Early investigation of QTc liability: the role of multiple ascending dose (MAD) study

The International Conference on Harmonization (ICH) guidance note E14 requires a thorough QT (TQT) study to characterize proactively the potential of a new drug to affect cardiac repolarization, as determined by prolongation of the corrected QT (QTc) interval. A typical TQT study is reviewed herein with a discussion on various practical issues concerning the use of a supratherapeutic dose, establishing assay sensitivity, the application of QT rate-correction methods, and restricting analyses of ECGs and plasma samples to key timepoints. We then discuss, and provide examples of, how multiple ascending dose (MAD) study protocols can be modified to integrate robust ECG monitoring and analyses to gather key information provided by a TQT study. Among the main advantages of this approach are the ability to study the ECG effects of a wide range of doses to the maximum tolerated doses, eliminating routine analyses at unnecessary timepoints, making early go-no-go decisions, making phase II studies more efficient and, if necessary, being able to implement rigorous ECG monitoring in populations and pivotal studies of regulatory interest. If clear evidence for the presence or absence of QTc effect is found, the data from a modified MAD study may support a request for a waiver from the requirement to conduct a TQT study. In the event that a TQT study is considered unnecessary, there are obvious significant savings without compromising collection of vital safety data.