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

Praxis Precision Medicines

Status and phase: Active, not recruiting; Phase 3; Phase 2

Conditions: SCN8A Encephalopathy; SCN2A Encephalopathy

Treatments: Drug: PRAX-562

Study type: Interventional

Funder types: Industry

Identifiers

NCT05818553

PRAX-562-221

Details and patient eligibility

About

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

Full 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.

Enrollment: 77 estimated patients

Sex: All

Ages: 1 to 18 years old

Volunteers: No Healthy Volunteers

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.

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Triple Blind

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77 participants in 4 patient groups

Part A: Randomized, Double-Blind 0.5mg/kg/day PRAX-562 or PRAX-562/Placebo

Experimental group

Description:

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).

Treatment:

Drug: PRAX-562

Part B: Open-Label Extension Treatment 0.5mg/kg/day PRAX-562

Experimental group

Description:

Eligible participants will receive 0.5mg/kg/day administered orally or via G-tube for up to 144 weeks.

Treatment:

Drug: PRAX-562

Part A: Randomized, Double-Blind 1.0 mg/kg/day PRAX-562 or PRAX-562/Placebo

Experimental group

Description:

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).

Treatment:

Drug: PRAX-562

Open-Label Extension Treatment 1.0 mg/kg/day PRAX-562

Experimental group

Description:

Eligible participants will receive 1.0 mg/kg/day administered orally or via G-tube for up to 144 weeks.

Treatment:

Drug: PRAX-562