A Study to Check Liver Health in Boys With XLMTM, a Serious Genetic Muscle Condition (EXCEL)

A Non-interventional, Epidemiologic Study of XLMTM and Clinical Expression in the Liver

XLMTM (X-linked myotubular myopathy) is a serious genetic muscle condition. It is caused by changes in the MTM1 gene which stops or slows down normal muscle development, causing severe muscle weakness. There is currently no cure for XLMTM. Ongoing care is needed to manage symptoms and prevent further medical problems from this condition.

Recent research shows that individuals with XLMTM often have reduced bile flow which can affect liver and gallbladder health. Bile is a liquid made in the liver that helps digest fat. Ongoing liver health checks may help with the routine care of people with XLMTM.

There is a need to understand liver problems that develop in individuals with XLMTM over time. The main aim of the study is to learn how many boys with XLMTM have new cases of liver problems during the study.

This study is about collecting information only. This is known as an observational study. The individual's doctor decides on treatment, not the study sponsor (Astellas).

In this study, boys under 18 diagnosed with XLMTM will be followed for about 1 year. The health of their liver and gallbladder will be checked about every 6 weeks. This can be done at home, if preferred. A scan called a Fibroscan (also known as transient elastography) will check for signs of scarring in the liver (fibrosis) and the build-up of lipids. It is suggested that each boy will have a Fibroscan when they start the study and another scan when they complete the study.

This study will help understand liver, gallbladder, and bile duct issues in individuals with XLMTM over time. The goal is to improve their care and provide information to use in future clinical studies.

Study Overview

• Status: Recruiting
• Conditions: X-Linked Myotubular Myopathy
• Intervention / Treatment: Other: No Intervention

• Study Type: Observational
• Enrollment (Estimated): 50

Contacts and Locations

• Study Contact: Name: Astellas Gene Therapies; Phone Number: 800-888-7704; Email: Astellas.registration@astellas.com

Study Locations

• United Kingdom
  • Leeds, United Kingdom
    • Recruiting
    • Site GB44006
  • London, United Kingdom
    • Recruiting
    • Site GB44003
  • Oxford, United Kingdom
    • Recruiting
    • Site GB44005
• United States
  • Illinois
    • Chicago, Illinois, United States, 60611
      • Recruiting
      • Ann & Robert H. Lurie Children's Hospital of Chicago
  • Massachusetts
    • Boston, Massachusetts, United States, 02115
      • Recruiting
      • Boston Children's Hospital
  • Ohio
    • Cincinnati, Ohio, United States, 45229
      • Recruiting
      • Cincinnati Children's Hospital Medical Center
  • Pennsylvania
    • Philadelphia, Pennsylvania, United States, 19104
      • Recruiting
      • Children's Hospital of Philadelphia
    • Pittsburgh, Pennsylvania, United States, 15224
      • Recruiting
      • UPMC Children's Hospital of Pittsburgh
  • Utah
    • Salt Lake City, Utah, United States, 84112
      • Recruiting
      • University of Utah

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Approximately 50 male participants < 18 years of age with genetically confirmed XLMTM will be enrolled at specialist sites.

Description

Inclusion Criteria:

• Participant has a diagnosis of XLMTM resulting from a genetically confirmed mutation in the MTM1 gene based on genetic test reports.
• Participant requires some mechanical ventilatory support (e.g., ranging from 24 hours per day full-time mechanical ventilation, to non-invasive support such as continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP) during sleeping hours)
• Participant (as applicable) and/or parent(s)/carer is willing to comply with the recommended schedule of assessments.

Exclusion Criteria:

• Participant is currently enrolled in an interventional study designed to treat XLMTM.

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Participants with XLMTM; Pediatric and adolescent participants with XLMTM.	Other: No Intervention; No investigational drug will be administered to participants in this study.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence rate of cholestasis	Calculated as the number of new cases of cholestasis over 48 weeks divided by total duration of follow-up for enrolled participants.	Up to Week 48
Point prevalence of cholestasis	Point prevalence of cholestasis is defined as the proportion of participants who have had at least 1 case of cholestasis prior to Day 1 (baseline).	Day 1
Prevalence of cholestasis	Prevalence of cholestasis is defined as the proportion of participants who have had at least 1 case of cholestasis within 1 year of Day 1 (baseline).	Up to 1 year

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Genetic variants of MTM1	The association between genetic variants of MTM1 and cholestasis will be evaluated.	Up to Week 48
Risk of cholestasis temporarily associated with environmental modifiers	Medication use, immunization history, infectious disease history and dietary habits will be collected.	Up to Week 48
Hospitalizations	Frequency and reason for hospitalizations will be collected.	Up to Week 48
Duration of Hospitalizations	Duration of hospitalization visits will be collected.	Up to Week 48
Emergency room visits	Frequency and reason for visit will be collected.	Up to Week 48
Hepatology specialist visits	Frequency and reason for visit will be collected.	Up to Week 48
Scheduled/unscheduled office visits	Frequency and reason for visit will be collected.	Up to Week 48
Non-study-specified home healthcare visits	Frequency and reason for visit will be collected.	Up to Week 48
Surgeries/procedures	Frequency and type will be collected.	Up to Week 48

Collaborators and Investigators

• Sponsor: Astellas Gene Therapies
• Investigators: Study Director: Medical Director, Astellas Gene Therapies

Study record dates

Study Major Dates

• Study Start (Actual): May 19, 2025
• Primary Completion (Estimated): May 31, 2027
• Study Completion (Estimated): May 31, 2027

Study Registration Dates

• First Submitted: August 19, 2024
• First Submitted That Met QC Criteria: August 29, 2024
• First Posted (Actual): September 3, 2024

Study Record Updates

• Last Update Posted (Actual): May 28, 2026
• Last Update Submitted That Met QC Criteria: May 27, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Hepatobiliary; XLMTM
• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Nervous System Diseases; Muscular Diseases; Neuromuscular Diseases; Myopathies, Structural, Congenital
• Other Study ID Numbers: 1600-MA-3536

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Access to anonymized individual participant level data will not be provided for this trial. Further details on Astellas' data sharing policy can be found at https://www.clinicaltrials.astellas.com/transparency/.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No