FDA Approves Enhanced Dosing Options for CRYSVITA in Adults with X-linked Hypophosphatemia
核心洞察
The FDA has approved new dosing options for CRYSVITA (burosumab-twza) in adults with X-linked hypophosphatemia (搜索), allowing healthcare providers to increase dose frequency for patients with suboptimal serum phosphorus levels.
Patients whose serum phosphorus remains below normal range after initial treatment can now receive 0.5 mg/kg every two weeks, with potential escalation to 1 mg/kg every two weeks if needed.
The expanded dosing regimen provides a more personalized treatment approach for the rare genetic disease that affects bone and muscle health through phosphorus deficiency.
The U.S. Food and Drug Administration has approved updated dosing guidelines for CRYSVITA® (burosumab-twza), expanding treatment options for adults living with X-linked hypophosphatemia (搜索) (XLH (搜索)). The approval, announced by Kyowa Kirin, Inc. on May 14, 2026, provides healthcare providers with enhanced flexibility to optimize treatment outcomes for patients whose serum phosphorus levels remain below the normal range after initial therapy.
Enhanced Dosing Flexibility
Under the new prescribing information, healthcare providers can now transition patients to a dosage of 0.5 mg/kg, not to exceed 90 mg, administered once every two weeks for those whose serum phosphorus remains below normal after the initial treatment period. If further dosage increases are needed after four weeks of treatment with the 0.5 mg/kg regimen, the dosage can be escalated to 1 mg/kg, not to exceed 90 mg, administered every two weeks.
"While most adults with XLH (搜索) maintain normal serum phosphorus levels with CRYSVITA administered every four weeks, this update enables a more personalized approach for those who need additional support to reach and maintain serum phosphorus levels within normal range," said Richard Wilson, Senior Vice President, Rare Disease Franchise Head at Kyowa Kirin.
Understanding X-linked Hypophosphatemia
X-linked hypophosphatemia (搜索) is a rare, lifelong genetic disease that impacts bones and muscles in both children and adults. The condition results from the body's inability to retain sufficient phosphorus, an essential mineral for bone health, due to excess production of fibroblast growth factor 23 (搜索) (FGF23 (搜索)). This excess FGF23 causes the body to release too much phosphorus through urine, leading to hypophosphatemia (搜索) that can cause bone softening and weakening.
CRYSVITA's Mechanism of Action
CRYSVITA is a recombinant, fully human monoclonal IgG1 antibody that binds to and inhibits the biological activity of FGF23 (搜索), addressing the underlying cause of hypophosphatemia (搜索) in XLH (搜索). By blocking FGF23, the treatment helps restore renal phosphorus reabsorption and increase serum concentration of active vitamin D.
The drug is indicated for treating XLH (搜索) in adult and pediatric patients 6 months of age and older, representing the only FDA-approved treatment for this rare condition.
Safety Considerations
The prescribing information includes important contraindications and warnings. CRYSVITA is contraindicated in patients taking oral phosphate and/or active vitamin D analogs due to hyperphosphatemia risk, when serum phosphorus is within or above normal range, and in patients with severe renal impairment or end-stage renal disease.
Key safety warnings include risks of hypersensitivity reactions, hyperphosphatemia with potential nephrocalcinosis, hypercalcemia, and injection site reactions. In pediatric patients, the most common adverse reactions include pyrexia, injection site reactions, cough, and vomiting. Adult patients commonly experience back pain, headache, tooth infection, and restless legs syndrome.
Clinical Impact
The dosing update reflects Kyowa Kirin's commitment to providing individualized treatment solutions for the XLH (搜索) community. As Wilson noted, "Kyowa Kirin is committed to delivering solutions that make a meaningful difference for people living with XLH. As the only FDA-approved treatment for XLH, CRYSVITA plays a critical role in care, and it's essential that clinicians have the flexibility to support optimal patient outcomes."
The enhanced dosing options are detailed in Section 2.3 of the full CRYSVITA Prescribing Information, specifically addressing recommended dosage for adult patients with X-linked hypophosphatemia (搜索) who are 18 years of age and older.