Biohaven Ltd. (NYSE:BHVN) is having a Thursday worth talking about. The stock is surging with session volume of 10.293 million versus an average volume of 2.585 million after an update on its spinocerebellar ataxia (SCA) program.

For the uninitiated, SCA is a rare, progressive, inherited neurodegenerative disorder that damages the cerebellum, the part of the brain responsible for balance and coordination, and sometimes the spinal cord.

Regulatory Scrutiny and the Real-World Evidence Question

The U.S. Food and Drug Administration (FDA) accepted Biohaven's new drug application resubmission for Vyglxia (troriluzole) in SCA for review, with a user fee goal date in the first quarter of 2027. The resubmission included new positive supportive analyses.

The FDA communicated that it considers the resubmission a complete response to the November 2025 action letter. But here's the catch: the agency cited issues that can be inherent to real-world evidence and external control studies, including potential bias, design flaws, lack of pre-specification, and unmeasured confounding factors.

In an SEC filing on Thursday, the company said that the FDA plans to convene a meeting of the Peripheral and Central Nervous System Advisory Committee to obtain input from external stakeholders. The anticipated date of the advisory committee meeting will be announced in the near term.

A Previous Trial Halt

This isn't the only regulatory wrinkle Biohaven has dealt with lately. In September, the FDA issued a partial clinical hold on new patient enrollment for Biohaven's BHV-7000 program, while maintaining timelines for its lead pivotal study in refractory focal epilepsy.

The regulatory action stems from nonclinical rodent testing that identified a specific metabolite requiring additional study to assess human risk. The FDA instructed the biopharmaceutical firm to pause new enrollment pending incoming nonclinical data expected within weeks. Biohaven voluntarily extended this pause to its international clinical sites outside the U.S.

What the Analysts Say

In August, William Blair said that Biohaven shares could be significantly undervalued if its clinical programs succeed. However, the firm said it needs more controlled clinical data and currently views the stock as fairly valued on a probability-adjusted basis.

Analyst Myles Minter reiterated a Market Perform rating. He said placebo-controlled results from Biohaven's priority assets over the next six to 12 months could support a more constructive outlook.

BHVN Price Action: Biohaven shares were up 31.36% at $15.43 at the time of publication on Thursday, according to market data.