Assay Translation of Preclinical Cardiovascular (CV) Assessments

Combinations of in vitro, ex vivo and in vivo animal testing have historically played a vital role in the research and the development of new therapeutic treatments. However, understanding the translation of these data across assays, as well as how these data translate to humans has proven to be challenging, especially with regards to the complex and integrated mechanism involved in blood pressure (BP) and heart rate (HR) regulation. We have evaluated the translation of several in vitro and ex vivo assays to in vivo CV assessments, as well as the translation of rat to large animal (LA), and LA to human BP and HR data. To investigate the translation of in vitro and ex vivo findings to in vivo hemodynamic results, 41 compounds with direct, indirect or unknown mechanisms of BP and/or HR modulation as well as 13 negative controls were evaluated in ppMLC (phosphorylation of myosin light chain), functional pharmacology (19 receptors/ion channels), ex vivo aortic vascular reactivity and isolated guinea pig Langendorff heart assays. Results from the in vitro and ex vivo assays were compared to in vivo conscious rat telemetry BP and HR findings. Vascular aortic relaxation and the paced guinea pig isolated heart assay detected 40% and 35%, respectively, of the in vivo positive compounds within 10× of the free Cmax that produced a 5 mmHg change in BP. The guinea pig isolated heart assay had a lower false positive rate than the aortic assay. The ppMLC assay detected 30% of compounds targeted at kinases within 10× the 5 mmHg in vivo Cmax concentration, but did not identify compounds with BP/HR risk with non‐kinase primary targets. Additional translation analyses were performed to more fully understand in vivo rat to large animal hemodynamic changes, as well as large animal preclinical to phase 1 clinical BP and HR measures. 83 compounds were assessed in both rat and LA studies. The specificity observed (true positive rate) was 71% and sensitivity (true negative rate) was 84%. Suggesting that rat is an effective model for evaluating hemodynamic risk. In evaluating 79 compounds in both LA and preclinical Phase 1 trials there was also good specificity (79%) and sensitivity (78%). These studies demonstrate that several in vitro/ex vivo assays are useful for identifying in vivo BP and HR changes; however due to the complexity of the CV system, have limited predictivity. Preclinical in vivo BP and HR testing was demonstrated to translate not only across species but also to the clinic. These data confirm the importance of pre‐clinical in vitro, ex vivo and animal models in the examination of the efficacy and safety of drugs, and the usefulness of these models for selection of compounds for advancement to clinical testing and ultimately the treatment of disease.