Biohaven · NYSE: BHVN · troriluzole (VYGLXIA)

Biohaven did not file an 8-K about the letter. The first 8-K after it, the Nov 10, 2025 earnings release, says the company requested a Type A meeting to begin an appeal. It does not mention the letter's deficiencies or its call for a new study; the 10-Q filed the same day mentions the FDA's recommendation to meet.

The letter says “substantial evidence of effectiveness has not been established” [FDA · Nov 4 · p. 2]. The Nov 10 8-K says: “We requested a Type A meeting with FDA as part of initiating an appeal process for the SCA CRL and plan to meet with the FDA to discuss potential next steps” [8-K · Nov 10], and quotes the CEO: “We will also continue to provide updates on any progress determining a path forward in SCA” [8-K · Nov 10].

The letter says Study 206-RWE “cannot be considered an adequate and well-controlled investigation” [FDA · Nov 4 · p. 2] and that “Methodological issues preclude the ability to use the secondary efficacy analyses” [FDA · Nov 4 · p. 5]. The 8-K does not mention any of the deficiencies. [8-K · searched]

The letter says “you will need to provide data from an adequate and well-controlled study” [FDA · Nov 4 · p. 5]. The 8-K does not mention this. [8-K · searched] The 10-Q filed the same day says “the FDA recommended that we meet with the Division of Neurology 1 within the FDA's Office of Neuroscience (the "Division") to discuss the evidence that will be needed to support a future NDA” [10-Q · Nov 10], and that the Type A request was made “given the large number of patients who are currently being treated in the expanded access program” [10-Q · Nov 10].

Biohaven's 10-K, filed Mar 2, 2026, describes Study 206-RWE as prespecified, rigorously matched and showing statistically significant benefit. The FDA's letter of Nov 4, 2025 states its own findings on each of these points.

The 10-K says “data across multiple analyses demonstrate a robust and clinically meaningful slowing of disease progression in SCA patients” [10-K · Mar 2]. The letter calls the Year 3 treatment difference “of uncertain clinical meaningfulness” [FDA · Nov 4 · p. 4].

On design, the 10-K: “All endpoints were prespecified, and both the study protocol and statistical analysis plan were submitted to, and reviewed by, FDA prior to topline data analysis” [10-K · Mar 2]. The letter: “It is our position that neither the design of Study 206-RWE nor the hypotheses underlying the SAP-specified analyses can be considered “prespecified”” [FDA · Nov 4 · p. 4].

On the control arm, the 10-K says propensity score matching ensured CRC-SCA patients “were rigorously matched to treated patients from Study BHV4157-206 on baseline characteristics” [10-K · Mar 2] and reports “statistically significant and sustained benefits at years 1, 2 and 3” [10-K · Mar 2]. The letter: “The propensity score matching could not address important factors that could affect disease progression” [FDA · Nov 4 · p. 2]; with 1-year progression rates matched, “the treatment effect became statistically nonsignificant at both Year 2 and Year 3” [FDA · Nov 4 · p. 2]; and under the Jump-to-Reference analysis “the 3-year result became statistically non-significant (p=0.1023 instead of p=0.0301)” [FDA · Nov 4 · p. 3].

The 10-K says EUROSCA results were “statistically significant and consistent with the primary efficacy analysis at all timepoints” [10-K · Mar 2]; the letter calls EUROSCA “inadequate as an external control” [FDA · Nov 4 · p. 5]. The 10-K says troriluzole “reduced the risk of fall events by approximately 53%” [10-K · Mar 2] in Study 206; the letter says “Inspections identified systematic under-reporting of adverse events and incorrect coding of fall events” [FDA · Nov 4 · p. 5] and, on a corrected dataset, the difference “did not achieve nominal statistical significance” [FDA · Nov 4 · p. 5].

The FDA concluded that substantial evidence of effectiveness had not been established. It gave six reasons why Study 206-RWE cannot be considered adequate and well-controlled, said methodological issues preclude using the proposed confirmatory evidence, and said a new adequate and well-controlled study is needed.

The letter says “substantial evidence of effectiveness has not been established for troriluzole for the treatment of spinocerebellar ataxia” [FDA · Nov 4 · p. 2]. Before the application, the FDA says it had “stated that Study 206-RWE was not considered to be an adequate and well-controlled investigation” [FDA · Nov 4 · p. 2].

Section I says Study 206-RWE “cannot be considered an adequate and well-controlled investigation” [FDA · Nov 4 · p. 2], for six numbered reasons. 1: the matching “could not address important factors that could affect disease progression” [FDA · Nov 4 · p. 2], and when it included 1-year progression rates “the treatment effect became statistically nonsignificant at both Year 2 and Year 3” [FDA · Nov 4 · p. 2]. 2: “Two-thirds of CRC-SCA natural history sites (12 of 18) were also among the 21 U.S. sites that conducted Study 206” [FDA · Nov 4 · p. 2]. 3: “52% of troriluzole-treated subjects and 79% of CRC-SCA controls missing Year 3” [FDA · Nov 4 · p. 3] data. 4: CRC-SCA subjects were assessed “up to 90 days at Year 3” [FDA · Nov 4 · p. 3] later. 5: CRC-SCA “used the original 40-point SARA scale” [FDA · Nov 4 · p. 3]. 6: on the company's claim of prespecification, “We do not agree that this constitutes “prespecification”” [FDA · Nov 4 · p. 3].

The letter calls the Year 3 difference “of uncertain clinical meaningfulness” [FDA · Nov 4 · p. 4]. Section II says “Methodological issues preclude the ability to use the secondary efficacy analyses of Study 206-RWE and post hoc analyses of Study 206 as confirmatory evidence” [FDA · Nov 4 · p. 5]: the secondary analyses “suffer from the same fundamental limitations” [FDA · Nov 4 · p. 5], the SCA3 subgroup results “were not statistically or clinically persuasive” [FDA · Nov 4 · p. 5], and on falls “Inspections identified systematic under-reporting of adverse events” [FDA · Nov 4 · p. 5].

To address the deficiencies, “you will need to provide data from an adequate and well-controlled study that demonstrates an effect on a clinically meaningful endpoint” [FDA · Nov 4 · p. 5]. The letter lists one comment that is “not approvability issues” [FDA · Nov 4 · p. 6]: “Reassess and propose the dosage modifications for relevant intrinsic and extrinsic factors” [FDA · Nov 4 · p. 6].

The letter calls for a new adequate and well-controlled study and a response within one year. The company's 10-K says it held a Type A meeting to begin an appeal; its 2026 10-Qs do not mention the CRL, while a note financing tied to troriluzole's approval and a securities class action about troriluzole remain in its filings.

The letter says the company “will need to provide data from an adequate and well-controlled study” [FDA · Nov 4 · p. 5], and “Within one year after the date of this letter, you are required to resubmit or take other actions available under 21 CFR 314.110” [FDA · Nov 4 · p. 7].

The Nov 10, 2025 8-K says the company “requested a Type A meeting with FDA as part of initiating an appeal process” [8-K · Nov 10]. The 10-K of Mar 2, 2026 says “we held a Type A meeting with the FDA to initiate an appeal process” [10-K · Mar 2] and “We remain committed to working with the FDA to find a path forward for our NDA” [10-K · Mar 2]. Biohaven's 10-Qs of May and Aug 2026, and the earnings releases furnished with them, do not mention the CRL, a Type A meeting, the NDA or a resubmission. [10-Q · searched]

The Aug 2026 10-Q still describes a second tranche of notes conditional on “the receipt of approval from the U.S. Food and Drug Administration ("FDA") for troriluzole, in a second tranche in up to three purchases on or before June 30, 2026” [10-Q · Aug 10]. It also reports an amended securities complaint for a class of purchasers “between March 24, 2023 and January 5, 2026” [10-Q · Aug 10] concerning “the outlook for and clinical data supporting troriluzole as a treatment for spinocerebellar ataxia” [10-Q · Aug 10].

Not in this record: FDA minutes of the Type A meeting, any FDA decision on an appeal, Biohaven press releases not filed with the SEC, and Biohaven's filings after Sep 10, 2026. [not in record]