Ultragenyx Receives FDA Agreement to Expand Ongoing Global Phase 1/2 Trial Evaluating GTX-102 in Patients with Angelman Syndrome in the U.S.

About this update from Ultragenyx Pharmaceutical Inc.

[{"type":"text","content":"Amended U.S. protocol increases loading and maintenance doses to similar range as ex-U.S. expansion cohorts\nNOVATO, Calif., May 17, 2023 (GLOBE NEWSWIRE) -- Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE) today announced that the U.S. Food and Drug Administration (FDA) has reviewed and agreed to a protocol amendment to the Phase 1/2 study of GTX-102 in pediatric patients with Angelman syndrome that enables the company to harmonize dose ranges in the U.S. with those being used in ex-U.S. cohorts of the study. Outside of the U.S., the Phase 1/2 study has been actively enrolling and dosing patients in the expansion cohorts to verify the GTX-102 dose and treatment regimen that will be used in the Phase 3 program. “Agreement on the protocol amendment enables comparable dose ranges across all geographies and allows us to move forward rapidly to complete the study. We have begun working urgently to activate multiple study sites in the U.S. and plan to begin enrollment as quickly as possible,” said Scott Stromatt, M.D., SVP and chief medical officer of neurology clinical development at Ultragenyx. “We are eager to expand the study in the U.S. to build on the encouraging data, which demonstrate important clinical activity across multiple functional domains impacted by Angelman syndrome with an acceptable safety profile.” About the Phase 1/2 study The Phase 1/2, open-label, dose-escalating study is evaluating the safety and tolerability of GTX-102 in pediatric patients with Angelman syndrome with a genetically confirmed diagnosis of full maternal UBE3A gene deletion. The study is also looking at clinical response as measured by a panel of efficacy assessments for the functional domains impacted in Angelman syndrome. Patients in the earlier dose-escalation cohorts of the study have moved into long-term maintenance dosing, and the study is now enrolling the new expansion cohorts to verify the GTX-102 dose range and treatment regimen that will be used in the Phase 3 program. As of May 4, 2023, 13 patients have had more than 12 months of exposure to GTX-102, with the longest more than 18 months. The ex-U.S. portion of the study, which includes sites in Europe, Canada and Australia, is currently enrolling patients in expansion cohorts. As additional investigator sites open in the U.S., the study will begin enrolling expansion cohorts using simi...

More updates from Ultragenyx Pharmaceutical Inc.