Testing the nonclinical Comprehensive In Vitro Proarrhythmia Assay (CiPA) paradigm with an established anti‐seizure medication: Levetiracetam case study

Figures

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  FIGURE 1. Schematic representation of core and follow‐up assays of the ICH S7B nonclinical guidance and nonclinical components of the Comprehensive in Vitro Proarrhythmia Assays (CiPA) approach (adapted from ICH E14/S7B Q&A training material and FDA Impact Story (Impact Story: Improved Assessment of Cardiotoxic Risk in Drug Candidates: The Comprehensive in vitro Proarrhythmia Assay | FDA

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  FIGURE 2. Panel A: Representative IKr current traces in the acute hERG assay (left) and the hERG trafficking assay (right) (black: control; red: 7.5 mM LEV); Panel B: concentration‐response curve of IKr current in the acute hERG assay (mean and standard error of the mean (SEM), n = 4) and the hERG trafficking assay (mean and SEM, n = 10).

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  FIGURE 3. Simulated LEV‐induced changes in action potential duration at 90% repolarisation (APD90, left) and electromechanical window (EMw, right) for control (A), large‐variability (B), and high‐risk (C) populations of virtual human adult cardiomyocytes. Results are shown for all tested concentrations, from control (no drug, 0x) to 30x the free therapeutic plasma concentration (FTPC). In each boxplot, the central mark is the median of the population, box limits are the 25th and 75th percentiles, and whiskers extend to the most extreme data points not considered outliers, which are plotted individually as separate crosses.

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  FIGURE 4. Simulated human ventricular action potential traces following the application of LEV (left), with models displaying early‐after depolarizations (EADs) highlighted in blue, and corresponding distribution of ionic current conductances (right), shown as scaling factors compared to their baseline values. Colored boxplots refer to the distribution in the whole population (reflecting the ranges described in the Materials and Methods section). In each boxplot, the central mark is the median of the population, box limits are the 25th and 75th percentiles, whiskers extend to the most extreme data points not considered outliers, while black squares are used to highlight the scaling factors of the models displaying EADs. Results are shown for the lowest LEV concentration inducing EADs in the maximum number of cells. (A) Large‐variability population with LEV 7.5 mM: 1 EAD out of 283 in silico human adult cardiomyocyte models. (B) High‐risk population with LEV 0.75 mM: 5 EADs out of 322 in silico human adult cardiomyocyte models.

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  FIGURE 5. Composite QT‐ogram plot showing the hERG/QT‐related parameters in the different models. Data are presented as % inhibition versus vehicle (hERG), % action potential duration at 90% repolarisation (APD90) change versus controls at 1 Hz (virtual human cardiomyocytes (CM) and dog Purkinje fibers), maximum % field potential duration corrected for beating rate (FPDc) change versus baseline, vehicle corrected (human induced pluripotent stem cell‐derived cardiomyocytes, hiPSC‐CM), % QTc change versus baseline (conscious dogs), and ΔΔQTc at steady‐state, upper bound of one‐sided 95% confidence interval (TQT study extracted from Hulhoven et al. 5 ). FTPC: free therapeutic plasma concentration (0.25 mM at a dose of 1500 mg LEV). The horizontal dotted line corresponds to 10 msec threshold level for a negative TQT study or 10% threshold for considering effects as biologically relevant in nonclinical models.