Crysvita meets goal in Phase III study for X-Linked hypophosphatemia

US ultra-rare diseases focussed biotech firm Ultragenyx Pharmaceutical (Nasdaq: RARE) and Japan’s Kyowa Hakko Kirin (TYO: 4151) have announced that the Phase III study of Crysvita (burosumab) met its primary endpoint demonstrating that Crysvita was superior to oral phosphate and active vitamin D (conventional therapy) in improving rickets in children with X-linked hypophosphatemia (XLH) after 40 weeks of treatment (LS Mean treatment difference of +1.14, p<0.0001).

The study also showed improvement in important metabolic and functional measures with Crysvita treatment, and a safety profile similar to that observed in other Crysvita pediatric XLH studies. 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.

Crysvita was approved by the Food and Drug Administration in April this year for the treatment of XLH in adult and pediatric patients 1 year of age and older. In February 2018 Crysvita received a positive European Commission decision granting conditional marketing authorization Crysvita for the treatment of XLH with radiographic evidence of bone disease in children 1 year of age and older and adolescents with growing skeletons. This Phase III pediatric study will serve as a confirmatory study in Europe; it was not required for the regulatory application in the USA, the companies noted.