Ultragenyx Announces Initiation of Phase 2 Study of Recombinant Human Beta-Glucuronidase in Patients Under Five Years Old With Mucopolysaccharidosis 7, FDA Fast Tracks rhGUS Program In MPS 7

Ultragenyx Pharmaceutical Inc.

, a biopharmaceutical company focused on the development of novel products for rare and ultra-rare diseases, today announced the dosing of the first patient in a Phase 2 study of investigational recombinant human beta-glucuronidase (rhGUS, UX003) in patients under five years old with mucopolysaccharidosis 7 (MPS 7, Sly syndrome), potentially including patients with non-immune hydrops fetalis, a severe infantile presentation of the disease. "This new Phase 2 study will enable us to assess the benefit of early intervention with rhGUS in very young patients as well as the potential to prevent some of the devastating consequences of this disease," said Sunil Agarwal, M.D., Chief Medical Officer of Ultragenyx. "The resulting data from patients under five years old, which can include infants with hydrops fetalis, will complement the data from the ongoing Phase 3 study in older patients with MPS 7." The Phase 2 open-label, multi-center clinical study will assess the safety, tolerability, and efficacy of rhGUS in up to seven pediatric patients under five years old. Patients will receive 4 mg/kg of rhGUS treatment every other week for 48 weeks, followed by a long-term continuation period. The primary efficacy endpoint is the reduction in urinary GAG excretion. Additional efficacy measures include growth velocity, hepatosplenomegaly, functional development, and cardiac and pulmonary function. Interim data from the study are expected by the end of 2016. This study is also intended to enroll patients with non-immune hydrops fetalis, a phenotype of MPS 7 in which patients are born with severe edema and often die within a few months to one year. Ultragenyx is currently treating one MPS 7 patient born with hydrops fetalis under compassionate use. FDA Fast Track Designation Ultragenyx also announced that the U.S. Food and Drug Administration (FDA) has granted Fast Track Designation to the rhGUS program in MPS 7. Fast Track Designation is intended to facilitate the development and expedite the review of drugs for serious and life-threatening conditions that have the potential to address an unmet medical need. The designation allows for more frequent interaction with the FDA review team. It also enables eligibility for priority review and the potential for a rolling review of the Biologics License Application, when and if filed.