The Food and Drug Administration has rejected the new drug application for elamipretide, an experimental treatment for rare mitochondrial diseases, leaving families of affected children uncertain about continued access to a medication they credit with life-changing improvements.
On May 29, 2025, the FDA's Division of Cardiology and Nephrology issued a letter denying approval for elamipretide as a treatment for conditions including Microphthalmia with Linear Skin Defects syndrome, a mitochondrial disorder affecting fewer than 100 people worldwide.
Patient Success Stories Contrast with Regulatory Decision
Four-year-old Hope Filchak from Hall County has been receiving elamipretide for 18 months after her heart function began declining in February 2024. The child was born with Microphthalmia with Linear Skin Defects syndrome, which has caused deafness, blindness, brain conditions, and multiple heart defects including cardiomyopathy.
"Ever since we've taken the drug, so a year and a half now, her heart has maintained where it has been. It hasn't decreased (in function) anymore," said Caroline Filchak, Hope's mother. The family also reported dramatic improvements in quality of life, with Hope's sleep reducing from 17 hours daily to normal levels, allowing her to attend school and engage in typical childhood activities.
Dr. Amy Goldstein, a leading mitochondrial disease expert, described similar success with the drug: "I myself personally saved a baby in my cardiac ICU with Barre syndrome. He went home with no cardiac manifestations after arriving here in severe heart failure and needing a heart transplant."
FDA's Rationale and Expert Criticism
According to Stealth Biotherapeutics, the Massachusetts-based pharmaceutical company that produces elamipretide, the FDA's rejection was partly based on the drug's failure to show improvement in six-minute walk tests during clinical trials.
"We all know in the field that a six-minute walk test is not the be-all end-all outcome measure for mitochondrial diseases," Goldstein said. She noted that the drug demonstrated improvements in quality of life and cardiac health measures.
Dr. Rossana Sanchez Russo, an Emory clinical geneticist, highlighted the inherent challenges in rare disease drug development: "Sometimes we don't have enough burden of proof to be able to formally say that. That doesn't mean that it may not be working for a family or that it might not work for other conditions. It may mean that we just do not have all the data."
Manufacturing Uncertainty Threatens Patient Access
The FDA rejection has created immediate supply concerns for patients currently benefiting from the treatment. Stealth Biotherapeutics has reduced its overhead by 30% in an attempt to continue manufacturing but estimates it can only sustain production for another six to nine months without regulatory approval.
Hope's family currently has a four-month supply remaining from their last six-month shipment. "Depending on how this goes with the FDA over the next couple of weeks and if we are able to make any headway and get to anybody that has any influence that could possibly help reverse this decision, then the four months that I have left in my refrigerator might be all that I get," Caroline Filchak said.
Regulatory Path Forward
The FDA has indicated that Stealth Biotherapeutics can reapply for approval, though the timeline and likelihood of success remain unclear. For families like the Filchaks, who administer daily injections of elamipretide to their daughter, the regulatory uncertainty represents a critical threat to continued treatment access.
The case highlights ongoing challenges in rare disease drug development, where small patient populations make traditional clinical trial designs difficult to execute while families face limited treatment options for devastating conditions.
