Cross clinical-experimental-computational qualification of in silico drug trials on human cardiac purkinje cells for proarrhythmia risk prediction

FIGURE 1. Combined experimental-computational pipeline used to perform this study. (A): In vitro estimation of IC50s through automated patch clamp. (B): Structure of the biophysically detailed computational model used to simulate human cardiac Purkinje electrophysiology (Trovato et al., 2020a). (C): Experimentally-calibrated population of 530 models generated using the Virtual Assay software (Oxford University Innovation © 2018); blue traces: computational models; green traces: experimental AP recordings from human healthy cardiac Purkinje cell (Nagy et al., 2015). (D): Representative example of human in silico drug trials on the population of models, including AP traces (with drug-induced repolarization abnormalities highlighted in pink) and biomarker boxplots. (E): In silico results were compared against pre-existing in vitro recordings from rabbit Purkinje fibers, obtained with the protocol depicted for multiple frequencies and concentrations. (F): Both in vitro and in silico results were compared against the clinical TdP risk from the CredibleMeds ® repository (Woosley and Romer, 1999).

FIGURE 2. Summary of drug-induced effects on the cardiac ion channels, computed with a simple pore-block model. Each panel shows one of the fourteen reference compounds, with the different bars representing the residual current after drug-application (in percentage), for each ion channel and drug concentration.

FIGURE 3. Comparison between clinical TdP risk and percent drug-induced AP changes in human simulations and rabbit experiments for each drug, at different concentrations and pacing frequencies. Columns description from left to right: first: drug name and maximum effective free plasma concentrations (EFTPCMAX, in µM); second: tested drug concentrations; third: ratio between tested concentrations and EFTPCMAX; from fourth to ninth: experimental and simulated AP biomarkers changes at slow pacing; 10th to 11th: percentage of EADs occurrences in simulations and experiments at slow pacing; from 12th to 23rd: experimental and simulated AP biomarkers changes at normal and fast pacing; 24th: drug risk category based on CredibleMeds ® (Woosley and Romer, 1999): high risk (1), conditional risk (2), NC (non-classified in any risk category). NA: data not available. Changes are shown as percentage with respect to control conditions. Colors indicates biomarker increase (red) or decrease (blue) and are scaled from the minimum to the maximum percent variations for each biomarker at each pacing frequencies.

FIGURE 4. Proarrhythmic risk predictions using in silico human or in vitro rabbit models. (A) Confusion matrix for in silico (green) and in vitro (blue) predictions, compared to clinical report of proarrhythmia, based on EADs occurrences (left panel) or APD90 (right panel); +: Risky drug; -: Safe drug. (B) Consistency between in silico and in vitro drug safety predictions based on APD90 prolongation at 1 Hz. The pie chart represents the percentage of compounds showing agreement for most of the concentration tested (green), partial agreement for at least half of the tested concentrations (blue), or disagreement (yellow).

FIGURE 5. Comparison between human in silico and in vitro rabbit AP traces at slow pacing, for six illustrative compounds. In each section, experimental recordings are at the top, and simulated traces at the bottom. One representative cell/model is shown for each drug. (A) Three explicative compounds showing EADs in both simulations and experiments: astemizole (left), cisapride (center), diltiazem (right). (B) The three compounds showing disagreement in EADs occurrence between in silico and in vitro results, i.e., EADs were observed only in simulations and not in experiments: bepridil (left), ranolazine (center), terfenadine (right).

FIGURE 6. Summary of the comparison between experiments and simulations at different pacing frequencies, for dV/dtMAX (top), APD90 (middle), and APD50 (bottom). Pie charts show the percentage of tested compounds at different concentrations in strong agreement (green), qualitative agreement (blue), or disagreement (yellow). Categories defined as in Section 2.3).

FIGURE 7. Comparison between simulated and experimental dose-response curves for APD90, APD50 and dV/dtMAX, for three representative compounds, at all pacing frequencies: (A) disopyramide; (B) bepridil; (C) dofetilide. Boxplots: human simulations at different concentrations (one color per concentration): on each box, the central mark is the median of the population, box limits are the 25 and 75th percentiles, and whiskers extend to the most extreme data points not considered outliers, plotted individually as separate crosses. Black squares: mean values of the in vitro rabbit data.