Benefits of early in vitro screening for seizure liability in problem solving and decision making

Abstract

Seizure liability remains a significant cause of attrition throughout drug development both in pre-clinical and clinical studies. This emphasizes the need for improved methodologies to detect seizure liability prior to in vivo toxicology studies, ideally with reduced reliance on animals and better translation to humans. Much like the Comprehensive in vitro Proarrhythmia Assay (CiPA) which is now widely accepted for early assessment of cardiovascular safety, we have developed an approach utilizing hiPSC-neuronal cell microelectrode array (MEA) and ion channel screening for early seizure prediction. In our MEA assay, seizurogenic compounds were identified correctly with high predictivity, and correlations were observed between the in vitro and clinical exposures of many therapies known to cause seizure. We have used these assays in the early phase of nonclinical testing, and successfully de-risked and prioritized a chemical series. For example, after testing a number of compounds, one was identified with low seizure risk compared to the others in the series – this compound had distinct structural features. In another study of compounds undergoing nonclinical testing, exposures that caused no CNS signs or convulsions in rats, aligned with the results of the MEA study. Conversely, where convulsions were reported in rats, seizurogenic responses were present in the MEA study at comparable concentrations. Since these studies use human derived cells, they can be used to determine the human relevance of seizures observed in nonclinical studies. For example, nonclinical testing of a compound caused convulsions only in dogs. Testing a range of metabolites in the MEA assay revealed only the dog-specific metabolite caused seizurogenic phenotype. In addition, screening this metabolite against a panel of ion channel targets revealed a hit, providing mechanistic insight and also the opportunity to redesign the compound to eliminate the liability. Collectively, these studies demonstrate the utility of this approach for early seizure prediction to provide mechanistic information, early de-risking, and support optimal drug design using human in vitro models.