NCT07531745 · Ionis Pharmaceuticals, Inc.
ASCEND: Safety and Tolerability of ION337 for the Treatment of Dravet Syndrome
What this study is about
The primary purpose of this study is to evaluate the safety and how well patients handle the treatment of ION337 in participants with Dravet syndrome (DS).
View original scientific description
The primary purpose of this study is to evaluate the safety and tolerability of ION337 in participants with Dravet syndrome (DS).
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Participant is aged ≥ 2 to ≤ 12 years old at the time of informed consent.
- Participant has at least 1 parent or caregiver ≥ 18 years old who is willing and able to provide informed consent (signed and dated) and attend all scheduled study visits.
- Has a documented diagnosis of DS according to the International League Against Epilepsy (ILAE) criteria and as agreed by the Epilepsy Study Consortium, Inc (ESCI).
- Has confirmation of a pathogenic or likely pathogenic SCN1A variant.
- Must be currently receiving ≥ 1 concomitant ASM at a stable dose/regimen for ≥ 4 weeks prior to informed consent.
- Must have all other interventions for epilepsy (including ketogenic diet or VNS) as well as any other concomitant medications including medications for behavioral management, sleep, and supplements or nutritional support stable for ≥ 4 weeks prior to informed consent. Vagus nerve stimulator implantation must have occurred ≥ 6 months prior to informed consent.
- Experiences the required number of major motor seizures during the Screening Period. Key
Exclusion criteria
- Known brain or spinal disease that would interfere with the LP procedure or CSF circulation, or presence of other factors that would affect the safety of the LP procedure.
- Pathogenic or likely pathogenic variant in another gene that causes epilepsy.
- Has had prior treatment with or is currently enrolled in an interventional clinical trial for a gene therapy or for another antisense oligonucleotide (ASO) for the treatment of DS.
- Has had treatment with or is currently enrolled in an interventional clinical trial of any other investigational drug, biological agent, or device within 30 days prior to Screening, or 5 half-lives of investigational agent, whichever is longer.
- Current treatment with an anti-seizure medication (ASM) acting primarily as a sodium channel blocker, as maintenance treatment.
- Prior brain surgeries including: corpus callosotomy, implantation of device for deep brain stimulation or any other palliative brain surgery intended to reduce seizure burden. Note: Other protocol pre-specified inclusion/exclusion criteria may apply.
Where
- Ann Arbor, Michigan
- Rochester, Minnesota
- Memphis, Tennessee
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jun 23, 2026 · Source of record for eligibility and locations