Kyowa Hakko Kirin : Announces Initiation of a Phase 2 Study of KRN23 for Pediatric X-Linked Hypophosphatemic Rickets in the US and EU

July 24, 2014

Tokyo, Japan, July 24, 2014 --- Kyowa Hakko Kirin Co., Ltd. (Tokyo: 4151, President and CEO: Nobuo Hanai, "Kyowa Hakko Kirin") announced today the initiation of a Phase 2 study of the human monoclonal anti-Fibroblast Growth Factor 23 (FGF23)*1 antibody KRN23 in pediatric patients with X-linked hypophosphatemic rickets(XLH)*2 in the US and EU, collaborating with Ultragenyx Pharmaceutical Inc. ("Ultragenyx"; NASDAQ: RARE)

The multi-center, randomized, open-label, dose-finding Phase 2 clinical study will evaluate safety and efficacy in approximately 30 prepubertal pediatric XLH patients. The primary objectives of the study are to identify a dose and dosing regimen and to establish the safety profile of treatment with KRN23 in pediatric XLH patients. Preliminary clinical effects of KRN23 treatment on bone health and deformity as measured by radiographic assessments, growth, muscle strength, and motor function will also be assessed, as well as markers of bone health and patient-reported outcomes of pain, disability, and quality of life.

The study consists of a 16-week individual dose-titration period followed by a 48-week treatment period. The goal of the dose-titration period is to identify the individualized dose of KRN23 required to achieve serum phosphorus levels in the target range. After the 16-week dose-titration period, patients will receive their individually-optimized dose of KRN23 for the 48-week treatment period. An interim analysis of safety and pharmacodynamic data will be conducted after 24 weeks of the treatment period.

The Kyowa Hakko Kirin Group companies strive to contribute to the health and well-being of people around the world by creating new value through the pursuit of advances in life sciences and technologies.

*1 Fibroblast Growth Factor 23 (FGF23)
FGF23 is a polypeptide consisting of 251 amino acids that is mainly produced in bone tissue. It acts upon the kidneys to inhibit the reabsorption of phosphorus in renal tubules. In recent years, there have been suggestions that FGF23 is involved in such diseases as hypophosphatemic rickets, neoplastic osteomalacia, and renal failure.

*2 About X-linked Hypophosphatemic Rickets (XLH)
XLH is a rare disease in which the patient develops hypophosphatemia when phosphorus is excreted by the body in excess because of a high concentration of FGF23 in the blood, and as a result, the growth and maintenance of bone is impeded.

< Outline of the Study >