MavriX Bio Doses First Patient in Landmark AAV Gene Therapy Trial for Angelman Syndrome

MIDDLETON, Mass., Nov. 6, 2025 /PRNewswire/ — MavriX Bio, a clinical-stage biotechnology company dedicated to developing transformative genetic therapies for Angelman syndrome (AS), today announced a significant clinical milestone: the first patient has been dosed in the Phase 1/2 ASCEND-AS clinical trial of MVX-220, an investigational AAV gene therapy for AS.

The ASCEND-AS trial (NCT07181837) marks the first clinical evaluation of an AAV-delivered gene therapy designed to treat Angelman syndrome. MVX-220 was specifically developed to restore functional expression of the UBE3A gene in neurons, the underlying cause of AS, utilizing targeted AAV delivery to the central nervous system. The trial is set to evaluate the safety, tolerability, and efficacy of MVX-220 in both adult and pediatric participants spanning different AS genotypes, including deletion, uniparental disomy, and imprinting center defects.

FDA Grants Orphan Drug Designation

Alongside the dosing milestone, MavriX Bio announced that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designation for MVX-220. This designation supports the development of therapies for rare diseases—those affecting fewer than 200,000 people in the US—and provides benefits such as tax credits, fee reductions, and potential market exclusivity.

“Dosing our first participant in the ASCEND-AS trial is a critical step in evaluating the potential of AAV gene targeted therapies for AS, made possible by the unwavering dedication of the Angelman community, our scientific collaborators, and development partners,” said Jennifer Panagoulias, Chief Operating Officer of MavriX Bio. “This milestone, combined with the recent receipt of Orphan Drug Designation from the FDA, reinforces the promise of MVX-220 and the urgency driving our work.”

Targeting the Genetic Root Cause with AAV

Dr. Elizabeth Berry-Kravis, MD, PhD, Professor and Director of the RUSH Pediatric Neurosciences F.A.S.T Center for Translational Research and Principal Investigator for the ASCEND-AS trial, highlighted the trial’s transformative potential.

“This trial represents a new era in Angelman syndrome research,” Dr. Berry-Kravis said. “For the first time, we are testing a one-time therapeutic approach that directly targets the genetic root cause of Angelman syndrome by replacing UBE3A expression in neurons. This AAV-based approach is a meaningful step forward for the entire Angelman community, serving as an example for other genetic neurodevelopmental disorders.”

Angelman syndrome affects approximately 1 in 12,000–20,000 individuals worldwide and currently has no approved disease-modifying treatments. MVX-220, the investigational AAV vector, was developed at the University of Pennsylvania with funding from the Foundation for Angelman Syndrome Therapeutics (FAST) and licensed to MavriX Bio.