FDA Places Clinical Hold on Aardvark PWS Studies

Rare Daily Staff

The U.S. Food and Drug Administration has placed a full clinical hold on Ardvark Therapeutics experimental therapy ARD-101, halting all ongoing studies of the of it in  Prader-Willi Syndrome.

The decision follows a previously disclosed voluntary pause by the company, as it continues discussions with regulators to determine a path forward.

The clinical hold affects both the phase 3 HERO trial, a randomized controlled study evaluating ARD-101 for hyperphagia in PWS patients, and its open-label extension. hyperphagia, a hallmark of PWS, is characterized by an insatiable and persistent hunger that can lead to severe health complications.

In response, Aardvark plans to unblind data from both trials to assess the combined safety and efficacy profile of ARD-101. As of late February, 68 patients had been enrolled in the HERO study and 19 in the extension trial. The company said the analysis will help guide its next steps as it works with the FDA to resolve the hold.

ARD-101 is an oral small-molecule therapy designed to activate bitter taste receptors in the gut, triggering the release of hormones involved in hunger regulation. The drug is part of Aardvark’s broader strategy to target neural pathways that control hunger, distinct from appetite-focused mechanisms addressed by therapies such as GLP-1 receptor agonists.

The regulatory setback introduces uncertainty for the program at a late stage of development, particularly given the limited treatment options available for PWS-related hyperphagia. However, the decision to unblind data could provide critical insight into whether ARD-101 demonstrates a meaningful clinical benefit that could support future regulatory engagement.

“We are continuing to work collaboratively with the agency to comprehensively evaluate the data and determine the best path forward for ARD-101,” said CEO Tien Lee.