Deferasirox does not induce QT/QTc-prolongation in healthy subjects

The International Conference on Harmonization (ICH) E14 guidance recommends that almost all drugs should undergo careful clinical testing in a thorough QT/QTc study. Deferasirox (Exjade, ICL670) is a once-daily oral iron chelator, developed for the treatment of blood transfusion-related iron overload.

This study was designed to investigate the effect of deferasirox on the QT/QTc interval.

A randomized, single-dose, placebo- and positive-controlled, parallel-group study was conducted in a total of 182 healthy subjects. Study participants were randomized to four treatments arms: deferasirox 20 mg/kg (n = 46), deferasirox 40 mg/kg (n = 46), placebo (n = 46) or moxifloxacin 400 mg (n = 44). Moxifloxacin tablets were taken in an open-label fashion, while the subjects and investigator staff remained blinded for the other treatments. Electrocardiograms, obtained at various time points during a 24-h period, were evaluated centrally in a blinded fashion. The primary endpoint was the average change from baseline in QT/QTc over the 24-h period following intake of study medication. It was prospectively defined that deferasirox will be considered devoid of inducing QT/QTc-prolongation if the upper bound of the 95% 2-sided confidence interval (CI) for the difference to placebo is below 8 milliseconds (i.e., being noninferior to placebo).

Deferasirox 20 and 40 mg/kg were noninferior to placebo with respect to the average change from baseline in QT/QTc, as indicated by 95% CIs for the mean treatment difference (deferasirox 20 or 40 mg/kg minus placebo), which were entirely below 8 milliseconds. The lower limit of the 95% 2-sided CI for the difference between moxifloxacin and placebo was greater than 0 milliseconds, demonstrating the sensitivity of the study. Deferasirox C(max) and AUC following intake of deferasirox 40 mg/kg was higher by factor 1.6 and 2.3, respectively, than observed at a steady state in beta-thalassemia patients treated for 6 months with deferasirox 30 mg/kg, the recommended maximum dose.

This study demonstrates that deferasirox does not prolong the QT/QTc interval at both therapeutic and supratherapeutic plasma concentrations. It is, therefore, not expected that deferasirox has a negative effect on cardiac repolarization in patients under treatment with this medication.