A Clinical Trial of PRAX-562 in Subjects With Developmental and Epileptic Encephalopathies (DEE) (EMBOLD)

January 27, 2026 updated by: Praxis Precision Medicines

A Phase 2,Double-Blind,Randomized Clinical Trial to Explore the Safety,Tolerability,Efficacy, and Pharmacokinetics of PRAX-562 in Pediatric Participants With Developmental and Epileptic Encephalopathies Followed by Open-Label Extension(OLE)

A Clinical Trial of PRAX-562 in Subjects With Developmental and Epileptic Encephalopathies (DEE)

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

Detailed Description

A Phase 2, double-blind, randomized clinical trial to evaluate the safety and tolerability of PRAX 562 in pediatric participants with SCN2A- and SCN8A- DEEs.

Study Type

Interventional

Enrollment (Estimated)

77

Phase

  • Phase 2
  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Israel
      • Tel Litwinsky, Israel, 52621
        • Praxis Research Site
  • Spain
      • Madrid, Spain, 28034
        • Praxis Research Site
  • United Kingdom
      • Glasgow, United Kingdom, G51 4TF
        • Praxis Research Site
      • London, United Kingdom, WC1N 3BH
        • Praxis Research Site
  • United States
    • Georgia
      • Atlanta, Georgia, United States, 30329
        • Praxis Research Site
    • Illinois
      • Chicago, Illinois, United States, 60611
        • Praxis Research Site
    • Minnesota
      • Minneapolis, Minnesota, United States, 55113
        • Praxis Research Site
    • New Jersey
      • Hackensack, New Jersey, United States, 07601
        • Praxis Research Site

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Has a documented variant in SCN2A with onset of seizures occurring in the first 3 months of life or has a diagnosis of SCN8A-DEE supported by both clinical and genetic findings.

  • Has a seizure frequency as follows:

    • At least 8 countable motor seizures in the 4 weeks immediately prior to Screening as reported by the parent/legal guardian or in the opinion of the investigator as documented in medical notes.

AND o At least 8 countable motor seizures during the 28 day Baseline Observation Period (during which seizure frequency is recorded in a daily seizure diary).

• Additional inclusion criteria apply and will be assessed by the study team.

Exclusion Criteria:

  • Has any clinically significant or known pathogenic or likely pathogenic genetic variant other than in SCN2A and SCN8A or a genetic variant that may explain or contribute to the participant's epilepsy and/or developmental disorder.
  • Has a documented, functionally characterized loss-of-function (LoF) missense variant or a presumed LoF variant (nonsense or frameshift variant) based on genetic testing and/or clinical evidence that prior exposure to a sodium channel blocker (SCB) medication worsened seizures.
  • Has 2 or more episodes of convulsive status epilepticus requiring hospitalization and intubation in the 6 months prior to Screening.
  • Additional exclusion criteria apply and will be assessed by the study team.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Part A: Randomized, Double-Blind 0.5mg/kg/day PRAX-562 or PRAX-562/Placebo
Eligible participants from each cohort will be randomized in a 1:1 ratio to either 0.5 milligrams/kilograms/day (mg/kg/day) PRAX-562 for 16 weeks (PRAX-562 arm) or 0.5 mg/kg/day PRAX-562 for 12 weeks and matching placebo for 4 weeks (PRAX-562/placebo arm) administered orally or via gastrostomy tube (G-tube).
Drug: PRAX-562
Once daily oral or G-tube treatment.
Experimental: Part B: Open-Label Extension Treatment 0.5mg/kg/day PRAX-562
Eligible participants will receive 0.5mg/kg/day administered orally or via G-tube for up to 144 weeks.
Drug: PRAX-562
Once daily oral or G-tube treatment.
Experimental: Part A: Randomized, Double-Blind 1.0 mg/kg/day PRAX-562 or PRAX-562/Placebo
Eligible participants from each cohort will be randomized in a 1:1 ratio to either 1.0 milligrams/kilograms/day (mg/kg/day) PRAX-562 for 16 weeks (PRAX-562 arm) or 1.0 mg/kg/day PRAX-562 for 12 weeks and matching placebo for 4 weeks (PRAX-562/placebo arm) administered orally or via gastrostomy tube (G-tube).
Drug: PRAX-562
Once daily oral or G-tube treatment.
Experimental: Open-Label Extension Treatment 1.0 mg/kg/day PRAX-562
Eligible participants will receive 1.0 mg/kg/day administered orally or via G-tube for up to 144 weeks.
Drug: PRAX-562
Once daily oral or G-tube treatment.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
PART A (Cohorts 1 and 2) RDB: To evaluate the safety and tolerability of PRAX 562 in pediatric participants with SCN2A- and SCN8A- DEEs
Time Frame: 16 weeks
Changes from baseline in monthly (28-day) motor seizure frequency
16 weeks
PART B (Cohorts 1 and 2) OLE: To evaluate the long-term safety and tolerability of PRAX-562 in pediatric participants with DEEs
Time Frame: 48 weeks
Incidence and severity of TEAEs
48 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
To assess the effect of PRAX-562 on the frequency of countable motor seizures in pediatric participants with DEEs
Time Frame: 16 weeks
Changes from baseline in monthly (28-day) motor seizure frequency
16 weeks
Plasma concentrations of PRAX-562
Time Frame: 16 weeks
Sparse pharmacokinetic (PK) sampling will be used to calculate mean concentrations at baseline, and at Weeks 2, 4, 6, 8,10, 12 and 16.
16 weeks
Seizure Frequency (OLE Extension)
Time Frame: 48 weeks
Efficacy assessments (seizure diary) will be collected daily and reviewed at timepoints Day 1, Week 16, Week 32, and Week 48.
48 weeks
Incidence of Treatment-Emergent Adverse Events (TEAEs) [Safety and Tolerability])
Time Frame: 16 weeks
The number of participants with treatment-emergent adverse events will be reported by severity and preferred term.
16 weeks
PART A (Cohorts 1 and 2) RDB: To assess the effect of PRAX-562 on the frequency of countable motor seizures in pediatric participants with DEEs
Time Frame: 16 weeks
Changes from baseline in monthly (28-day) motor seizure frequency
16 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Praxis Precision Medicines

Investigators

  • Study Director: Medical Director, Praxis Precision Medicines

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

August 2, 2023

Primary Completion (Actual)

November 12, 2025

Study Completion (Estimated)

March 1, 2027

Study Registration Dates

First Submitted

March 17, 2023

First Submitted That Met QC Criteria

April 17, 2023

First Posted (Actual)

April 19, 2023

Study Record Updates

Last Update Posted (Actual)

January 29, 2026

Last Update Submitted That Met QC Criteria

January 27, 2026

Last Verified

January 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • PRAX-562-221

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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