Phase III study of Crysvita meets primary endpoint in X-linked hypophosphatemia.- Ultragenyx Pharma/Kyowa Hakko Kirin.
Ultragenyx Pharmaceutical, Kyowa Hakko Kirin, and Kyowa Kirin International 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).
This Phase III Pediatric XLH randomized, open-label study enrolled 61 patients ages one through 12 in the US, Europe, Canada, Australia, Japan, and Korea, and compared the efficacy and safety of Crysvita (n=29) to conventional therapy (n=32). The study met its primary endpoint demonstrating that Crysvita significantly improved rickets compared to conventional therapy, as assessed by three independent blinded pediatric radiologists using the RGI-C scale. In addition, substantial healing was observed in 72% of patients receiving Crysvita compared to 6% of patients receiving conventional therapy.
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. Full results will be presented at an upcoming medical meeting.
Comment: On April 17, 2018 the FDA approved Crysvita for the treatment of XLH in adult and pediatric patients 1 year of age and older. On February 23, 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 U.S.