Comparison of the I_Kr blockers moxifloxacin, dofetilide and E‐4031 in five screening models of pro‐arrhythmia reveals lack of specificity of isolated cardiomyocytes

Abstract

BACKGROUND AND PURPOSE Drug development requires the testing of new chemical entities for adverse effects. For cardiac safety screening, improved assays are urgently needed. Isolated adult cardiomyocytes (CM) and human embryonic stem cell‐derived cardiomyocytes (hESC‐CM) could be used to identify pro‐arrhythmic compounds. In the present study, five assays were employed to investigate their sensitivity and specificity for evaluating the pro‐arrhythmic properties of IKr blockers, using moxifloxacin (safe compound) and dofetilide or E‐4031 (unsafe compounds). EXPERIMENTAL APPROACH Assays included the anaesthetized remodelled chronic complete AV block (CAVB) dog, the anaesthetized methoxamine‐sensitized unremodelled rabbit, multi‐cellular hESC‐CM clusters, isolated CM obtained from CAVB dogs and isolated CM obtained from the normal rabbit. Arrhythmic outcome was defined as Torsade de Pointes (TdP) in the animal models and early afterdepolarizations (EADs) in the cell models. KEY RESULTS At clinically relevant concentrations (5–12 µM), moxifloxacin was free of pro‐arrhythmic properties in all assays with the exception of the isolated CM, in which 10 µM induced EADs in 35% of the CAVB CM and in 23% of the rabbit CM. At supra‐therapeutic concentrations (≥100 µM), moxifloxacin was pro‐arrhythmic in the isolated rabbit CM (33%), in the hESC‐CM clusters (18%), and in the methoxamine rabbit (17%). Dofetilide and E‐4031 induced EADs or TdP in all assays (50–83%), and the induction correlated with a significant increase in beat‐to‐beat variability of repolarization. CONCLUSION AND IMPLICATIONS Isolated cardiomyocytes lack specificity to discriminate between TdP liability of the IKr blocking drugs moxifloxacin and dofetilide or E4031.

Assessment of Testing Methods for Drug-Induced Repolarization Delay and Arrhythmias in an iPS Cell–Derived Cardiomyocyte Sheet: Multi-site Validation Study

“…In previous studies using the Langendorff-perfused rabbit heart, 0.5 mM of E-4031 induced early afterdepolarization and triggered activity (19,20). Also, in human embryonic stem cell-derived cardiomyocyte clusters, 1 mM of E-4031 induced early afterdepolarization in half of the clusters (11). Meanwhile, in the human engineered heart tissue sheet made of the human embryonic stem cells, 10 nM of E-4031 was reported to induce arrhythmias (12).…”

Electrophysiological and contractile function of cardiomyocytes derived from human embryonic stem cells

“…Nifedipine, an L-type calcium channel blocker, shortens APD in single cells (Peng et al, 2010). E-4031 blocks the rapid delayed rectifier channel, and prolongs potential duration in both single (Otsuji et al, 2010; Pekkanen-Mattila et al, 2010; Peng et al, 2010; Sartiani et al, 2007) and multicellular preparations (hEBs or small cell aggregates) (Braam et al, 2010; Caspi et al, 2009; He et al, 2003; Jonsson et al, 2010; Nalos et al, 2012). E-4031 has a greater effect on action potential duration at later stages of differentiation in multicellular preparations (Caspi et al, 2009; Otsuji et al, 2010).…”

Cardiomyocytes from human pluripotent stem cells: From laboratory curiosity to industrial biomedical platform

“…Work from GlaxoSmithKline cross-compared pharmacological responses of hPSC-CMs and animal models, concluding that the human cells offered a reliable and cost-effective surrogate to preclinical in vitro testing [41]. Direct comparison between CMs isolated from hPSCs or dog and rabbit hearts showed the human cells more accurately predicted moxifloxacin-induced cardiotoxicity [42]. Studies have extended to screening antivirals as a treatment for B3-strain of coxsackievirus, a major causative agent for viral myocarditis [43].…”