Publications of Interest
Haffner D, et al. Clinical practice recommendations for the diagnosis and management of X-linked
Nat Rev Nephrol. 2019 Jul;15(7):435-455.
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
randomised, active controlled,
open-label, phase 3 trial.
Lancet. 2019 Jun 15;393(10189):2416-2427.
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 Mar;7(3):189-199.
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 Feb 26;14(1):58.
PubMed link: https://www.ncbi.nlm.nih.gov/pubmed/30808384
Carpenter TO, et al. Burosumab therapy in children with X-Linked hypophosphatemia.
N Engl J Med. 2018 May 24;378(21):1987-1998.
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 lifelong 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 mutations6-8
What is XLH caused by?
XLH is caused by mutations in the PHEX gene4,5 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 life9
XLH is not just a bone disease – it is a multisystemic disease that impacts muscle and dentition as well4,10
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
How does CRYSVITA work?
By inhibiting excess FGF23 activity, CRYSVITA helps restore phosphate homeostasis in children with XLH and improve bone mineralisation11-12
Who can receive CRYSVITA?
CRYSVITA is indicated for the treatment of XLH with radiographic evidence of bone disease in children ≥ 1 years and adolescents with growing skeletons11
Why use CRYSVITA?
The efficacy and safety of CRYSVITA in children aged 1-12 years with XLH
have been studied in a global clinical development programme.12-14
A phase 3 clinical study showed that compared with continuing conventional therapy, switching children with XLH to CRYSVITA:12
- 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 XLH12
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 hypophosphatemia
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.