Troriluzole, in development for spinocerebellar ataxia, was rejected nearly a year ago when the FDA took issue with the design of Biohaven’s registrational study. The agency has now agreed to review a new application and render a decision in the first quarter of 2027.
Shares of Biohaven popped by as much as 36% on Thursday morning after the company disclosed the FDA’s acceptance of a resubmission for troriluzole—which the agency rejected late last year—in the rare, degenerative disorder spinocerebellar ataxia.
The FDA has assigned a new action date for troriluzole—also known as Vyglxia—in the first quarter of next year, according to a Thursday SEC filing. The agency also intends to hold an advisory committee meeting for the application, according to the document. A date for the adcomm will be set “in the near term.”
“The Vyglxia AdCom will be the most de-risking event here,” William Blair wrote to investors Thursday morning, citing the FDA’s previous reluctance to accept Biohaven’s three-year real-world evidence trial. Coined study 206-RWE, the program compared troriluzole to a natural history database on a movement scale modified for spinocerebellar ataxia (SCA) as primary evidence to support effectiveness.
SCA is a group of rare diseases that lead to the progressive loss of control over movement. Many types of the disease are genetic and there is currently no cure.
The FDA issued a complete response letter (CRL) for troriluzole’s use in SCA in November 2025, citing “issues that can be inherent to real-world evidence and external control studies including potential bias” and spurring a contentious reaction from Biohaven.
“We are extremely disappointed on behalf of patients by this action from the Office of Neuroscience at FDA,” CEO Vlad Coric said in a statement following the rejection. “Beyond substantial evidence of safety and efficacy, patients with rare diseases also deserve an efficient, fair and flexible regulatory process that aligns with the urgency of their high unmet medical needs.”
Prior to finalizing the Phase 3 study design, Biohaven had received feedback from the FDA warning that “a large and robust treatment effect would be needed to overcome the biases of an externally controlled trial, in order for it to be used as the primary basis for substantial evidence for effectiveness,” according to a Nov. 4, 2025, press release from Biohaven. But the biotech believed it had achieved this goal.
“Biohaven believes the statistical significance and clinical meaningfulness achieved on the primary endpoint and eight consecutive secondary endpoints in 206-RWE . . . clearly met criteria of ‘a large and robust treatment effect,’” the company said after receiving the CRL.
The regulatory rejection led Biohaven to cut R&D spending by 60% and caused its stock to crater by nearly 45% to $7.60 per share. As of 10:40 am ET on Thursday, shares of the biotech had risen to $15.41, 30% higher than yesterday’s closing price.
The resubmission includes new positive supportive analyses and the FDA said it considers the application a complete response to the Nov. 4 CRL, according to Biohaven’s SEC filing.
“Overall, we continue to see the risk/benefit of troriluzole as favorable in SCA, where there is no currently approved FDA therapy,” William Blair wrote on Thursday.
Despite missing the Phase 3 study’s primary endpoint of f-SARA—a modified scale designed specifically for SCA that focuses on sitting, standing, walking and talking—comparisons to natural history controls showed a 50–70% slower rate of decline for patients taking a 200 mg dose of Biohaven’s drug, William Blair noted, representing a delay of 1.5–2.2 years in disease progression over three years.
