Ultragenyx Pharmaceutical, Kyowa Hakko Kirin Co., and Kyowa Kirin International PLC have announced that the U.S. Food and Drug Administration (FDA) has approved Crysvita® (burosumab-twza) for the treatment of X-linked hypophosphatemia (XLH) in adult and paediatric patients. Crysvita is an antibody that blocks fibroblast growth factor 23 (FGF23), a hormone that causes phosphate urinary excretion and suppresses active vitamin D production by the kidney.
XLH is a rare, hereditary, progressive and lifelong skeletal disorder characterised by renal phosphate wasting caused by excess FGF23 production. It affects both children and adults. In children, XLH causes rickets that leads to lower-extremity deformity, delayed growth and decreased height. Adults with XLH have an increased risk of fractures.
Crysvita is designed to bind the excess FGF23 in these patients, normalising phosphorus levels, improving bone mineralisation, improving rickets in children and healing fractures in adults.
Tom Carpenter, the lead study investigator, Director of the Yale Center for X-Linked Hypophosphatemia said, “The dosing regimen for Crysvita is less of a burden than currently available therapies and should be readily acceptable by families. I expect it to revolutionise the care of patients with XLH.”