Biohaven's Troriluzole Fails Phase 3 Trial in OCD, Development Halted

Biohaven Pharmaceuticals has announced the discontinuation of its troriluzole program for obsessive-compulsive disorder (OCD) following disappointing results from a phase 3 clinical trial. This setback adds to a series of challenges faced by the Connecticut-based biotech company in its efforts to expand the potential applications of the small molecule drug.

Latest Trial Failure and Program Termination

Troriluzole, a prodrug of riluzole, failed to meet its primary endpoint in the recent phase 3 trial for OCD. This outcome prompted Biohaven to terminate the development program for this indication, as disclosed in the company's second-quarter earnings release. The full results of the trial are expected to be presented at an upcoming scientific conference.

This failure follows a previous setback in 2020 when troriluzole did not meet the primary outcome in a phase 2/3 OCD trial. The compound has also encountered difficulties in other indications, including a 2021 failure in a phase 2/3 Alzheimer's disease trial and an initial phase 3 trial failure in spinocerebellar ataxia.

Regulatory Challenges and Ongoing FDA Review

Despite the string of clinical setbacks, troriluzole remains under consideration by the U.S. Food and Drug Administration (FDA) for the treatment of spinocerebellar ataxia, a rare neurological disorder. The regulatory journey for this indication has been complex:

1. In 2023, the FDA initially refused to review troriluzole for spinocerebellar ataxia.
2. A subsequent phase 3 trial showed more promising results, demonstrating the drug's potential to significantly slow disease progression.
3. In May 2025, Biohaven revealed that the FDA had decided to convene an advisory committee to evaluate the drug's potential approval.
4. The FDA's decision on troriluzole for spinocerebellar ataxia is now expected in the fourth quarter of 2025.

Historical Context and Future Outlook

Troriluzole's development is rooted in the history of its parent compound, riluzole, which was approved in 1995 as the first drug for the treatment of amyotrophic lateral sclerosis (ALS). Biohaven's efforts to expand the therapeutic potential of this molecule have faced significant challenges across multiple indications.

As the company awaits the FDA's decision on troriluzole for spinocerebellar ataxia, it has indicated plans to redirect resources to other programs in its pipeline. The outcome of the upcoming advisory committee meeting and subsequent regulatory decision will be crucial in determining the future of troriluzole and its potential impact on patients with rare neurological disorders.