The US Food and Drug Administration (FDA) has delayed its decision on Stealth BioTherapeutics’ new drug application (NDA) for elamipretide, a treatment for the ultra-rare disease Barth syndrome.
The Prescription Drug User Fee Act (PDUFA) action date has been extended by three months to 29 April 2025, following the submission of additional information by Stealth.
Stealth stated that the FDA required more time to fully review the supplemental data, which was submitted in response to requests following the FDA’s Cardiovascular and Renal Drugs Advisory Committee (CRDAC) meeting in October 2024. At that meeting, the advisory panel voted 10-6 in favour of elamipretide’s approval. The FDA classified the new data as a major amendment to the NDA, which triggered the standard three-month extension.
Despite the delay, Stealth emphasised that the FDA has not raised any safety concerns or requested additional pre-market studies. In the announcement accompanying the extension, Stealth’s CEO Reenie McCarthy said: “We continue to work closely with the agency as it completes its review of the elamipretide NDA and are actively preparing to support broad access to this therapy for individuals living with Barth syndrome as quickly as possible following potential approval.”
It’s not the first time elamipretide’s development has faced regulatory challenges. The FDA rejected the company’s initial NDA in 2021, citing the lack of “an adequate and well-controlled trial that provides evidence of effectiveness”. That application was based on the SPIBA-001 study (NCT04689360), a Phase III trial incorporating data from prior studies and historical controls. The FDA expressed concerns about potential biases in the trial design, including selection bias and confounding bias, and questioned the methods used to analyse the results. Specifically, the trial compared data from a natural history cohort monitored in 2012 and 2019 with data from treated patients, which the FDA argued did not sufficiently address these biases.
The October 2024 AdCom meeting also faced difficulties. The panel discussed findings from the SPIBA-201 clinical trial (NCT03098797), which assessed the impact of elamipretide in 12 male patients over 12 weeks of daily treatment. The trial failed to meet the primary endpoint of improving walking distance.

Check out our AAV CDMO service to expedite your gene therapy research
PackGene Biotech is a world-leading CRO and CDMO, excelling in AAV vectors, mRNA, plasmid DNA, and lentiviral vector solutions. Our comprehensive offerings span from vector design and construction to AAV, lentivirus, and mRNA services. With a sharp focus on early-stage drug discovery, preclinical development, and cell and gene therapy trials, we deliver cost-effective, dependable, and scalable production solutions. Leveraging our groundbreaking π-alpha 293 AAV high-yield platform, we amplify AAV production by up to 10-fold, yielding up to 1e+17vg per batch to meet diverse commercial and clinical project needs. Moreover, our tailored mRNA and LNP products and services cater to every stage of drug and vaccine development, from research to GMP production, providing a seamless, end-to-end solution.
Related News
Navega Therapeutics Receives $4 Million CIRM Grant to Advance Epigenetic Gene Therapy for Chronic Pain
SAN DIEGO, CA – February 4, 2025 – Navega Therapeutics, a pioneering biotechnology company developing cutting-edge epigenetic gene therapies, today announced a significant milestone with the receipt of a $4 million Translational Science grant from the California...
Akribion Therapeutics Secures €8 Million in Seed Financing to Advance Novel RNA-Guided Cell Depletion Technology
ZWINGENBERG, Germany, February 4, 2025 – Akribion Therapeutics, a biotechnology company pioneering a unique, RNA-guided, nuclease-based technology for programmable cell depletion, today announced the closing of an €8 million Seed financing round. The round was led by...
UF-Kure19 CAR-T Cell Therapy Demonstrates High CR Rates, Low Toxicity in R/R NHL
Treatment with UF-Kure19, a rapidly manufactured CAR T-cell therapy, led to complete responses (CR) and low toxicity in patients with relapsed/refractory non-Hodgkin lymphoma, according to data from a single-arm, mult-center phase 1 study (NCT05400109) presented at...
Opinion: Companies Vie to Develop a Hunter Syndrome Therapy That Reaches the Brain
Several companies—including JCR Pharmaceuticals, Denali Therapeutics and Regenxbio—have products in the pipeline that could improve treatment options for this rare disease. Hunter syndrome is a rare, X‐linked disease caused by a deficiency of the lysosomal enzyme...
Related Services

AAV Packaging Services
READ MORE

Off-the-Shelf AAV Products
READ MORE