Spinocerebellar Ataxia Study Fails; Biohaven Stock Down 10%

James Radke

Stock in Biohaven Pharmaceutical Holding Company Ltd. (NYSE: BHVN) is down around 10% this week following the announcement that its Phase 2/3 clinical trial assessing trigriluzole to treat patients with spinocerebellar ataxia (SCA) failed to meet its primary endpoint.

Based on the disappointing results, the company will not continue to develop the SCA treatment.

SCA are a group of hereditary ataxias in which degenerative changes to the cerebellum and spinal cord lead to a variety of symptoms, often related to movement and coordination. There are over 12 SCA subtypes based on the genetic mutation involved. While the dominate symptom is ataxia, many patients have problems with speech, vision, and a number of non-cerebellar motor symptoms.

Trigriluzole is a prodrug that modulates glutamate with the hypothesis that administration of the prodrug would reduce ataxia in SCA patients, however, studies show that it did not display that clinical benefit. After this recent failure, physicians continue to seek the first treatment to be approved for any of the SCA subtypes.

The failed Phase 2/3 study compared the safety and efficacy of trigiluzole vs placebo in 141 adult SCA patients. At the end of the 8-week trial, the primary endpoint— mean change from baseline on the Scale for the Assessment and Rating of Ataxia (SARA)—remained the same between the 2 treatment groups. Trigriluzole-treated patients had a mean change in SARA of -0.81 vs -1.05 in the placebo treated patients (P = .52). 

The secondary outcome measure in the study, Patient's Global Impression of Change (PGI-C), was also not statistically different between the 2 treatment groups.

On the plus side, trigriluzole showed a favorable safety and tolerability profile, with no drug-related serious adverse events.

Per Biohaven: "We are obviously disappointed that today's topline clinical results do not support continued development of trigriluzole as a symptomatic agent for patients with SCA, a devastating neurologic disorder for which novel treatments are urgently needed. This was the largest SCA clinical trial performed to date and important knowledge has been generated -- we plan to share our data with the ataxia clinical leaders and the National Ataxia Foundation to help refine clinical trials in this therapeutic area. We thank the patients and clinical investigators who participated in this program and sincerely appreciate all that they have done to see this study through completion," stated Vlad Coric, M.D., Chief Executive Officer of Biohaven.

Robert Berman, M.D., Chief Medical Officer of Biohaven added, "The Biohaven team had hoped this trial would bring a long-awaited treatment for patients with SCA and we are grateful for how the community of patients and researchers rallied around this trial, allowing us to enroll the study in under six months.  While the efficacy results were unfortunately disappointing, this study did demonstrate important characteristics of trigriluzole, including a favorable safety and tolerability profile. For the first time, trigriluzole was dosed chronically for over 24 weeks in some patients."

While the trigrluzole / SCA program will not endure at Biohaven (an open label extension study will continue as planned), the company remains optimistic that its other drug candidates in development to treat migraines, amyotrophic lateral sclerosis (ALS), and Rett syndrome will prove to be more effective.

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