articles and announcements

Ultragenyx Announces Positive Interim Phase 1/2 Data from GTX-102

April 15, 2024

Ultragenyx Announces Positive Interim Phase 1/2 Data from GTX-102

See a letter to the Angelman community.


Ultragenyx reported positive interim data from the ongoing Phase 1/2 study in patients living with deletion genotype Angelman syndrome after treatment with investigational GTX-102.

From company press release:

“The totality of these interim data demonstrates that treatment with GTX-102 resulted in rapid, multi-domain improvements that continued during maintenance dosing. These broad developmental gains are having a meaningful impact on patients and their families. For example, we’re hearing about children who are now able to routinely communicate their needs to family members, which greatly improves their ability to interact with their caregivers.

We have also heard from families about their children who are accumulating additional developmental gains such as running, swimming and independent eating,” said Eric Crombez, M.D., chief medical officer at Ultragenyx. “Our next step is an end of Phase 2 meeting with the FDA and interactions with other health authorities to enable timely initiation of a Phase 3 pivotal study.”

There were no unexpected serious adverse events. Three patients had serious adverse events (mild to moderate) of lower extremity weakness assessed as related to study treatment; one in Cohort 7, two in Cohorts A & B; none reported in Cohorts C–E to date. All resolved rapidly without sequelae and remain in the study without ongoing safety concerns.

Ultragenyx reports that they expect initiation of the Phase 3 study late in 2024.  They will meet with the FDA and other regulatory agencies to finalize the Phase 3 study, but current plans are to enroll 100-120 patients ages 4-17 years of age in the USA, Europe, Latin America, and Japan.  Ultragenyx explained that half of patients participating in the study will receive GTX-102 while the other half will receive placebo.  At the completion of the study, all participants would receive GTX-102 in an open-label extension phase.

This is truly an exciting time for our community, and we’re grateful for the continued dedication of companies like Ultragenyx in advancing potential treatment options for Angelman syndrome. Ultragenyx is currently working on a community letter that we will share in the coming days.

Stay tuned for more updates as we progress on this journey together towards improved outcomes and enhanced quality of life for individuals with Angelman syndrome.

See the full press release from Ultragenyx

Read a letter to the Angelman community

Listen to a presentation