Ultragenyx Offers Presentation of Disease Burden Data in Adult Patients with X-Linked Hypophosphatemia

Ultragenyx Pharmaceutical Inc. RARE, a biopharmaceutical company focused on the development of novel products for rare and ultra-rare diseases, today announced the presentation of data highlighting the significant impairment in skeletal health outcomes and physical function in adult patients affected by X-linked hypophosphatemia (XLH). The data were presented at the 2015 ENDO meeting of The Endocrine Society in San Diego, California. The data were generated from a 13-country disease burden survey, conducted by Ultragenyx, which was completed to further characterize the significant health challenges facing this patient population. XLH is an inherited metabolic bone disease characterized by short stature, skeletal deformities, bone pain, fractures, and muscle weakness. A total of 165 adults with XLH from 13 countries elected to complete an institutional review board approved online questionnaire to assess medical and diagnostic history. "The results of this disease burden survey provide additional evidence that XLH can lead to significant long-term morbidity in the form of pain, stiffness, functional limitations, and fractures," said Sunil Agarwal, M.D., Chief Medical Officer of Ultragenyx. "I would like to thank the participating patients for their assistance in helping the medical community to better understand their disease and in informing Ultragenyx's ongoing development efforts for KRN23." The majority of XLH responders reported significant skeletal conditions, such as short stature, dental abscesses, bowing of the upper and lower legs, and intoeing as a result of unresolved childhood disease. Bone pain, joint pain, and joint stiffness were reported by 75%, 90%, and 87% of patients, respectively. Functional limitations and related pain were also common, with more than 70% of patients reporting restricted range of motion, gait disturbance, and muscle pain/weakness. Bone fractures were reported by nearly half of responders. The burden of the symptoms and conditions reported by responders was reflected by scores on patient-reported outcome (PRO) measures. Scores on the Pain, Stiffness, and Physical Function domains of the WOMAC, an instrument developed for osteoarthritis, were well below general population norms, indicating considerable impairment. These findings were supported by other PRO measures including the SF-36 Physical Component Summary (PCS). The majority of patients reported current treatment for XLH (69%), as well as for the bone or joint pain associated with the disease (71%). Phosphate and vitamin D therapy was reported by 50% of the survey respondents, and over-the-counter and opioid pain medication taken at least once a week were reported by 66% and 19% of respondents, respectively. Calcification outside of the bone, a common feature of XLH in adults that can be exacerbated by phosphate and vitamin D metabolite therapy, was commonly reported and included osteophytes (46%), enthesopathy (32%), nephrocalcinosis (23%), spinal stenosis (23%), and kidney stones (16%). The results of the survey support that adults with XLH can experience progressively debilitating complications that cause pain and negatively impact functional independence and quality of life despite long-term treatment in childhood with the current standard of care therapy of oral phosphate and vitamin D metabolites. Data collection for the pediatric and adult versions of the survey is ongoing. The survey is hosted on the company's website at www.ultragenyx.com.