BASELINE DEMOGRAPHICS OF MMPOWER-3: A CLINICAL TRIAL OF ELAMIPRETIDE IN PRIMARY MITOCHONDRIAL MYOPATHY

INTRODUCTION: Primary mitochondrial myopathies (PMMs) are genetic disorders of the mitochondrial respiratory chain affecting predominantly, but not exclusively, skeletal muscle. Clinical manifestations include fatigue, exercise intolerance, and muscle weakness which adversely affect physical function, exercise capacity, and quality of life. The investigational product elamipretide localizes to the inner mitochondrial membrane and associates with cardiolipin to improve mitochondrial respiratory chain efficiency and adenosine triphosphate production. OBJECTIVE: MMPOWER‐3 is an ongoing, phase‐3 randomized, double‐blind, placebo‐controlled trial evaluating the efficacy/ safety/tolerability of elamipretide. METHODS: Genetically‐confirmed PMM patients were administered daily subcutaneous injections of elamipretide 40 mg or placebo for 24 weeks. A 144‐week open label treatment extension will follow for eligible patients. RESULTS: As of March 7, 2019, 147 subjects (50 male, 83 female, 14 gender not provided; mean age: 44.2 years; 84% white) were enrolled. Genetic tests showed that the majority of defects (75.5%) were mitochondrial DNA mutations, while the remainder were nuclear DNA mutations. At baseline, the mean distance walked for evaluable patients (n=145) on the 6‐minute walk test was 329.8±77.6 m, the mean score for total fatigue on the Primary Mitochondrial Myopathy Symptom Assessment questionnaire (n=141) was 10.5±2.4, and the mean T‐score for the Neuro‐QOL Fatigue Short Form (n=145) was 54.3±7.9. Complete descriptions for assessments will be provided. SUMMARY/CONCLUSION: Compared to literature control subject and previous trial data, patients in the MMPOWER‐3 trial were impaired in their baseline functional and patient‐reported assessments. MMPOWER‐3 will provide safety and efficacy data for elamipretide in patients with PMMs.