Biohaven Ltd, a biopharmaceutical company, has expressed disappointment in the wake of its rare disease therapy facing US Food and Drug Administration (FDA) setback despite promising results.

In a release, the pharma company said that FDA has issued a Complete Response Letter (CRL) for its New Drug Application (NDA) seeking approval of VYGLXIA (troriluzole) for the treatment of spinocerebellar ataxia (SCA), notwithstanding clinical data suggesting slow disease progression by 50-70%.

The FDA setback highlights ongoing tensions between patient needs, regulatory processes, and the use of real-world evidence in evaluating treatments for rare diseases, the company said.

Vlad Coric, Chairman and Chief Executive Officer of Biohaven said, "We are extremely disappointed on behalf of patients by this action from the Office of Neuroscience at FDA. Beyond substantial evidence of safety and efficacy, patients with rare diseases also deserve an efficient, fair and flexible regulatory process that aligns with the urgency of their high unmet medical needs."

"The development of VYGLXIA (troriluzole) by Biohaven embodies a strong scientific process and deep commitment that is critical to bringing safe and effective treatments to patients with rare diseases like SCA. Our efforts over eight years, included developing the f-SARA scale in collaboration with the FDA and a real-world evidence study in SCA that showed VYGLXIA achieved highly consistent, sustained, robust and clinically meaningful treatment effects with a safe, once-daily oral pill that slowed disease progression by 50-70%."

Coming down heavily on FDA, he said, "Real-world evidence is an important research approach to assessing and delivering new therapies for complex rare diseases but, despite FDA policy initiatives supporting such tools, the front-line review divisions are not yet embracing FDA policy for the use of real-world evidence or the application of regulatory flexibility for rare disease."

Jeremy Schmahmann, Professor of Neurology at Harvard Medical School and Founding Director of the Ataxia Unit at Massachusetts General Hospital (MGH), added, "Patients with SCA and clinicians who treat them deserve to be heard on this important NDA filing. There is too much at stake for patients. The FDA decision not to listen to disease experts and respect the patient perspective before taking action represents a misstep in the due process."