Windley Monique J, Abi-Gerges Najah, Fermini Bernard, Hancox Jules C, Vandenberg Jamie I, Hill Adam P
Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, 405 Liverpool Street, Sydney, NSW 2010, Australia; St. Vincent's Clinical School, University of New South Wales, Sydney, NSW 2052, Australia.
AnaBios Corp., 3030 Bunker Hill St., San Diego, CA 92109, USA.
J Pharmacol Toxicol Methods. 2017 Sep;87:99-107. doi: 10.1016/j.vascn.2017.02.017. Epub 2017 Feb 10.
The Comprehensive in vitro Proarrhythmic Assay (CiPA) aims to update current cardiac safety testing to better evaluate arrhythmic risk. A central theme of CiPA is the use of in silico approaches to risk prediction incorporating models of drug binding to hERG. To parameterize these models, accurate in vitro measurement of potency and kinetics of block is required. The Ion Channel Working Group was tasked with: i) selecting a protocol that could measure kinetics of block and was easily implementable on automated platforms for future rollout in industry and ii) acquiring a reference dataset using the standardized protocol.
Data were acquired using a 'step depolarisation' protocol using manual patch-clamp at ambient temperature.
Potency, kinetics and trapping characteristics of hERG block for the CiPA training panel of twelve drugs were measured. Timecourse of block and trapping characteristics could be reliably measured if the time constant for onset of block was between ~500ms and ~15s. Seven drugs, however had time courses of block faster than this cut-off.
Here we describe the implementation of the standardized protocol for measurement of kinetics and potency of hERG block for CiPA. The results highlight the challenges in identifying a single protocol to measure hERG block over a range of kinetics. The dataset from this study is being used by the In Silico Working Group to develop models of drug binding for risk prediction and is freely available as a 'gold standard' ambient temperature dataset to evaluate variability across high throughput platforms.
综合体外致心律失常试验（CiPA）旨在更新当前的心脏安全性测试，以更好地评估心律失常风险。CiPA的一个核心主题是使用计算机方法进行风险预测，其中纳入了药物与hERG结合的模型。为了对这些模型进行参数化，需要准确地体外测量阻断的效力和动力学。离子通道工作组的任务是：i）选择一种能够测量阻断动力学且易于在自动化平台上实施以便未来在行业中推广的方案，以及ii）使用标准化方案获取一个参考数据集。
在环境温度下使用手动膜片钳通过“阶跃去极化”方案获取数据。
测量了十二种药物的CiPA训练组对hERG阻断的效力、动力学和捕获特性。如果阻断开始的时间常数在约500毫秒至约15秒之间，则可以可靠地测量阻断的时间进程和捕获特性。然而，有七种药物的阻断时间进程快于这个临界值。
在此我们描述了用于CiPA的hERG阻断动力学和效力测量的标准化方案的实施情况。结果突出了在确定一种能够在一系列动力学范围内测量hERG阻断的单一方案时所面临的挑战。本研究的数据集正被计算机工作组用于开发药物结合风险预测模型，并且作为一个“金标准”环境温度数据集可免费获取，以评估高通量平台之间的变异性。
