Ultragenyx Announces Presentation of Disease Burden Data in Adult Patients With X-Linked Hypophosphatemia

NOVATO, Calif., March 9, 2015 (GLOBE NEWSWIRE) -- Ultragenyx Pharmaceutical Inc. (Nasdaq: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.

About X-Linked Hypophosphatemia (XLH)

XLH is a disorder of phosphate metabolism caused by phosphate wasting in the urine leading to severe hypophosphatemia. XLH is the most common heritable form of rickets that is inherited as an X-linked dominant trait affecting both males and females, though some reports indicate that the disease may be more severe in males. XLH is a distinctive bone disease characterized by inadequate mineralization of bone that leads to a spectrum of abnormalities, including rickets, progressive bowing of the leg, osteomalacia, bone pain, waddling gait, short stature, gross motor impairment, muscle weakness, frequent/poorly healing pseudofractures, spinal stenosis, enthesopathy, and osteoarthritis.

Most pediatric patients and some adult patients are managed using oral phosphate replacement and vitamin D (calcitriol) therapy, which requires frequent divided doses and careful medical monitoring. It is partially effective at reducing rickets in pediatric patients, but it does not improve growth and can be challenging to optimize the dose without increasing the risk of depositing phosphate-calcium precipitates in the kidneys (nephrocalcinosis).

About KRN23 and FGF23

KRN23 is an investigational recombinant fully human monoclonal IgG1 antibody, discovered by Kyowa Hakko Kirin, against the phosphaturic hormone fibroblast growth factor 23 (FGF23). It is being developed by Ultragenyx to treat XLH, a disease characterized by excess activity of FGF23. FGF23 is a hormone that reduces serum levels of phosphorus and vitamin D by regulating phosphate excretion and vitamin D production by the kidney. Phosphate wasting in XLH is caused by excessive levels and activity of FGF23. KRN23 is designed to bind to and thereby inhibit the excessive biological activity of FGF23. By blocking excess FGF23 in patients with XLH, KRN23 is intended to restore normal phosphate reabsorption from the kidney and increase the production of vitamin D, which enhances intestinal absorption of phosphate and calcium.

Multiple clinical studies of KRN23 in adult patients with XLH have been completed and Ultragenyx intends to continue development of KRN23 in adults with XLH. In addition, a Phase 2 study in pediatric patients with XLH is ongoing.

KRN23 is also being developed for tumor-induced osteomalacia (TIO), a disease characterized by typically benign tumors that produce excess levels of FGF23, which can lead to severe osteomalacia, fractures, bone and muscle pain, and muscle weakness.

Ultragenyx and Kyowa Hakko Kirin entered into a collaboration and license agreement in August 2013 to develop and commercialize KRN23.

About Ultragenyx

Ultragenyx is a clinical-stage biotechnology company committed to bringing to market novel products for the treatment of rare and ultra-rare diseases, with a focus on serious, debilitating genetic diseases. Founded in 2010, the company has rapidly built a diverse portfolio of product candidates with the potential to address diseases for which the unmet medical need is high, the biology for treatment is clear, and for which there are no approved therapies.

The company is led by a management team experienced in the development and commercialization of rare disease therapeutics. Ultragenyx's strategy is predicated upon time and cost-efficient drug development, with the goal of delivering safe and effective therapies to patients with the utmost urgency.

For more information on Ultragenyx, please visit the company's website at www.ultragenyx.com.

About Kyowa Hakko Kirin

Kyowa Hakko Kirin is a leading biopharmaceutical company in Japan focusing on its core business area of oncology, nephrology, and immunology/allergy. Kyowa Hakko Kirin leverages antibody-related leading-edge technologies to discover and develop innovative new drugs aiming to become a global specialty pharmaceutical company which contributes to the health and well-being of people around the world.

For more information, please visit www.kyowa-kirin.com.

Forward-Looking Statements

Except for the historical information contained herein, the matters set forth in this press release, including statements regarding the intended continued development of KRN23 to help both pediatric and adult patients with XLH, are forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. Such forward-looking statements involve substantial risks and uncertainties that could cause our clinical development programs, future results, performance, or achievements to differ significantly from those expressed or implied by the forward-looking statements. Such risks and uncertainties include, among others, the uncertainties inherent in the clinical drug development process, including the regulatory approval process, the timing of our regulatory filings, and other matters that could affect the availability or commercial potential of our drug candidates. Ultragenyx undertakes no obligation to update or revise any forward-looking statements. For a further description of the risks and uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to the business of the Company in general, see Ultragenyx's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on August 11, 2014, and its subsequent periodic reports filed with the Securities and Exchange Commission.

CONTACT: Ultragenyx Pharmaceutical Inc. Investors & Media Robert Anstey 844-758-7273

Source:Ultragenyx Pharmaceutical Inc.