Ultragenyx Pharmaceutical Inc. announced the completion of patient enrollment in its Phase 1/2 clinical trial of GTX-102 for the treatment of pediatric patients with Angelman syndrome (AS). The dose-expansion cohorts (Cohorts A-E) have enrolled 53 patients for a total of 74 patients enrolled globally in the Phase 1/2 trial. GTX-102 is an investigational antisense oligonucleotide delivered via intrathecal administration and is designed to target and inhibit expression of UBE3A antisense transcript (UBE3A-AS).

In October 2023, interim data from the extension cohorts (Cohorts 4-7) of the ongoing Phase 1/2 study were announced and showed improvements across multiple domains compared to natural history data, where available, and clinical changes were associated with quantitative changes in EEG. Long-term data showed patients who stopped and restarted treatment reacquired previously gained developmental skills when they were re-dosed with the current regimen. As of the data cut-off, there have been no additional treatment-related SAEs, including lower extremity weakness, since November 2022.