Soleno Therapeutics have released the results of the Randomised Withdrawal Trial stage of their DCCR clinical programme. These findings, now published in the Journal of Clinical Endocrinology and Metabolism, offer clarity, reassurance, and renewed hope for families affected by Prader‑Willi syndrome (PWS).
Please note, this Withdrawal Trial was conducted and completed before the FDA approved VYKAT XT (DCCR) in the United States in March 2025. The data formed a key part of the evidence package regulators reviewed when assessing the medication’s long‑term effectiveness and safety.
Why Was a Withdrawal Trial Needed?
Regulators often require evidence not only that a treatment works, but that its benefits depend on continued use. This was the case for Soleno Therapeutics as they worked toward approval of DCCR (VYKAT XR). The U.S. Food and Drug Administration (FDA) requested additional evidence, and this Withdrawal Trial fulfilled this request.
A Withdrawal Trial helps answer several important questions:
- Does the medication provide a true, ongoing therapeutic effect?
- Do symptoms return if treatment is interrupted?
- Is long‑term use necessary to maintain benefit?
- How does stopping treatment affect safety or behaviour?
Because DCCR had shown promising long‑term improvements in hyperphagia during earlier open‑label studies, this stage of the trial aimed to confirm that these improvements were truly due to the medication, and to see whether they would reverse if treatment was withdrawn.
What Was This Study All About?
For many people taking part in the trial, DCCR/VYKAT XR had already been life‑changing, reducing food‑seeking behaviours and easing the constant anxiety around hunger.
But researchers needed to understand something crucial- What happens if someone who has been stable on DCCR suddenly stops taking it?
This question matters for long‑term treatment planning, access discussions, and understanding how essential the medication truly is.
The study followed individuals with PWS who had been taking DCCR for up to six years. This long‑term use created a rare opportunity to observe what happens when treatment is interrupted.
Participants were divided into two groups – one group continued taking DCCR, and the other was switched to a placebo (a non‑medicated “dummy” version) for 16 weeks. The assignment of groups was random and “blind,” meaning neither participants nor researchers knew who was receiving the real medication. Families completed detailed questionnaires about hunger‑related behaviours, just as they had in earlier phases of the trial, and outcomes were carefully assessed.
What Did the Study Find?
The results of the Randomised Withdrawal Trial strongly supported the effectiveness of DCCR.
- Participants switched to placebo experienced a clear worsening of hunger symptoms. Behaviours that had previously improved began to re‑emerge.
- Those who stayed on DCCR maintained the progress they had made, showing that the medication’s benefits are sustained over time.
- No new safety concerns were identified, even among people who had been taking DCCR for several years.
What Happens Next?
These newly published results provide further evidence for the effectiveness and importance of DCCR/VYKAT XR. With FDA approval already secured and the medication now available in the United States, attention is turning to global access.
Families in the UK, Europe, and beyond are watching closely as regulatory discussions continue. The European Medicines Agency (EMA) is currently reviewing the treatment, and while the UK no longer follows EMA decisions, a positive outcome in Europe will hopefully strengthen UK regulatory applications.
As always, we will update you as soon as we hear more and the full publication can be found at https://doi.org/10.1210/clinem/dgaf661