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ION337

Phase 1

Dravet Syndrome | Small molecule | Other |Ionis Pharmaceuticals, Inc.|Last Updated: May 20, 2026

Success Probability
Approval Probability 71%
TA Base Rate26%
Adjusted LOA41%
ML RiskLOW_RISK
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Market & Valuation
rNPV $3.2B
Market Size $9.4B
Revenue Basis $1.6B
Competitors 6
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Trial Design
CONTROLLEDDMC
Total Trials1
Total Enrollment32
FDA Designations
No designations recorded
Clinical Trials (1)
NCT IDTitlePhaseStatusEnrollmentVelocityDesignStartCompletionLast UpdatedSitesCountries
NCT07531745ASCEND: Safety and Tolerability of ION337 for the Treatment of Dravet SyndromePHASE1 RECRUITING 32 — — Apr 1, 2026Dec 1, 2030May 20, 20263 United States
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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 — 12 Years
SexALL
Healthy VolunteersNo
Study Sites3

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 States
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Recent Changes (Last 90 Days)
LOWMay 26, 2026NCT07531745primaryCompletionDate: changed
LOWMay 24, 2026NCT07531745studyFirstPostDate: changed
LOWMay 21, 2026NCT07531745NEW_TRIAL: changed
LOWMay 21, 2026NCT07531745NEW_TRIAL: changed