Stealth BioTherapeutics Submits Elamipretide New Drug Application to FDA for Treatment of Barth Syndrome

 

Stealth BioTherapeutics Corp, announced the submission of a New Drug Application (NDA) to the U.S. Food and Drug Adminstration (FDA) for elamipretide, the company's lead product candidate, for the treatment of Barth syndrome, an ultra-rare genetic condition with no FDA- or EMA-approved therapies.

 

"Children and young adults affected by Barth syndrome are suffering from life limiting, progressive cardiomyopathy, exercise intolerance, and debilitating fatigue for which there are no approved treatment options," said Chief Executive Officer Reenie McCarthy. "We initiated our Barth syndrome development efforts at the request of the Barth syndrome community. We respect the patient community's perspective regarding its tolerance for some uncertainty of benefit in considering therapies for this ultra rare disease, and with our NDA submission, have answered its petition that we submit our application. We know that the FDA has similarly heard the voice of these patients, and we look forward to continued dialogue with the FDA as it evaluates our submission for filing and review."

The NDA submission is based on results from the SPIBA-001 Phase 3 Retrospective Natural History Control Trial, which compared data from the open-label portion of the TAZPOWER Phase 2/3 clinical trial to matched natural history controls. SPIBA-001 met its primary and most secondary endpoints, demonstrating elamipretide-mediated improvements in assessments of exercise tolerance, strength and cardiac function that are unexpected in the natural course of this progressively debilitating disease. In addition, improvements were observed during the TAZPOWER Phase 2/3 clinical trial and open label extension in several surrogate and intermediate clinical endpoints that may be reasonably likely to predict clinical benefit for patients suffering from this serious disease, potentially supporting an accelerated approval pathway. Although the FDA has recommended that additional controlled data be generated to support NDA review, neither the FDA nor the Company has identified a feasible trial design due to the ultra-rare nature of this disease. In light of FDA's view that the existing clinical data are insufficient to demonstrate substantial evidence of effectiveness and would not support NDA review, there is no assurance that the FDA will file the NDA. Stealth believes, however, that the data could support an NDA review, and has accordingly submitted the NDA as requested by the Barth syndrome patient community.

Elamipretide was previously granted rare pediatric designation, fast track designation, and orphan drug designation by the FDA, and orphan drug designation by the EMA, for the treatment of Barth Syndrome.  

About Barth Syndrome

Barth syndrome is an ultra-rare genetic condition characterized by cardiac abnormalities often leading to heart failure and reduced life expectancy, recurrent infections, muscle weakness and delayed growth. Barth syndrome occurs almost exclusively in males and is estimated to affect one in 200,000 to 400,000 individuals worldwide. There are currently no FDA- or EMA-approved therapies for patients with Barth syndrome.

https://en.wikipedia.org/wiki/Elamipretide

FDA Grants Accelerated Approval to Forzinity (elamipretide hydrochloride) for the Treatment of Barth Syndrome

In continuation of mu update on elamipretide

Stealth BioTherapeutics Inc. (the “Company” or “Stealth”),  announced  the U.S. Food and Drug Administration (FDA) accelerated approval of  Forzinity™ (elamipretide HCl) to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kilograms (kg) (approximately 66 pounds). Barth syndrome is a life-limiting pediatric mitochondrial cardioskeletal disease that affects approximately 150 individuals in the United States.

“The approval of Forzinity, the first treatment option for Barth syndrome and the first approved mitochondria-targeted therapeutic, is a pivotal victory for the Barth syndrome community and offers hope for expedited regulatory attention to other ultra-rare diseases,” said Reenie McCarthy, Stealth’s Chief Executive Officer. “We appreciate the FDA’s close engagement in recent months and are grateful to the trial participants, caregivers, advocates, researchers and healthcare providers who persevered in partnership with us over this decade-long journey. We plan to continue providing expanded access to children weighing less than 30 kilograms who are currently receiving treatment or require emergency access, while we work with the FDA to generate data needed to expand the indication to include these children. We are committed to the continued development of therapies to treat all patients with Barth syndrome and other devastating diseases of mitochondrial dysfunction.”

The approval of Forzinity is supported by the efficacy and safety data from the TAZPOWER clinical trial. During the open-label portion of the TAZPOWER trial, knee extensor muscle strength improved from study baseline. The most common adverse reactions were injection site reactions which can be treated with oral antihistamines or topical corticosteroids. Continued approval for this indication may be contingent upon verification of clinical benefit in a confirmatory trial.

This decision follows months of collaborative dialogue with the FDA to resolve the final regulatory milestones following Stealth’s May 2025 receipt of a complete response letter from the FDA. The approval reflects a shared commitment to ensuring timely access for patients facing this devastating disease. Many of these patients and their families, along with their healthcare providers, have worked tirelessly to educate the FDA about the significant burden of this ultra-rare disease.

“We are grateful that FDA leadership has listened to our community and approved Forzinity for some of our population. Barth syndrome patients live every day with progressively diminishing quality of life,” said Kate McCurdy, Board Chair of the Barth Syndrome Foundation whose son passed away from the disease at age 28. “I witnessed the terrible toll this disease took every day of my son’s life and the many serious medical challenges that ensued. Our patients and their physicians have seen the truly positive impact Forzinity can have on the devastating muscle weakness that restricts daily activities. While we celebrate this critical milestone, we are deeply aware that only half of our patients survive long enough to weigh the 30 kilograms they must in order to be eligible for this treatment now. Therefore, we deeply appreciate Stealth’s pledge to work closely with the FDA on prompt and broad label expansion, so that our youngest and most vulnerable patients can also gain access to this therapy.”

“I am thrilled to have an FDA-approved treatment to offer to patients with Barth syndrome, who often face serious manifestations including severe muscle weakness,” said Hilary Vernon, M.D., Ph.D., Professor of Genetic Medicine at Johns Hopkins University School of Medicine and Founder and Director of the Barth Syndrome Clinic at the Kennedy Krieger Institute. “As the director of one of only two interdisciplinary Barth syndrome clinics worldwide, I have the privilege of interacting with a large percentage of the Barth community in the U.S. and around the world, and I am grateful to have a new therapeutic option available for patients living with Barth syndrome. I look forward to chairing the Trial Scientific Review Committee for the post-marketing trial as I know there is tremendous interest in participation from patients around the world.”

Forzinity received Orphan Drug, Fast Track, Priority Review, and Rare Pediatric Designations from the FDA and Orphan Drug Designation from the European Medicines Agency (EMA) for the treatment of Barth syndrome. In connection with the approval, Stealth has been granted a Rare Pediatric Disease Priority Review Voucher from the FDA.

The approval is limited to children and adults weighing at least 30 kg. Stealth intends to work with the FDA on a plan to collect additional data in children weighing less than 30 kg and to qualify its preservative-free formulation used in expanded access for newborns. Pending potential label expansion and qualification of the preservative-free formulation, Stealth will continue to provide compassionate use access for patients weighing less than 30 kg currently enrolled in its expanded access program or for whom emergency access is necessary.

Stealth is committed to ensuring uninterrupted access for all current patients living with Barth syndrome. Stealth plans to work with payers and providers to ensure timely and equitable access to Forzinity, which it expects will be available for prescriptions in the United States through a specialty pharmacy by year-end. Stealth expects to announce its patient support and access initiatives in the coming weeks.

https://en.wikipedia.org/wiki/Elamipretide

FDA Grants Accelerated Approval to Forzinity (elamipretide hydrochloride) for the Treatment of Barth Syndrome