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ION337

Phase 1

Dravet Syndrome | Small molecule | Neurology |Ionis Pharmaceuticals, Inc.|Trials Updated: Sep 3, 2026

ION337 development status

Highest phase Phase 1
Registered trials 1 across 1 sponsor since Apr 2026

ION337 target and mechanism

Molecular targetSCN1A
ModalitySmall molecule

Success Probability

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Market & Valuation

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Trial Design

CONTROLLEDDMC
Total Trials1
Total Enrollment32

FDA Designations

No designations recorded

ION337 clinical trials

ION337 · 1 trial · 1 indication

Phase 1 1
NCT07531745ASCEND: Safety and Tolerability of ION337 for the Treatment of Dravet SyndromeDravet Syndrome
RECRUITING32 Analytics
PHASE1RECRUITING
ASCEND: Safety and Tolerability of ION337 for the Treatment of Dravet Syndrome
Dravet SyndromeUnlock trial analytics

Study Endpoints

Primary Endpoints

Parts 1 and 2: Number of Participants with Treatment-emergent Adverse Events (TEAEs) and Serious TEAEs
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
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
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)
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
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)
Part 1: up to 6 months; Part 2: up to 31 months

Secondary Endpoints

Pharmacokinetic (PK) Parameters Measure Description: Analysis of plasma concentrations of ION337
Pre-Dose Day 1 (Dosing) until 6 months after dosing in Part 1 and up to 31 months in Part 2
Exposure of ION337 in Cerebrospinal Fluid (CSF) Measure Description: Measurement of ION337 concentrations
Pre-dose Day 1 (Dosing) until 6 months after dosing in Part 1 and up to 31 months in Part 2
Parts 1 and 2: Percent Change From Baseline in 28-day Normalized Major Motor Seizure (MMS) Frequency
Part 1: up to 6 months; Part 2: up to 31 months
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Study Design & Arms

AllocationNON_RANDOMIZED
MaskingNONE
ModelSEQUENTIAL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Part 1: Single Ascending Dose (SAD): Dose Level 1EXPERIMENTALParticipants aged 2 to ≤ 12 years will receive a single intrathecal bolus (ITB) injection of ION337.
Part 1: SAD: Dose Level 2EXPERIMENTALParticipants aged 2 to ≤ 12 will receive a single dose of ION337.
Part 1: SAD: Dose Level 3EXPERIMENTALParticipants aged 2 to ≤ 12 will receive a single dose of ION337.
Part 1: SAD: Dose Level 4EXPERIMENTALParticipants aged 2 to ≤ 12 will receive a single dose of ION337.
Part 2: Multiple Ascending Dose (MAD): Dose Level 1-4EXPERIMENTALOnly participants who complete Part 1 will be eligible to participate in Part 2. Participants will receive multiple doses of ION337. Participants will begin treatment at the same dose level assigned in Part 1.

Interventions

NameTypeDescription
ION337DRUGION337 will be administered by ITB injection.
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Eligibility Criteria

Age Range2 Years to 12 Years
SexALL
Healthy VolunteersNo
Study Sites6

Key Inclusion Criteria: 1. Participant is aged ≥ 2 to ≤ 12 years old at the time of informed consent. 2. 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. 3. Has a documented di...

Countries:United StatesCanada
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Recent Changes (Last 90 Days)

LOWSep 3, 2026NCT07531745lastUpdatePostDate: changed
LOWSep 3, 2026NCT07531745lastUpdatePostDate: changed
LOWAug 5, 2026NCT07531745lastUpdatePostDate: changed

Frequently asked questions about ION337

What is ION337 used for in Dravet Syndrome?

ION337 is an investigational small molecule being developed for the treatment of Dravet Syndrome, a severe genetic epilepsy. It is currently in Phase 1 clinical development and is not yet approved by regulatory authorities. The drug is being studied to evaluate its safety and tolerability in patients with this condition.

What does ION337 target?

ION337 targets the SCN1A gene, which encodes the sodium channel Nav1.1. Mutations in SCN1A are the primary cause of Dravet Syndrome. By targeting SCN1A, ION337 aims to address the underlying genetic basis of the disorder, though its precise mechanism of action is still under investigation.

Who makes ION337?

ION337 is being developed by Ionis Pharmaceuticals, Inc., a biopharmaceutical company traded on NASDAQ under the ticker symbol IONS. Ionis is responsible for the clinical development and manufacturing of this investigational drug candidate for Dravet Syndrome.

What phase is ION337 in?

ION337 is currently in Phase 1 clinical development. It is an investigational drug, meaning it has not been approved by the FDA or other regulatory agencies. The ongoing Phase 1 trial is designed to assess the safety, tolerability, and preliminary effects of ION337 in patients with Dravet Syndrome.

What clinical trials is ION337 in?

ION337 is being evaluated in a Phase 1 clinical trial with the identifier NCT07531745, titled "ASCEND: Safety and Tolerability of ION337 for the Treatment of Dravet Syndrome." This trial is currently recruiting participants in the United States and Canada, with an enrollment target of 32 patients aged 2 years and older.