Ultragenyx Offers Positive Interim Data from Phase 1/2 Study of Recombinant Human Beta-Glucuronidase

Ultragenyx Pharmaceutical Inc.

, a biopharmaceutical company focused on the development of novel products for rare and ultra-rare diseases, today announced the presentation of positive interim data from the Phase 1/2 study of recombinant human beta-glucuronidase (rhGUS, UX003), an investigational therapy for the treatment of mucopolysaccharidosis 7 (MPS 7, Sly syndrome). The data are being presented at the Society for the Study of Inborn Errors of Metabolism (SSIEM) Annual Symposium in Innsbruck, Austria. The Phase 1/2 open-label clinical study is assessing the safety, efficacy, and dose of rhGUS administered every other week via intravenous infusion in three patients. A 12-week primary analysis phase evaluating 2 mg/kg of rhGUS every other week is being followed by dose-exploration and long-term extension. "We are pleased with the 12-week results of the first clinical study to be conducted in MPS 7 and are grateful to the patients and investigators who are participating in the study," commented Emil D. Kakkis, Ph.D., M.D., Chief Executive Officer and President of Ultragenyx. "Based on the reduction of lysosomal storage shown in all patients in the Phase 1/2 study, we plan to move into Phase 3 testing." Results from the primary analysis phase show evidence of clearance of lysosomal storage as indicated by the decline in urinary glycosaminoglycan (GAG) excretion and the reduction in liver size. The change in urinary GAG excretion was observed by two weeks after the first dose of rhGUS and declined by approximately 40-50% from baseline after 12 weeks of treatment. Decreases in liver size were observed in the two patients who had enlarged livers at baseline. No serious adverse events were observed in the 12-week primary analysis phase and through up to 28 total weeks of treatment. The most common adverse events reported to date are infections and gastrointestinal disorders. No infusion-associated reactions were observed after a total of 38 infusions to date in these three subjects. In addition to the Phase 1/2 study, one patient continues to be treated under an emergency Investigational New Drug application (eIND) sponsored by Dr. Joyce Fox and the Steven and Alexandra Cohen Children's Medical Center of New York. Through 24 weeks of treatment, a decline in urinary GAG excretion of 50-70% and a sustained reduction in the size of the enlarged liver and spleen have been observed. The data also show improved pulmonary function based on reduced carbon dioxide retention. No serious adverse events or infusion-associated reactions were observed through 12 infusions. The Phase 1/2 study will continue through the dose-exploration phase and long-term extension. Based on the Phase 1/2 study results and the 24-week results of the patient treated under an eIND, the company intends to initiate a pivotal Phase 3 study by year-end 2014.