Patel, Aarti

Importance Friedreich ataxia (FA), a fatal, autosomal recessive disorder caused by pathogenic variants in the frataxin ( FXN ) gene, is characterized by progressive neurologic and cardiac disease, with cardiac disease being the major cause of death. Preclinical studies have demonstrated that systemic administration of AAVrh.10hFXN, an rh.10 serotype cardiotropic adenoassociated virus (AAV) vector expressing the normal human FXN coding sequence, reverses the cardiomyopathy in FXN-deficient mice. Objective To assess the safety and preliminary efficacy of administration of AAVrh.10hFXN to adults with FA cardiomyopathy. Design, Setting, and Participants This nonrandomized clinical trial evaluates the pooled data of 2 independent, open-label, dose-escalation trials that used the same gene therapy vector and similar clinical protocols among patients with FA cardiomyopathy at academic medical centers. Data were collected from February 22, 2022, to October 4, 2025, for trial 1 and from February 14, 2023, to September 10, 2025, for trial 2 and analyzed together from November 5, 2025, to March 12, 2026. Intervention AAVrh.10hFXN, administered intravenously in 3 dose cohorts (1.8 × 10 11 , 5.6 × 10 11 , and 1.2 × 10 12 vector genomes per kilogram of body weight). Main Outcomes and Measures In addition to safety as the primary outcome, multiple parameters of exploratory end points were assessed, including cardiac biopsy levels of FXN protein, cardiac magnetic resonance imaging–derived left ventricular mass index (LVMI), and serum high-sensitivity (hs) troponin I. Results Seventeen patients with FA cardiomyopathy (mean [SD] age, 25 [6] years; 11 [65%] female) were followed up for a mean (SD) of 20 (8) months. There were 4 serious adverse events, 3 possibly related to prednisone immunosuppression and 1 possibly vector-related myocarditis 12 months after therapy, all of which resolved. Other adverse events were transient, nonserious, or not treatment related. In all 8 patients with cardiac biopsy 3 months after therapy, there were higher levels of cardiac FXN (dose cohort 1, 20%; cohort 2, 81%; cohort 3, 123%). After therapy, LVMI was lower by at least 10% in 9 patients and stabilized in 8 patients. Excluding the patient with myocarditis, posttherapy values of serum hs troponin I were lower by at least 10% in 15 patients and higher by at least 10% in 2 patients. Conclusions and Relevance Findings of this nonrandomized clinical trial suggest that intravenous administration of AAVrh.10hFXN was well tolerated and may be a potential treatment for FA cardiomyopathy, as evidenced by preliminary improvement in exploratory efficacy end points. Trial Registration ClinicalTrials.gov Identifiers: NCT05302271 and NCT05445323

Background: Cardiac disease is the leading cause of premature mortality in Friedreich Ataxia (FA). However, validated prognostic indicators or early imaging biomarkers that can reliably predict cardiac events are lacking. To address this gap, we created a multicenter FA cardiac registry to characterize disease progression and identify early echocardiographic (echo) predictors of major adverse cardiac events (MACE). Methods: FA subjects from 6 North American centers with at least two echos performed ≥5 years apart were included. Demographics, FA-specific disease characteristics, and MACE (a composite of death, heart failure hospitalization, aborted sudden cardiac death, and/or life-threatening arrhythmia) were abstracted. Digital echo images were re-read at a centralized core lab. Paired T tests were utilized for comparison of the normally distributed first and second echo parameters, and logistic regression models were utilized to evaluate for predictors of MACE. Results: Of 115 subjects, 52 (45%) were female. Mean age at diagnosis was 10 ± 3 years, median GAA1 repeat length (a marker of genetic severity) was 700 (range 66–1200), and median age at first analyzed echo was 12 years (range 4-36). MACE occurred in 35 (30%) of the cohort. Serial echocardiograms demonstrated progressive worsening of multiple cardiac parameters over time, including markers of ventricular thickness and hypertrophy, chamber size, systolic function, and novel markers of atrial and ventricular strain (Table 1). On univariate analysis, several markers of hypertrophy and systolic function from the earliest analyzed echo predicted MACE. However, after adjusting for age of diagnosis, GAA1 repeat length, and collinearity among variables, only posterior wall thickness in diastole (PWTd) remained an independent predictor of MACE (odds ratio 1.8 per mm increase, 95% CI 1.1–3.3, p = 0.028). Conclusions: This multicenter FA registry identifies early posterior wall thickness as a significant and independent predictor of major adverse cardiac events in FA. Each millimeter increase in PWTd on early echo is associated with nearly double the odds of MACE. This commonly acquired parameter is often overlooked and may serve as a powerful early marker of cardiac risk. Further investigation of PWTd as a potential surrogate endpoint for therapeutic trials in FA is warranted.