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SRP-1003

Phase 1

Myotonic Dystrophy 1 | Small molecule | Rare Disease |Arrowhead Pharmaceuticals, Inc.|Trials Updated: Oct 5, 2026

SRP-1003 target and mechanism

Molecular targetDMPK
ModalitySmall molecule

Also known as SRP-1003 IV Infusion, SRP-1003 Infusion, SRP-1003 SC Injection

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLED
Total Trials1
Total Enrollment78

FDA Designations

No designations recorded

SRP-1003 clinical trials

SRP-1003 · 1 trial · 1 indication

Phase 1 1
NCT06138743Study of SRP-1003 in Participants With Type 1 Myotonic DystrophyMyotonic Dystrophy 1
ENROLLING BY_INVITATION78 Analytics
PHASE1ENROLLING BY_INVITATION
Study of SRP-1003 in Participants With Type 1 Myotonic Dystrophy
Myotonic Dystrophy 1Unlock trial analytics

Study Endpoints

Primary Endpoints

Number of Participants with Treatment-emergent Adverse Events Over Time Through End of Study (EOS)
Single-dose phase (Part 1): Up to Day 90 (EOS); multiple-dose phase (Part 2): Up to Day 180 (EOS)

Secondary Endpoints

PK of SRP-1003: Maximum Observed Plasma Concentration (Cmax)
Single-dose phase (Part 1): Up 24 hours post-dose; multiple-dose phase (Part 2): Through 24 hours post first and second dose
PK of SRP-1003: Area Under the Plasma Concentration Versus Time Curve from Zero to 24 Hours (AUC0-24)
Single-dose phase (Part 1): Up 24 hours post-dose; multiple-dose phase (Part 2): Through 24 hours post first and second dose
PK of SRP-1003: Area Under the Plasma Concentration Versus Time Curve from Zero to the Last Quantifiable Plasma Concentration (AUClast)
Single-dose phase (Part 1): Up 24 hours post-dose; multiple-dose phase (Part 2): Through 24 hours post first and second dose
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Study Design & Arms

AllocationRANDOMIZED
MaskingQUADRUPLE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
SRP-1003 IV InfusionEXPERIMENTALSingle or multiple doses of SRP-1003 by intravenous (IV) infusion
Placebo by IV InfusionPLACEBO_COMPARATORSingle or multiple doses of placebo by IV infusion
SRP-1003 SC InjectionEXPERIMENTALSingle or multiple doses of SRP-1003 by subcutaneous (SC) injection
Placebo by SC InjectionPLACEBO_COMPARATORSingle or multiple doses of placebo by SC injection

Interventions

NameTypeDescription
SRP-1003 IV InfusionDRUGSRP-1003 by IV infusion
Placebo IV InfusionDRUG0.9% sodium chloride (NaCl) calculated volume to match active treatment by IV infusion
SRP-1003 SC InjectionDRUGSRP-1003 by SC injection(s)
Placebo SC InjectionDRUG0.9% NaCl calculated volume to match active treatment by SC injection(s)
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Eligibility Criteria

Age Range18 Years to 65 Years
SexALL
Healthy VolunteersNo
Study Sites35

Key Inclusion Criteria: * Genetically confirmed diagnosis of DM1 * Clinician-assessed signs of DM1 including clinically apparent myotonia * Onset of DM1 symptoms occurred after the age of 12 years * Walk for at least 10 meters independently at screening * Participants of childbearing potential must...

Countries:AustraliaBelgiumCanadaFranceGermanyItalyNew ZealandSpainTaiwanThailandUnited Kingdom
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Recent Changes (Last 90 Days)

LOWOct 5, 2026NCT06138743Status: RECRUITING → ENROLLING_BY_INVITATION
LOWOct 5, 2026NCT06138743Status: RECRUITING → ENROLLING_BY_INVITATION
MEDIUMAug 11, 2026NCT06138743primaryCompletionDate: changed
MEDIUMAug 11, 2026NCT06138743primaryCompletionDate: changed

Frequently asked questions about SRP-1003

What is SRP-1003?

SRP-1003 is an investigational small molecule drug being developed by Arrowhead Pharmaceuticals, Inc. for the treatment of myotonic dystrophy type 1, a rare inherited muscle disorder. It is currently in Phase 1 clinical development and has not been approved by any regulatory agency.

What is SRP-1003 used for in myotonic dystrophy 1?

SRP-1003 is being studied as a potential treatment for myotonic dystrophy type 1, a rare genetic condition that causes progressive muscle weakness, myotonia, and other systemic symptoms. It is investigational and has not been approved for any indication. Its safety and efficacy in this patient population are still being evaluated in clinical trials.

What does SRP-1003 target?

SRP-1003 targets DMPK, the gene and transcript associated with myotonic dystrophy type 1. The disease is caused by expanded CTG repeats in the DMPK gene, and SRP-1003 is designed as a small molecule directed at this target. It is being evaluated in a Phase 1 study in adults with the condition.

Who is developing SRP-1003?

SRP-1003 is being developed by Arrowhead Pharmaceuticals, Inc., which trades on the Nasdaq under the ticker symbol ARWR. The company is the sponsor of the Phase 1 clinical trial evaluating SRP-1003 in participants with type 1 myotonic dystrophy.

What phase is SRP-1003 in?

SRP-1003 is in Phase 1 clinical development. It is an investigational drug and has not been approved by the FDA or any other regulatory authority. The ongoing Phase 1 trial is enrolling participants with type 1 myotonic dystrophy to evaluate the drug's safety and tolerability.

What clinical trials is SRP-1003 in?

SRP-1003 is being evaluated in one active clinical trial, NCT06138743, titled "Study of SRP-1003 in Participants With Type 1 Myotonic Dystrophy." The Phase 1 study is randomized, double-blind, and placebo-controlled, with an planned enrollment of 78 adults aged 18 and older across sites in Australia, Belgium, Canada, France, Germany, Italy, New Zealand, Spain, Taiwan, Thailand, and the United Kingdom.

Is SRP-1003 the same as SRP-1003 IV Infusion or SRP-1003 SC Injection?

Yes. SRP-1003 IV Infusion, SRP-1003 Infusion, and SRP-1003 SC Injection are alternative names referring to the same investigational drug, SRP-1003, developed by Arrowhead Pharmaceuticals for myotonic dystrophy type 1. These names reflect different routes of administration being studied in the Phase 1 program.