A Study to Evaluate the Safety and Efficacy of CBD-OS in Participants With DEE

A Phase 3, Multicenter, Randomized, Double-blind, Placebo-Controlled Study to Evaluate the Safety and Efficacy of Cannabidiol Oral Solution (CBD-OS, JZP926-OS) in Participants Aged 1 Year and Older With Developmental and Epileptic Encephalopathy (DEE)

The efficacy, safety, and tolerability of CBD-OS have been evaluated for the treatment of seizures associated with Lennox-Gastaut syndrome (LGS), Dravet syndrome (DS), and Tuberous sclerosis complex (TSC). The current JZP926-303 study is being conducted to evaluate the safety and efficacy of CBD-OS in participants with Developmental and Epileptic Encephalopathy (DEE).

Study Overview

• Status: Not yet recruiting
• Conditions: Developmental and Epileptic Encephalopathy (DEE)
• Intervention / Treatment: Drug: CBD-OS; Drug: Placebo

Detailed Description

This Phase 3, multicenter, randomized, placebo-controlled, double-blind study will evaluate the efficacy and safety of CBD-OS in participants aged ≥ 1 year with DEE. The primary objective of the 6-week Double-blind Treatment Period of the study is to assess the efficacy of CBD-OS in reducing the frequency of countable motor seizures compared with placebo in participants with DEE. In addition, the Double-Blind Treatment Period will also assess the safety and tolerability of CBD-OS. The optional 6-month open-label extension (OLE) will provide additional data on the long-term efficacy, safety, and tolerability of CBD-OS.

• Study Type: Interventional
• Enrollment (Estimated): 120
• Phase: Phase 3

Contacts and Locations

• Study Contact: Name: Clinical Trial Disclosure & Transparency; Phone Number: 215-832-3750; Email: ClinicalTrialDisclosure@JazzPharma.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Participants are eligible to be included in the study only if all the following criteria apply:

1. Is at least 1 year of age at the time of signing the informed consent/assent.
2. Meets the clinical phenotype for DEE as specified in the protocol.
3. Per the investigator, the underlying etiology contributes to developmental impairment and seizures.
4. Has had, or is willing to complete, confirmatory imaging and/or genetic testing to determine etiology of DEE.
5. Is currently receiving antiseizure intervention, such as treatment with a stable regimen of at least 1 ASM or an established intervention for epilepsy (eg, ketogenic diet or neurostimulation).
6. All medications or interventions for epilepsy have been stable for ≥ 28 days prior to starting the baseline period (Visit 2) with no planned changes to the regimen for the duration of the Double-blind Treatment Period.

Participants are excluded from the study if any of the following criteria apply:

1. Has a concurrent, confirmed diagnosis of non-epileptic seizures or events that can confound the assessment of the efficacy measures, in the opinion of the investigator.
2. The etiology of the participant's seizures is a progressive neurologic disease.
3. Has known or suspected hypersensitivity to cannabinoids or any of the excipients of the study intervention, such as sesame oil.
4. Has an active central nervous system (CNS) infection, demyelinating disease, degenerative neurologic disease, or any CNS disease deemed to be progressive during the study that may confound the interpretation of the study results (including autoimmune encephalitis).
5. Is currently being treated with Epidiolex or recently received treatment with Epidiolex within 28 days prior to screening.
6. Has experienced a lack of efficacy and/or poor tolerability to an adequate treatment regimen of Epidiolex based on medical history and the clinical judgement of the investigator. Participants who discontinued treatment for reasons other than safety, tolerability, or lack of efficacy and previously received Epidiolex ≥ 28 days prior to starting the Baseline Period (Visit 2) may be eligible for the study after consultation with the medical monitor and/or sponsor representative.
7. Has been taking felbamate for less than 12 months prior to screening. Participants who are stable on felbamate for ≥ 12 months are eligible for inclusion.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: CBD-OS; Participants with DEE will be randomized to CBD-OS up to 10 mg/kg twice daily for a 6-week treatment period.	Drug: CBD-OS; Oral solution, twice daily; Other Names: JZP926-OS
Placebo Comparator: Placebo; Participants with DEE will be randomized to matching placebo for a 6-week treatment period.	Drug: Placebo; Oral solution, twice daily
Experimental: Open-Label Extension: CBD-OS; Participants with DEE who completed the double-blind phase of the study and enter the optional OLE will begin a 22-week open-label treatment period with CBD-OS up to 10 mg/kg twice daily following a 2-week Blinded Transition Period.	Drug: CBD-OS; Oral solution, twice daily; Other Names: JZP926-OS

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Change in Countable Motor Seizure Frequency Per 28 Days	Baseline up to 6 weeks of double-blind treatment period

Secondary Outcome Measures

Outcome Measure	Time Frame
Change in Total Seizure Frequency Per 28 Days	Baseline up to 6 weeks of double-blind treatment period
Proportion of Participants Who Achieve ≥ 50% Reduction From Baseline in Countable Motor Seizure Frequency	Baseline up to 6 weeks of double-blind treatment period
Caregiver Global Impression of Change (CaGI-C) Score	Week 6 of double-blind treatment period
Change from Baseline in Caregiver Global Impression of Severity (CaGI-S) Score	Week 6 of double-blind treatment period
Change From Baseline in Number of Countable Motor Seizure-free Days per 28 Days	Baseline up to 6 weeks of double-blind treatment period
Clinical Global Impression of Change (CGI-C) Score	Week 6 of double-blind treatment period
Change from Baseline in Clinical Global Impression of Severity (CGI-S) Score	Week 6 of double-blind treatment period
Number of Participants Reporting Treatment-emergent Adverse Events	Baseline up to 6 weeks of double-blind treatment period
Mean Plasma Concentration of CBD	Baseline up to 6 weeks of double-blind treatment period
Mean Plasma Concentration of Metabolite 7-OH-CBD	Baseline up to 6 weeks of double-blind treatment period
Mean Plasma Concentration of Metabolite 7-COOH-CBD	Baseline up to 6 weeks of double-blind treatment period

Collaborators and Investigators

• Sponsor: Jazz Pharmaceuticals
• Collaborators: Jazz Pharmaceuticals Research UK Limited

Study record dates

Study Major Dates

• Study Start (Estimated): October 30, 2026
• Primary Completion (Estimated): September 4, 2029
• Study Completion (Estimated): September 4, 2029

Study Registration Dates

• First Submitted: July 20, 2026
• First Submitted That Met QC Criteria: July 20, 2026
• First Posted (Actual): July 23, 2026

Study Record Updates

• Last Update Posted (Actual): July 24, 2026
• Last Update Submitted That Met QC Criteria: July 22, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: CBD-OS; Developmental and Epileptic Encephalopathy; JZP926-OS
• Other Study ID Numbers: JZP926-303

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: In accordance with ICMJE requirements, Jazz Pharmaceuticals may provide qualified external researchers access to individual participant data (IPD) and clinical trial data that underlie the results of this trial upon request. Qualified researchers can submit a request on https://www.jazzpharma.com/science/clinical-trial-data-sharing/ as outlined. Jazz Pharmaceuticals reserves the right not to consider a request. For inquiries about Jazz's data sharing policy contact clinicaldatasharing@jazzpharma.com.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No