AAV-mediated Delivery of Plakophilin-2a Arrests Progression of Arrhythmogenic Right Ventricular Cardiomyopathy in Murine Hearts: Preclinical Evidence Supporting Gene Therapy in Humans

ABSTRACT Background Pathogenic variants in plakophilin-2 (PKP2) cause arrhythmogenic right ventricular cardiomyopathy (ARVC), a disease characterized by life-threatening arrhythmias and progressive cardiomyopathy leading to heart failure. No effective medical therapy is available to prevent and/or arrest the disease. We tested the hypothesis that AAV-mediated delivery of the human PKP2 gene to an adult mammalian heart deficient in PKP2 can arrest disease progression and significantly prolong survival. Methods Experiments were carried out using a cardiac-specific, tamoxifen (TAM)-activated PKP2 knockout murine model (PKP2-cKO). The potential therapeutic, AAVrh.74-PKP2a (RP-A601), is a recombinant AAVrh.74 gene therapy viral vector encoding the human PKP2 variant A (PKP2a). AAVrh.74-PKP2a was delivered to adult mice by a single tail vein injection either before or after TAM-activated PKP2-cKO. PKP2 expression was confirmed by molecular and histopathologic analyses. Cardiac function and disease progression were monitored by survival analyses, echocardiography and electrocardiography. Results Consistent with prior findings, loss of PKP2 expression caused 100% mortality within 50 days after TAM injection. In contrast, AAVrh.74-PKP2a-mediated PKP2a expression resulted in 100% survival for more than 5 months (at study termination). Echocardiographic analysis revealed that AAVrh.74-PKP2a prevented right ventricle dilation, arrested left ventricle functional decline, and mitigated arrhythmia burden. Molecular and histological analysis showed AAVrh.74-PKP2a– mediated transgene mRNA and protein expression and appropriate PKP2 localization at the cardiomyocyte intercalated disc. Importantly, therapeutic benefit was shown in mice receiving AAVrh.74-PKP2a after disease onset. Conclusion These preclinical data demonstrate the potential for AAVrh.74-PKP2a (RP-A601) as a therapeutic for PKP2-related ARVC in both early and more advanced stages of disease.