Positive

Ultragenyx Announces Progress Across Broad Gene Therapy Portfolio and Positive Longer-Term Data from Multiple Phase 1/2 Gene Therapy Studies

Durable and Clinically Meaningful Responses Reported from Phase 1/2 Studies of DTX401 for GSDIa and DTX301 for OTC

Phase 3 Studies for DTX401 and DTX301 to Begin in 2021

IND for UX701 for Wilson Disease Submitted; Expect to Enter Clinic in First Half 2021 using AAV Drug Product Made by HeLa PCL Platform

NOVATO, Calif. , Jan. 08, 2021 (GLOBE NEWSWIRE) — Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE), a biopharmaceutical company focused on the development and commercialization of novel products for rare and ultra-rare diseases, today announced positive longer-term safety and efficacy data from the first three cohorts of the ongoing Phase 1/2 studies of DTX401, an investigational adeno-associated virus (AAV) gene therapy for Glycogen Storage Disease Type Ia (GSDIa), and DTX301, an AAV gene therapy for ornithine transcarbamylase (OTC) deficiency. In addition, dosing is nearing completion for the prophylactic steroid cohorts in both studies. Discussions with regulatory agencies continue to