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Condition (MeSH)

Prader-Willi Syndrome

ClinicalTrials.gov lists 140 trials for Prader-Willi Syndrome or a narrower condition beneath it. Soleno Therapeutics, Inc. has the most among industry and government lead sponsors, with 6.

MeSH D011218 Nervous System Diseases C10 C16 C18 Listed by Orphanet as a rare disease
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Phase 1 Phase 1 5 Phase 1/2 Phase 1/2 7 Phase 2 Phase 2 20 Phase 2/3 Phase 2/3 4 Phase 3 Phase 3 21 Phase 4 Phase 4 7 Not applicable Not applicable 39 Observational Observational 37 Phase 1 Phase 1 5 Phase 1/2 Phase 1/2 7 Phase 2 Phase 2 20 Phase 2/3 Phase 2/3 4 Phase 3 Phase 3 21 Phase 4 Phase 4 7 Not applicable Not applicable 39 Observational Observational 37

Trials per phase

140 of the 140 trials are tagged with Prader-Willi Syndrome itself; the rest are tagged with a narrower condition beneath it.

Get the Prader-Willi Syndrome report as a PDF

The PDF carries up to 50 rows of each section, where the page shows the first few, with the sources listed. Enter a work email and confirm it from the message we send, and the report follows by email.

When did Prader-Willi Syndrome trials start? (24)

Shown in this order: most recent first, 1990 onwards. 2026 is partial: trials registered with a 2026 start date so far, not a full year. 1 trial is registered to start in 2027 or later, and not listed here.

Trials over time, by phase

  • Phase 1
  • Phase 1/2
  • Phase 2
  • Phase 2/3
  • Phase 3
  • Phase 4
  • Not applicable
  • Observational

Top of scale: 13

1999: 1 trials (Observational 1) 2002: 1 trials (Not applicable 1) 2004: 2 trials (Not applicable 1, Phase 3 1) 2005: 4 trials (Observational 1, Not applicable 2, Phase 3 1) 2006: 3 trials (Observational 2, Not applicable 1) 2007: 4 trials (Observational 2, Not applicable 1, Phase 3 1) 2008: 3 trials (Observational 2, Phase 1/2 1) 2009: 4 trials (Observational 2, Phase 4 1, Phase 2 1) 2011: 5 trials (Observational 2, Not applicable 1, Phase 1/2 1, Phase 1 1) 2012: 5 trials (Observational 1, Not applicable 2, Phase 4 1, Phase 3 1) 2013: 5 trials (Observational 1, Not applicable 2, Phase 2 1, Phase 1/2 1) 2014: 9 trials (Observational 1, Not applicable 3, Phase 3 2, Phase 2/3 1, Phase 1/2 1, Phase 1 1) 2015: 5 trials (Observational 1, Phase 2 2, Phase 1 2) 2016: 7 trials (Observational 1, Not applicable 5, Phase 4 1) 2017: 7 trials (Observational 1, Not applicable 3, Phase 4 1, Phase 2 1, Phase 1/2 1) 2018: 13 trials (Observational 3, Not applicable 2, Phase 3 4, Phase 2 4) 2019: 7 trials (Observational 2, Not applicable 2, Phase 4 1, Phase 3 1, Phase 2/3 1) 2020: 8 trials (Observational 1, Not applicable 2, Phase 4 1, Phase 3 1, Phase 2 2, Phase 1/2 1) 2021: 6 trials (Observational 1, Not applicable 2, Phase 3 2, Phase 2 1) 2022: 8 trials (Observational 3, Phase 2/3 2, Phase 2 2, Phase 1 1) 2023: 12 trials (Observational 3, Not applicable 4, Phase 3 2, Phase 2 3) 2024: 9 trials (Observational 2, Not applicable 2, Phase 3 4, Phase 1/2 1) 2025: 8 trials (Observational 3, Not applicable 2, Phase 4 1, Phase 3 1, Phase 2 1)

Trials registered with a start date in each year, 1990 onward, stacked by phase (complete years only; the current partial year is in the table's notes). The table below lists the same counts, most recent years first.

Trials started per year
Year Trials started
2026 (partial year) 2
2025 8
2024 9
2023 12
2022 8
2021 6
2020 8
2019 7
2018 13
2017 7

Showing 10 of 24 earlier years.

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Forecast of the full-year count, planned starts included, not rows of this table: about 3 trials starting in 2026 and about 5 in 2027, the average of the 24 months through September, counted as registered and carried forward. The rows of this table count trials registered so far with a start date in the year, planned starts included; the forecast looks ahead to the count for the whole year, so it is not the same measure. In backtests on conditions of this size, forecasts made part-way through the year were typically off by about 28 percent and ran about 20 percent low against the count later registered; forecasts made before the year began were off by about 39 percent and ran about 37 percent low against the count later registered. These figures rest on a few years of history (target years from 2018 to 2025, varying by figure), place each condition as it is mapped today rather than as it was then, and score against a count for the newest year that was still being revised. Only condition series were scored.

Prediction, not a registry value: median of 36 months from start to primary completion across 12 trials still running at the 2026-10-09 snapshot; registered median of 19 months across 86 trials with a primary completion typed Actual. Source: ClinicalTrials.gov / AACT (CTTI), public domain.

What phase are Prader-Willi Syndrome trials in? (8)

Shown in this order: phase order.

Show the trials by phase as a table
Trials by phase
Phase Trials
Phase 1 5
Phase 1/2 7
Phase 2 20
Phase 2/3 4
Phase 3 21
Phase 4 7
Not applicable 39
Observational 37

How many Prader-Willi Syndrome trials are recruiting? (8)

Shown in this order: the order a trial moves through, from not yet recruiting to unknown.

Trials by recruitment status
Status Trials
Not yet recruiting 3
Recruiting 15
Enrolling by invitation 3
Active, not recruiting 6
Completed 76

Showing 5 of 8 statuses.

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Status as registered on ClinicalTrials.gov. Each trial is counted once.

Which lead sponsors run the most Prader-Willi Syndrome trials? (5)

Shown in this order: most trials first. Lead sponsors the registry classes as industry, NIH, US federal, other government or network. A hospital or university the registry files as government can appear here. Sponsors it classes as academic or other are shown on the full page, because that class cannot separate an institution from a named investigator.

Lead sponsors
Sponsor Trials
Soleno Therapeutics, Inc. 6
Radius Pharmaceuticals, Inc. 4
Aardvark Therapeutics, Inc. 3
Harmony Biosciences Management, Inc. 3
Rhythm Pharmaceuticals, Inc. 3

Which drugs are being tested for Prader-Willi Syndrome? (4)

Shown in this order: most trials first. One row per drug, matched to a single molecule under all its names, ranked by number of trials.

Drugs tested
Drug Trials
Pitolisant 3
ARD-101 3
Cannabidiol 2
Exenatide 2

Interventions as named in the registry (11)

Shown in this order: most trials first.

Interventions as named in the registry
Drug Trials
IM Oxytocin 6
somatropin AQ 6
DCCR 5
8IU intranasal oxytocin 3
LAR Octreotide 3

Showing 5 of 11 interventions.

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These are the names sponsors entered on ClinicalTrials.gov that we have not matched to a single molecule. Some are drugs under a brand or code name; others are procedures, doses or arm labels.

Which serious adverse events do Prader-Willi Syndrome trials report? (10)

Shown in this order: most subjects affected first. Subjects affected summed across trials, a cross-trial signal, not a rate.

Serious adverse events in this condition's trials
Adverse event Subjects affected Trials
Impulse control disorder 2 1
Lower respiratory tract infection 2 2
Pneumonia 2 1
Abnormal behaviour 1 1
Affect lability 1 1

Showing 5 of 10 adverse events.

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Which publications cover Prader-Willi Syndrome? (113)

Shown in this order: major-topic papers first, then newest, then most linked to trials.

Publications
Publication Journal Year Major topic
Early oxytocin treatment in infants with Prader-Willi syndrome is safe and is associated with better endocrine, metabolic and behavioral outcomes. Orphanet journal of rare diseases 2025 Yes
Improvement in body composition of Japanese participants with Prader-Willi syndrome following somatropin treatment: an open-label, multi cohort Phase 3 study. Endocrine journal 2025 Yes
A proof-of-concept study of pitolisant for excessive daytime sleepiness in patients with Prader-Willi syndrome. Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine 2025 Yes
Behavioral changes in patients with Prader-Willi syndrome receiving diazoxide choline extended-release tablets compared to the PATH for PWS natural history study. Journal of neurodevelopmental disorders 2024 Yes
Diazoxide choline extended-release tablet in people with Prader-Willi syndrome: results from long-term open-label study. Obesity (Silver Spring, Md.) 2024 Yes

Showing 5 of 113 publications.

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Prevalence (48)

Shown in this order: jurisdiction, then disease name. Orphanet observation for the mapped ORPHA concept; the mapping relation column says whether that concept is exactly this condition or broader or narrower.

Prevalence
Orphanet disease Type Class Geography Jurisdiction Mapping relation
Prader-Willi syndrome Prevalence at birth 1-9 / 100 000 United Kingdom GB Exact
Prader-Willi syndrome Point prevalence 1-9 / 100 000 United Kingdom GB Unspecified
Prader-Willi syndrome Prevalence at birth 1-9 / 100 000 United Kingdom GB Exact
Prader-Willi syndrome Point prevalence 1-9 / 100 000 United Kingdom GB Exact
Prader-Willi syndrome Prevalence at birth 1-9 / 100 000 United Kingdom GB Unspecified

Showing 5 of 48 prevalence observations.

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Rare-disease identity (2)

Shown in this order: exact, broader, narrower, other.

Rare-disease identity
Orphanet disease ORPHA code Relation Source
Prader-Willi syndrome 739 Exact Orphadata Science knowledge files, Product 1
Prader-Willi syndrome 739 Exact Orphanet Rare Disease Ontology (ORDO)

Not on this page

Not measured: delivery record.

Checked, with nothing recorded for this condition: sub-conditions in mesh.

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