Patient Enrollment Begins in GTX-102 Trial for Angelman Syndrome

In a news release from May 19, 2021, startup biotechnology company GeneTx Biotherapeutics LLC (“GeneTx”) and biopharmaceutical company Ultragenyx Pharmaceutical Inc. (“Ultragenyx”) shared that the pair received Health Canada clearance for a Phase 1/2 clinical trial. During the trial, researchers will evaluate the investigational GTX-102 for pediatric patients with Angelman syndrome. Now that the trial received clearance, GeneTx and Ultragenyx can begin patient enrollment.

Angelman Syndrome

Caused by spontaneously occurring maternal UBE3A mutations, Angelman syndrome is a rare neurological and genetic disorder. The gene mutations typically appear on chromosome 15. Most patients with Angelman syndrome do not have a family history of the condition. Altogether, the developmental delays associated with Angelman syndrome typically begin within the first year of life. Following this, epileptic symptoms usually appear between ages 2-3 years old. The condition is often misdiagnosed as cerebral palsy or autism. Although no cure exists, many patients have a normal lifespan. However, many patients also require life-long assistance.

Symptoms of Angelman syndrome include:

  • Frequent laughing and smiling, with happy and excitable personalities
  • Developmental delays
    • Note: For example, developmental delays may include a lack of crawling or babbling in infancy.
  • Microcephaly (small head size)
  • Tongue thrusting
  • Minimal speech (or in some cases, no speech)
  • Difficulty walking or moving
  • Muscle stiffness or jerkiness
  • Obesity
  • Feeding difficulties
  • Hand-flapping
  • Anxiety
  • Sleep disturbances
  • Diminished OR increased muscle tone (hypotonia vs. hypertonia)

Learn more about Angelman syndrome.


Developed by GeneTx in conjunction with Ultragenyx, GTX-102 is an investigational antisense oligonucleotide treatment. According to the National Cancer Institute (NCI), antisense oligonucleotides (ASOs) are:

Small pieces of DNA or RNA that can bind to specific molecules of RNA [and block] the ability of the RNA to make a protein or work in other ways. Antisense oligonucleotides may be used to block the production of proteins needed for cell growth.

In this particular treatment, the ASO is designed to target and inhibit UBE3A-AS. By doing so, GTX-102 promotes paternal UBE3A, which mitigates some Angelman syndrome neurological characteristics. The therapy is administered intrathecally, or directly into the spinal canal. Thus far, GTX-102 received Fast Track, Orphan Drug, and Rare Pediatric Disease designations.

Altogether, Ultragenyx and GeneTx hope to begin patient enrollment by the middle of 2021. Within the study, researchers will evaluate multiple GTX-102 doses, as well as safety, efficacy, and tolerability. Additionally, researchers will evaluate how much GTX-102 is found in plasma and cerebrospinal fluid. An estimated 12 patients will enroll, split into categories by age. The younger group will receive 3.3mg GTX-102 between 3-4x monthly, while the older group will receive 5mg GTX-102 under the same schedule.

Jessica Lynn

Jessica Lynn

Jessica Lynn has an educational background in writing and marketing. She firmly believes in the power of writing in amplifying voices, and looks forward to doing so for the rare disease community.

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