Drug-induced cardiotoxicity is among the leading causes for drug failures and became a major safety concern during pharmaceutical development. A number of animal models using rabbits, rats, mice, pigs and dogs have been developed aiming to detect off-target effects of drugs early in preclinical development. However, physiological differences of the various species did not always correctly predict the clinical outcome. Since there is no clear understanding on the primary mode of action leading to delayed cardiotoxicity induced by anthracyclines, also the development of relevant in vitro tests is a challenge.
A recent European project was carried out targeting the reduction on the number of animals for repeated dose toxicity testing. Since irreversible heart failures are well described for cancer patients receiving a standard medication with anthracyclines, cumulative dose dependent cardiotoxicity has been selected as a case study to elucidate the needs for the development of clinically relevant in vitro tests. Three major challenges have been addressed in this study: i) the use of a humanised in vitro model based on induced pluripotent stem cell derived cardiomyocytes; ii) the development of a sophisticated experimental protocol addressing the detection of chronic toxicities after repeated dosing of the drug and iii) the identification of sensitive biomarker that are pointing to irreversible changes in the cellular physiology and functionality of human cells.
The analysis of the transcriptomic data revealed modulations in the gene expression profile indicating effects of three different anthracyclines on the formation of sarcomeric structures, the regulation of ion homeostasis and the induction of apoptosis. The relevance of this genetic signature was verified at a higher biological level by investigating protein expressions and the functionality of cardiomyocytes using immunocytochemistry and impedance measurements.
The recent study illustrates how transcriptomics studies can guide the development of in vitro tests for the detection of adverse effects for which the primary mode of action has not been identified.