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FDA & Stealth Biotherapeutics: Allow Individuals with Barth Syndrome Access to Elamipretide

Elamipretide, produced by Stealth BioTherapeutics, is an experimental drug which has been shown to reduce debilitating fatigue and potentially improve important baseline health measures in people with the ultra-rare disease Barth syndrome.  Given the risk of life-threatening cardiac complications in this population, individuals with Barth syndrome cannot wait for additional studies of elamipretide before receiving access. 


Dr. John Lynn Jefferies, including 25 additional physicians who serve as key opinion leaders (KOLs) in the care of Barth syndrome, undersigned a letter to FDA in October 2020. In their appeal, they asked the Agency to encourage the sponsor to submit a new drug application (NDA) for elamipretide for the treatment of Barth syndrome and that FDA commit to promptly reviewing the NDA. Click the button below to read the letter.

FDA has repeatedly signaled the importance of incorporating the “patient voice” in drug development. This is especially critical in rare diseases. The 21st Century Cures Act requires sponsors to include and FDA consider the patient perspective.  The voice of affected individuals and organizational advocacy is critical in communicating to FDA the extreme unmet need in Barth syndrome. In 2018, the externally-led Patient-Focused Drug Development meeting on Barth syndrome revealed that 100% of patients experience fatigue, 90% (based on cardiomyopathy occurrence) have heart failure or other life-threatening cardiac complications related to their disease, and 100% of patients surveyed would like access to therapies that improve quality of life even if they do not reverse disease.

As of today, there are only 126 known affected living individuals in the U.S. In a very small clinical trial like TAZPOWER, it is very challenging to see compelling clinical data that reach statistical significance. The majority of trial participants experienced improvements in fatigue, strength and quality of life. The patient voice becomes particularly critical in this setting. We are asking FDA and Stealth to work together to provide access to elamipretide to people with Barth syndrome as soon as possible.


In the open-label extension portion of the Phase 2/3 TAZPOWER study, treatment with elamipretide resulted in a 27% increase in average cardiac stroke volume, or the amount of blood pumped by the heart's left ventricle per contraction. Most patients with Barth syndrome have underlying heart disease, often leading to heart failure and death. Even a modest improvement in heart function could potentially represent an opportunity for longer and improved quality of life for an individual with Barth syndrome.

People with Barth syndrome who were enrolled in the open-label extension of the TAZPOWER clinical trial for one year showed positive changes in functional assessments such as fatigue, muscle strength, and endurance. Compared to natural history information (data collected from patients not receiving an experimental treatment), patients receiving elamipretide showed an average improvement of 116.92 meters on their six-minute walk test compared to 1.73 meters for those in the natural history group over the same period of time.  Improvements were also seen in muscle strength and sit-to-stand assessments. Quality of life for people with Barth syndrome is of utmost importance and can be improved by access to therapies which increase the individual’s strength and endurance as well as reduce fatigue.

The trial also showed elamipretide is generally safe and well-tolerated, which builds upon Stealth’s experience testing this experimental drug for other, more prevalent conditions.


Barth syndrome is a serious and life-threatening genetic disorder, primarily affecting males. It is caused by a mutation in the tafazzin gene resulting in an inborn error of lipid metabolism.  Cardinal characteristics of this multi-system disorder often include combinations and various degrees of cardiomyopathy, neutropenia, muscle weakness, growth delay, fatigue and exercise intolerance.  These symptoms limit the day-to-day quality of life for people with Barth syndrome, and often lead to life-threatening complications and early death. In the last 12 months, the ultra-rare global Barth syndrome population has lost seven patients to complications of the disease. Given that there are currently 255 in the world living this disease, this means that nearly 3% of the world’s cohort has succumbed in the last year, predominantly due to cardiac-related causes. Although improved diagnosis, symptom monitoring and symptom management have improved the survival rate, heart disease (cardiomyopathy, sudden cardiac death, heart failure) remains the primary cause of premature death in the Barth syndrome population.

Given the results of the trial, Stealth BioTherapeutics and FDA must give patients with Barth syndrome, who currently have no other choice for treatment, access to elamipretide. FDA has emphasized the importance of the patient voice, especially for rare conditions without FDA-approved treatment options. As summarized in the “Voice of the Patient: Barth Syndrome” report, people with Barth syndrome experience compromised quality of life caused by fatigue and other symptoms. Affected individuals and families deserve the right to have access to elamipretide in order to potentially experience improvements as seen in the clinical trials.

Data from the clinical trial evaluating the use of elamipretide in Barth syndrome demonstrate meaningful potential benefit and low risk, particularly evidenced by people who participated in open-label extension and have used elamipretide for over one year. Individuals with Barth syndrome have been informed during the course of elamipretide clinical trials and are willing to accept the potential risks given the potential for benefit and the absence of any other FDA-approved therapies.

Therefore, we ask Stealth and FDA to address this issue with urgency by submitting and approving an NDA for elamipretide in Barth syndrome based on existing evidence from clinical trials.

Individuals with Barth syndrome have a reduced quality of life and many are dying. We need treatment choices now.

If you have any questions or would like more information, please visit our elamipretide resources page by clicking the button below or email

Barth syndrome is an ultra-rare disease, but we certainly are a global #BarthSTRONG family. In less than two weeks, your advocacy helped generate over 4000 signatures and nearly 1000 testimonials!

Both FDA and Stealth BioTherapeutics are hearing our collective voice.  Although nothing is at all guaranteed, we believe we are one step closer to gaining access to elamipretide, potentially the first-ever therapy specifically for Barth syndrome.

Our advocacy work is not over; however, your response has shown how powerful we are when we work together.

Click the button below to read the submitted community petition.

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