FDA Delays Decision on Biohaven's Rare Disease Drug, Plans Advisory Committee Meeting

Biohaven Pharmaceuticals faced a setback as the U.S. Food and Drug Administration (FDA) announced a delay in its decision on the company's rare disease candidate, troriluzole, and plans to convene an advisory committee to discuss the application. This development comes just days after the company had assured investors that its filing was on track, causing significant volatility in Biohaven's stock price.

Regulatory Hurdles for Troriluzole

The FDA has pushed back its approval decision on troriluzole, a treatment for spinocerebellar ataxia (SCA), by three months. The new Prescription Drug User Fee Act (PDUFA) date is now set for the fourth quarter of 2025, instead of the previously anticipated third quarter decision. This delay is attributed to the need for a "full review of Biohaven's recent submissions related to information requests from the FDA," according to the company.

The regulatory agency's decision to hold an advisory committee meeting adds another layer of scrutiny to troriluzole's application. While no specific date has been set for this meeting, it signals that the FDA may have concerns or questions about the drug's data that require expert input.

Market Reaction and Analyst Insights

The news of the delay and planned advisory committee meeting had an immediate impact on Biohaven's stock. Shares fell 12% in premarket trading on Thursday, dropping to around $17 from the previous day's closing price of $19.66.

William Blair analysts, after discussions with Biohaven management, reported that the delay was triggered by a 'major amendment' status. However, they noted that there was "no obvious large body of data submitted for review that would have triggered this." The analysts also raised the possibility that the delay could be linked to recent FDA layoffs and restructuring, drawing parallels to a similar hold-up faced by argenx in 2023.

Historical Context and Clinical Data Challenges

This is not the first hurdle troriluzole has faced in its path to potential approval. In 2023, the FDA initially refused to review Biohaven's filing, which was based on a study that missed its primary endpoint. The company subsequently refiled for approval, presenting data that compared troriluzole-treated patients to a historical control group.

Biohaven claims that patients in the historical study were "rigorously matched" to those taking troriluzole, showing a significant slowing in disease progression. However, the failure of the earlier placebo-controlled study provides grounds for skepticism regarding the improvement over historical controls.

As the pharmaceutical industry watches closely, this case may provide insights into the FDA's flexibility under its new leadership, particularly in evaluating complex datasets and alternative study designs for rare diseases.