Crysvita submitted to FDA in sBLA for hypophosphatemia associated with phosphaturic mesenchymal tumors.- Ultragenyx Pharmaceutical and Kyowa Kirin

Ultragenyx Pharmaceutical and Kyowa Kirin announced that they submitted a supplemental Biologics License Application (sBLA) to the FDA on December 18, 2019, for Crysvita (burosumab) for the treatment of FGF23-related hypophosphatemia associated with phosphaturic mesenchymal tumors (tumor-induced osteomalacia; TIO) that cannot be curatively resected or localized. The companies expect to hear back from FDA on submission acceptance and review designation in February 2020. The sBLA package includes data from two single-arm Phase II studies, a 144-week study in 14 adult patients conducted by Ultragenyx in the U.S. and an 88-week study in 13 adult patients conducted by Kyowa Kirin in Japan and South Korea. In both studies, Crysvita was associated with increases in serum phosphorus and serum 1,25-dihydroxyvitamin D levels. Increased phosphate levels led to improvements in osteomalacia, mobility and vitality. Bone scans also demonstrated an increase in healed fractures and a decrease in new fractures during Crysvita treatment. During the studies, adverse events generally reflected the patients’ underlying disease, and there were no serious treatment-related adverse events.Comment: Crysvita is approved by the FDA for the treatment of X-linked hypophosphatemia (XLH) in adult and pediatric patients six months of age and older, and by Health Canada and Brazil’s National Health Surveillance Agency (ANVISA) for the treatment of XLH in adult and pediatric patients one year of age and older. It is approved by Japan’s Ministry of Health, Labor and Welfare (MHLW) for the treatment of FGF23-related hypophosphatemic rickets and osteomalacia. The medicine has received European conditional marketing authorization for the treatment of XLH with radiographic evidence of bone disease in children 1 year of age and older and adolescents with growing skeletons, and an application for the expanded use in adults with XLH is currently under review by the European Medicines Agency.