Biohaven Ltd. (NYSE:BHVN) shares plunged on Thursday after the Food and Drug Administration (FDA) unexpectedly delayed the review date for its rare-disease drug troriluzole.

The Division of Neurology 1 within FDA’s Office of Neuroscience informed Biohaven that they are extending the PDUFA date for the troriluzole new drug application (NDA) for spinocerebellar ataxia (SCA) by three months to provide time for a full review of Biohaven’s recent submissions related to information requests from the FDA.

If approved, troriluzole would be the first and only FDA-approved treatment for SCA. Spinocerebellar ataxia is a group of dominantly inherited neurodegenerative disorders characterized by progressive loss of voluntary motor control and atrophy of the cerebellum and brainstem. SCA affects approximately 15,000 people in the United States and 24,000 in Europe and the United Kingdom.

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Patients experience significant morbidity, including impaired gait leading to falls, loss of ambulation and progression to a wheelchair, inability to communicate due to speech impairment, difficulty swallowing, and premature death.

The Division also informed Biohaven that it is currently planning to hold an advisory committee meeting to discuss the application, but no date has been scheduled.

The FDA did not raise any new concerns in the letter. The FDA’s decision regarding the NDA is expected in the fourth quarter of 2025, compared to the third quarter of 2025, which was expected earlier.

Vlad Coric, Chairman and Chief Executive Officer of Biohaven, stated, “The clinical data presented in the NDA show a highly favorable benefit-risk profile with troriluzole, a once-daily oral pill, slowing disease progression by 50-70%, as measured by the f-SARA scale, and reducing the risk of falls.”

The company recently completed the FDA mid-cycle review meeting and regulatory inspections of Biohaven and key clinical research sites for troriluzole for SCA. The mid-cycle review concluded that there were no previously unidentified major safety concerns, and it does not appear a Risk Evaluation and Mitigation Strategy (REMS) is needed.

In April, the company announced an up to $600 million non-dilutive capital agreement with Oberland Capital Management LLC. The agreement, with $250 million in gross proceeds received on closing on April 30, 2025, is expected to support commercial launch planning in SCA, clinical development activities, and ongoing business operations.

Cash, cash equivalents, marketable securities and restricted cash as of April 30, 2025 totaled approximately $518 million.

Analysts at William Blair called the delay surprising, especially given the proximity to the completed mid-cycle review. Biohaven shares are trading down in response to the PDUFA extension and an FDA regulatory landscape with increasing uncertainty given restructuring efforts, as per William Blair.

“We understand the uncertainty here and the perceived increase in regulatory uncertainty, but we remain optimistic that the FDA will show more regulatory flexibility than the EMA given the rare-disease nature of SCA, lack of treatment options for the disease, and troriluzole’s risk/benefit compared to propensity-matched natural history data,” William Blair analysts said.

William Blair reiterates the Outperform rating given the conviction in the likelihood of approval.

Price Action: BHVN stock is down 14.3% at $16.85 at the last check on Thursday.

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