Burosumab

X-linked hypophosphatemia is caused by excess fibroblast growth factor 23 (FGF23) which suppresses renal tubular phosphate reabsorption and the renal production of 1,25 dihydroxy vitamin D. Burosumab-twza binds to and inhibits the biological activity of FGF23 restoring renal phosphate reabsorption and increasing the serum concentration of 1,25 dihydroxy vitamin D.

• CRYSVITA is a fibroblast growth factor 23 (FGF23) blocking antibody indicated for: The treatment of X-linked hypophosphatemia (XLH) in adult and pediatric patients 6 months of age and older. ( 1.1 ) The treatment of FGF23-related hypophosphatemia in tumor-induced osteomalacia (TIO) associated with phosphaturic mesenchymal tumors that cannot be curatively resected or localized in adult and pediatric patients 2 years of age and older.

• CRYSVITA is contraindicated: In concomitant use with oral phosphate and/or active vitamin D analogs (e.g. calcitriol, paricalcitol, doxercalciferol, calcifediol) due to the risk of hyperphosphatemia [see Warnings and Precautions (5.2) and Drug Interactions (7.1) ] .contraindicated

For subcutaneous use only ( 2 ) Prior to starting CRYSVITA, discontinue oral phosphate and/or active vitamin D analogs for one week ( 2.1 ) Pediatric XLH (6 months and older): For patients who weigh less than 10 kg, starting dose regimen is 1 mg/kg of body weight rounded to the nearest 1 mg, administered every two weeks ( 2.2 ) For patients who weigh 10 kg and greater, starting dose regimen is 0.8 mg/kg of body weight rounded to the nearest 10 mg, administered every two weeks. The minimum starting dose is 10 mg up to a maximum dose of 90 mg. ( 2.2 ) Dose may be increased up to approximately 2 mg/kg (maximum 90 mg), administered every two weeks to achieve normal serum phosphorus. ( 2.2 ) Adult XLH: Dose regimen is 1 mg/kg body weight rounded to the nearest 10 mg up to a maximum dose of 90 mg administered every four weeks. ( 2.3 ) Pediatric TIO (2 years and older): Starting dose is 0.4 mg/kg of body weight rounded to the nearest 10 mg every 2 weeks. Dose may be increased up to 2 mg/kg not to exceed 180 mg, administered every two weeks. ( 2.4 ) Adult TIO: Starting dose is 0.5 mg/kg every four weeks. Dose may be increased up to 2 mg/kg not to exceed 180 mg, administered every two weeks. ( 2.5 ) 2.1 Important Information Prior to Initiation of CRYSVITA Prior to starting CRYSVITA, discontinue oral phosphate and/or active vitamin D analogs (e.g. calcitriol, paricalcitol, doxercalciferol, calcifediol) for one week [see Contraindications (4) , Warnings and Precautions (5.3) ] .

Hypersensitivity : Discontinue CRYSVITA if serious hypersensitivity reactions occur and initiate appropriate medical treatment. ( 5.1 ) Hyperphosphatemia and Risk of Nephrocalcinosis : For patients already taking CRYSVITA, dose interruption and/or dose reduction may be required based on a patient's serum phosphorus levels. ( 5.2 , 6.1 ) Hypercalcemia : Increases in serum calcium been reported. Monitor serum calcium and parathyroid hormone levels in patients at high risk for hypercalcemia before and during treatment. ( 5.3 ) Injection Site Reactions : Administration of CRYSVITA may result in local injection site reactions. Discontinue CRYSVITA if severe injection site reactions occur and administer appropriate medical treatment. ( 5.4 , 6.1 ) 5.1 Hypersensitivity Hypersensitivity reactions (e.g. rash, urticaria) have been reported in patients with CRYSVITA. Discontinue CRYSVITA if serious hypersensitivity reactions occur and initiate appropriate medical treatment [see Adverse Reactions (6.1) ] . 5.2 Hyperphosphatemia and Risk of Nephrocalcinosis Increases in serum phosphorus to above the upper limit of normal may be associated with an increased risk of nephrocalcinosis. For patients already taking CRYSVITA, dose interruption and/or dose reduction may be required based on a patient's serum phosphorus levels. Patients with tumor-induced osteomalacia who undergo treatment of the underlying tumor should have dosing interrupted and adjusted to prevent hyperphosphatemia [see Dosage and Administration (2) and Adverse Reactions (6.1) ] .

The following adverse reactions are described below and elsewhere in the labeling: Hypersensitivity [see Warnings and Precautions (5.1) ] Hyperphosphatemia and Risk of Nephrocalcinosis [see Warnings and Precautions (5.2) ] Hypercalcemia [see Warnings and Precautions (5.3) Injection Site Reactions [see Warnings and Precautions (5.4) ] Most common adverse reactions (≥25% in the CRYSVITA group and > Active Control) in pediatric XLH patients are: pyrexia, injection site reaction, cough, vomiting, pain in extremity, headache, tooth abscess, dental caries. ( 6.1 ) Most common adverse reactions (>5% and in at least 2 patients more than placebo) in adult XLH patients are: back pain, headache, tooth infection, restless legs syndrome, vitamin D decreased, dizziness, constipation, muscle spasms, blood phosphorus increased. ( 6.1 ) Most common adverse reactions (>10%) in TIO patients are: tooth abscess, muscle spasms, dizziness, constipation, injection site reaction, rash, and headache. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Kyowa Kirin, Inc. at 1-844-768-3544 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Adverse Reactions in Pediatric Patients with XLH CRYSVITA was studied in three pediatric XLH studies.

8.1 Pregnancy Risk Summary There are no available data on CRYSVITA use in pregnant women to inform a drug-associated risk of adverse developmental outcomes. In utero, burosumab-twza exposure in cynomolgus monkeys did not result in teratogenic effects. Adverse effects such as late fetal loss and preterm birth were observed in pregnant cynomolgus monkeys, however, these effects are unlikely to indicate clinical risk because they occurred at a drug exposure that was 15-fold higher, by AUC, than the human exposure at the maximum recommended human dose (MRHD) of 2 mg/kg every 2 weeks and were accompanied by maternal hyperphosphatemia and placental mineralization ( see Data ). Serum phosphorus levels should be monitored throughout pregnancy [see Dosage and Administration (2.2) ]. Report pregnancies to the Kyowa Kirin, Inc. Adverse Event reporting line at 1-844-768-3544. The background risk of major birth defects and miscarriage for the indicated population is unknown; however, the estimated background risk in the U.S. general population of major birth defects is 2% to 4% and of miscarriage is 15% to 20% of clinically recognized pregnancies.

Metabolism

The following pharmacokinetic parameters were observed in patients with XLH administered the approved recommended starting dosage based on a 70 kg patient, unless otherwise specified. Based on the population PK analysis, the PK characteristics of burosumab-twza were similar between patients with XLH and TIO.

There have been no reports of overdose with CRYSVITA. CRYSVITA has been administered in pediatric clinical trials without dose limiting toxicity using doses up to 2 mg/kg body weight with a maximal dose of 90 mg, administered every two weeks. In XLH adult clinical trials, no dose limiting toxicity has been observed using doses up to 1 mg/kg or a maximal total dose of 128 mg every 4 weeks. In non-XLH rabbits and cynomolgus monkeys, ectopic mineralization in multiple tissues and organs was observed at doses of burosumab-twza that resulted in supra-physiologic serum phosphate levels. Adverse effects on bone including reductions in bone mineral density, bone mineralization and bone strength were also observed at exposure greater than human exposure [ see Nonclinical Toxicology (13.2) ]. In case of overdose, it is recommended that serum phosphorus levels, serum calcium levels and renal function be measured immediately and monitored periodically until resolution to normal/baseline levels. In case of hyperphosphatemia, withhold CRYSVITA and initiate appropriate medical treatment.

• Apr 17, 2018BLABLA761068Kyowa Kirin

1. 1Inappropriate Schedule Of Product Administration69811%
2. 2Product Dose Omission Issue63510%
3. 3Blood Phosphorus Decreased5829.5%
4. 4Pain3776.1%
5. 5Arthralgia3655.9%
6. 6Pain In Extremity3425.6%
7. 7Restless Legs Syndrome2744.5%
8. 8Headache2714.4%
9. 9Incorrect Dose Administered2474.0%
10. 10Fatigue2423.9%
11. 11Injection Site Pain2373.9%
12. 12Bone Pain2053.3%
13. 13Contraindicated Product Administered1903.1%
14. 14Back Pain1873.0%
15. 15Covid-191782.9%

The 10 most recently updated of 38 ClinicalTrials.gov registrations naming Burosumab as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• Tumor-induced Osteomalacia Disease Monitoring Program
  Active not recruiting · Observational · 23 enrolled · Ultragenyx Pharmaceutical Inc
  NCT04783428updated 2026-06-03
• Treatment Patterns, Biochemical Profiles and Clinical Outcomes in Adults With X-Linked Hypophosphatemia
  Not yet recruiting · Observational · 100 enrolled · Novo Nordisk A/S
  NCT07607600updated 2026-05-26
• X-linked Hypophosphatemia Disease Monitoring Program
  Active not recruiting · Observational · 782 enrolled · Ultragenyx Pharmaceutical Inc
  NCT03651505updated 2026-05-22
• Effective Dosing of Burosumab in XLH
  Recruiting · Observational · 120 enrolled · University of Nottingham
  NCT07183579updated 2026-05-11
• Burosumab and 1-25 (OH) Vitamin D on Human Osteoblasts
  Recruiting · Observational · 20 enrolled · Hospices Civils de Lyon
  NCT04159675updated 2026-04-16
• Burosumab for Fibroblast Growth Factor-23 Mediated Hypophosphatemia in Fibrous Dysplasia
  Completed · Phase 2 · Interventional · 12 enrolled · National Institute of Dental and Craniofacial Research (NIDCR)
  NCT05509595updated 2026-02-02
• Post Marketing Surveillance Study to Observe Safety and Effectiveness of CRYSVITA® in S. Korean Patients
  Recruiting · Observational · 100 enrolled · Kyowa Kirin Korea Co., Ltd.
  NCT06202027updated 2025-08-29
• Expanded Access to Burosumab
  Available · Expanded access · Kyowa Kirin Co., Ltd.
  NCT03775187updated 2025-03-05
• Study to Assess the Safety, Tolerability, Pharmacokinetics and Efficacy of Burosumab in Patients Less Than 1 Year of Age
  Completed · Phase 1 · Phase 2 · Interventional · 16 enrolled · Kyowa Kirin Pharmaceutical Development Ltd
  NCT04188964updated 2024-11-07
• Registry for Patients With X-Linked Hypophosphatemia
  Recruiting · Observational · 1,343 enrolled · Kyowa Kirin Pharmaceutical Development Ltd
  NCT03193476updated 2024-09-19

Frequently asked questions

How does Burosumab work?

X-linked hypophosphatemia is caused by excess fibroblast growth factor 23 (FGF23) which suppresses renal tubular phosphate reabsorption and the renal production of 1,25 dihydroxy vitamin D. Burosumab-twza binds to and inhibits the biological activity of FGF23 restoring renal phosphate reabsorption and increasing the serum concentration of 1,25 dihydroxy vitamin D.

What is Burosumab used for?

According to FDA labeling, Burosumab carries indications including: CRYSVITA is a fibroblast growth factor 23 (FGF23) blocking antibody indicated for: The treatment of X-linked hypophosphatemia (XLH) in adult and pediatric patients 6 months of age and older. ( 1.1 ) The treatment of FGF23-related hypophosphatemia in tumor-induced osteomalacia (TIO) associated with phosphaturic mesenchymal tumors that cannot be curatively resected or localized in adult and pediatric patients 2 years of age and older.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Burosumab?

Burosumab is classified as Other drugs affecting bone structure and mineralization, Decreased Growth Factor Activity.

What are the brand names for Burosumab?

Burosumab is marketed under brand names including Crysvita.

What are the contraindications for Burosumab?

Burosumab labeling lists contraindications including: CRYSVITA is contraindicated: In concomitant use with oral phosphate and/or active vitamin D analogs (e.g. calcitriol, paricalcitol, doxercalciferol, calcifediol) due to the risk of hyperphosphatemia [see Warnings and Precautions (5.2) and Drug Interactions (7.1) ] .. Always consult the full prescribing information and a clinician.