Active Clinical Trials For Prader-Willi Syndrome


PWSA (USA) has been supporting research since 1983. Many of the world’s most renowned PWS researchers and clinicians are on our scientific and clinical advisory boards; together they dedicate thousands of hours yearly to enhance research, write educational materials, and provide consultation.

Nearly all of the major breakthroughs in understanding and treating PWS have come from these pioneers and heroes. PWSA (USA) has funded over $2,000,000 in research projects and is committed to facilitating further breakthroughs through ongoing research grant opportunities.


Summary of Active Clinical Trials for Prader-Willi Syndrome 

It is an exciting time for drug development for Prader-Willi syndrome! Trials for several drugs have begun or will begin soon. We urge all families/caregivers to consider enrolling in a clinical trial. It is important for our community that enrollment in these studies is completed as soon as possible. However, clinical trials involve risks and labor—please consult with your physicians and refer to the following resources for more background on participating in clinical trials.




Sponsored content

CARE-PWS is a clinical study evaluating an investigational medicine for the treatment of Prader-Willi syndrome (PWS) in 7-18 year olds. People with PWS have a constant feeling of hunger, known as hyperphagia. Find out more.




  • Drugs in development go through three stages called Phase 1, Phase 2 and Phase 3. Phase 1 is the first phase of in human tests and is usually done in healthy volunteers. Phase II usually include treatment in patients to judge efficacy and is often done to determine dosing. Phase 3 is the stage needing the most patients and lasts the longest. It is the typically done with randomized, placebo-controlled trials to finalize the testing before FDA review.
  • Definitions of Study Type:
    1. Placebo—a “fake” drug that looks like the active drug but has no medicine. Placebo is given to compare results for an active drug to a fake drug to see if the active drug is actually making a difference.
    2. Randomized— this refers to a trial that randomly chooses which patients are on active drug and which are on placebo.
      1. For a crossover study, it is randomized whether one is put on active drug or on placebo first
      2. For a parallel arm study, it is randomized whether one is put on placebo or on active drug
    3. Triple blind or blinded—to avoid bias, trials often prevent patients, doctors and companies from knowing if they have received active drug or placebo. This is referred to as blinding or a blinded trial. With a triple blind trial, neither the patient, the doctor or the company know who is getting active drug and who is getting placebo.
    4. Crossover design—each patient receives both placebo and active drug over equal time periods but no one knows if the placebo is first followed by the active or vice versa.
  • BMI – “Body Mass Index” is a measure of obesity used by clinicians and is calculated by measuring weight and height. Individuals with BMIs over 25 are considered “Overweight” and individuals with BMIs over 30 are considered obese.
  • Primary Endpoint: Clinical trials typically have one measurement that is the primary determinant of the success of the trial. For example, in most PWS hyperphagia trials, companies will use a hyperphagia questionnaire to measure changes in levels of hyperphagia as the primary endpoint. Clinical trials usually also have secondary endpoints that are measure in addition to the primary endpoint.
  • Open label – often clinical trials have a blinded phase followed by an “open label” extension where all patients receive active drug and continue to be monitored for longer term safety and tolerability.

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