FDA Declines Approval for PTC Therapeutics' Friedreich's Ataxia Treatment Drug

In a recent development, PTC Therapeutics has announced that the Food and Drug Administration (FDA) has rejected its proposed treatment for Friedreich's ataxia, named vatiquinone. This rejection follows a series of setbacks in the rare disease space, with other biotech companies like Stealth BioTherapeutics and gene/cell therapy developers facing similar regulatory hurdles.

Vatiquinone is a small molecule that blocks some cellular pathways that go awry in patients with frataxin mutations, a genetic defect causing Friedreich's ataxia. The rejection was based on the FDA's statement that "substantial evidence of efficacy was not demonstrated" for vatiquinone. As a result, PTC Therapeutics must conduct an "additional adequate and well-controlled study" to support a resubmission for vatiquinone's approval.

Friedreich's ataxia is a rare neuromuscular disorder affecting approximately 25,000 people globally. Symptoms include loss of coordination, muscle strength, difficulty speaking, swallowing, and breathing. The treatment, vatiquinone, had previously failed a Phase III trial in 2023, missing the mark in its primary endpoint of improving gait, stability, and limb function after 72 weeks.

This rejection is not unique to PTC Therapeutics. In July 2025, the FDA issued Complete Response Letters (CRLs) delaying or rejecting three advanced gene and cell therapy programs: Capricor's CAP-1002 for Duchenne muscular dystrophy, Ultragenyx’s UX111 for Sanfilippo Syndrome Type A, and Rocket Pharmaceuticals' Kresladi for leukocyte adhesion deficiency-I. These delays were primarily due to manufacturing and Chemistry, Manufacturing, and Controls (CMC) deficiencies rather than safety or efficacy problems.

One notable case is Stealth BioTherapeutics' elamipretide, developed for the ultra-rare Barth syndrome. The drug faced multiple FDA rejections and reviews, leading to significant operational and financial strain. The continued delays and negative verdicts led Stealth to lay off 30% of its workforce and pause other clinical trials, severely impacting the company's financial stability and operational capacity.

The impact of these regulatory setbacks in the rare disease sector generally includes financial burden on the biotech companies due to prolonged approval timelines and subsequent investor uncertainty. Forced operational downsizing and halting of alternative clinical programs are also common, as are delays in patient access to potentially transformative treatments. Heightened scrutiny over manufacturing and data quality pushes companies to bolster Chemistry, Manufacturing, and Controls (CMC) strategies beyond clinical innovation alone.

These rejections underscore the complex balance regulators maintain between ensuring rigorous safety and quality standards and enabling access to therapies for rare diseases with urgent unmet needs.

In response to the rejection, Matthew Klein, the CEO of PTC Therapeutics, plans to meet with the FDA to discuss potential next steps. Despite the setback, shares of PTC Therapeutics are up approximately 6% in Tuesday morning trading.

This press release regarding the FDA's decision was issued by PTC Therapeutics on Tuesday morning. The rejection letter from the FDA was addressed to PTC Therapeutics.

In a separate development, Biogen acquired Reata Pharmaceuticals for about $7.3 billion following Skyclarys' approval. Skyclarys, the only drug on the market for Friedreich's ataxia, was approved in early 2023 while it was held by Reata Pharmaceuticals.

These developments serve as a reminder of the challenges facing biotech companies in the rare disease space and the need for continued investment in research and development to bring much-needed treatments to patients.

[1] FDA's Increasing Scrutiny on Manufacturing for Advanced Therapies: [Link to Source] [2] Stealth BioTherapeutics' Struggles with Elamipretide: [Link to Source] [3] Stealth BioTherapeutics' Layoffs and Clinical Trial Pauses: [Link to Source] [4] Stealth BioTherapeutics' Financial Impact from Delays: [Link to Source] [5] Patient Access Issues due to Stealth BioTherapeutics' Delays: [Link to Source]