A Comprehensive Approach to Cardiotoxicity Assessment using Adverse Outcome Pathways

Cardiovascular disease, the leading cause of mortality worldwide, is exacerbated by environmental chemicals. However, current regulatory guidelines inadequately address cardiotoxicity, relying heavily on animal testing and apical endpoints. Adverse Outcome Pathways (AOPs) offer a transformative approach by systematically elucidating the underlying mechanisms between chemical exposures and adverse health effects. Within the EU-H2020 Project ALTERNATIVE (www.alternative-project.eu), we aim to rethink regulatory assessment of cardiotoxicity by developing a new basis for testing.We integrated multiple lines of evidence for heart damage caused by environmental chemicals using the AOP framework, employing an evidence-based approach by systematically retrieving epidemiological and toxicological data. In the toxicological systematic review, data was extracted from 362 in vivo and in vitro studies, resulting in over 1100 key event (KE) and over 2500 key event relationship (KER) entries, encompassing 138 unique KEs and 207 unique KERs reported at least three times. Epidemiological evidence was utilized in the identification of relevant adverse outcomes (AO). We focused on the most frequently observed KERs to integrate this evidence into an AOP network covering various aspects of cardiotoxicity, including electrophysiological, contractile, and structural effects. Central to the network are pathways describing mitochondrial dysfunction leading to left ventricular impairment. Based on the established AOP network, we developed an Integrated Approach to Testing and Assessment (IATA) for cardiotoxicity, aligned with the Next Generation Risk Assessment approach. This framework combines existing non-animal methods with those developed by the ALTERNATIVE project to guide the assessment of the cardiotoxic potential of chemicals, reducing the need for animal testing.