FDA approves label extension for Crysvita in X-linked hypophosphatemia.- Ultragenyx Pharmaceutical/Kyowa Kirin

Ultragenyx Pharmaceutical and Kyowa Kirin announced that the FDA has approved a label expansion for Crysvita (burosumab) in X-linked hypophosphatemia. The label has been updated to include new clinical data demonstrating superiority of treatment with Crysvita versus oral phosphate and active vitamin D (conventional therapy) in pediatric patients with XLH, and improvement in stiffness, and maintenance of efficacy of Crysvita in adult patients with longer-term treatment. The indication has also been expanded to include infants as young as six months of age.

For the pediatric XLH population, the U.S. label update is based on 64-week efficacy and safety data from the randomized active-controlled Phase III study of Crysvita compared with oral phosphate and active vitamin D (conventional therapy) in 61 children with XLH. The results showed that Crysvita was superior to conventional therapy for all key efficacy endpoints, showing a meaningful improvement in rickets severity, lower limb deformity and growth. The 64-week safety profile was similar to that observed at 40 weeks and in other Crysvita pediatric XLH studies.

For the adult XLH population, the label update incorporates results from the open-label treatment period of the Phase III study in 134 adult patients with XLH through week 48, demonstrating that serum phosphorus levels were maintained with no evidence of loss of effect. The updated label also includes results demonstrating the continued healing of fractures and pseudofractures at week 48 and improvement in the patient-reported outcome of stiffness at week 24. The safety profile is consistent with what has been previously observed in this study, with no new adverse reactions identified during the extended treatment period.