NCT06100887

Brief Summary

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

Trial Health

75
On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
43

participants targeted

Target at P25-P50 for phase_2

Timeline
10mo left

Started Mar 2024

Typical duration for phase_2

Geographic Reach
1 country

7 active sites

Status
active not recruiting

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

Click on a node to explore related trials.

Study Timeline

Key milestones and dates

Study Progress74%
Mar 2024Mar 2027

First Submitted

Initial submission to the registry

October 20, 2023

Completed
5 days until next milestone

First Posted

Study publicly available on registry

October 25, 2023

Completed
5 months until next milestone

Study Start

First participant enrolled

March 22, 2024

Completed
2.9 years until next milestone

Primary Completion

Last participant's last visit for primary outcome

March 1, 2027

Expected
Same day until next milestone

Study Completion

Last participant's last visit for all outcomes

March 1, 2027

Last Updated

November 6, 2025

Status Verified

November 1, 2025

Enrollment Period

2.9 years

First QC Date

October 20, 2023

Last Update Submit

November 5, 2025

Conditions

Duchenne Muscular Dystrophy

Keywords

Duchenne Muscular Dystrophy

Outcome Measures

Primary Outcomes (2)

  • Number of adverse events during treatment with sevasemten or placebo

    All participants

    36 months

  • Severity of adverse events during treatment with sevasemten or placebo

    All participants

    36 months

Secondary Outcomes (4)

  • Incidence of laboratory test-related treatment emergent adverse events

    36 months

  • Pharmacokinetics as measured by steady state plasma concentration

    36 months

  • Change from Baseline in serum creatine kinase

    12 weeks

  • Change from Baseline in fast skeletal muscle troponin I

    12 weeks

Study Arms (3)

Cohort 1

EXPERIMENTAL

Drug: Sevasemten Drug: Placebo

Drug: Sevasemten Dose 1Drug: Placebo

Cohort 2

EXPERIMENTAL

Drug: Sevasemten Drug: Placebo

Drug: Sevasemten Dose 2Drug: Placebo

Cohort 3

EXPERIMENTAL

Drug: Sevasemten Drug: Placebo

Drug: Sevasemten Dose 3Drug: Placebo

Interventions

Sevasemten Dose 1DRUG

Sevasemten is administered orally once per day

Cohort 1
Sevasemten Dose 2DRUG

Sevasemten is administered orally once per day

Cohort 2
Sevasemten Dose 3DRUG

Sevasemten is administered orally once per day

Cohort 3
PlaceboDRUG

Placebo is administered orally once per day

Cohort 1Cohort 2Cohort 3

Eligibility Criteria

Age6 Years - 17 Years
Sexmale
Healthy VolunteersNo
Age GroupsChild (0-17)

You may qualify if:

  • Aged 6 to 17 with a documented mutation on the DMD gene and phenotype consistent with DMD.
  • Prior receipt of an AAV-based gene therapy (≥ 2 years after documented receipt of gene therapy administration or ≥ 3 years after randomization in a randomized study).
  • Able to complete stand from supine in ≤ 8 seconds at the Screening visit and able to perform the 4-stair climb in \< 10 seconds at the Screening visit.
  • Body weight ≥ 15 kg at the Screening visit.
  • Treatment with a stable dose of corticosteroids for a minimum of 6 months prior to the Baseline visit.

You may not qualify if:

  • 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 sampling.
  • Screening visit cardiac echocardiography showing left ventricular ejection fraction (LVEF) \< 40%.
  • Receipt of an exon-skipping therapy within 6 months prior to the Screening visit.

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (7)

UCLA Medical Center

Los Angeles, California, 90095, United States

Location

UC Davis Medical Center

Sacramento, California, 95817, United States

Location

University of Florida

Gainesville, Florida, 32610, United States

Location

University of Massachusetts Memorial Medical Center

Worcester, Massachusetts, 01605, United States

Location

Washington University School of Medicine

St Louis, Missouri, 63110, United States

Location

Rare Disease Research

Hillsborough, North Carolina, 27278, United States

Location

Nationwide Children's Hospital

Columbus, Ohio, 43205, United States

Location

Related Links

MeSH Terms

Conditions

Muscular Dystrophy, Duchenne

Condition Hierarchy (Ancestors)

Muscular DystrophiesMuscular Disorders, AtrophicMuscular DiseasesMusculoskeletal DiseasesNeuromuscular DiseasesNervous System DiseasesGenetic Diseases, X-LinkedGenetic Diseases, InbornCongenital, Hereditary, and Neonatal Diseases and Abnormalities

Study Design

Study Type
interventional
Phase
phase 2
Allocation
RANDOMIZED
Masking
QUADRUPLE
Who Masked
PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
Purpose
TREATMENT
Intervention Model
SEQUENTIAL
Sponsor Type
INDUSTRY
Responsible Party
SPONSOR

Study Record Dates

First Submitted

October 20, 2023

First Posted

October 25, 2023

Study Start

March 22, 2024

Primary Completion (Estimated)

March 1, 2027

Study Completion (Estimated)

March 1, 2027

Last Updated

November 6, 2025

Record last verified: 2025-11

Data Sharing

IPD Sharing
Will not share

Locations

US(7)