A Study of EDG-5506 in Children With Duchenne Muscular Dystrophy (LYNX) (LYNX)

A 2-part Phase 2 Study of Safety, Pharmacokinetics and Biomarkers in Children With Duchenne Muscular Dystrophy Including a Randomized, Double-Blind, Placebo-Controlled Part A, Followed by an Open-Label Part B

The LYNX study is a 2-part, multicenter, Phase 2 study of safety, pharmacokinetics and biomarkers in children with Duchenne muscular dystrophy including a randomized, double-blind, placebo-controlled part A, followed by an open-label part B.

Study Overview

• Status: Active, not recruiting
• Conditions: Duchenne Muscular Dystrophy
• Intervention / Treatment: Drug: Placebo; Drug: Sevasemten Dose 1; Drug: Sevasemten Dose 2; Drug: Sevasemten Dose 3; Drug: Sevasemten Dose 4; Drug: Sevasemten Dose 5

Detailed Description

This is a 2-part, multi-center, Phase 2 study to evaluate the effect of sevasemten (EDG-5506) on safety, pharmacokinetics and biomarkers of muscle damage in approximately 72 children with DMD treated with oral, once-daily sevasemten for up to 48 months. This study will have up to a 4-week Screening period, a 12-week randomized, double-blind, placebo controlled treatment period (Part A), up to a 196-week open-label extension period (Part B), and a 2-week follow up period.

Approximately 72 participants aged 4 to 9 years inclusive will be randomized to sevasemten or placebo in a 2:1 ratio. Five dose cohorts (C1, C2, C3, C4 and C5) of approximately 9 participants each will be enrolled sequentially. Approximately 18 total additional participants may be added across Cohorts 2, 3, or 4.

An additional cohort, Cohort 2NS, to include participants (aged 4 to 7 years inclusive) not currently treated with corticosteroids, will enroll approximately 9 participants after Cohort 2 safety review and in parallel with the additional cohorts.

After review of emerging data, the protocol was amended so all dose cohorts receive the same dose in Part B.

• Study Type: Interventional
• Enrollment (Actual): 76
• Phase: Phase 2

Contacts and Locations

Study Locations

• United States
  • Arkansas
    • Little Rock, Arkansas, United States, 72202
      • Arkansas Children's Hospital
  • California
    • Los Angeles, California, United States, 90095
      • UCLA Medical Center
    • Sacramento, California, United States, 95817
      • UC Davis Medical Center
  • Colorado
    • Aurora, Colorado, United States, 80045
      • Children's Hospital Colorado
  • Florida
    • Gainesville, Florida, United States, 32610
      • University of Florida
  • Georgia
    • Atlanta, Georgia, United States, 30329
      • Rare Disease Research
  • Iowa
    • Iowa City, Iowa, United States, 52242
      • University of Iowa
  • Kansas
    • Kansas City, Kansas, United States, 66160
      • University of Kansas Medical Center
  • Maryland
    • Baltimore, Maryland, United States, 21205
      • Kennedy Krieger Institute
  • Massachusetts
    • Worcester, Massachusetts, United States, 01605
      • University of Massachusetts Memorial Medical Center
  • Missouri
    • St Louis, Missouri, United States, 63110
      • Washington University School of Medicine
  • Ohio
    • Cincinnati, Ohio, United States, 45229
      • Cincinnati Children's Hospital
    • Columbus, Ohio, United States, 43205
      • Nationwide Children's Hospital
  • Texas
    • Fort Worth, Texas, United States, 76104
      • Cook Children's Medical Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 4 years to 9 years (Child)
• Accepts Healthy Volunteers: No

Description

Key Common Inclusion Criteria:

1. A documented mutation on the DMD gene and phenotype consistent with Duchenne muscular dystrophy.
2. Able to complete the stand from supine in ≤ 10 seconds and able to perform the 4-stair climb in < 10 seconds at the Screening visit.
3. Body weight greater than or equal to 15 kg at the Screening visit.

For Cohorts 1, 2, 3, 4 and 5:

Aged 4-9 years on a stable dose of corticosteroids for a minimum of 6 months prior to the Baseline visit.

For Cohort 2 Non-Steroid (Cohort 2NS):

Aged 4-7 years not on corticosteroids within 6 months prior to the Baseline visit.

Key Common Exclusion Criteria:

1. Medical history or clinically significant physical exam/laboratory result that, in the opinion of the investigator, would render the participant unsuitable for the study. This includes venous access that would be too difficult to facilitate repeated blood testing.
2. A forced vital capacity < 60% predicted at the Screening visit for those participants who are > 8 years old at Screening.
3. A cardiac echocardiography showing left ventricular ejection < 45% at the Screening visit.
4. Receipt of an investigational drug within 30 days or 5 half-lives (whichever is longer) of the Screening visit in the present study.
5. Receipt of a stable dose of an approved exon-skipping therapy with a treatment duration of less than 1 year prior to the Screening visit.

For Cohort 2 Non-Steroid (Cohort 2NS):

Receipt of oral corticosteroids for the treatment of Duchenne muscular dystrophy in the previous 6 months. Participants will not be tapered off steroids for the purpose of this study and oral corticosteroids for the treatment of Duchenne muscular dystrophy may be initiated after the Week 16 visit.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Sequential Assignment
• Masking: Quadruple

Number of Arms

6

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Cohort 1; Drug: Sevasemten Drug: Placebo	Drug: Placebo; Placebo is administered orally once per day; Drug: Sevasemten Dose 1; Sevasemten is administered orally once per day
Experimental: Cohort 2; Drug: Sevasemten Drug: Placebo	Drug: Placebo; Placebo is administered orally once per day; Drug: Sevasemten Dose 2; Sevasemten is administered orally once per day
Experimental: Cohort 3; Drug: Sevasemten Drug: Placebo	Drug: Placebo; Placebo is administered orally once per day; Drug: Sevasemten Dose 3; Sevasemten is administered orally once per day
Experimental: Cohort 4; Drug: Sevasemten Drug: Placebo	Drug: Placebo; Placebo is administered orally once per day; Drug: Sevasemten Dose 4; Sevasemten is administered orally once per day
Experimental: Cohort 5; Drug: Sevasemten Drug: Placebo	Drug: Placebo; Placebo is administered orally once per day; Drug: Sevasemten Dose 5; Sevasemten is administered orally once per day
Experimental: Cohort 2NS; Drug: Sevasemten Drug: Placebo	Drug: Placebo; Placebo is administered orally once per day; Drug: Sevasemten Dose 2; Sevasemten is administered orally once per day

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of adverse events during treatment with sevasemten or placebo	All participants	48 months
Severity of adverse events during treatment with sevasemten or placebo	All participants	48 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from Baseline in serum creatinine kinase	All participants	12 weeks
Change from Baseline in fast skeletal muscle troponin I	All participants	12 weeks
Incidence of laboratory test-related treatment emergent adverse events	All participants	48 months
Pharmacokinetics as measured by steady state plasma concentration	All participants	48 months

Collaborators and Investigators

• Sponsor: Edgewise Therapeutics, Inc.
• Investigators: Study Chair: Sam Collins, MBBS, PhD, Edgewise Therapeutics, Inc.

Publications and helpful links

Helpful Links

• Sponsor Website

Study record dates

Study Major Dates

• Study Start (Actual): October 24, 2022
• Primary Completion (Estimated): January 1, 2027
• Study Completion (Estimated): January 1, 2027

Study Registration Dates

• First Submitted: September 6, 2022
• First Submitted That Met QC Criteria: September 12, 2022
• First Posted (Actual): September 15, 2022

Study Record Updates

• Last Update Posted (Actual): November 12, 2025
• Last Update Submitted That Met QC Criteria: November 10, 2025
• Last Verified: November 1, 2025

More Information

Terms related to this study

• Keywords: Duchenne Muscular Dystrophy
• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Nervous System Diseases; Muscular Diseases; Neuromuscular Diseases; Genetic Diseases, Inborn; Genetic Diseases, X-Linked; Muscular Disorders, Atrophic; Muscular Dystrophies; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Muscular Dystrophy, Duchenne
• Other Study ID Numbers: EDG-5506-210

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No