First-in-human study of Angelman gene therapy set for this year
FDA OKs Mavrix Bio's request to begin clinical trial on MVX-220 safety, efficacy

The U.S. Food and Drug Administration (FDA) has given Mavrix Bio the go-ahead to start a first-in-human clinical trial testing MVX-220, the company’s experimental gene therapy for Angelman syndrome.
The FDA approved Mavrix’s investigational new drug application (IND), which is a formal request to begin clinical trials of the gene therapy. Mavrix said that it plans to initiate the trial later this year, and that the study will evaluate the safety, tolerability, and efficacy of MVX-220 in children and adults with Angelman who have a variety of of disease-causing genetic anomalies.
The company noted that further details on the study’s design and expected timeline will be announced in the coming months.
“We are thrilled to achieve this critical milestone and move one step closer to delivering the first gene therapy to individuals living with Angelman syndrome,” Allyson Berent, chief development officer at Mavrix, said in a company press release. “The clearance of our IND signals a key transition point for our development program and our unwavering commitment to advance novel therapeutic options and a potential single treatment therapy for the Angelman community.”
Angelman syndrome is caused by mutations in the UBE3A gene. These mutations essentially stop the gene from functioning, which disrupts the activity of brain cells and ultimately leads to abnormal behavior and motor development, as well as other disease symptoms.
A gene replacement therapy, MVX-220 is designed to deliver a healthy copy of the UBE3A gene to the body’s cells. The therapy delivers its genetic payload using an adeno-associated virus (AAV) vector, a harmless, engineered virus designed to carry a therapeutic gene rather than cause a harmful infection. AAV is commonly used as a basis for gene therapy delivery because it is easy to work with in laboratory settings and doesn’t typically cause problematic infections in people.
MVX-220 was developed at the University of Pennsylvania with funding from the Foundation for Angelman Syndrome Therapeutics. Mavrix was then launched by the foundation to conduct clinical testing in hopes of ultimately bringing the therapy to market. Mavrix will be leading clinical development of MVX-220 in collaboration with Gemmabio, a company that focuses on developing therapies for rare diseases.
“This collaboration represents the culmination of decades of partnership and scientific innovation aimed at addressing complex monogenic neurological disorders,” said Jim Wilson, MD, PhD, president and CEO of Gemmabio. “We are excited to support MavriX Bio as they advance MVX-220 into clinical evaluation — an important milestone offering renewed hope for families affected by Angelman syndrome.”