Primary Mitochondrial Myopathy Trials


As listed on, Stealth BioTherapeutics Inc. is conducting two studies in primary mitochondrial myopathy (PMM):
  • RePOWER: A prospective, non-interventional study of patients with PMM. RePOWER is fully enrolled.
  • MMPOWER-3: A phase 3, randomized trial to evaluate the efficacy and safety of elamipretide in patients with PMM followed by an open-label treatment extension with elamipretide. MMPOWER-3 is fully enrolled.
If you or a loved one has been diagnosed with PMM, you may be interested in learning more about RePOWER and MMPOWER-3.
About the Studies
About RePOWER Study

• RePOWER was a prospective, non-interventional study. This means no investigational treatment was given.

• The study primarily assessed the relationship between a patient’s diagnosis and experience living with PMM, as well as local and regional differences in care and diagnosis.


• Able to walk.

• Between 16 years to 80 years of age.

• Had a clinical presentation of PMM, such as exercise intolerance, fatigue and/or muscle weakness or physical exam findings of myopathy.

*Other eligibility criteria applied


• Patients were asked to complete a questionnaire about their current symptoms and quality of life, and perform certain functional assessments, including a test called the six-minute walk test (6MWT).

Study Enrollment

• The study enrolled approximately 400 patients, aged 16-80, across North America, Europe and Australia.

• For more information, please visit

Frequently Asked Questions About RePOWER

What are primary mitochondrial disease (PMD) and primary mitochondrial myopathy (PMM)?

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.

What did participation in RePOWER entail?

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.

About MMPOWER-3 Trial

• 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.


• Have previous genetic testing results available.

• Able to walk.

• Between 16 years to 80 years of age.

• Diagnosed with PMM in the opinion of the investigator.

*Other eligibility criteria applied

Trial Enrollment

• The trial enrolled approximately 200 patients, aged 16-80, across North America and Europe. Visit for a list of trial sites.

Clinical Trial Sites in North America for MMPOWER-3
1. Seattle Children's Hospital

Seattle, WA 98105
Contact: Laurie Guidry
[email protected]

2. Stanford University School of Medicine

Stanford, CA 94305-5208
Contact: Thu Quan
[email protected]

3. UCSD (University of California, San Diego)

La Jolla, CA 92093
Contact: Jessica Reit
[email protected]

4. University of Utah Hospital

Salt Lake City, UT 84132
Contact: Jenny Billy, BS,
[email protected]

5. Children's Hospital Colorado

Aurora, CO 80045
Contact: Michelle Hite
[email protected]

6. The University of Texas

Houston, TX 77030
Contact: Stephanie Maldonado
[email protected]

7. Baylor College of Medicine

Houston, TX 77030
Contact: Dr. May Ali
[email protected]

8. Rare Disease Research, LLC

Atlanta, GA 30318
Contact: Han C. Phan, MD
[email protected]

9. Cleveland Clinic Neurological Institute

Cleveland, OH 44195
Contact: Irys Caristo
[email protected]

10. Akron Children’s Hospital

Akron, OH 44308
Contact: Hilary Tonni
[email protected]

11. Children's Hospital of Pittsburgh

Pittsburgh, PA 15224
Contact: Michele Graham

12. The Children's Hospital of Philadelphia

Philadelphia, PA 19104
Contact: Brianna Soreth
[email protected]

13. Columbia University Medical Center

New York, NY 10032
Contact: Dr. Michio Hirano

14. Massachusetts General Hospital

Boston, MA 02114
Contact: Erica Kelly
[email protected]

Contact: Michele Guyette
[email protected]

15. McMaster University Medical Center

Hamilton, Ontario, L8N 3Z5
Contact: Dr. Mark Tarnopolsky

16. Adult Metabolic Diseases Clinic

Vancouver, B.C. Canada V5Z 1M9
Contact: Dr. Anna Lehman

Frequently Asked Questions About MMPOWER-3

What is MMPOWER-3 studying?

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.

What is the drug being studied, and how does it work?

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.

Enrollment in MMPOWER-3

How will investigators select patients to participate in the MMPOWER-3 trial?

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.

Are patients potentially eligible to participate in MMPOWER-3 if they were not part of RePOWER?

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

Duration of Trial and Terms of Treatment

How long does MMPOWER-3 last?

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.

Is hospitalization required?

No trial-specific hospitalization is required.

Will patients be required to discontinue their current treatment and supplements if selected to participate?

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

What is double-blind treatment assessment?

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

What is open-label extension?

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.

Other Commonly Asked Questions

Can a patient withdraw from the clinical trial after it has begun?

Yes, patients have the right to withdraw from a clinical trial at any time.

If a patient doesn’t qualify for MMPOWER-3, is there a future study or another pathway for patients to be treated with elamipretide?

Information about Stealth BioTherapeutics’ ongoing clinical trials can be found at or in Programs & Pipeline at

We believe the best way for patients to access medicines prior to approval is through participation in clinical trials. However, in some rare and very specific circumstances when enrollment into a clinical trial is not feasible, physicians caring for patients with a life-threatening or imminently debilitating disease or condition may seek special access to investigational medicines (referred to as compassionate use or also known as expanded access). Read more about Expanded Access on under the Our Company tab.