Primary mitochondrial disease (PMD) refers to a group of disorders caused by mutations in the patient’s nuclear DNA (nDNA) and/or mitochondrial DNA (mtDNA), which limits a patient’s ability to adequately and appropriately produce energy for the body (also known as adenosine triphosphate or ATP). There are more than 250 identified genetic defects that can cause PMD.

Signs and symptoms of PMD are different for each person, but often affect multiple organ systems, including the skeletal muscle, central nervous system, eyes, heart and kidneys. For a sample list of symptoms, please visit The United Mitochondrial Disease Foundation (UMDF), Mito Action or Foundation for Mitochondrial Medicine (FMM) websites.

Primary mitochondrial myopathy (PMM) is a PMD, as described above, affecting predominately, but not exclusively, a patient’s skeletal muscle. Skeletal muscle myopathy can include muscle weakness (especially in the upper and lower limbs), fatigue, exercise intolerance and pain. Other symptoms may also be present.

The study required one in-person enrollment visit, at which time the patient met with the clinical investigator at one of the study sites. The purpose of this single visit was to collect and review existing medical information, as well as to complete the questionnaires and functional assessments. Following the enrollment visit, patients were asked to participate in telephone interviews with their clinical investigator every six months to discuss any change in their disease.

MMPOWER-3 is a phase 3, randomized, double-blind, parallel-group, placebo-controlled trial to evaluate the efficacy and safety of daily subcutaneous (under the skin) injections of elamipretide in patients with PMM followed by an open-label treatment extension.

The trial will primarily assess the change in distance walked during the 6MWT and patient-reported fatigue using a PMM-specific questionnaire, the Primary Mitochondrial Myopathy Symptom Assessment (PMMSA). Secondarily, the trial will evaluate changes in fatigue during activities using the PMMSA, quality of life, impact on the patient’s most bothersome symptom on the PMMSA, and safety and tolerability of treatment with elamipretide.

In MMPOWER-3, Stealth is evaluating elamipretide delivered by subcutaneous (under the skin) injection. Elamipretide is an investigational drug that associates with cardiolipin, a key structural component of the inner mitochondrial membrane, and has shown to improve mitochondrial function in preclinical and early clinical studies.

Patients that have a genetic confirmation of mitochondrial disease are potentially eligible for participation of MMPOWER-3. The clinical trial investigator will identify potential patients.

Yes, patients that have previous genetic testing results available which confirmed mitochondrial disease and are interested in participating in MMPOWER-3 should visit ClinicalTrials.gov for more information including the locations and study site contact information.

Subjects enrolled in the trial will receive daily injections of elamipretide or placebo for six months. At the end of the six month period, subjects may elect to participate in the open-label treatment extension and will receive elamipretide for the duration of the trial.

No trial-specific hospitalization is required.

Patients are allowed to continue their current treatments and therapies during the course of this trial.

In the double-blind treatment assessment period, neither patients nor investigators participating in MMPOWER-3 are aware of the treatment assignment, elamipretide or placebo.

In the optional open-label extension period, patients participating in MMPOWER-3 can receive elamipretide to allow for evaluation of long-term safety and tolerability.