NCT04252586 is a Phase 3 clinical trial of GWP42003-P in Rett Syndrome, sponsored by Jazz Pharmaceuticals.

Who is sponsoring NCT04252586?

NCT04252586 is sponsored by Jazz Pharmaceuticals.

What drugs are being tested in NCT04252586?

Interventions in NCT04252586: GWP42003-P.

What condition does NCT04252586 study?

NCT04252586 studies Rett Syndrome, RTT.

Is NCT04252586 still recruiting?

NCT04252586 is currently terminated. Last updated 8 August 2022.

Are results published for NCT04252586?

Yes — primary outcome results have been posted to ClinicalTrials.gov. See the outcomes section above for details.

Last reviewed 2022-08-08 · How we verify

NCT04252586

Name: Drug Landscape Pharmaceutical Database
Creator: Drug Landscape
Published: 2026-01-01
License: https://creativecommons.org/licenses/by/4.0/

A Long-term Safety Study of Cannabidiol Oral Solution (GWP42003-P, CBD-OS) in Patients With Rett Syndrome

Terminated Phase 3 Results posted Last updated 8 August 2022

What this trial tests

Phase 3 trial testing GWP42003-P in Rett Syndrome in 21 participants. Terminated before completion.

Timeline

28 February 2020

Primary endpoint
9 June 2021

9 June 2021

Quick facts

Lead sponsor	Jazz Pharmaceuticals
Phase	Phase 3
Status	Terminated
Study type	INTERVENTIONAL
Allocation	na
Design	single group
Masking	none
Primary purpose	treatment
Enrollment	21
Start date	28 February 2020
Primary completion	9 June 2021
Estimated completion	9 June 2021
Sites	31 locations across Italy, United Kingdom, Canada, Australia, United States, Spain

Drugs / interventions tested

GWP42003-P — full drug profile →

Conditions studied

Rett Syndrome — all drugs for Rett Syndrome →
RTT — all drugs for RTT →

Sponsor

Jazz Pharmaceuticals — full company profile →

Who can join

Adults 2 to 18, any sex, with Rett Syndrome or RTT. Patients with the condition only — healthy volunteers not accepted.

Results — posted to ClinicalTrials.gov

Per-arm endpoint measurements with 95% confidence intervals where reported. Source: trial results section.

Number of Participants With Any Treatment-emergent Adverse Events (TEAEs), Discontinuations Due to AEs, Serious AEs, and Treatment-related AEs Primary · Baseline of randomized controlled trial (RCT) Visit 1 (Day 1) up to Visit 16 (Day 767) in the OLE

Adverse events (AEs) were defined as any new unfavorable/unintended signs/symptoms (including abnormal laboratory findings when relevant) or diagnosis or worsening of a pre-existing condition that occurs during the study. TEAEs were defined as the AEs that started or worsened in severity or seriousness following the first dose of GWP42003-P. A serious AE was defined as any AE that results in any of the following outcomes: death, life-threatening adverse experience, inpatient hospitalization or prolongation of existing hospitalization, persistent or significant disability/incapacity, congenital

Any TEAE

Group	Value	95% CI
GWP42003-P	19

Treatment-related TEAEs

Group	Value	95% CI
GWP42003-P	7

TEAEs leading to discontinuation

Group	Value	95% CI
GWP42003-P	3

Treatment-related TEAE leading to discontinuation

Group	Value	95% CI
GWP42003-P	1

Serious TEAEs

Group	Value	95% CI
GWP42003-P	5

Treatment-related serious TEAEs

Group	Value	95% CI
GWP42003-P	0

Number of Participants With Treatment-emergent Clinical Laboratory Parameters From the Baseline at Any Time Post-dose Primary · Baseline of randomized controlled trial (RCT) Visit 1 (Day 1) up to Visit 14 (Day 729) in the OLE

Treatment-emergent clinical parameters were defined as the following: Treatment-emergent alanine transferase (ALT) \> 3×upper limit of normal (ULN), \> 5×ULN and \> 8×ULN; Treatment-emergent aspartate aminotransferase (AST) \> 3×ULN, \> 5×ULN and \> 8×ULN; Treatment-emergent ALT or AST \> 3×ULN, \> 5×ULN and \> 8×ULN; Treatment-emergent ALT or AST \> 3×ULN and either bilirubin \> 2×ULN or international normalized ratio (INR) \> 1.5.

Treatment-emergent ALT >3xULN

Group	Value	95% CI
GWP42003-P	1

Treatment-emergent ALT >5xULN

Group	Value	95% CI
GWP42003-P	0

Treatment-emergent ALT >8xULN

Group	Value	95% CI
GWP42003-P	0

Treatment-emergent AST >3xULN

Group	Value	95% CI
GWP42003-P	0

Treatment-emergent AST >5xULN

Group	Value	95% CI
GWP42003-P	0

Treatment-emergent AST >8xULN

Group	Value	95% CI
GWP42003-P	0

Treatment-emergent ALT or AST >3xULN

Group	Value	95% CI
GWP42003-P	1

Treatment-emergent ALT or AST >5xULN

Group	Value	95% CI
GWP42003-P	0

Number of Participants With Potentially Clinically Significant Changes in Vital Sign Values of Blood Pressure From the Baseline at Any Time Post-dose Primary · Baseline of randomized controlled trial (RCT) Visit 1 (Day 1) up to Visit 15 (Day 739) in the OLE

Potentially clinically significant vital sign values of blood pressure (BP) were defined as sitting systolic BP (mmHg) change: \< -20 or \> 20 mmHg and sitting diastolic BP change: \< -10 or \> 10 mmHg. Vital sign measurements were taken in a sitting position at rest for 5 minutes. Blood pressure readings were recorded using the same arm throughout the trial, when possible.

Systolic BP Change <-20 mmHg, Baseline

Group	Value	95% CI
GWP42003-P	4

Systolic BP Change <-20 mmHg, Day 29

Group	Value	95% CI
GWP42003-P	2

Systolic BP Change <-20 mmHg, Day 57

Group	Value	95% CI
GWP42003-P	1

Systolic BP Change <-20 mmHg, Day 85

Group	Value	95% CI
GWP42003-P	1

Systolic BP Change <-20 mmHg, Day 141

Group	Value	95% CI
GWP42003-P	2

Systolic BP Change <-20 mmHg, Day 197

Group	Value	95% CI
GWP42003-P	2

Systolic BP Change <-20 mmHg, Day 281

Group	Value	95% CI
GWP42003-P	0

Systolic BP Change <-20 mmHg, Day 365

Group	Value	95% CI
GWP42003-P	0

Number of Participants With Clinically Significant Changes in the Vital Sign Values of Pulse Rate From the Baseline at Any Time Post-dose Primary · Baseline of randomized controlled trial (RCT) Visit 1 (Day 1) up to Visit 15 (Day 739) in the OLE

Potentially clinically significant vital sign values of pulse rate were defined as pulse rate change: \< -10 or \> 10 beats per minute. Vital sign measurements were taken in a sitting position at rest for 5 minutes.

Pulse Rate Change <-10beats/min, Baseline

Group	Value	95% CI
GWP42003-P	9

Pulse Rate Change <-10beats/min, Day 29

Group	Value	95% CI
GWP42003-P	8

Pulse Rate Change <-10beats/min, Day 57

Group	Value	95% CI
GWP42003-P	7

Pulse Rate Change <-10beats/min, Day 85

Group	Value	95% CI
GWP42003-P	7

Pulse Rate Change <-10beats/min, Day 141

Group	Value	95% CI
GWP42003-P	2

Pulse Rate Change <-10beats/min, Day 197

Group	Value	95% CI
GWP42003-P	5

Pulse Rate Change <-10beats/min, Day 281

Group	Value	95% CI
GWP42003-P	1

Pulse Rate Change <-10beats/min, Day 365

Group	Value	95% CI
GWP42003-P	1

Number of Participants With Clinically Significant Percent Change in Body Weight From the Baseline at Any Time Post-dose Primary · Baseline of randomized controlled trial (RCT) Visit 1 (Day 1) up to Visit 14 (Day 729) in the OLE

Clinically significant body weight changes were defined as the percent change in body weight (≤7% change or ≥7% change).

Weight Percent Change ≤7%, Baseline

Group	Value	95% CI
GWP42003-P	1

Weight Percent Change ≤7%, End of Treatment (up to Day 729)

Group	Value	95% CI
GWP42003-P	1

Weight Percent Change ≥7%, Baseline

Group	Value	95% CI
GWP42003-P	8

Weight Percent Change ≥7%, End of Treatment (up to Day 729)

Group	Value	95% CI
GWP42003-P	10

Number of Participants With At Least One Post Open Label Extension Baseline Flagged ECG Result Primary · Visit 4 (Day 29) up to Visit 15 (Day 739) in the OLE

Electrocardiogram assessments were performed for QTcB and QTcF \>450 msec, \>480 msec, and \>500 msec. QTcB = corrected QT interval with Bazette correction. QTcF = QTc corrected by Fridericia.

QTcB Interval, Aggregate > 450 msec, Day 29

Group	Value	95% CI
GWP42003-P	4

QTcB Interval, Aggregate > 450 msec, Day 57

Group	Value	95% CI
GWP42003-P	0

QTcB Interval, Aggregate > 450 msec, Day 85

Group	Value	95% CI
GWP42003-P	4

QTcB Interval, Aggregate > 450 msec, Day 141

Group	Value	95% CI
GWP42003-P	0

QTcB Interval, Aggregate > 450 msec, Day 197

Group	Value	95% CI
GWP42003-P	0

QTcB Interval, Aggregate > 450 msec, Day 365

Group	Value	95% CI
GWP42003-P	0

QTcB Interval, Aggregate > 450 msec, End of Treatment (up to Day 729)

Group	Value	95% CI
GWP42003-P	4

QTcB Interval, Aggregate > 450 msec, Day 739

Group	Value	95% CI
GWP42003-P	0

Number of Participants With Any Changes In Menstruation Cycle at Any Time Post-dose Primary · Baseline of randomized controlled trial (RCT) Visit 1 (Day 1) up to Visit 14 (Day 729) in the OLE

Participants were evaluated for any changes to typical menstrual cycles, duration of menstrual cycles, and typical strength of the menstrual cycles during the study.

Any change to typical cycle, Yes; Day 1

Group	Value	95% CI
GWP42003-P	1

Any change to typical cycle, No; Day 1

Group	Value	95% CI
GWP42003-P	1

Any change to typical cycle; Day 1 Unknown/Missing

Group	Value	95% CI
GWP42003-P	19

Typical duration of menstruation cycle, <3 days; Day 1

Group	Value	95% CI
GWP42003-P	0

Typical duration of menstruation cycle, 3-7 days; Day 1

Group	Value	95% CI
GWP42003-P	1

Typical duration of menstruation cycle, >7 days; Day 1

Group	Value	95% CI
GWP42003-P	0

Typical duration of menstruation cycle; Day 1 Unknown/Missing

Group	Value	95% CI
GWP42003-P	20

Typical strength of menstruation cycle, Light; Day 1

Group	Value	95% CI
GWP42003-P	1

Number of Participants With Suicidal Ideation or Behavior at the Baseline and at Any Time Post-dose Primary · Baseline of randomized controlled trial (RCT) Visit 1 (Day 1) up to Visit 14 (Day 729) in the OLE

Suicidal ideation and behavior was assessed by the investigator via a clinical interview with the caregiver. The questionnaire included following questions: Has the child expressed any wish to be dead?, Has the child made any suicide attempts?, Has the child shown any non-suicidal self-injurious behavior? The responses were recorded as Yes/No.

Has the child expressed any wish to be dead? Yes, Baseline

Group	Value	95% CI
GWP42003-P	0

Has the child expressed any wish to be dead? No, Baseline

Group	Value	95% CI
GWP42003-P	16

Has the child expressed any wish to be dead? Unknown/Missing, Baseline

Group	Value	95% CI
GWP42003-P	5

Has the child expressed any wish to be dead? Yes, End of Treatment (up to Day 729)

Group	Value	95% CI
GWP42003-P	0

Has the child expressed any wish to be dead? No, End of Treatment (up to Day 729)

Group	Value	95% CI
GWP42003-P	18

Has the child made any suicide attempts? Yes, Baseline

Group	Value	95% CI
GWP42003-P	0

Has the child made any suicide attempts? No, Baseline

Group	Value	95% CI
GWP42003-P	16

Has the child made any suicide attempts? Unknown/Missing, Baseline

Group	Value	95% CI
GWP42003-P	5

Mean Change From Baseline in Insulin-like Growth Factor-1 (IGF-1) Levels at End of Treatment Primary · Baseline of randomized controlled trial (RCT) Visit 1 (Day 1) up to Visit 14 (Day 729) in the OLE

Blood samples were collected to assess changes in serum IGF-1 levels. A negative mean change from baseline indicates a reduction in IGF-1 levels.

Group	Value	95% CI
GWP42003-P	-41.1	± 100.77

Number of Participants With Changes in Tanner Staging at the Baseline and at End of Treatment Primary · Baseline of randomized controlled trial (RCT) Visit 1 (Day 1) up to Visit 14 (Day 729) in the OLE

Pubic hair growth and breast development of all adolescents were assessed by the investigator or caregiver using Tanner Staging categorization from 1 to 5. Stage 1- No glandular tissue; areola follows skin contours of chest; No pubic hair Stage 2- Breast bud forms; areola begins to widen; a small amount of long, downy hair with slight pigmentation on labia majora Stage 3- Breast begins to become more elevated and extends beyond borders of the areola, which continues to widen but remains in contour with surrounding breast; Hair becomes more coarse and curly and begins to extend laterally Stage

Baseline, Tanner Stage 1

Group	Value	95% CI
GWP42003-P	6

Baseline, Tanner Stage 2

Group	Value	95% CI
GWP42003-P	3

Baseline, Tanner Stage 3

Group	Value	95% CI
GWP42003-P	1

Baseline, Tanner Stage 4

Group	Value	95% CI
GWP42003-P	2

Baseline, Tanner Stage 5

Group	Value	95% CI
GWP42003-P	4

Baseline, Tanner Stage Missing

Group	Value	95% CI
GWP42003-P	5

End of Treatment (up to Day 729), Tanner Stage 1

Group	Value	95% CI
GWP42003-P	4

End of Treatment (up to Day 729), Tanner Stage 2

Group	Value	95% CI
GWP42003-P	2

Mean Change From Baseline in Rett Syndrome Behaviour Questionnaire (RSBQ) Overall Score at End of Treatment Secondary · Baseline of randomized controlled trial (RCT) Visit 1 (Day 1) up to Visit 14 (Day 729) in the OLE

RSBQ is a caregiver-completed questionnaire that assesses the overall condition (45 items) in individuals with Rett Syndrome. Each item is rated on a 3-point scale (0-2); 0 indicating an item that is "not true as far as you know," 1 indicating an item is "somewhat or sometimes true," and 2 indicating an item that is "very true or often true". " Item 31 ("Uses eye gaze to convey feelings, needs and wishes") is reverse-scored (0 indicating "very true or often true", 1 indicating "somewhat or sometimes true," and 2 indicating "not true as far as you know"). The total summed score ranges from 0 to

Group	Value	95% CI
GWP42003-P	-7.4	± 14.93

Mean Clinical Global Impressions-Improvement (CGI-I) Continuous Score at End of Treatment Secondary · Visit 14 (Day 729) in the OLE

CGI-I is a 7-point scale that requires the clinician to assess whether a patient's condition has improved or worsened relative to a baseline state at the beginning of the intervention. This was rated as: 1 = very much improved; 2 = much improved; 3 = minimally improved; 4 = no change; 5 = minimally worse; 6 = much worse; or 7 = very much worse. The mean continuous CGI-I score (averaged from each treatment enrolled under protocol and under annex) at Visit 14 (Day 729) is being reported. Higher mean scores indicate worse condition.

Group	Value	95% CI
GWP42003-P	3.3	± 1.15

Adverse events — posted to ClinicalTrials.gov

Time frame: Adverse event data were collected from baseline of randomized controlled trial (RCT) Visit 1 (Day 1) up to Visit 16 (Day 767) in the OLE.. Reporting threshold: 5%. Adverse-event reports describe events observed during the trial — not all are caused by the drug.

GWP42003-P

Serious: 5/21 (24%)

Deaths: 2/21

Serious adverse events (8 terms)

Reaction	System	GWP42003-P
Respiratory failure	Respiratory, thoracic and mediastinal disorders	—
Rett Syndrome	Congenital, familial and genetic disorders	—
COVID-19	Infections and infestations	—
Lower respiratory tract infection	Infections and infestations	—
Postoperative wound infection	Infections and infestations	—
Generalised tonic-clonic seizure	Nervous system disorders	—
Status epilepticus	Nervous system disorders	—
Respiratory arrest	Respiratory, thoracic and mediastinal disorders	—

Other adverse events (19 terms — click to expand)

Reaction	System	GWP42003-P
Vomiting	Gastrointestinal disorders	—
Diarrhoea	Gastrointestinal disorders	—
Pyrexia	General disorders	—
Upper respiratory tract infection	Infections and infestations	—
Monocyte count decreased	Investigations	—
Decreased appetite	Metabolism and nutrition disorders	—
Seizure	Nervous system disorders	—
Irritability	Psychiatric disorders	—
Neutropenia	Blood and lymphatic system disorders	—
Otitis media	Infections and infestations	—
Fall	Injury, poisoning and procedural complications	—
Mean cell volume increased	Investigations	—
Epilepsy	Nervous system disorders	—
Tremor	Nervous system disorders	—
Anxiety	Psychiatric disorders	—
Bruxism	Psychiatric disorders	—
Cough	Respiratory, thoracic and mediastinal disorders	—
Rett syndrome	Congenital, familial and genetic disorders	—
Respiratory failure	Respiratory, thoracic and mediastinal disorders	—

Most-reported serious reactions: Respiratory failure, Rett Syndrome, COVID-19, Lower respiratory tract infection, Postoperative wound infection, Generalised tonic-clonic seizure, Status epilepticus, Respiratory arrest.

Data from ClinicalTrials.gov NCT04252586 adverse events section.

Sponsor's own description

This study will be conducted to evaluate the long-term safety of cannabidiol oral solution (GWP42003-P, CBD-OS) in participants with Rett syndrome.

Publications & conference data

1 peer-reviewed publication reference this trial (live from Europe PMC):

Medical Cannabis in Pediatric Oncology: Friend or Foe?
Malach M, Kovalchuk I, Kovalchuk O. · · 2022 · cited 8× · PMID 35337156 · DOI 10.3390/ph15030359

Verify or expand the search:

Other trials of GWP42003-P

Trials testing the same drug.

NCT05288283 — Efficacy and Safety of GWP42003-P Oral Solution in Children With Epilepsy With Myoclonic-atonic Seizures · Phase 3 · terminated
NCT04745026 — Trial to Investigate the Safety and Efficacy of Cannabidiol Oral Solution (GWP42003-P; CBD-OS) in Children and Adolescen · Phase 2 · completed
NCT04485104 — Assessment of Adjunctive Cannabidiol Oral Solution (GWP42003-P) in Children With Tuberous Sclerosis Complex (TSC), Drave · Phase 3 · terminated
NCT04421456 — Trial to Investigate the Safety and Efficacy of GWP42003-P Versus Placebo as Adjunctive Therapy in Participants With Sch · Phase 2 · terminated
NCT03848832 — Efficacy and Safety of Cannabidiol Oral Solution (GWP42003-P, CBD-OS) in Patients With Rett Syndrome · Phase 3 · terminated

Other recruiting trials for Rett Syndrome

Currently open trials in the same condition.

NCT06840496 — To Investigate the Efficacy of Treatment With Oral NA-921 (Bionetide) Versus Placebo in Females With Rett Syndrome · Phase 3 · recruiting
NCT07151950 — Obi Medical Robot: Evaluating Effectiveness Related to Usability · active not recruiting
NCT06856759 — Single-Dose AAV-MECP2 Safety/Tolerability and Efficacy in Rett Syndrome · EARLY_PHASE1 · recruiting
NCT07418905 — Technology-supported Motor Rehabilitation for People With Rett Syndrome · NA · active not recruiting
NCT06152237 — Safety and Efficacy of TSHA-102 in Pediatric Females With Rett Syndrome (REVEAL Pediatric Study) · Phase 1, PHASE2 · active not recruiting

Other Jazz Pharmaceuticals trials

Trials by the same sponsor.

NCT07533942 — A Study of JZP3507 (ONC206) in Recurrent Grade 2 or 3 Meningioma · Phase 2 · not yet recruiting
NCT07459634 — A Study of Lurbinectedin in Combination With Durvalumab for the Treatment of Participants With ES-SCLC · Phase 2 · not yet recruiting
NCT07377539 — A Study to Investigate the Safety, Tolerability, Pharmacokinetics, and Food Effect of JZP047 in Healthy Participants · Phase 1 · not yet recruiting
NCT07282587 — Study of ONC206 (JZP3507) in Advanced Pheochromocytoma and Paraganglioma · Phase 2 · recruiting
NCT07233239 — A Study to Evaluate the Efficacy and Safety of Cannabidiol Oral Solution (CBD-OS [GWP42003-P, JZP926]) for the Treatment · Phase 1 · recruiting

Verify against primary sources

ClinicalTrials.gov — authoritative US registry record
WHO ICTRP — international registry index
EU Clinical Trials Register
Sponsor press releases (Google)

Data sources for this page

Trial protocol + status: ClinicalTrials.gov NCT04252586 (US National Library of Medicine, public domain)
Publications: Europe PMC API search by NCT ID, retrieved 10 June 2026
Drug + disease cross-links: matched in real time against Drug Landscape's normalised drug + company + condition tables
Sponsor: as reported to ClinicalTrials.gov by Jazz Pharmaceuticals
Last refreshed: 8 August 2022

Drug Landscape aggregates and links these public records for informational use only. Always verify against the primary source before clinical or regulatory decisions. Canonical URL: https://druglandscape.com/trial/NCT04252586.

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