Long-term treatment with CRYSVITA® ▼ (burosumab) reduces the burden of disease in adults with X-linked hypophosphataemia (XLH), a rare genetic metabolic bone disease

TOKYO–(BUSINESS WIRE) – Kyowa Kirin Co., Ltd. (TSE: 4151, Kyowa Kirin) today announced the release of new data demonstrating the continued benefit of treatment with CRYSVITA® (burosumab) in adults with X-linked hypophosphatemia (XLH), a rare genetic metabolic bone disease. The data show that adults with XLH experience significant pain, stiffness, fatigue, and impaired ability to exercise and walk. Treatment with CRYSVITA was associated with a significant improvement from baseline at 96 weeks

The data are from a phase 3, randomized, double-blind, placebo-controlled, open-label study to evaluate the efficacy and safety of CRYSVITA in adults with XLH.2 The study met its primary endpoint and showed a statistically significant effect with increasing serum phosphate concentrations after 24 Weeks versus placebo.3 After 24 weeks, all patients were switched to CRYSVITA treatment and data on metabolic and biochemical markers, patient-reported outcomes (PROs), and mobility measurements were collected for up to 96 weeks. This new publication focuses on the results of the PRO analysis and mobility assessments

At Week 96, the study showed statistically significant improvements in PROs, including the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Brief Pain Inventory – Short Form (BPI-SF), and Brief Fatigue Inventory (BFI) compared to the Baseline. 1 Statistically significant improvements in walking ability, measured with the 6-minute walk test (6MWT), were also observed after 96 weeks compared to the initial value, as well as fracture healing. 3

Lead author Pr Karine Briot, Hôpital Cochin, Paris, France said, “The study highlights the many physical challenges adult patients with XLH face, including pain, stiffness, fatigue, and difficulty walking or exercising. Treatment with burosumab has previously been shown to improve phosphate homeostasis in adult XLH patients compared to placebo. This new analysis suggests that, despite the long-term complications and physical impairments associated with XLH in adults, treatment with burosumab can also improve the physical function and quality of life of adults with XLH in the longer term. ”

Tomohiro Sudo, Kyowa Kirin’s Executive Officer, Head of Global Product Strategy Department, said, “Kyowa Kirin is committed to improving the lives of people with XLH and their families. One of our main focuses is generating new data that will improve our understanding of the best treatment and management for XLH. This important new data highlights the many physical challenges people with XLH face on a daily basis, how their needs might be better met, and how Kyowa Kirin serves its purpose of making people smile. ”

The data were published today in the BMJ journal RMD Open, Rheumatic and Musculoskeletal Diseases.1 CRYSVITA is approved in Europe for the treatment of XLH in children and adolescents aged 1 to 17 years with radiographic evidence of a bone disease and in adults.4

▼ This medicine is subject to additional monitoring.

About X-linked hypophosphatemia

X-linked hypophosphatemia (XLH) is a rare genetic disease that causes abnormalities in bones, muscles, and joints.5,6 XLH is not life threatening, but its burden is lifelong and progressive and can affect a person’s quality of life.7

People with XLH have a genetic defect on the X chromosome that results in excessive loss of phosphate in the urine and poor absorption from the gut due to an excess of a hormone called fibroblast growth factor-23 (FGF23), resulting in chronic low blood phosphate levels.4,8 Phosphate is an important mineral needed for the body’s energy levels, muscle function, and the formation of healthy bones and teeth.9,10 There is no cure for XLH, but therapies that point to it aiming to help restore and maintain normal phosphate levels in the body may help improve the progression of disease symptoms

XLH is the most common form of hereditary rickets.11 It can sometimes appear in people who have never had a family history of the disease, but is usually passed on from a parent who carries the defective gene.12

About CRYSVITA® (burosumab)

CRYSVITA (burosumab) was developed and developed by Kyowa Kirin and is a recombinant fully human IgG1 monoclonal antibody to the phosphorous hormone fibroblast growth factor 23 (FGF23). FGF23 is a hormone that lowers serum phosphate levels by regulating phosphate excretion and active vitamin D production by the kidney. Phosphate waste and the resulting hypophosphatemia in X-linked hypophosphatemia (XLH) is caused by excess FGF23. CRYSVITA is said to bind to the biological activity of FGF23 and thereby inhibit the biological activity. By blocking excess FGF23 in patients, CRYSVITA is said to increase phosphate reabsorption from the kidney and increase the production of active vitamin D, which improves the intestinal absorption of phosphate and calcium.

CRYSVITA has been available for clinical use since 2018. The first approval was granted by the European Commission, which required a conditional marketing authorization for CRYSVITA for the treatment of XLH with radiological evidence of a bone disease in children from one year of age and adolescents with growing skeletons. In 2020, this authorization was then extended to older adolescents and adults. 2

CRYSVITA is approved by the US Food and Drug Administration (FDA) for patients with XLH 6 months and older and Health Canada for patients with XLH 1 year and older.13,14

In 2019, CRYSVITA was approved by the Japanese Ministry of Health, Labor and Welfare for the treatment of FGF23-related hypophosphatemic rickets and osteomalacia. In 2020, CRYSVITA was reimbursed by National Health Insurance (NHI) of Japan as a self-injecting drug for the treatment of FGF23-related hypophosphatemic rickets and osteomalacia.

In January 2020, Swissmedic launched CRYSVITA for the treatment of adults, adolescents and children (from one year of age) with XLH.15. authorized

In June 2020, the U.S. Food and Drug Administration (FDA) approved CRYSVITA for patients age two and older with tumor-induced osteomalacia (TIO), a rare disease characterized by the development of tumors that cause weakened and softened bones. 16

Kyowa Kirin and Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE: Ultragenyx) are collaborating to develop and commercialize CRYSVITA worldwide based on the collaboration and licensing agreement between Kyowa Kirin and Ultragenyx.

About Kyowa Kirin

Kyowa Kirin is committed to developing and delivering novel medicines with life changing value. As a Japan-based global specialty pharmaceutical company with more than 70 years of history, the company applies cutting-edge science including an expertise in antibody research and engineering to meet the needs of patients and society in multiple therapeutic areas such as nephrology, oncology, immunology / Allergy and Neurology. In our four regions – Japan, Asia Pacific, North America and EMEA / International – we focus on our goal of making people smile and share our shared values ​​of commitment to life, teamwork / wa, innovation and integrity. To learn more about Kyowa Kirin’s business, please visit:

Kyowa Kirin International /

Galabank Business Park

Galashiels, TD1 1QH

United Kingdom


1 Briot K, Portals AA, Brandi ML, et al. RMD Open 2021; 7: e001714. doi: 10.1136 / rmdopen-2021-001714.

2 Insogna KL, Rauch F, Kamenický P, et al. Burosumab improved histomorphometric measurements of osteomalacia in adults with X-linked hypophosphatemia: a single-arm, international phase 3 study. J Bone Miner Res. 2019; 34: 2183-2191.

3 Portals AA, Carpenter TO, Brandi ML, et al. Calcif Tissue Int 2019; 105: 271-84.

4 European Medicines Agency. CRYSVITA EPAR product information. Summary of the product features. Available from: Crysvita, INN-burosumab; ( Last updated: June 2021. Last accessed: July 2021.

5 A. Linglart, M. Biosse-Duplan, K. Briot et al. Therapeutic management of hypophosphatemic rickets from infancy to adulthood. Endocr-Connect. 2014; 3: R13-30.

6 D. Haffner, F. Emma, ​​DM Eastwood et al. Consensus Statement. Evidence-based guide. Recommendations from clinical practice for the diagnosis and treatment of X-linked hypophosphatemia. Nat. Rev Nephrol. 2019; 15; 435-455.

7 A. Skrinar, M. Dvorak-Ewell, A. Evins et al. The Lifelong Impact of X-Linked Hypophosphatemia: Results of a Burden of Disease Survey. J Endocr Soc. 2019; 3: 1321-1334.

8 Beck-Nielsen SS, Mughal Z, Haffner D, et al. FGF23 and its role in X-linked hypophosphatemia-related morbidity. Orphanet J Rare Dis. 2019; 14:58.

9 Pesta D, Tsirigotis DN, Befroy DE, et al. Hypophosphatemia promotes lower rates of muscle ATP synthesis. The FAESB journal. 2016; 39: 3378-3387.

10 Unnanuntana A, Rebolledo BJ, Khair MM, et al. Diseases Affecting Bone Quality: Beyond Osteoporosis. Clin Orthop Relat Res. 2011; 469: 2194-2206.

11 Zimmermann TO, Imel EA, Holm IA, et al. A Clinician’s Guide to X-Linked Hypophosphatemia. J Bone Miner Res. 2011; 26: 1381-8.

12 National Center for the Promotion of Translation Studies. X-linked hypophosphatemia. Available at: Last updated: February 2018. Last accessed: July 2021.

13 Health Canada. Executive Decision Summary – CRYSVITA. Available at: Last updated: April 2020. Last accessed: April 2021.

14 Available at: Last accessed July 2021

15 Swissmedic. Crysvita, solution for injection (burosumabum). Available at: Last updated: January 2020. Last accessed: July 2021.

16 FDA. Available from: FDA Approves First Therapy for Rare Diseases That Cause Low Blood Phosphate Levels and Bone Softening | FDA. Last accessed July 2021

KKI / INT / BUR / 1174

Related Articles