Assessing variability of hERG data generated using a mock action potential waveform and automated patch clamp platforms – A HESI-coordinated, multi-laboratory comparison of 28 drugs across 3 platforms

Abstract

New ICH E14/S7B Q&As describe how nonclinical data, including cardiac ion channel pharmacology studies generated following best practices, can support clinical interpretation of QT studies as part of an integrated proarrhythmic risk assessment. Automated patch clamp (APC) systems offer high-throughput capabilities and remove technical barriers to generate cardiac ion channel pharmacology data compared to the traditional, manual patch clamp technique. These advantages are achieved by adjusting experimental aspects such as including the use of fluoride to reduce leak current, fixed duration recordings across all cells, and the use of multi-hole recording chips to optimize catching a cell. Literature search revealed limited information regarding the consequences of these changes on cardiac ion channels pharmacology. Additionally, variability of APC data generated using the same voltage protocol across different laboratories operating either the same or different platforms is unclear. This study is a part of a HESI-coordinated international effort to assess block potencies of 28 drugs on cardiac hERG current using APC systems. Four laboratories participated in the study: one operated QPatch 48; one, SyncroPatch 384; and two, Qube 384. The voltage protocol resembled a ventricular action potential (ICH S7B Q&A 2.1), and was presented at 0.2 Hz. All laboratories generated data at ambient or room temperature (RT). Two laboratories additionally generated data at near physiological temperature (PT). Two laboratories tested single-hole recording chips; one laboratory multi-hole; and one laboratory tested both. Solution samples were collected by two laboratories for concentration verification. Overall variability of the hERG data was estimated by first removing drug-specific effects and laboratory-specific effects, and then pooling the adjusted values. Laboratory-specific systematic tendencies were identified. Comparison of RT to near PT data revealed systematically lower potencies at room temperature across all drugs. Concentration verification of 13 drugs by one laboratory revealed a relationship between the amount of drug lost during the assay and the hydrophobicity of the drug. Variability measures will be shared on the poster. Results of this study will inform the expected variability of hERG current data under best practice recommendations feasible for APC platforms and using these data to support integrated nonclinical risk assessment.