MIDDLETON, Mass., Oct. 1, 2026 /PRNewswire/ — AS²Bio: MavriX Bio, a clinical-stage biotechnology company focused on the development of transformative genetic therapies for Angelman syndrome (AS), today announced that the U.S. Food and Drug Administration (FDA) has granted Rare Pediatric Disease Designation (RPDD) to its investigational gene therapy, MVX-220, for the treatment of AS, a rare and debilitating neurogenetic disorder caused by the loss of function of the maternally inherited Ubiquitin Protein Ligase E3A (UBE3A) gene. There are no approved treatments for individuals living with AS.

Rare Pediatric Disease Designation is granted by the FDA to therapies intended to treat serious or life-threatening diseases that primarily affect individuals from birth through 18 years of age and affect fewer than 200,000 people in the United States.

“We are pleased to receive Rare Pediatric Disease Designation for MVX-220, which recognizes both the significant unmet medical need faced by patients and families affected by Angelman syndrome and the potential of MVX-220 as a one-time, gene replacement approach to treatment,” said Jennifer Panagoulias, RAC, Chief Operating Officer at MavriX Bio. “This designation represents an important milestone in our development program and reinforces our commitment to advancing innovative genetic treatments for individuals living with Angelman syndrome.”

Developed with funding from the Foundation for Angelman Syndrome Therapeutics (FAST), MVX-220 was advanced by MavriX Bio for clinical development following a research collaboration with Gemma Biotherapeutics. MVX-220 is an investigational adeno-associated virus (AAV)-based gene therapy designed to deliver a functional copy of the UBE3A gene to neurons with the goal of addressing the underlying genetic cause of the disease. MVX-220 is currently being evaluated in the first-in-human ASCEND-AS study (NCT07181837).

The FDA’s RPDD provides important incentives to support the development of therapies for children with serious, rare diseases. If MVX-220 receives FDA approval and meets applicable statutory requirements, the program may be eligible for a Rare Pediatric Disease Priority Review Voucher (PRV). A PRV can be used to obtain priority review of a subsequent marketing application or sold to another sponsor.

“Angelman syndrome is caused by the loss of a single gene, which makes it a compelling target for gene replacement. We are proud of the collaboration that helped bring MVX-220 forward, and we congratulate the MavriX Bio team on this milestone, reflecting the urgent need for treatments for children and adults living with Angelman syndrome. It is an encouraging step for the Angelman community,” said James M. Wilson, MD, PhD, President and Chief Executive Officer at GEMMABio.

About MVX-220

MVX-220 is an investigational gene therapy designed to restore functional expression of the UBE3A gene in neurons, the underlying cause of AS, using targeted AAV delivery.

MVX-220 was developed by Jim Wilson’s team in academia with support from FAST, which funded both the development and nonclinical research activities. The program was subsequently licensed to MavriX Bio, a portfolio company of FAST’s drug development accelerator AS²Bio.

About ASCEND-AS

ASCEND-AS (NCT07181837) is a Phase 1/2 clinical study of MVX-220 that is evaluating safety and tolerability in adult and pediatric individuals living with various genotypes of AS, including deletion, uniparental disomy and imprinting center defects. Further details can be referenced at https://clinicaltrials.gov/study/NCT07181837.

About MavriX Bio

MavriX Bio is a clinical-stage biotechnology company developing genetic medicines for severe neurological disorders with high unmet need. The company advances programs from discovery through early clinical development and collaborates with academic centers, investigators, and patient organizations to accelerate responsible innovation. For more information, visit www.mvxbio.com.

About Gemma Biotherapeutics (GEMMABio)

GEMMABio is a clinical-stage therapeutics company focused on speeding the research of and global access to life-changing advanced therapies for those living with rare diseases. The company conducts research and product development functions to bring gene therapy discoveries from the bench to the bedside faster and affordably. GEMMABio is led by gene therapy industry pioneer Jim Wilson and his team of experts, who previously conducted their work in academia. Learn more about GEMMABio at gemmabiotx.com.

Forward-Looking Statements

This press release contains forward-looking statements regarding the development, regulatory progress, and potential therapeutic benefits of MVX-220. These statements are based on current expectations and are subject to risks and uncertainties that could cause actual results to differ materially from those expressed or implied. Mavrix Bio undertakes no obligation to update any forward-looking statements except as required by law.

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SOURCE AS2Bio