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Anti-FGF23 (Burosumab) in Adult Patients With XLH (BurGER)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details. Identifier: NCT04695860
Recruitment Status : Recruiting
First Posted : January 5, 2021
Last Update Posted : January 14, 2021
Kyowa Kirin
Information provided by (Responsible Party):
Wuerzburg University Hospital

Brief Summary:

X-linked hypophosphatemia (XLH) rare genetic disorder due by inactivating mutations in the PHEX gene leading to increased levels in FGF-23. Elevated FGF-23 reduces renal phosphate reabsorbtion and and limits 1-alpha hydroxylase driven Vitamin D activation, eventually leading to phosphate wasting, defective bone mineralization and additional health issues.

Burosumab is a recombinant fully human IgG1 monoclonal antibody developed to treat XLH by binding FGF23, thereby restoring normal phosphate homeostasis.

BUR03 is a Phase 3b open-label, single-arm, single-center study to confirm the efficacy and safety of Burosumab treatment in adult (age ≥18 years) XLH patients without upper age limit and irrespective of baseline pain level and to further evaluate the efficacy in this cohort and the assocaited effect of treatment on physical functioning, mobility and activity.

The study aims at enrolling and treating 34 subjects with a confirmed diagnosis of XLH with q4w s.c. injection of Burosumab 1mg/kg body weight over 48 weeks.

Primary objective is to attiain normal serum phosphorus levels, secondary objectives include key parameters of physical function and activity, mobility and mineral homeostasis.

Condition or disease Intervention/treatment Phase
X-linked Hypophosphatemia Drug: Burosumab Phase 3

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 34 participants
Allocation: N/A
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: An Investigator-sponsored Phase 3b Open-label Study of Anti- FGF23 Antibody Burosumab (KRN23) in Adult Patients With Xlinked Hypophosphatemia (XLH) in GERmany - BurGER
Actual Study Start Date : January 7, 2021
Estimated Primary Completion Date : June 2022
Estimated Study Completion Date : December 2022

Arm Intervention/treatment
Experimental: Open label Burosumab
Burosumab Q4W, 1mg/kg body weight s.c.
Drug: Burosumab
Q4w, 1mg/kg Body weight, s.c.

Primary Outcome Measures :
  1. Effect of Burosumab treatment on attaining serum phosphorus levels within the normal range in adults with XLH [ Time Frame: 48 weeks ]
    Proportion of subjects attaining a serum phosphorus concentration within the normal range

Secondary Outcome Measures :
  1. Change in chari rise test completion time [ Time Frame: 48 weeks ]
    Change in chair rise test completion time from baseline to end of study visit

  2. Change in 6-Minute-Walk test [ Time Frame: 48 weeks ]
    Change in 6-Minute-Walk test distance from baseline to end of study visit

  3. Change in timed up-and down stairs completion time [ Time Frame: 48 weeks ]
    Change in timed up-and down stairs completion time from baseline to end of study visit

  4. Normalization of TmP/GFR [ Time Frame: 48 weeks ]
    Normalization of renal tubular maximum reabsorption rate of phosphate to glomerular filtration rate (TmP/GFR), proportion of subjects achieving normal values

  5. Activity tracking [ Time Frame: 48 weeks ]
    Activity tracking using 'Actibelt', to delineate total hours of physical activity per week

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Male or female, aged ≥ 18 years, inclusive
  • Diagnosis of X-linked Hypophosphatemia supported by classic clinical features of adult XLH (e.g. short statue or bowed legs, clinical symptoms as judged by the investigator) and at least one of the following at Screening visit:

    • documented PHEX mutation in either the patient, or
    • in a directly related family member with appropriate X-linked inheritance
    • Increased serum levels of c-term FGF23 or iFGF23
  • Biochemical findings consistent with XLH at Screening visit following overnight fasting:

    • Serum phosphorus level or
    • TmP/GFR below lab specific lower limit of normal (LLN)
  • Estimated glomerular filtration rate (eGFR) ≥ 60 mL/min (using the Chronic Kidney Disease Epidemiology Collaboration equitation) or eGFR of 30 up to 60 mL/min at Screening visit with confirmation that the renal insufficiency is not due to nephrocalcinosis
  • Subjects who provide written informed consent after the nature of the study has been explained, and prior to any research-related procedures.
  • Participants must, in the opinion of the investigator, be willing and able to complete all aspects of the study, adhere to the study visit schedule and comply with the assessments.
  • Females of child-bearing potential must have a negative urine pregnancy test at Screening and be willing to have additional pregnancy tests during the study. Females considered not to be of child-bearing potential include those who have been in menopause for at least 2 years prior to Screening, or have had tubal ligation at least one year prior to Screening, or have had a total hysterectomy or bilateral salpingo-oophorectomy.
  • Female Participants of child-bearing potential who are sexually active must consent to use an effective method of contraception as determined by the site investigator (i.e. oral hormonal contraceptives, patch hormonal contraceptives, vaginal ring, intrauterine devices, surgical hysterectomy, vasectomy, tubal ligation, or true abstinence) from the period following the signing of the informed consent through 12 weeks after the last dose of study drug.

Exclusion Criteria:

  • Hypocalcemia or hypercalcemia, defined as serum calcium levels outside the age-adjusted normal limits and deemed as clinically significant in the opinion of the investigator.
  • Vitamin D deficiency (25OH D3 < 20ng/ml); if Vitamin D is low at screening, substitution is allowed and recompensation has to be confirmed before treatment start by normalized levels of Vitamin D (25OH D3 ≥ 20ng/ml)
  • Serum intact parathyroid hormone (iPTH) >2.5-fold the upper limit of normal (ULN)
  • Severe renal insufficiency with a Glomerular filtration rate (eGFR) <30 at screening
  • Treatment with oral phosphate and / or active vitamin D analogues in addition to Burosumab treatment. (In order to ensure appropriate patient care and preclude any harm due to deficient supply, required supplementation with oral phosphate salts and/or active vitamin D analogues at screening can be continued during the run-in phase but has to be stopped before Baseline and Initiation of treatment with Burosumab.)
  • Treatment with bisphosphates or Denosumab within the last 6 months
  • Treatment with Teriparatide within the last 3 months
  • Intake of calcimimetics within 30 days before screening
  • Patients with known hypersensitivity to Burosumab and the active substances of any of the excipients of Burosumab
  • Presence of a concurrent disease or condition that would interfere with study participation or affect safety in the opinion of the investigator
  • Use of any investigational product other than Burosumab or investigational medical device within 30 days prior to screening, or requirement for any investigational agent prior to completion of all scheduled study assessments.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT04695860

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Contact: Lothar Seefried, MD +49 931 803 ext 3575

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Clinical Trial Unit, Orthopedic Department, Wuerzburg University Recruiting
Würzburg, Germany, 97074
Contact: Jasmin Baumann    +49 931 803 ext 3590   
Contact: Hellwich Ursula    +49 931 803 ext 3578   
Principal Investigator: Lothar Seefried, MD         
Sponsors and Collaborators
Wuerzburg University Hospital
Kyowa Kirin
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Principal Investigator: Lothar Seefried, MD University Hospital Wuerzburg
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Responsible Party: Wuerzburg University Hospital Identifier: NCT04695860    
Other Study ID Numbers: BUR03
First Posted: January 5, 2021    Key Record Dates
Last Update Posted: January 14, 2021
Last Verified: December 2020
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No
Plan Description: Only aggregated, analyzed participant data will be shared

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Product Manufactured in and Exported from the U.S.: No
Additional relevant MeSH terms:
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Familial Hypophosphatemic Rickets
Phosphorus Metabolism Disorders
Metabolic Diseases
Rickets, Hypophosphatemic
Bone Diseases, Metabolic
Bone Diseases
Musculoskeletal Diseases
Hypophosphatemia, Familial
Renal Tubular Transport, Inborn Errors
Kidney Diseases
Urologic Diseases
Metal Metabolism, Inborn Errors
Metabolism, Inborn Errors
Genetic Diseases, Inborn
Calcium Metabolism Disorders
Vitamin D Deficiency
Deficiency Diseases
Nutrition Disorders