FDA Accepts Troriluzole NDA Resubmission for Spinocerebellar Ataxia

The FDA has accepted the resubmitted new drug application (NDA) for troriluzole (Vyglxia; Biohaven) for the treatment of spinocerebellar ataxia (SCA), according to a Form 8-K the company filed, and assigned a user fee goal date in the first quarter of 2027. The agency also plans to convene an advisory committee to review the application.¹

The FDA considers the resubmission a complete response to the action letter it issued on November 4, 2025. Biohaven said the resubmission included new positive supportive analyses, though the filing did not describe the analyses or report trial data.

Troriluzole NDA resubmission and FDA review timeline

Biohaven disclosed the FDA's decision in a Form 8-K dated October 22, 2026, filed under Regulation FD. The agency accepted the resubmission for review and set a user fee goal date in the first quarter of 2027 without specifying a day; the company noted the goal date does not guarantee action or approval, and that the FDA may extend the review, request more information, or issue another complete response letter.

The FDA plans to convene its Peripheral and Central Nervous System Advisory Committee to gather external input on troriluzole; Biohaven said the anticipated meeting date would be announced in the near term.

Troriluzole evidence base and the November 2025 complete response letter

The FDA issued the complete response letter on November 4, 2025, for the original NDA in SCA. Biohaven characterized the agency's concerns as issues inherent to real-world evidence and external control studies, including potential bias, design flaws, lack of prespecification, and unmeasured confounding. The company also said FDA meeting minutes from March 8, 2024, stated a large and robust treatment effect would be needed for an externally controlled trial to serve as the primary basis for substantial evidence of effectiveness.²

The application relied on Study 206-RWE, a 3-year real-world evidence study comparing troriluzole-treated patients with matched untreated external controls drawn from 2 third-party natural history studies in the US and Europe. Biohaven reported the study met statistical significance on its prespecified primary endpoint and 8 consecutive secondary endpoints, with a 50% to 70% slowing of disease progression versus external controls.

The program also included Study 206, a 1-year, double-blind, placebo-controlled study. In its safety analysis, Biohaven reported a fall-risk reduction of more than 50% versus placebo. The company said the Functional Scale for the Assessment and Rating of Ataxia (f-SARA) was developed with the FDA, and noted that an advisory committee planned for the original application was canceled weeks before the expected meeting.

After the complete response letter, Biohaven said it would request a meeting with the FDA to define a path forward for the NDA, and cut annual direct research and development spending by about 60%. The company now awaits the advisory committee date and the first-quarter 2027 action.²

REFERENCES
1. Biohaven Ltd. Form 8-K: current report. US Securities and Exchange Commission. Filed October 22, 2026. Accessed October 22, 2026. https://www.sec.gov/Archives/edgar/data/0001935979/000193597926000083/bhvn-20261022.htm
2. FDA issues complete response letter for Biohaven's Vyglxia (troriluzole) new drug application for spinocerebellar ataxia. News release. Biohaven. Published November 4, 2025. Accessed October 22, 2026. https://www.prnewswire.com/news-releases/fda-issues-complete-response-letter-for-biohavens-vyglxia-troriluzole-new-drug-application-for-spinocerebellar-ataxia-302604884.html