An Analysis of the Relationship Between Preclinical and Clinical QT Interval-Related Data

There has been significant focus on drug-induced QT interval prolongation caused by block of the human ether-a-go-go-related gene (hERG)-encoded potassium channel. Regulatory guidance has been implemented to assess QT interval prolongation risk: preclinical guidance requires a candidate drug's potency as a hERG channel blocker to be defined and also its effect on QT interval in a non-rodent species; clinical guidance requires a "Thorough QT Study" during development, although some QT prolonging compounds are identified earlier via a Phase I study. Clinical, heart rate-corrected QT interval (QTc) data on 24 compounds (13 positives; 11 negatives) were compared with their effect on dog QTc and the concentration of compound causing 50% inhibition (IC50) of hERG current. Concordance was assessed by calculating sensitivity and specificity across a range of decision thresholds, thus yielding receiver operating characteristic curves of sensitivity versus (1-specificity). The area under the curve of ROC curves (for which 0.5 and 1 indicate chance and perfect concordance, respectively) was used to summarize concordance. Three aspects of preclinical data were compared with the clinical outcome (receiver operating characteristic area under the curve values shown in brackets): absolute hERG IC50 (0.78); safety margin between hERG IC50 and clinical peak free plasma exposure (0.80); safety margin between QTc effects in dogs and clinical peak free plasma exposure (0.81). Positive and negative predictive values of absolute hERG IC50 indicated that from an early drug discovery perspective, low potency compounds can be progressed on the basis of a low risk of causing a QTc increase.