Actively Recruiting
Study of ASP2957 in Male Participants With X-linked Myotubular Myopathy Who Need Ventilators
Led by Astellas Gene Therapies · Updated on 2026-04-15
9
Participants Needed
4
Research Sites
97 weeks
Total Duration
On this page
AI-Summary
What this Trial Is About
X-linked myotubular myopathy (XLMTM) is a rare and serious condition present at birth where the muscles do not work properly. There are currently no approved therapies for XLMTM. The protein myotubularin is needed for muscle development, movement and breathing. A gene called MTM1 tells the body to make myotubularin. XLMTM is caused by changes, or mutations, in the MTM1 gene. Changes in the MTM1 gene cause low or no levels of myotubularin to be made, so the muscles do not work properly. Gene therapy is a way of getting a healthy copy of a gene into the body. This allows the body's cells to make a normal protein that may reduce disease symptoms. Researchers have developed ASP2957 to get a healthy MTM1 gene into the body. This could help improve muscle development and function in young children with XLMTM. In this study, ASP2957 will be given to humans for the first time. ASP2957 has the healthy MTM1 gene inside a type of empty (killed) virus. The virus delivers the healthy MTM1 gene directly into cells in the body. It's possible that some boys may have antibodies to the virus if they have previously been infected with a similar virus. The antibodies could stop ASP2957 from working properly and cause an immune reaction to ASP2957. To prevent this, the boys will also be given medicines to lower the immune system. The main aims of this study are to check the safety of ASP2957, how well it is tolerated, and to find a suitable dose of ASP2957. The study was designed in 2 phases. In Phase 1, different small groups of boys will receive lower to higher doses of ASP2957. Each boy will receive a single infusion of ASP2957. Any medical problems will be recorded for each dose. This is done to find a suitable dose of ASP2957 to use in Phase 2. In Phase 2, another small group of young boys will receive a single infusion of ASP2957. The most suitable dose of ASP2957 worked out from Phase 1 will be used. The boys will be checked for up to 1 year after their single infusion of ASP2957. After this, there will be the option for the boys to join another study so they will continue to be checked longer term.
CONDITIONS
Official Title
Study of ASP2957 in Male Participants With X-linked Myotubular Myopathy Who Need Ventilators
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Participant is projected to be 64 36 months of age at dosing.
- Participant has a molecular genetic report confirming XLMTM with a pathogenic or likely pathogenic MTM1 gene variant.
- Participant is ventilator-dependent with respiratory support required at birth.
- Participant requires 65 20 hours per day of invasive ventilator support.
- Participant has a tracheostomy tube.
- Participant has no clinically important abnormal liver ultrasound findings.
- Participant can receive immunosuppression as per protocol.
- Participant's hepatobiliary and hematological laboratory measurements meet specified criteria during screening and retrospective assessment.
- Participant's parent(s) or legally authorized representative is current with recommended immunizations or has documented medical reasons for any missed immunizations.
- Participant and parent(s)/LAR(s) are willing and able to comply with study visits and procedures.
- Participant will not participate in another interventional study from consent through week 52.
- Parent(s)/LAR(s) agree to transition participant to a long-term follow-up study after completion.
You will not qualify if you...
- Participant born before 35 weeks gestation and still not term by corrected age.
- Participant is nutritionally unstable with weight below the fifth percentile or has vitamin A, E, or K deficiency.
- Participant requires routine or chronic supplemental oxygen.
- Participant currently has clinically important respiratory or other active infections.
- Participant tests positive for tuberculosis, active hepatitis A, B, or C, HIV-1 or HIV-2, COVID-19, or cytomegalovirus with significant viral load or symptoms.
- Participant has history of cholestatic liver dysfunction or treatment for cholestasis (with some exceptions).
- Participant has prior abnormal liver enzyme or bilirubin metabolism associated with serious symptoms.
- Participant has other significant medical or life-threatening conditions interfering with study adherence or increasing immunosuppression risk.
- Participant has severe musculoskeletal complications limiting neuromuscular assessment.
- Participant has received or plans to receive systemic immunomodulating agents within 90 days before day 1 (inhaled corticosteroids allowed).
- Participant has previously received monoclonal antibodies except RSV prevention outside 4 weeks prior to immunosuppression.
- Participant plans surgery within 12 weeks before day 1 through week 52 that may affect study data (with specific exceptions).
- Participant has received treatment for cholestasis prior to consent.
- Participant is in another interventional study or has received AAV-based gene therapy.
- Participant tests positive for anti-MyoAAV3.8 total antibody (with possible rescreening if 64 6 months old).
- Participant has known or suspected hypersensitivity to study drugs or ASP2957 components.
- Participant has contraindications to general anesthesia, MRI, or muscle biopsy.
- Any other reason that makes participant unsuitable or at risk for non-adherence.
AI-Screening
AI-Powered Screening
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Trial Site Locations
Total: 4 locations
1
Lurie Children's Hospital
Chicago, Illinois, United States, 60611
Actively Recruiting
2
Boston Children's Hospital
Boston, Massachusetts, United States, 02115
Actively Recruiting
3
Oregon Health & Science University
Portland, Oregon, United States, 97239
Actively Recruiting
4
The Hospital for Sick Children
Toronto, Ontario, Canada
Actively Recruiting
Research Team
A
Astellas Gene Therapies
CONTACT
How is the study designed?
Study Type
INTERVENTIONAL
Masking
NONE
Allocation
NON_RANDOMIZED
Model
SEQUENTIAL
Primary Purpose
TREATMENT
Number of Arms
2
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