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Study of Elsunersen in Children with SCN2A Developmental and Epileptic Encephalopathy to Reduce Seizures

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study focuses on children with SCN2A developmental and epileptic encephalopathy (DEE), a rare genetic condition that causes severe seizures starting in early infancy. The research evaluates a new medication called PRAX-222 (elsunersen), which is given as an injection into the spinal fluid through a procedure called intrathecal administration. The purpose is to determine if this treatment can reduce the frequency of seizures in children with this specific genetic condition.

The study uses a double-blind design where some participants receive the study medication while others undergo a sham procedure. The treatment period lasts 24 weeks, during which participants receive regular doses of the medication. Throughout the study, doctors monitor how often seizures occur and track any changes in the participants' overall condition.

During the trial, participants continue their regular seizure medications while receiving the study treatment. The study medication is administered at specific intervals over the course of treatment, with a maximum daily dose of 1 mg and a total maximum dose of 12 mg over 48 weeks. Doctors closely monitor participants' health through regular check-ups, including evaluations of their physical condition, neurological status, and laboratory tests.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial screening and observation

    Your eligibility for the trial will be evaluated based on specific medical criteria, including genetic testing confirmation of SCN2A variant.

    A baseline observation period will track your seizure frequency. You will need to maintain a seizure diary for at least 80% of days during this period.

    Medical tests will be conducted, including kidney function (eGFR), liver function tests (ALT, AST), and bilirubin levels.

  2. Step 2

    Pre-treatment evaluation

    An Eligibility Review Committee will review your medical documentation, including brain imaging (MRI) results and seizure frequency records.

    Your current anti-seizure medications must remain stable for one month before screening.

    Initial assessments will include physical examination, vital signs, laboratory tests, and heart monitoring (ECG).

  3. Step 3

    Treatment period

    The treatment period will last 24 weeks.

    You will receive either elsunersen or a sham procedure through intrathecal injection (injection into the spinal fluid).

    Regular monitoring of seizure frequency and documentation in the seizure diary will continue.

    Blood and spinal fluid samples will be collected to measure medication levels.

  4. Step 4

    Monitoring and assessments

    Regular evaluations will track changes in seizure frequency and seizure-free days.

    Your doctor will assess your condition using clinical rating scales (CGI-S and CGI-I).

    Your caregiver will complete assessment forms about your condition (CgGI-S and CgGI-I).

    Sleep patterns will be monitored throughout the study.

    Regular safety assessments will include physical examinations, vital signs, laboratory tests, and heart monitoring.

  5. Step 5

    Extension period

    After the initial 24-week treatment period, the study will continue with an extension phase.

    During this period, changes to anti-seizure medications may be permitted.

    Continued monitoring of safety and effectiveness will occur.

    The total study duration is expected to run until April 2027.

Who can join the trial?

11 criteria

  • Patient or parent/legal guardian must be willing to sign an informed consent form showing understanding of the study requirements and procedures
  • Patient must have normal kidney function with an eGFR (estimated glomerular filtration rate - a measure of kidney function) of at least 60 mL/min/1.73 m²
  • Patient must have a confirmed genetic test showing a Gain of Function SCN2A variant (a specific genetic change)
  • Patient must have experienced first seizures before 3 months of age
  • Patient must be between newborn (at least 37 weeks and 1 day of pregnancy) and 18 years old when entering the study
  • Patient must have at least 4 countable motor seizures within 28 days during the observation period that do not respond to current treatment
  • If patient is taking any anti-seizure medications or using treatments like ketogenic diet (special high-fat diet) or vagus nerve stimulation (device that helps control seizures), the treatment must be stable for 1 month before screening
  • Patient must be reviewed by the Eligibility Review Committee, including review of genetic tests, brain MRI (detailed images of the brain), and seizure frequency
  • Patient must complete seizure diary entries for at least 80% of days during screening period
  • Patient must have normal or near-normal liver function tests, including:
    • Bilirubin (liver protein) less than 1.5 times the normal limit
    • ALT and AST (liver enzymes) less than 3 times the normal limit

Who cannot join the trial?

13 criteria

  • Age below 2 years or above 17 years
  • No confirmed genetic diagnosis of SCN2A mutation (a change in a specific gene that affects brain function)
  • History of severe allergic reactions to similar medications
  • Participation in other clinical trials within the last 30 days
  • Presence of other significant medical conditions that could interfere with the study
  • Current use of medications that could interact with the study drug
  • Inability to comply with study procedures or follow-up visits
  • Pregnancy or breastfeeding
  • History of major surgery in the past 3 months
  • Severe liver or kidney problems
  • Unable to provide informed consent (for parents/guardians in case of minors)
  • History of non-compliance with medical treatments
  • Any condition that, in the opinion of the study doctor, makes participation unsafe
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Investigated drugs

Elsunersen is an investigational medication designed to treat seizures in children with SCN2A-related developmental and epileptic encephalopathy (SCN2A-DEE). This medication aims to reduce the frequency of seizures in young patients who have this rare genetic condition. The medication is being studied to determine how well it works compared to a sham procedure (placebo).

What is already known about the treatment

Elsunersen - An investigational medication being studied in clinical trials for the treatment of SCN2A developmental and epileptic encephalopathy (SCN2A-DEE), a rare genetic condition affecting children. The drug is designed to target voltage-gated sodium channel type II alpha subunit (SCN2A) mutations that cause seizures and developmental delays in pediatric patients. While the exact mechanism of action involves modulation of sodium channels at the molecular level, this treatment is being evaluated through a double-blind, sham-controlled study to assess its effectiveness in reducing seizure frequency in early-onset cases. As a novel therapeutic approach, elsunersen represents a potential targeted treatment option for this specific form of genetic epilepsy.

Investigated diseases

SCN2A Developmental and Epileptic Encephalopathy – A rare genetic neurological disorder caused by mutations in the SCN2A gene, which affects the function of sodium channels in brain cells. The condition typically begins in early childhood and is characterized by frequent seizures that can vary in type and severity. This disorder affects brain development and can cause developmental delays. Children with this condition often experience different types of seizures, which may occur multiple times per day. The condition also impacts cognitive development, movement abilities, and in some cases, communication skills.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-515598-82-00Protocol codePRAX-222-311Estimated enrolment40 patientsSponsorPraxis Precision Medicines Inc.

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