Monday, Ultragenyx Pharmaceutical Inc ( RARE ) revealed new data from the Phase 1/2 study of GTX-102 for Angelman syndrome, a genetic disorder causing developmental disabilities and nerve-related symptoms.

Patients in Expansion Cohorts A & B treated with a set dose and regimen of GTX-102 showed rapid and clinically meaningful improvement across multiple domains consistent with or exceeding Dose-escalation Cohorts 4-7 data at Day 170. 

Treatment of the dose-escalation cohorts 4-7 showed long-term increasing and sustained clinical benefits far exceeding Natural History data at Day 758. 

Expansion Cohorts at Day 170 on 24 patients:

Cognition and receptive communication showed rapid and clinically significant improvement compared with Natural History data. 

 Hyperactivity and noncompliance showed rapid and clinically significant improvement at Day 170 compared with Natural History data.

 Sleep, gross motor function, and behavior assessed by ASA showed rapid and clinically meaningful improvement, exceeding treatment benefit observed in the Dose-escalation Cohorts at Day 170.

 Multi-domain Responder Index (MDRI) analysis across the four domains of Cognition, Receptive Communication, Behavior and Sleep resulted in a total net response of +2.0 (p-value