FDA Grants Orphan-Drug Designation to Angelman Syndrome Treatment


The FDA granted GeneTx Biotherapeutics LLC orphan-drug designation for GTX-101, the company’s potential treatment for Angelman syndrome.

Yesterday, the U.S. Food and Drug Administration (FDA) granted GeneTx Biotherapeutics LLC orphan-drug designation for GTX-101, the company’s potential treatment for Angelman syndrome.

GTX-101 is an investigational therapy designed to inhibit the transcription of the UBE3A-antisense (UBE3A-AS) transcript across UBE3A, which is expressed across the usually silent paternal allele of UBE3A. If approved, it would be the first available drug for the condition.1

The orphan-drug designation of GTX-101 holds promise and significance. Historical studies have shown promising results using antisense technology for other neurogenetic disorders, such as spinal muscular atrophy (SMA) and amyotrophic lateral sclerosis (ALS). Previous in vitro studies show that inhibiting transcription of the UBE3A-AS transcript restores expression of the paternal UBE3A allele in neurons of the central nervous system. GTX-101, an antisense oligonucleotide, is a string of nucleic acids that interferes with the normal processing of a target gene.

Allyson Berent, Chief Operating Officer of GeneTx and Chief Science Officer of FAST, expressed her optimism following the news of the designation: “No approved treatments for Angelman syndrome exist today. The FDA’s orphan-drug designation for GTX-101 highlights the significant need for treatments for individuals with Angelman syndrome, and we believe that targeted delivery of GTX-101 represents a promising, novel approach to treat this devastating disorder.”

Angelman syndrome is a rare neurogenetic disorder that causes developmental disabilities associated with motor and cognitive function. It affects approximately one in 15,000 people — about 500,000 individuals worldwide. Loss of function of the maternally inherited UBE3A allele and imprinting of the paternally inherited UBE3A allele leads to an absence of the UBE3A protein in neurons of the central nervous system, causing the symptoms associated with AS. The UBE3A-AS transcript regulates imprinting of the paternal UBE3A allele. Symptoms associated with AS include motor impairment, developmental delay, balance issues, and debilitating seizures.1

Scott Dindot, Ph.D., Associate Professor at Texas A&M College of Veterinary Medicine & Biomedical Sciences, also aired his excitement for the drug’s potential. “This is a new area of medicine, known as a targeted therapy. Historically, clinicians have treated symptoms of a disease or disorder with medication but not the cause of the condition. A targeted therapy goes after the cause of the condition and attempts to fix it.”

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  1. “GeneTx Biotherapeutics receives FDA orphan-drug designation for Angelman syndrome treatment.” GlobeNewswire. 27, Mar. 2018
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