Actively Recruiting
A Phase 1/2 Study of ASP2957 Gene Therapy in Male Participants Up to 36 Months Old With Ventilator-dependent X-linked Myotubular Myopathy to Evaluate Safety and Tolerability
Led by Astellas Gene Therapies · Updated on 2026-05-28
9
Participants Needed
4
Research Sites
N/A
Total Duration
On this page
AI-Summary
What this Trial Is About
X-linked myotubular myopathy (XLMTM) is a rare genetic condition present at birth that affects muscle function, causing muscles not to work properly. It is caused by mutations in the MTM1 gene, which leads to low or no production of a protein called myotubularin needed for muscle development, movement, and breathing. Researchers are studying a gene therapy, ASP2957, designed to deliver a healthy copy of the MTM1 gene to potentially improve muscle function in young boys with XLMTM. This is the first time ASP2957 will be given to humans, and the study aims to assess its safety, tolerability, and find the right dose. Participants will receive a single infusion of ASP2957 along with medicines to reduce immune system activity, including methylprednisolone, prednisolone, and sirolimus, to help prevent immune reactions against the therapy. The study has two parts: Phase 1 will test increasing doses in small groups of boys to identify a suitable dose, and Phase 2 will give the chosen dose to another group. All participants will be ventilator-dependent boys up to 36 months old. After infusion, boys will be monitored closely for up to one year, with an option to join a follow-up study for longer-term observation. During the study, researchers will conduct various assessments including physical exams, liver ultrasounds, muscle biopsies, MRIs, ECGs, and echocardiograms to monitor safety and any side effects. Laboratory tests will track blood and immune responses, and ventilation support needs will be measured. Participants and their caregivers will attend scheduled visits for these evaluations, and safety data will be collected throughout the year. The study is open-label and non-randomized, focusing on careful dose escalation and expansion to understand ASP2957's effects in this population.
CONDITIONS
Brief 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 36 months of age or younger at dosing
- Confirmed diagnosis of XLMTM with a pathogenic or likely pathogenic MTM1 gene variant
- Participant is ventilator-dependent requiring at least 20 hours per day of invasive ventilator support
- Participant has a tracheostomy tube
- No clinically important liver abnormalities on ultrasound
- Participant can receive immunosuppression as per study protocol
- Hematological and hepatobiliary laboratory values meet study criteria
- Participant's parent(s) or legally authorized representatives are current with recommended immunizations or have documented medical reasons
- Participant and parent(s)/legally authorized representatives agree to comply with study visits and procedures
- Participant will not join another interventional study through week 52
- Parent(s)/legally authorized representatives agree to transition participant to long-term follow-up after study completion
You will not qualify if you...
- Participant born before 35 weeks gestation and not yet term by corrected age
- Nutritionally unstable with weight below the 5th percentile or deficiency in vitamins A, E, or K
- Requires routine supplemental oxygen (except during acute illnesses)
- Has any active clinically important infection including tuberculosis, hepatitis A, B, or C, HIV-1 or HIV-2, COVID-19, or cytomegalovirus with symptoms
- History of cholestatic liver dysfunction or treatment for cholestasis
- Prior abnormal liver enzyme or bilirubin metabolism associated with severe symptoms
- Significant or life-threatening conditions other than XLMTM affecting participation or increasing risk
- Severe musculoskeletal complications limiting neuromuscular function assessment
- Received systemic immunomodulating agents or monoclonal antibodies recently (exceptions apply)
- Plans surgery that may affect study data from 12 weeks before dosing through week 52 (exceptions apply)
- Previously received AAV-based gene therapy or is in another interventional study
- Positive for anti-MyoAAV3.8 total antibody (with some exceptions for very young infants)
- Contraindications or hypersensitivity to study drugs or procedures
- Unsuitable for participation due to risk of non-adherence or other reasons
AI-Screening
AI-Powered Screening
Complete this quick 3-step screening to check your eligibility
Your Study Journey
Duration - 2 to 4 weeks
Participants are screened for eligibility to participate in the trial.
1 visit (in-person)
Duration - Up to 52 weeks
Participants receive a single infusion of ASP2957 gene therapy along with immunosuppression prophylaxis including methylprednisolone, prednisolone, and sirolimus.
Multiple visits for treatment administration and monitoring
Duration - Up to 52 weeks post-infusion
Participants are monitored for safety, tolerability, and treatment effects including ventilation support and laboratory assessments.
Regular visits for assessments through week 52
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
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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