Tauro-Urso-Deoxycholic Acid Trials in Amyotrophic Lateral Sclerosis: What is Achieved and What to Expect.

Phase II studies on tauro-urso-deoxycholic acid (TUDCA) raised the promise of safety and efficacy in patients with amyotrophic lateral sclerosis, a currently incurable and devastating disease. We review the available evidence on the efficacy and safety of TUDCA, administered alone or in combination, by analyzing and comparing published and ongoing studies on amyotrophic lateral sclerosis. Two independent phase II studies (using TUDCA solo or combined with sodium phenylbutyrate) showed similar efficacy in slowing disease progression measured by functional scales. One open-label follow-up TUDCA+sodium phenylbutyrate study suggested a benefit on survival. Two subsequent phase III studies with TUDCA (solo or combined with sodium phenylbutyrate) have been initiated and are currently ongoing. Their completion is expected by the end of 2023 and beginning of 2024. Evidence collected by phase II studies indicates that there are no safety concerns in patients with amyotrophic lateral sclerosis. The efficacy shown in phase II studies was considered sufficient to grant approval in some countries but not in others, owing to discrepant views on the strength of evidence. It will be necessary to wait for the results of ongoing phase III studies to attain a full appreciation of these data.