FDA Delays Decision on Biohaven's Rare Disease Drug, Shares Tumble

Biohaven Pharmaceuticals faced a setback as the U.S. Food and Drug Administration (FDA) announced a delay in its approval decision for troriluzole, a potential treatment for spinocerebellar ataxia (SCA). The news, which came just days after the company had reported positive progress, sent Biohaven's stock price plummeting and raised questions about the drug's regulatory future.

FDA Extends Review Period and Plans Advisory Committee Meeting

The FDA has extended its review period for troriluzole by three months, pushing the Prescription Drug User Fee Act (PDUFA) date into the fourth quarter of 2025. Additionally, the agency plans to convene an advisory committee meeting to discuss the application, a step that was not initially anticipated.

Biohaven CEO Vlad Coric stated that the delay would "provide time for a full review of Biohaven's recent submissions related to information requests from the FDA." The company had previously reported that during a mid-cycle review meeting, the FDA had not indicated any intention of holding an advisory committee meeting.

This unexpected turn of events comes as a surprise to investors and analysts, particularly given Biohaven's statement just 48 hours earlier that the filing was on track. The news has prompted a reevaluation of the drug's approval prospects and the company's overall regulatory strategy.

Market Reaction and Analyst Perspectives

The announcement had an immediate impact on Biohaven's stock price, which fell approximately 15% in pre-market trading on Thursday, reaching around $16.75 per share. This decline adds to a series of setbacks that have affected investor confidence in recent months.

Analysts have offered mixed views on the implications of the FDA's decision. Leonid Timashev of RBC Capital Markets suggested that while the delay doesn't significantly alter Biohaven's stock outlook, it does raise questions about the "overall regulatory picture" for troriluzole and increases the risk of an FDA rejection.

Despite the uncertainty, some analysts remain optimistic. Marc Goodman of Leerink Partners expressed continued positivity, stating, "Whatever the reason [for these changes], we remain optimistic for approval and continue to be positive on the stock."

William Blair analysts noted that the delay was triggered by a 'major amendment' status, although they reported that there was no obvious large body of data submitted for review that would typically prompt such a classification.

Troriluzole's Significance and Regulatory History

Troriluzole represents a critical component of Biohaven's pipeline, especially following the company's sale of its migraine medication portfolio to Pfizer in 2022 for nearly $12 billion. The drug is designed to break down into a molecule already approved for treating amyotrophic lateral sclerosis (ALS) in the U.S. and Europe.

Biohaven's journey with troriluzole has been complex. In 2023, the FDA initially refused to review the company's filing, which was based on a study that missed its primary endpoint. Biohaven subsequently refiled for approval, presenting data that compared troriluzole-treated patients to a historical control group, demonstrating a significant slowing in disease progression.

The upcoming advisory committee meeting and extended review period will provide crucial insights into the FDA's stance on the drug's efficacy and the acceptability of historical control data in the absence of positive results from placebo-controlled trials.