block, cardiac arrest, and serious ventricular arrhythmias such as torsade de pointes.

MANAGEMENT: Patients treated with eliglustat should avoid consumption of grapefruit and grapefruit juice.