FDA Rejects PTC Therapeutics' Friedreich's Ataxia Drug, Dealing Blow to Rare Disease Treatment Efforts

The U.S. Food and Drug Administration (FDA) has rejected PTC Therapeutics' vatiquinone, a proposed treatment for Friedreich's ataxia (FA) in children and adults, citing a lack of substantial evidence of efficacy. The decision marks a significant setback for the company and highlights ongoing challenges in the development of treatments for rare neurodegenerative disorders.

Regulatory Setback and Clinical Trial Results

PTC Therapeutics received a complete response letter (CRL) from the FDA, stating that the company would need to conduct an additional "adequate and well-controlled study" to support a resubmission. This rejection comes despite PTC's efforts to demonstrate the drug's efficacy through multiple studies, including the Phase III Move-FA trial and subsequent extension studies.

The Move-FA trial, completed in 2023, failed to meet its primary endpoint of improving gait, stability, and limb function as measured by the modified Friedreich Ataxia Rating Scale (mFARS). However, PTC had pushed forward with its approval bid based on meeting some secondary endpoints, particularly improvements in the mFARS upright stability subscale, which the company argued was "the most sensitive and relevant" measure for the enrolled population.

Company Response and Future Plans

Matthew Klein, CEO of PTC Therapeutics, expressed disappointment with the FDA's decision but maintained confidence in vatiquinone's potential. "We believe the data collected to date demonstrate that vatiquinone could provide a safe and effective therapy for both children and adults living with Friedreich's ataxia," Klein stated. The company plans to meet with the FDA to discuss potential next steps and address the issues raised in the CRL.

Market Implications and Competition

The rejection of vatiquinone leaves Biogen's Skyclarys as the only FDA-approved treatment for Friedreich's ataxia. Skyclarys, which gained approval in early 2023, is limited to patients aged 16 and older. PTC had hoped to gain an edge with a broader label that included children, potentially addressing a larger portion of the estimated 25,000 FA patients globally.

This development follows recent setbacks for other biotechnology companies in the rare disease space, including Capricor Therapeutics and Ultragenyx, both of which received unexpected FDA rejections for their respective rare disease treatments in recent weeks.