FDA lifts clinical hold on Aardvark's Prader-Willi drug ARD-101 after new heart data

The FDA has lifted its clinical hold on ARD-101, Aardvark Therapeutics' oral drug for hyperphagia (extreme, constant hunger) in Prader-Willi syndrome (PWS). The company announced the decision on 22 October and held a webcast the following morning to go through data from its halted trials.

How it got here

The trouble started in a separate study in healthy volunteers. On 27 February 2026, routine safety monitoring there picked up reversible ECG changes, and Aardvark voluntarily paused dosing in its Phase 3 HERO trial and the open-label extension (OLE). BioSpace reports that the volunteers involved had received doses above the therapeutic range, and that the company later disclosed heart findings in people given 1,600 mg twice daily without dose escalation, twice the HERO strength.

The FDA put HERO and the OLE on full clinical hold in May. By August, Aardvark had unblinded both studies and said it would not restart them in their original form.

What changed the FDA's mind

Working with the agency, Aardvark ran a thorough ECG study in more healthy volunteers, plus a lab study of the cardiac sodium channel NaV1.5. The ECG study saw no cardiac events at 200 mg or 400 mg twice daily. That was enough for the hold to come off, but not for dosing to start again straight away. Development can resume once Aardvark has finished further discussions with the FDA on the Phase 3 design, and the company has said it may be asked for more studies.

Tien Lee, M.D., Aardvark's Founder and Chief Executive Officer, said the company had "completed the work necessary to allow for the resumption of clinical studies", and that people with PWS and their families "continue to face profound unmet need".

The numbers

Aardvark is a small company and the pause has cost it. BioSpace, citing company filings, reports cash and short-term investments of $73.9 million at 30 June, and a headcount that fell from 40 employees at the end of April to 28 by 31 July. According to BioSpace, an unnamed Aardvark spokesperson said the company will seek a meeting with the FDA to settle its Phase 3 plans, and that it expects PWS clinical work to restart in 2027. BioSpace also reports that the company expects its cash to carry it through that FDA meeting.

The bigger picture

ARD-101 takes a gut-based approach. It activates bitter taste receptors in the gut, which triggers the release of gut hormones including GLP-1. The PWS market already has an approved option in Vykat XR, which Neurocrine gained through its $2.9 billion purchase of Soleno. BioSpace notes that seven deaths in patients taking Vykat XR were reported in August, which keeps safety front and centre for everyone in this space.