Cardiotoxicity with carfilzomib at doses greater than 27 mg/m 2 : A case series.

Carfilzomib is a second-generation proteasome inhibitor that irreversibly inhibits chymotrypsin-like (CT-L) activities of the proteasome, and is indicated for relapsed or refractory multiple myeloma. Cardiotoxicity is a well-established adverse effect of carfilzomib. The extent of cardiac toxicity in the literature spans anywhere from palpitations to cardiac arrest, with the most commonly reported manifestation being new-onset or worsening heart failure. A pre-clinical study of the pharmacokinetics and pharmacodynamics of carfilzomib given via intravenous bolus or 30-minute infusion in rats showed that carfilzomib can strongly induce apoptosis and potently damage cardiac myocytes at clinically relevant concentrations. Moreover, the mortality rate with the bolus administration was 44% whereas the same dose administered as a 30-minute infusion did not result in mortality. There remains limited clinical data regarding the safety of carfilzomib at doses of 27-56 mg/m(2) based on infusion times as these doses have not been well studied. This retrospective review was conducted to evaluate the safety of carfilzomib at doses >27 mg/m(2) at all infusion times.