Crysvita Approval Urged in EU for Older Adolescents, Adults With XLH

The Committee for Medicinal Products for Human Use (CHMP), an arm of the European Medicines Agency, has recommended that the approval of Crysvita (burosumab) be expanded to include all adolescents and adults with X-linked hypophosphataemia (XLH) and evidence of bone disease.

If accepted by the European Commission — which makes the final decision based on the CHMP’s recommendation — Crysvita will become the first medication approved in the EU that addresses the underlying cause of XLH in older adolescents and adults with fully grown skeletons.

Crysvita was first approved in the European Union in 2018, with conditions, for treating XLH with evidence of bone disease in children ages 1 and older, and adolescents with growing skeletons. It is marketed by Kyowa Kirin and Ultragenyx Pharmaceutical.

A similar label update also has taken place in the U.S., making Crysvita available to all XLH patients, 6 months and older.

“Today’s positive CHMP opinion marks a crucial step forward for the XLH community,” Abdul Mullick, president of Kyowa Kirin International, said in a press release.

“There is currently no approved therapy in Europe for older adolescents and adults with XLH that targets the underlying cause of this debilitating, progressive and life-long disease,” Mullick said. “Should Crysvita be approved for expanded use, it will enable adolescents to continue to receive the benefits of treatment after their bones have stopped growing, and offer adults with XLH a treatment that has been shown to reduce pain and stiffness, improve physical functioning and mobility, and heal pseudofractures and fractures.”

XLH is caused by mutations in the gene PHEX that lead to increased activity of the protein FGF23, which causes the kidneys to excrete too much phosphate into the urine. Phosphate is necessary for proper bone health, so low blood levels of phosphate lead to symptoms such as soft bones, bone malformation, and rickets.

Crysvita is a monoclonal antibody that blocks the activity of FGF23, thereby increasing phosphate reabsorption from the kidney and boosting vitamin D production.

The CHMP’s recommendation was based on findings from two Phase 3 clinical trials involving adults with XLH.

The open label UX023-CL304 trial (NCT02537431) included 14 patients who had not received any treatment for their disease for at least two years before enrolling in the study. The results showed that Crysvita reduced bone softening and improved bone mineralization in these patients.

The second trial, named UX023-CL303 (NCT02526160), involved 134 participants who received either Crysvita or a placebo, given as an under-the-skin (subcutaneous) injection every four weeks, for 48 weeks. Crysvita promoted reabsorbtion of phosphate in the kidneys and continued healing of fractures, the results of this trial showed.

“Adult XLH patients’ response to conventional therapy, which includes phosphate and activated vitamin D, is variable and the evidence-base for its efficacy is limited,” said Karine Briot, MD, PhD, of Hôpital Cochin, in France, who has worked on clinical trials of Crysvita.

“Having access to an efficacious treatment consistently from childhood through adulthood will be highly valuable to patients and to the physicians administering their care,” Briot added. “Today’s recommendation is an important step forward for all people with XLH and those who care for and support them.”