Publications of interest
Portale AA, et al. Continued beneficial effects of burosumab in adults with X-linked hypophosphatemia: Results from a 24-week treatment continuation period after a 24-week double-blind placebo-controlled period. Calcif Tissue Int. 2019;105:271–84.
PubMed link: https://pubmed.ncbi.nlm.nih.gov/31165191/
Insogna KL, et al. Burosumab improved histomorphometric measures of osteomalacia in adults with X‐linked hypophosphatemia: A phase 3, single‐arm, international trial. J Bone Miner Res. 2019;34:2183–91
PubMed link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6916280/
Haffner D, et al. Clinical practice recommendations for the diagnosis and management of X-linked
Nat Rev Nephrol. 2019;15:435-55.
PubMed link: https://www.ncbi.nlm.nih.gov/pubmed/31068690
Imel EA, et al. Burosumab versus conventional therapy in children with X-linked hypophosphataemia: a
open-label, phase 3 trial.
PubMed link: https://www.ncbi.nlm.nih.gov/pubmed/31104833
Whyte MP, et al. Efficacy and safety of burosumab in children aged 1–4 years with X-linked
hypophosphataemia: a multicentre,
open-label, phase 2 trial.
Lancet Diabetes Endocrinol. 2019;7:189-99.
PubMed link: https://www.ncbi.nlm.nih.gov/pubmed/30638856
Beck-Nielsen SS, et al. FGF23 and its role in X-linked hypophosphatemia-related morbidity.
Orphanet J Rare Dis. 2019;14:58.
PubMed link: https://www.ncbi.nlm.nih.gov/pubmed/30808384
Insogna KL, et al. A randomized, double-blind, placebo-controlled, phase 3 trial evaluating the efficacy of burosumab, an anti-FGF23 antibody, in adults with X-linked hypophosphatemia: Week 24 primary analysis. J Bone Miner Res. 2018;33:1383-93.
PubMed link: https://pubmed.ncbi.nlm.nih.gov/29947083/
Carpenter TO, et al. Burosumab therapy in children with X-linked hypophosphatemia.
N Engl J Med. 2018;378:1987-98.
PubMed link: https://www.ncbi.nlm.nih.gov/pubmed/29791829
Key Facts about XLH and CRYSVITA
What is XLH?
X-linked hypophosphataemia (XLH) is a rare, hereditary, progressive and life-long phosphate wasting disorder, caused by mutations in the PHEX (phosphate-regulating endopeptidase homolog, X-linked) gene that leads to excess fibroblast growth factor 23 (FGF23)1-4
What is the prevalence?
How is it inherited?
XLH is inherited in an X-linked dominant pattern; however, 20–30% of cases arise from spontaneous mutations5,7,8
What is XLH caused by?
XLH is caused by mutations in the PHEX gene4,9, which is located on the X chromosome
What does it mean for patients with XLH?
- Decreases renal phosphate reabsorption, which increases urinary phosphate excretion
- Decreases active vitamin D (1,25[OH]2D) production, which reduces intestinal phosphate absorption
The resulting chronic hypophosphataemia impairs bone mineralisation, leading to a variety of clinical manifestations that can impair patients’ physical function and quality of life10
XLH is not just a bone disease – it is a multisystemic disease that impacts muscle and dentition as well5
What is CRYSVITA?
CRYSVITA is a recombinant, fully human monoclonal antibody (IgG1) that binds to
and inhibits excess FGF23 activity11
It is the first and only disease-modifying biologic treatment that targets the pathophysiology of XLH11-12
How does CRYSVITA work?
By inhibiting excess FGF23 activity, CRYSVITA helps restore phosphate homeostasis in people with XLH and improve bone mineralisation11,13,17
Who can receive CRYSVITA?
CRYSVITA (burosumab) is indicated for the treatment of XLH, in children and adolescents aged 1 to 17 years with radiographic evidence of bone disease, and in adults11
Why use CRYSVITA?
The efficacy and safety of CRYSVITA in children aged 1–12 years, and adults, with XLH
have been studied in a global clinical development programme12–17
A phase III clinical study in children showed that, compared with continuing conventional therapy, switching children with XLH to CRYSVITA:14
- Restores phosphate homeostasis
- Significantly improved rickets healing and reduced severity
- Significantly improved growth and mobility outcomes
- Significantly improved biochemical markers of phosphate regulation and bone health
CRYSVITA has an acceptable safety profile over 64 weeks in children with XLH14
Phase III clinical studies in adults with XLH have shown that CRYSVITA:12,16–17
- Restored phosphate homeostasis
- Improved bone quality and enhanced bone mineralisation
Fully or partially healed 80% of baseline fractures in an exploratory endpoint in adults with XLH by
- Improved mobility, stiffness, functional disability, fatigue and pain
CRYSVITA was well tolerated and had an acceptable safety profile up to 48 weeks in adults with XLH12,16–17
XLH information websites for healthcare professionals
(Healthcare professional website). This website is developed and funded by Kyowa Kirin International.
European Society for Paediatric Endocrinology
European Calcified Tissue Society
European Society for Paediatric Nephrology
XLH information websites for patients
(Patient website). This website is developed and funded by Kyowa Kirin International.
Founded in 2018, the XLH Alliance is an alliance of patient
groups for individuals affected by
X-linked hypophosphataemia and related disorders. The XLH Alliance will direct you to organisations in your country that can provide information, education and a community to join that could provide support to patients and their families.