The U.S. Food and Drug Administration issued a Complete Response Letter on November 4, 2025, rejecting Biohaven’s experimental drug VYGLXIA (troriluzole) for the treatment of spinocerebellar ataxia (SCA). The letter cited concerns about the design and validity of the real‑world evidence that Biohaven used to support the drug’s efficacy claims.
VYGLXIA had attracted attention after a 3‑year real‑world evidence study and a 1‑year randomized trial showed a 50‑70 % slowing of disease progression and a greater than 50 % reduction in fall risk among patients with SCA. Those results were the basis for the company’s New Drug Application, but the FDA determined that the evidence was insufficient to overcome potential bias, lack of pre‑specification, and unmeasured confounding inherent in externally controlled studies.
The rejection forces Biohaven to collect additional data and to redesign its clinical development plan for VYGLXIA. In response, the company announced a 60 % cut in annual direct research and development spending and will shift focus to other late‑stage assets, including extracellular degraders for IgA nephropathy, Opakalim for epilepsy and depression, and Taldefgrobep alfa for obesity and spinal muscular atrophy.
Financially, Biohaven reported a Q3 2024 net loss of $160.3 million ($1.70 per share) versus $102.6 million ($1.50) in Q3 2023, and cash, cash equivalents, marketable securities and restricted cash totaled approximately $642 million as of October 2, 2024. The CRL is expected to further pressure the company’s cash runway and valuation, prompting a reassessment of its pipeline priorities.
CEO Vlad Coric expressed disappointment, stating that Biohaven remains committed to working with the FDA to find a path forward while prioritizing other assets that promise stronger commercial prospects.
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