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Study of KRN23 (Burosumab), a Recombinant Fully Human Monoclonal Antibody Against Fibroblast Growth Factor 23 (FGF23), in Pediatric Subjects With X-linked Hypophosphatemia (XLH)

Primary Purpose

X-linked Hypophosphatemia

Status
Completed
Phase
Phase 2
Locations
International
Study Type
Interventional
Intervention
burosumab
Sponsored by
Kyowa Kirin, Inc.
About
Eligibility
Locations
Arms
Outcomes
Full info

About this trial

This is an interventional treatment trial for X-linked Hypophosphatemia focused on measuring X-linked hypophosphatemia, XLH, FGF23, KRN23

Eligibility Criteria

5 Years - 12 Years (Child)All SexesDoes not accept healthy volunteers

Inclusion

  1. Male or female, aged 5 - 12 years, inclusive, with open growth plates
  2. Tanner stage of 2 or less based on breast and testicular development
  3. Diagnosis of XLH supported by ONE of the following:

    • Confirmed Phosphate regulating gene with homology to endopeptidases located on the X chromosome (PHEX) mutation in the patient or a directly related family member with appropriate X-linked inheritance
    • Serum FGF23 level > 30 pg/mL by Kainos assay
  4. Biochemical findings associated with XLH including:

    • Serum phosphorus ≤ 2.8 mg/dL (0.904 mmol/L)*
    • Serum creatinine within age-adjusted normal range*
  5. Standing height < 50th percentile for age and gender using local normative data.
  6. Radiographic evidence of active bone disease including rickets in the wrists and/or knees, AND/OR femoral/tibial bowing, OR, for expansion subjects, a Rickets Severity Score (RSS) score in the knee of at least 1.5 as determined by central read.
  7. Willing to provide access to prior medical records for the collection of historical growth, biochemical and radiographic data, and disease history.
  8. Provide written or verbal assent (if possible) and written informed consent by a legally authorized representative after the nature of the study has been explained, and prior to any research-related procedures.
  9. 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.
  10. Females who have reached menarche must have a negative pregnancy test at Screening and undergo additional pregnancy testing during the study. If sexually active, male and female subjects must be willing to use an acceptable method of contraception for the duration of the study.

    • Criteria to be determined based on overnight fasting (minimum 4 hours) values collected at Screening Visit 2

Exclusion

  1. Use of a pharmacologic vitamin D metabolite or analog (e.g. calcitriol, doxercalciferol, alfacalcidiol, and paricalcitol) within 14 days prior to Screening Visit 2; washout will take place during the Screening Period
  2. Use of oral phosphate within 7 days prior to Screening Visit 2; washout will take place during the Screening Period
  3. Use of calcimimetics, aluminum hydroxide antacids (e.g. Maalox® and Mylanta®), systemic corticosteroids, and thiazides within 7 days prior to Screening Visit 1
  4. Use of growth hormone therapy within 3 months before Screening Visit 1
  5. Use of bisphosphonates for 6 months or more in the 2 years prior to Screening Visit 1
  6. Presence of nephrocalcinosis on renal ultrasound graded ≥ 3 based on the following scale: 0 = Normal 1 = Faint hyperechogenic rim around the medullary pyramids 2 = More intense echogenic rim with echoes faintly filling the entire pyramid 3 = Uniformly intense echoes throughout the pyramid 4 = Stone formation: solitary focus of echoes at the tip of the pyramid
  7. Planned or recommended orthopedic surgery, including staples, 8-plates or osteotomy, within the clinical trial period
  8. Hypocalcemia or hypercalcemia, defined as serum calcium levels outside the age-adjusted normal limits *
  9. Evidence of tertiary hyperparathyroidism as determined by the Investigator
  10. Use of medication to suppress parathyroid hormone (PTH) (e.g. Sensipar®, cinacalcet, calcimimetics) within 2 months prior to Screening Visit 1
  11. Presence or history of any condition that, in the view of the investigator, places the subject at high risk of poor treatment compliance or of not completing the study
  12. Presence of a concurrent disease or condition that would interfere with study participation or affect safety
  13. Previously diagnosed with human immunodeficiency virus antibody, hepatitis B surface antigen, and/or hepatitis C antibody
  14. History of recurrent infection or predisposition to infection, or of known immunodeficiency
  15. Use of a therapeutic monoclonal antibody within 90 days prior to Screening Visit 1 or history of allergic or anaphylactic reactions to any monoclonal antibody
  16. Presence or history of any hypersensitivity to recombinant human immunoglobulin G1 (IgG1) monoclonal antibody to FGF23 (burosumab) excipients that, in the judgment of the investigator, places the subject at increased risk for adverse effects
  17. Use of any investigational product or investigational medical device within 30 days prior to screening, or requirement for any investigational agent prior to completion of all scheduled study assessments

    • Criteria to be determined based on overnight fasting (minimum 4 hours) values collected at Screening Visit 2

Sites / Locations

  • University of California San Francisco
  • Yale University School of Medicine
  • Indiana University Hospital
  • Shriners Hospital for Children
  • Bicetre Hospital
  • University Medical Center Groningen
  • Royal Manchester Hospital
  • Birmingham Children's University
  • Great Ormond Street Hospital

Arms of the Study

Arm 1

Arm 2

Arm Type

Experimental

Experimental

Arm Label

Burosumab Q2W

Burosumab Q4W Then Q2W

Arm Description

Burosumab subcutaneous (SC) injections every 2 weeks (Q2W). Dose was determined by the participant's weight and prescribed dose by their study doctor.

Burosumab SC injections every 4 weeks (Q4W). Dose was determined by the participant's weight and prescribed dose by their study doctor. Participants in Q4W were to switch to Q2W beginning with Week 64 dosing.

Outcomes

Primary Outcome Measures

Change From Baseline in RSS Total Score Over Time
The RSS system is a 10-point radiographic scoring method that was developed to assess the severity of nutritional rickets in the wrists and knees based on the degree of metaphyseal fraying, cupping, and the proportion of the growth plate affected. Scores are assigned for the unilateral wrist and knee X-rays deemed by the rater to be the more severe of the bilateral images. The maximum total score on the RSS is 10 points and the minimum score is 0, with a total possible score of 4 points for the wrists and 6 points for the knees. Higher scores indicate greater rickets severity.
Change From Baseline in Serum Phosphorus Over Time
Change From Baseline in Serum 1,25(OH)2D Over Time
Change From Baseline in TmP/GFR Over Time
Data for urinary phosphorus and TRP were used in calculation TmP/GFR.

Secondary Outcome Measures

Change From Baseline in RSS Knee Scores Over Time
The RSS system is a 10-point radiographic scoring method that was developed to assess the severity of nutritional rickets in the wrists and knees based on the degree of metaphyseal fraying, cupping, and the proportion of the growth plate affected. Scores are assigned for the unilateral wrist and knee X-rays deemed by the rater to be the more severe of the bilateral images. The maximum total score on the RSS is 10 points and the minimum score is 0, with a total possible score of 4 points for the wrists and 6 points for the knees. Higher scores indicate greater rickets severity.
Change From Baseline in RSS Wrist Scores Over Time
The RSS system is a 10-point radiographic scoring method that was developed to assess the severity of nutritional rickets in the wrists and knees based on the degree of metaphyseal fraying, cupping, and the proportion of the growth plate affected. Scores are assigned for the unilateral wrist and knee X-rays deemed by the rater to be the more severe of the bilateral images. The maximum total score on the RSS is 10 points and the minimum score is 0, with a total possible score of 4 points for the wrists and 6 points for the knees. Higher scores indicate greater rickets severity.
Radiographic Global Impression of Change (RGI-C) Global Scores Over Time
Changes in the severity of rickets and bowing were assessed centrally by three independent pediatric radiologists contracted by a central imaging facility using a disease specific qualitative RGI-C scoring system. The RGI-C is a seven point ordinal scale with possible values: +3 = very much better (complete or near complete healing of rickets), +2 = much better (substantial healing of rickets), +1 = minimally better (i.e., minimal healing of rickets), 0 = unchanged, -1 = minimally worse (minimal worsening of rickets), -2 = much worse (moderate worsening of rickets), -3 = very much worse (severe worsening of rickets).
RGI-C Knee Scores Over Time
Changes in the severity of rickets and bowing were assessed centrally by three independent pediatric radiologists contracted by a central imaging facility using a disease specific qualitative RGI-C scoring system. The RGI-C is a seven point ordinal scale with possible values: +3 = very much better (complete or near complete healing of rickets), +2 = much better (substantial healing of rickets), +1 = minimally better (i.e., minimal healing of rickets), 0 = unchanged, -1 = minimally worse (minimal worsening of rickets), -2 = much worse (moderate worsening of rickets), -3 = very much worse (severe worsening of rickets).
RGI-C Wrist Scores Over Time
Changes in the severity of rickets and bowing were assessed centrally by three independent pediatric radiologists contracted by a central imaging facility using a disease specific qualitative RGI-C scoring system. The RGI-C is a seven point ordinal scale with possible values: +3 = very much better (complete or near complete healing of rickets), +2 = much better (substantial healing of rickets), +1 = minimally better (i.e., minimal healing of rickets), 0 = unchanged, -1 = minimally worse (minimal worsening of rickets), -2 = much worse (moderate worsening of rickets), -3 = very much worse (severe worsening of rickets).
Change From Baseline in Growth Velocity Over Time
Change From Baseline in Standing Height Z Score Over Time
Standing height Z scores are measures of height adjusted for a child's age and sex. The Z score indicates the number of standard deviations away from a reference population (from the CDC growth charts) in the same age range and with the same sex. A Z score of 0 is equal to the mean with negative numbers indicating values lower than the mean and positive values higher. Higher Z scores indicate a better outcome.
Change From Baseline in Growth (Standing Height) Over Time
Change From Baseline in Growth (Sitting Height) Over Time
Change From Baseline in Growth (Arm Length) Over Time
Change From Baseline in Growth (Leg Length) Over Time
6MWT Distance (Predicted Percent of Normal) Change From Baseline Over Time
The total distance walked (meters) in a 6-minute period was measured. The percent of predicted values were calculated using published normative data based on age, gender, and height (Geiger et al. 2007).
Change From Baseline in POSNA-PODCI (Normative Score) Upper Extremity Scale Scores Over Time
The POSNA-PODCI yields 4 functional assessment scores: Upper Extremity Function,Transfers and Basic Mobility, Sports and Physical Function, and Comfort/Pain. In addition, a Global Function score, which is an average of the 4 functional assessments, and a Happiness score are calculated. Raw, mean, standardized, and normative scores are calculated for each scale. Normative scores are calculated so that higher scores indicate better functioning. All scores are referenced to the general, healthy population with a normative mean score of 50 and a standard deviation of 10.
Change From Baseline in POSNA-PODCI (Normative Score) Transfer and Basic Mobility Scale Scores Over Time
The POSNA-PODCI yields 4 functional assessment scores: Upper Extremity Function,Transfers and Basic Mobility, Sports and Physical Function, and Comfort/Pain. In addition, a Global Function score, which is an average of the 4 functional assessments, and a Happiness score are calculated. Raw, mean, standardized, and normative scores are calculated for each scale. Normative scores are calculated so that higher scores indicate better functioning. All scores are referenced to the general, healthy population with a normative mean score of 50 and a standard deviation of 10.
Change From Baseline in POSNA-PODCI (Normative Score) Sports/Physical Functioning Scale Scores Over Time
The POSNA-PODCI yields 4 functional assessment scores: Upper Extremity Function,Transfers and Basic Mobility, Sports and Physical Function, and Comfort/Pain. In addition, a Global Function score, which is an average of the 4 functional assessments, and a Happiness score are calculated. Raw, mean, standardized, and normative scores are calculated for each scale. Normative scores are calculated so that higher scores indicate better functioning. All scores are referenced to the general, healthy population with a normative mean score of 50 and a standard deviation of 10.
Change From Baseline in POSNA-PODCI (Normative Score) Pain/Comfort Scale Scores Over Time
The POSNA-PODCI yields 4 functional assessment scores: Upper Extremity Function,Transfers and Basic Mobility, Sports and Physical Function, and Comfort/Pain. In addition, a Global Function score, which is an average of the 4 functional assessments, and a Happiness score are calculated. Raw, mean, standardized, and normative scores are calculated for each scale. Normative scores are calculated so that higher scores indicate better functioning. All scores are referenced to the general, healthy population with a normative mean score of 50 and a standard deviation of 10.
Change From Baseline in POSNA-PODCI (Normative Score) Happiness Scale Scores Over Time
The POSNA-PODCI yields 4 functional assessment scores: Upper Extremity Function,Transfers and Basic Mobility, Sports and Physical Function, and Comfort/Pain. In addition, a Global Function score, which is an average of the 4 functional assessments, and a Happiness score are calculated. Raw, mean, standardized, and normative scores are calculated for each scale. Normative scores are calculated so that higher scores indicate better functioning. All scores are referenced to the general, healthy population with a normative mean score of 50 and a standard deviation of 10.
Change From Baseline in POSNA-PODCI (Normative Score) Global Functioning Scale Scores Over Time
The POSNA-PODCI yields 4 functional assessment scores: Upper Extremity Function,Transfers and Basic Mobility, Sports and Physical Function, and Comfort/Pain. In addition, a Global Function score, which is an average of the 4 functional assessments, and a Happiness score are calculated. Raw, mean, standardized, and normative scores are calculated for each scale. Normative scores are calculated so that higher scores indicate better functioning. All scores are referenced to the general, healthy population with a normative mean score of 50 and a standard deviation of 10.
Change From Baseline in FEP Over Time
FEP is defined as 100% × (urine phosphorus × serum creatinine)/(urine creatinine × serum phosphorus), where the 2-hour urine sample was used for urine phosphorus and urine creatinine.
Change From Baseline in P1NP Over Time
Change From Baseline in CTx Over Time
Change From Baseline in ALP Over Time
Change From Baseline in BALP Over Time
Serum Pre-Dose Concentrations of Burosumab
Number of Participants With Treatment Emergent Adverse Events (TEAEs), Serious Adverse Events (SAEs) and Discontinuations Due to Adverse Events (AEs)
An AE is defined as any untoward medical occurrence associated with the use of a drug in humans, whether or not considered drug related. An SAE is defined as an AE or suspected adverse reaction that at any dose results in any of the following outcomes: death; life-threatening AE; inpatient hospitalization or prolongation of existing hospitalization; persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions; a congenital anomaly/birth defect. Severity was graded as 1 (mild), 2 (moderate), 3 (severe), 4 (life-threatening), 5 (death). TEAEs are defined as AEs with onset on or after the time of initiation of study drug administration.

Full Information

First Posted
June 9, 2014
Last Updated
April 11, 2023
Sponsor
Kyowa Kirin, Inc.
Collaborators
Kyowa Kirin Co., Ltd.
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1. Study Identification

Unique Protocol Identification Number
NCT02163577
Brief Title
Study of KRN23 (Burosumab), a Recombinant Fully Human Monoclonal Antibody Against Fibroblast Growth Factor 23 (FGF23), in Pediatric Subjects With X-linked Hypophosphatemia (XLH)
Official Title
A Randomized, Open-Label, Dose Finding, Phase 2 Study to Assess the Pharmacodynamics and Safety of the Anti-FGF23 Antibody, KRN23, in Pediatric Patients With X-linked Hypophosphatemia (XLH)
Study Type
Interventional

2. Study Status

Record Verification Date
July 2019
Overall Recruitment Status
Completed
Study Start Date
July 2, 2014 (Actual)
Primary Completion Date
October 30, 2018 (Actual)
Study Completion Date
October 30, 2018 (Actual)

3. Sponsor/Collaborators

Responsible Party, by Official Title
Sponsor
Name of the Sponsor
Kyowa Kirin, Inc.
Collaborators
Kyowa Kirin Co., Ltd.

4. Oversight

Data Monitoring Committee
Yes

5. Study Description

Brief Summary
The objectives of the study are to: Identify a dose and dosing regimen of burosumab, based on safety and pharmacodynamic (PD) effect, in pediatric XLH participants Establish the safety profile of burosumab for the treatment of children with XLH including ectopic mineralization risk, cardiovascular effects, and immunogenicity profile Characterize the pharmacokinetic (PK)/PD profile of the KRN23 doses tested in the monthly (Q4) and biweekly (Q2) dose regimens in pediatric XLH patients Determine the PD effects of burosumab treatment on markers of bone health in pediatric XLH patients Obtain a preliminary assessment of the clinical effects of burosumab on bone health and deformity, muscle strength, and motor function Obtain a preliminary assessment of the effects of burosumab on participant-reported outcomes, including pain, disability, and quality of life in pediatric XLH patients Evaluate the long-term safety and efficacy of burosumab

6. Conditions and Keywords

Primary Disease or Condition Being Studied in the Trial, or the Focus of the Study
X-linked Hypophosphatemia
Keywords
X-linked hypophosphatemia, XLH, FGF23, KRN23

7. Study Design

Primary Purpose
Treatment
Study Phase
Phase 2
Interventional Study Model
Parallel Assignment
Masking
None (Open Label)
Allocation
Randomized
Enrollment
52 (Actual)

8. Arms, Groups, and Interventions

Arm Title
Burosumab Q2W
Arm Type
Experimental
Arm Description
Burosumab subcutaneous (SC) injections every 2 weeks (Q2W). Dose was determined by the participant's weight and prescribed dose by their study doctor.
Arm Title
Burosumab Q4W Then Q2W
Arm Type
Experimental
Arm Description
Burosumab SC injections every 4 weeks (Q4W). Dose was determined by the participant's weight and prescribed dose by their study doctor. Participants in Q4W were to switch to Q2W beginning with Week 64 dosing.
Intervention Type
Biological
Intervention Name(s)
burosumab
Other Intervention Name(s)
KRN23, Crysvita®, UX023
Intervention Description
solution for SC injection
Primary Outcome Measure Information:
Title
Change From Baseline in RSS Total Score Over Time
Description
The RSS system is a 10-point radiographic scoring method that was developed to assess the severity of nutritional rickets in the wrists and knees based on the degree of metaphyseal fraying, cupping, and the proportion of the growth plate affected. Scores are assigned for the unilateral wrist and knee X-rays deemed by the rater to be the more severe of the bilateral images. The maximum total score on the RSS is 10 points and the minimum score is 0, with a total possible score of 4 points for the wrists and 6 points for the knees. Higher scores indicate greater rickets severity.
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in Serum Phosphorus Over Time
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in Serum 1,25(OH)2D Over Time
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in TmP/GFR Over Time
Description
Data for urinary phosphorus and TRP were used in calculation TmP/GFR.
Time Frame
Baseline, Week 40, 64, 160
Secondary Outcome Measure Information:
Title
Change From Baseline in RSS Knee Scores Over Time
Description
The RSS system is a 10-point radiographic scoring method that was developed to assess the severity of nutritional rickets in the wrists and knees based on the degree of metaphyseal fraying, cupping, and the proportion of the growth plate affected. Scores are assigned for the unilateral wrist and knee X-rays deemed by the rater to be the more severe of the bilateral images. The maximum total score on the RSS is 10 points and the minimum score is 0, with a total possible score of 4 points for the wrists and 6 points for the knees. Higher scores indicate greater rickets severity.
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in RSS Wrist Scores Over Time
Description
The RSS system is a 10-point radiographic scoring method that was developed to assess the severity of nutritional rickets in the wrists and knees based on the degree of metaphyseal fraying, cupping, and the proportion of the growth plate affected. Scores are assigned for the unilateral wrist and knee X-rays deemed by the rater to be the more severe of the bilateral images. The maximum total score on the RSS is 10 points and the minimum score is 0, with a total possible score of 4 points for the wrists and 6 points for the knees. Higher scores indicate greater rickets severity.
Time Frame
Baseline, Week 40, 64, 160
Title
Radiographic Global Impression of Change (RGI-C) Global Scores Over Time
Description
Changes in the severity of rickets and bowing were assessed centrally by three independent pediatric radiologists contracted by a central imaging facility using a disease specific qualitative RGI-C scoring system. The RGI-C is a seven point ordinal scale with possible values: +3 = very much better (complete or near complete healing of rickets), +2 = much better (substantial healing of rickets), +1 = minimally better (i.e., minimal healing of rickets), 0 = unchanged, -1 = minimally worse (minimal worsening of rickets), -2 = much worse (moderate worsening of rickets), -3 = very much worse (severe worsening of rickets).
Time Frame
Baseline, Week 40, 64, 160
Title
RGI-C Knee Scores Over Time
Description
Changes in the severity of rickets and bowing were assessed centrally by three independent pediatric radiologists contracted by a central imaging facility using a disease specific qualitative RGI-C scoring system. The RGI-C is a seven point ordinal scale with possible values: +3 = very much better (complete or near complete healing of rickets), +2 = much better (substantial healing of rickets), +1 = minimally better (i.e., minimal healing of rickets), 0 = unchanged, -1 = minimally worse (minimal worsening of rickets), -2 = much worse (moderate worsening of rickets), -3 = very much worse (severe worsening of rickets).
Time Frame
Baseline, Week 40, 64, 160
Title
RGI-C Wrist Scores Over Time
Description
Changes in the severity of rickets and bowing were assessed centrally by three independent pediatric radiologists contracted by a central imaging facility using a disease specific qualitative RGI-C scoring system. The RGI-C is a seven point ordinal scale with possible values: +3 = very much better (complete or near complete healing of rickets), +2 = much better (substantial healing of rickets), +1 = minimally better (i.e., minimal healing of rickets), 0 = unchanged, -1 = minimally worse (minimal worsening of rickets), -2 = much worse (moderate worsening of rickets), -3 = very much worse (severe worsening of rickets).
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in Growth Velocity Over Time
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in Standing Height Z Score Over Time
Description
Standing height Z scores are measures of height adjusted for a child's age and sex. The Z score indicates the number of standard deviations away from a reference population (from the CDC growth charts) in the same age range and with the same sex. A Z score of 0 is equal to the mean with negative numbers indicating values lower than the mean and positive values higher. Higher Z scores indicate a better outcome.
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in Growth (Standing Height) Over Time
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in Growth (Sitting Height) Over Time
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in Growth (Arm Length) Over Time
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in Growth (Leg Length) Over Time
Time Frame
Baseline, Week 40, 64, 160
Title
6MWT Distance (Predicted Percent of Normal) Change From Baseline Over Time
Description
The total distance walked (meters) in a 6-minute period was measured. The percent of predicted values were calculated using published normative data based on age, gender, and height (Geiger et al. 2007).
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in POSNA-PODCI (Normative Score) Upper Extremity Scale Scores Over Time
Description
The POSNA-PODCI yields 4 functional assessment scores: Upper Extremity Function,Transfers and Basic Mobility, Sports and Physical Function, and Comfort/Pain. In addition, a Global Function score, which is an average of the 4 functional assessments, and a Happiness score are calculated. Raw, mean, standardized, and normative scores are calculated for each scale. Normative scores are calculated so that higher scores indicate better functioning. All scores are referenced to the general, healthy population with a normative mean score of 50 and a standard deviation of 10.
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in POSNA-PODCI (Normative Score) Transfer and Basic Mobility Scale Scores Over Time
Description
The POSNA-PODCI yields 4 functional assessment scores: Upper Extremity Function,Transfers and Basic Mobility, Sports and Physical Function, and Comfort/Pain. In addition, a Global Function score, which is an average of the 4 functional assessments, and a Happiness score are calculated. Raw, mean, standardized, and normative scores are calculated for each scale. Normative scores are calculated so that higher scores indicate better functioning. All scores are referenced to the general, healthy population with a normative mean score of 50 and a standard deviation of 10.
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in POSNA-PODCI (Normative Score) Sports/Physical Functioning Scale Scores Over Time
Description
The POSNA-PODCI yields 4 functional assessment scores: Upper Extremity Function,Transfers and Basic Mobility, Sports and Physical Function, and Comfort/Pain. In addition, a Global Function score, which is an average of the 4 functional assessments, and a Happiness score are calculated. Raw, mean, standardized, and normative scores are calculated for each scale. Normative scores are calculated so that higher scores indicate better functioning. All scores are referenced to the general, healthy population with a normative mean score of 50 and a standard deviation of 10.
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in POSNA-PODCI (Normative Score) Pain/Comfort Scale Scores Over Time
Description
The POSNA-PODCI yields 4 functional assessment scores: Upper Extremity Function,Transfers and Basic Mobility, Sports and Physical Function, and Comfort/Pain. In addition, a Global Function score, which is an average of the 4 functional assessments, and a Happiness score are calculated. Raw, mean, standardized, and normative scores are calculated for each scale. Normative scores are calculated so that higher scores indicate better functioning. All scores are referenced to the general, healthy population with a normative mean score of 50 and a standard deviation of 10.
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in POSNA-PODCI (Normative Score) Happiness Scale Scores Over Time
Description
The POSNA-PODCI yields 4 functional assessment scores: Upper Extremity Function,Transfers and Basic Mobility, Sports and Physical Function, and Comfort/Pain. In addition, a Global Function score, which is an average of the 4 functional assessments, and a Happiness score are calculated. Raw, mean, standardized, and normative scores are calculated for each scale. Normative scores are calculated so that higher scores indicate better functioning. All scores are referenced to the general, healthy population with a normative mean score of 50 and a standard deviation of 10.
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in POSNA-PODCI (Normative Score) Global Functioning Scale Scores Over Time
Description
The POSNA-PODCI yields 4 functional assessment scores: Upper Extremity Function,Transfers and Basic Mobility, Sports and Physical Function, and Comfort/Pain. In addition, a Global Function score, which is an average of the 4 functional assessments, and a Happiness score are calculated. Raw, mean, standardized, and normative scores are calculated for each scale. Normative scores are calculated so that higher scores indicate better functioning. All scores are referenced to the general, healthy population with a normative mean score of 50 and a standard deviation of 10.
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in FEP Over Time
Description
FEP is defined as 100% × (urine phosphorus × serum creatinine)/(urine creatinine × serum phosphorus), where the 2-hour urine sample was used for urine phosphorus and urine creatinine.
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in P1NP Over Time
Time Frame
Baseline, Week 40, 64
Title
Change From Baseline in CTx Over Time
Time Frame
Baseline, Week 40, 64
Title
Change From Baseline in ALP Over Time
Time Frame
Baseline, Week 40, 64, 160
Title
Change From Baseline in BALP Over Time
Time Frame
Baseline, Week 40, 64, 160
Title
Serum Pre-Dose Concentrations of Burosumab
Time Frame
Week 40, 64, 160
Title
Number of Participants With Treatment Emergent Adverse Events (TEAEs), Serious Adverse Events (SAEs) and Discontinuations Due to Adverse Events (AEs)
Description
An AE is defined as any untoward medical occurrence associated with the use of a drug in humans, whether or not considered drug related. An SAE is defined as an AE or suspected adverse reaction that at any dose results in any of the following outcomes: death; life-threatening AE; inpatient hospitalization or prolongation of existing hospitalization; persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions; a congenital anomaly/birth defect. Severity was graded as 1 (mild), 2 (moderate), 3 (severe), 4 (life-threatening), 5 (death). TEAEs are defined as AEs with onset on or after the time of initiation of study drug administration.
Time Frame
Up to 216 weeks

10. Eligibility

Sex
All
Minimum Age & Unit of Time
5 Years
Maximum Age & Unit of Time
12 Years
Accepts Healthy Volunteers
No
Eligibility Criteria
Inclusion Male or female, aged 5 - 12 years, inclusive, with open growth plates Tanner stage of 2 or less based on breast and testicular development Diagnosis of XLH supported by ONE of the following: Confirmed Phosphate regulating gene with homology to endopeptidases located on the X chromosome (PHEX) mutation in the patient or a directly related family member with appropriate X-linked inheritance Serum FGF23 level > 30 pg/mL by Kainos assay Biochemical findings associated with XLH including: Serum phosphorus ≤ 2.8 mg/dL (0.904 mmol/L)* Serum creatinine within age-adjusted normal range* Standing height < 50th percentile for age and gender using local normative data. Radiographic evidence of active bone disease including rickets in the wrists and/or knees, AND/OR femoral/tibial bowing, OR, for expansion subjects, a Rickets Severity Score (RSS) score in the knee of at least 1.5 as determined by central read. Willing to provide access to prior medical records for the collection of historical growth, biochemical and radiographic data, and disease history. Provide written or verbal assent (if possible) and written informed consent by a legally authorized representative after the nature of the study has been explained, and prior to any research-related procedures. 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 who have reached menarche must have a negative pregnancy test at Screening and undergo additional pregnancy testing during the study. If sexually active, male and female subjects must be willing to use an acceptable method of contraception for the duration of the study. Criteria to be determined based on overnight fasting (minimum 4 hours) values collected at Screening Visit 2 Exclusion Use of a pharmacologic vitamin D metabolite or analog (e.g. calcitriol, doxercalciferol, alfacalcidiol, and paricalcitol) within 14 days prior to Screening Visit 2; washout will take place during the Screening Period Use of oral phosphate within 7 days prior to Screening Visit 2; washout will take place during the Screening Period Use of calcimimetics, aluminum hydroxide antacids (e.g. Maalox® and Mylanta®), systemic corticosteroids, and thiazides within 7 days prior to Screening Visit 1 Use of growth hormone therapy within 3 months before Screening Visit 1 Use of bisphosphonates for 6 months or more in the 2 years prior to Screening Visit 1 Presence of nephrocalcinosis on renal ultrasound graded ≥ 3 based on the following scale: 0 = Normal 1 = Faint hyperechogenic rim around the medullary pyramids 2 = More intense echogenic rim with echoes faintly filling the entire pyramid 3 = Uniformly intense echoes throughout the pyramid 4 = Stone formation: solitary focus of echoes at the tip of the pyramid Planned or recommended orthopedic surgery, including staples, 8-plates or osteotomy, within the clinical trial period Hypocalcemia or hypercalcemia, defined as serum calcium levels outside the age-adjusted normal limits * Evidence of tertiary hyperparathyroidism as determined by the Investigator Use of medication to suppress parathyroid hormone (PTH) (e.g. Sensipar®, cinacalcet, calcimimetics) within 2 months prior to Screening Visit 1 Presence or history of any condition that, in the view of the investigator, places the subject at high risk of poor treatment compliance or of not completing the study Presence of a concurrent disease or condition that would interfere with study participation or affect safety Previously diagnosed with human immunodeficiency virus antibody, hepatitis B surface antigen, and/or hepatitis C antibody History of recurrent infection or predisposition to infection, or of known immunodeficiency Use of a therapeutic monoclonal antibody within 90 days prior to Screening Visit 1 or history of allergic or anaphylactic reactions to any monoclonal antibody Presence or history of any hypersensitivity to recombinant human immunoglobulin G1 (IgG1) monoclonal antibody to FGF23 (burosumab) excipients that, in the judgment of the investigator, places the subject at increased risk for adverse effects Use of any investigational product or investigational medical device within 30 days prior to screening, or requirement for any investigational agent prior to completion of all scheduled study assessments Criteria to be determined based on overnight fasting (minimum 4 hours) values collected at Screening Visit 2
Overall Study Officials:
First Name & Middle Initial & Last Name & Degree
Medical Director
Organizational Affiliation
Ultragenyx Pharmaceutical Inc
Official's Role
Study Director
Facility Information:
Facility Name
University of California San Francisco
City
San Francisco
State/Province
California
ZIP/Postal Code
94158
Country
United States
Facility Name
Yale University School of Medicine
City
New Haven
State/Province
Connecticut
ZIP/Postal Code
06520-8064
Country
United States
Facility Name
Indiana University Hospital
City
Indianapolis
State/Province
Indiana
ZIP/Postal Code
46202
Country
United States
Facility Name
Shriners Hospital for Children
City
Saint Louis
State/Province
Missouri
ZIP/Postal Code
63110
Country
United States
Facility Name
Bicetre Hospital
City
Le Kremlin- Bicetre
ZIP/Postal Code
94275
Country
France
Facility Name
University Medical Center Groningen
City
Groningen
ZIP/Postal Code
9700RB
Country
Netherlands
Facility Name
Royal Manchester Hospital
City
Manchester
State/Province
Lancashire
ZIP/Postal Code
M13 9WL
Country
United Kingdom
Facility Name
Birmingham Children's University
City
Birmingham
ZIP/Postal Code
B4 6NH
Country
United Kingdom
Facility Name
Great Ormond Street Hospital
City
London
ZIP/Postal Code
WC1N3JH
Country
United Kingdom

12. IPD Sharing Statement

Citations:
PubMed Identifier
34636899
Citation
Linglart A, Imel EA, Whyte MP, Portale AA, Hogler W, Boot AM, Padidela R, Van't Hoff W, Gottesman GS, Chen A, Skrinar A, Scott Roberts M, Carpenter TO. Sustained Efficacy and Safety of Burosumab, a Monoclonal Antibody to FGF23, in Children With X-Linked Hypophosphatemia. J Clin Endocrinol Metab. 2022 Feb 17;107(3):813-824. doi: 10.1210/clinem/dgab729.
Results Reference
derived
PubMed Identifier
32721016
Citation
Mao M, Carpenter TO, Whyte MP, Skrinar A, Chen CY, San Martin J, Rogol AD. Growth Curves for Children with X-linked Hypophosphatemia. J Clin Endocrinol Metab. 2020 Oct 1;105(10):3243-9. doi: 10.1210/clinem/dgaa495.
Results Reference
derived
PubMed Identifier
29791829
Citation
Carpenter TO, Whyte MP, Imel EA, Boot AM, Hogler W, Linglart A, Padidela R, Van't Hoff W, Mao M, Chen CY, Skrinar A, Kakkis E, San Martin J, Portale AA. Burosumab Therapy in Children with X-Linked Hypophosphatemia. N Engl J Med. 2018 May 24;378(21):1987-1998. doi: 10.1056/NEJMoa1714641.
Results Reference
derived

Learn more about this trial

Study of KRN23 (Burosumab), a Recombinant Fully Human Monoclonal Antibody Against Fibroblast Growth Factor 23 (FGF23), in Pediatric Subjects With X-linked Hypophosphatemia (XLH)

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