A Phase 1/2 interventional study of MVX-220 in Angelman Syndrome, sponsored by MavriX Bio, LLC. Recruiting at 3 sites in United States. Open to participants aged 4 Years to 50 Years. Per ClinicalTrials.gov, last updated 2026-07-24.
Sponsored by MavriX Bio, LLC · Phase 1/2, Interventional, and Treatment
The purpose of this study is to evaluate the safety and efficacy of MVX-220 gene therapy in children and adults with Angelman syndrome with UBE3A gene deletion, uniparental disomy, or imprinting center defect genotypes.
MVX-220 is an investigational gene replacement therapy intended to provide a functional copy of the UBE3A gene to individuals with Angelman syndrome. This study is designed to evaluate the safety, tolerability and efficacy of MVX-220 in participants with Angelman syndrome who have deletion, uniparental disomy, or imprinting center disorder genotypes. The study has 2 primary cohorts: Cohort 1 that includes adults followed by Cohort 2 that includes children. All patients will receive a single dose of MVX-220 administered by injection into the cisterna magna. There is no control group and all individuals will receive the gene therapy. An independent data safety monitoring board will review the safety information from Cohort 1 before individuals can be enrolled in Cohort 2. An optional cohort of adults and/or children (Cohort 3) may be enrolled based on a review of data from Cohorts 1 and 2. All patients will be required to take steroids before and for a brief period during the study to help mitigate the risk of immune response to the gene therapy. Patients will be followed for safety and efficacy for an initial 2-year period post-treatment and then transition to less frequent monitoring schedule for an additional 3 years. The total duration of follow up in the study is 5 years.
Key Inclusion Criteria:
Symptoms consistent with AS and documented genetic confirmation of one of the following genotypes resulting in a diagnosis of AS:
Key Exclusion Criteria:
Laboratory abnormalities including but not limited to:
MVX-220, single dose intra cisterna magna injection
Genetic: MVX-220
MVX-220, single dose intra cisterna magna injection
Genetic: MVX-220
MVX-220, single dose intra cisterna magna injection
Genetic: MVX-220
AAVhu68 viral vector
Incidence of Adverse Events, Serious Adverse Events, and Adverse Events of Special Interest as assessed through clinical safety, laboratory tests, ECG, vital sign measurements, and physical examinations
Time frame: Up to Week 104
Change in communication ability as assessed by the Observer Reported Communication Ability (ORCA) measure
The ORCA measure is a caregiver reporter assessment of communication ability that was developed specifically for Angelman syndrome. The ORCA measure produces a single score that is an estimate of an individual's overall level of communication ability, with higher T-scores reflecting greater communication ability.
Time frame: From Baseline to Week 104
Change in developmental milestones as assessed by the Bayley Scale of Infant and Toddler Development, Fourth Edition (Bayley-4)
The Bayley-4 is a performance-based assessment of developmental functioning across communication, cognition, and motor skills. The total raw score reflects the sum of all the item scores within a subdomain, with higher scores reflecting greater ability.
Time frame: From Baseline to Week 104
Change in adaptive behaviors as assessed by Vineland Adaptive Behavior Scale (VABS-3)
The VABS-3 assesses adaptive behaviors across multiple domains through a clinician-directed interview of a caregiver of an individual with AS. The total raw score reflects the sum of all the item scores within a subdomain, with higher scores reflecting greater ability.
Time frame: From Baseline to Week 104
Change in Symptoms by the Angelman Severity Assessment (ASA)
The ASA is a clinician-reported outcome measure for Angelman syndrome. The clinicians rate their overall impression of the improvement in disease-related symptoms utilizing a 7-point scale, ranging from "very much improved" to "very much worse".
Time frame: From Baseline to Week 104
Change in behaviors as assessed by the Aberrant Behavior Checklist-Community (ABC-C)
The ABC-C is a caregiver-rated questionnaire that evaluates key domains in behavior. Items are assessed on a 4 point scale ranging from "not at all a problem" to "the behavior is a severe problem".
Time frame: From Baseline to Week 104
Change in ambulatory ability as assessed by the wearable device (Syde®)
The Syde is a wearable device that collects continuous data on the ambulatory ability of participants with AS.
Time frame: From Baseline to Week 104
Change in sleep parameters as assessed by a sleep diary
The sleep diary is a caregiver-reported measure of sleep in individuals with AS.
Time frame: From Baseline to Week 104
Change in health-related quality of life as assessed by Quality of Life Inventory-Disability (QI-Disability)
The QI-Disability is a caregiver-reported outcome assessment of the health-related quality of life for children and adolescents with intellectual disabilities. Item are rated on a 5-point scale, ranging from "never" to "always ".
Time frame: Baseline to Week 104
Change in viral deoxyribonucleic acid (vDNA) levels in CSF and blood
Time frame: Baseline to Week 104
Change in viral DNA levels in urine and feces
Time frame: From Baseline to Week 104
Change in relevant Electroencephalogram (EEG) parameters (delta power, epileptiform activity)
Time frame: From Baselien through Week 104
Plan to share: No
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