Abstract 9852: Targeting Mek/Erk Signaling in the Treatment of Mitral Valve Prolapse

Abstract

Introduction: Mitral valve prolapse (MVP) is one of the most common forms of cardiac valve disease, affecting 1 in 40 humans and ~70% of small breed dogs. There are no effective nonsurgical treatments for MVP and therapeutic efforts have been hindered due to an incomplete understanding of its fundamental causes. Recent studies by our group have described the genetic basis for non-syndromic MVP and have provided new insights into molecular processes that underlie the disease. We have used this genetic information to identify druggable targets that can provide a non-surgical option for humans. In particular, we have identified the MEK/ERK pathway as the major disease initiating pathway and prolonged hyperactivation of MEK/ERK drives disease progression and severity. Hypothesis: Pharmacological blockade of MEK/ERK activities will sufficiently arrest the disease pathway and maintain the valves in a sub-clinical condition. Methods and Results: The FDA-approved MEK1 inhibitor Trametinib was administered to Dzip1 S24R/+ mice; a disease model that phenocopies human MVP. Preliminary results suggest safety concerns in mice associated with chronic administration of Trametinib (1 mg/kg/day). Animals demonstrated signs of cardiotoxicity on echocardiography, including left atrial enlargement; a reduction in E/A wave intensity; left ventricular wall movement abnormalities; prolonged isovolumetric relaxation time, and a reduced ejection fraction. As such, our lab has focused our efforts on identifying novel MEK1 inhibitors with a favorable safety profile. Utilizing a machine learning based workflow, we have identified highly selective MEK1 inhibitors with retained activity (<100nM IC50 values); high gastrointestinal absorption (>85%); favorable predicted LD50 values (>1,000 mg/kg), and devoid of major cytochrome interactions. Conclusions: MEK1 may serve as a druggable target in the treatment of mitral valve prolapse; however, currently available MEK inhibitors demonstrate limiting toxicities. Future studies will involve in vivo administration of our novel compounds to Dzip1 S24R/+ mice. We envision results from this study will help guide the development of systemic or targeted therapies for the use in human patients with mitral valve prolapse.