RecruitingPhase 1/2

ASCEND: Safety and Tolerability of ION337 for the Treatment of Dravet Syndrome

United States32 participantsStarted 2026-05-21

Plain-language summary

The primary purpose of this study is to evaluate the safety and tolerability of ION337 in participants with Dravet syndrome (DS).

Who can participate

Age range

2 Years – 12 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

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.

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.

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

What they're measuring

Parts 1 and 2: Number of Participants with Treatment-emergent Adverse Events (TEAEs) and Serious TEAEs

Timeframe: Part 1: up to 6 months; Part 2: up to 31 months

Number of Participants With Clinically Significant Change From Baseline in Safety Laboratory Values

Timeframe: Part 1: up to 6 months; Part 2: up to 31 months

Parts 1 and 2: Number of Participants With Clinically Significant Change From Baseline in Vital Signs

Timeframe: Part 1: up to 6 months; Part 2: up to 31 months

Parts 1 and 2: Number of Participants With Clinically Significant Change From Baseline in Electrocardiogram (ECG)

Timeframe: Part 1: up to 6 months; Part 2: up to 31 months

Parts 1 and 2: Number of Participants With Clinically Significant Change From Baseline in Physical and Neurological Examination Findings

Timeframe: Part 1: up to 6 months; Part 2: up to 31 months

Parts 1 and 2: Number of Participants with Change in Columbia Suicidality Severity Rating Scale (C-SSRS)

Timeframe: Part 1: up to 6 months; Part 2: up to 31 months

Trial details

NCT IDNCT07531745

SponsorIonis Pharmaceuticals, Inc.

Sponsor typeINDUSTRY

Study typeINTERVENTIONAL

Primary completion2030-12

Contact for this trial

Ionis Pharmaceuticals, Inc.

(844) 867-4309 IonisDravetSyndrome@clinicaltrialmedia.com

View on ClinicalTrials.gov More Dravet Syndrome trials

Who can participate

Age range

2 Years – 12 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

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.

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.

What they're measuring

Parts 1 and 2: Number of Participants with Treatment-emergent Adverse Events (TEAEs) and Serious TEAEs

Timeframe: Part 1: up to 6 months; Part 2: up to 31 months

Number of Participants With Clinically Significant Change From Baseline in Safety Laboratory Values

Timeframe: Part 1: up to 6 months; Part 2: up to 31 months

Parts 1 and 2: Number of Participants With Clinically Significant Change From Baseline in Vital Signs

Timeframe: Part 1: up to 6 months; Part 2: up to 31 months

Parts 1 and 2: Number of Participants With Clinically Significant Change From Baseline in Electrocardiogram (ECG)

Timeframe: Part 1: up to 6 months; Part 2: up to 31 months

Parts 1 and 2: Number of Participants With Clinically Significant Change From Baseline in Physical and Neurological Examination Findings

Timeframe: Part 1: up to 6 months; Part 2: up to 31 months

Parts 1 and 2: Number of Participants with Change in Columbia Suicidality Severity Rating Scale (C-SSRS)

Timeframe: Part 1: up to 6 months; Part 2: up to 31 months