Study of KRN23 (Burosumab), a Recombinant Fully Human Monoclonal Antibody Against Fibroblast Growth Factor 23 (FGF23), in Pediatric Subjects With X-linked Hypophosphatemia (XLH)
CompletedPhase 2Results postedLast updated 6 May 2024
What this trial tests
Phase 2 trial testing burosumab in X-linked Hypophosphatemia in 52 participants. Completed in 30 October 2018.
Adults 5 to 12, any sex, with X-linked Hypophosphatemia. Patients with the condition only — healthy volunteers not accepted.
Results — posted to ClinicalTrials.gov
Per-arm endpoint measurements with 95% confidence intervals where reported. Source: trial results section.
Change From Baseline in RSS Total Score Over TimePrimary· Baseline, Week 40, 64, 160
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 to Week 40
Group
Value
95% CI
Burosumab Q2W
-1.06
± 0.100
Burosumab Q4W Then Q2W
-0.73
± 0.100
Change to Week 64
Group
Value
95% CI
Burosumab Q2W
-1.00
± 0.110
Burosumab Q4W Then Q2W
-0.84
± 0.098
Change to Week 160
Group
Value
95% CI
Burosumab Q2W
-0.98
± 0.129
Burosumab Q4W Then Q2W
-0.83
± 0.122
Change From Baseline in Serum Phosphorus Over TimePrimary· Baseline, Week 40, 64, 160
Change at Week 40
Group
Value
95% CI
Burosumab Q2W
0.92
± 0.480
Burosumab Q4W Then Q2W
0.57
± 0.265
Change at Week 64
Group
Value
95% CI
Burosumab Q2W
0.99
± 0.502
Burosumab Q4W Then Q2W
0.69
± 0.370
Change at Week 160
Group
Value
95% CI
Burosumab Q2W
0.97
± 0.338
Burosumab Q4W Then Q2W
1.08
± 0.377
Change From Baseline in Serum 1,25(OH)2D Over TimePrimary· Baseline, Week 40, 64, 160
Change at Week 40
Group
Value
95% CI
Burosumab Q2W
28.27
± 29.312
Burosumab Q4W Then Q2W
17.62
± 18.802
Change at Week 64
Group
Value
95% CI
Burosumab Q2W
23.58
± 24.502
Burosumab Q4W Then Q2W
11.50
± 16.522
Change at Week 160
Group
Value
95% CI
Burosumab Q2W
17.03
± 24.889
Burosumab Q4W Then Q2W
19.64
± 22.857
Change From Baseline in TmP/GFR Over TimePrimary· Baseline, Week 40, 64, 160
Data for urinary phosphorus and TRP were used in calculation TmP/GFR.
Change at Week 40
Group
Value
95% CI
Burosumab Q2W
1.14
± 0.686
Burosumab Q4W Then Q2W
0.80
± 0.506
Change at Week 64
Group
Value
95% CI
Burosumab Q2W
1.11
± 0.626
Burosumab Q4W Then Q2W
0.90
± 0.632
Change at Week 160
Group
Value
95% CI
Burosumab Q2W
1.24
± 0.548
Burosumab Q4W Then Q2W
1.45
± 0.653
Change From Baseline in RSS Knee Scores Over TimeSecondary· Baseline, Week 40, 64, 160
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 at Week 40
Group
Value
95% CI
Burosumab Q2W
-0.62
± 0.08
Burosumab Q4W Then Q2W
-0.55
± 0.08
Change at Week 64
Group
Value
95% CI
Burosumab Q2W
-0.70
± 0.087
Burosumab Q4W Then Q2W
-0.61
± 0.072
Change at Week 160
Group
Value
95% CI
Burosumab Q2W
-0.70
± 0.105
Burosumab Q4W Then Q2W
-0.62
± 0.093
Change From Baseline in RSS Wrist Scores Over TimeSecondary· Baseline, Week 40, 64, 160
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 at Week 40
Group
Value
95% CI
Burosumab Q2W
-0.44
± 0.05
Burosumab Q4W Then Q2W
-0.18
± 0.05
Change at Week 64
Group
Value
95% CI
Burosumab Q2W
-0.30
± 0.057
Burosumab Q4W Then Q2W
-0.24
± 0.051
Change at Week 160
Group
Value
95% CI
Burosumab Q2W
-0.27
± 0.065
Burosumab Q4W Then Q2W
-0.20
± 0.047
Radiographic Global Impression of Change (RGI-C) Global Scores Over TimeSecondary· Baseline, Week 40, 64, 160
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 (sever
Change at Week 40
Group
Value
95% CI
Burosumab Q2W
1.67
± 0.12
Burosumab Q4W Then Q2W
1.46
± 0.12
Change at Week 64
Group
Value
95% CI
Burosumab Q2W
1.56
± 0.112
Burosumab Q4W Then Q2W
1.58
± 0.112
Change at Week 160
Group
Value
95% CI
Burosumab Q2W
1.92
± 0.111
Burosumab Q4W Then Q2W
1.86
± 0.119
RGI-C Knee Scores Over TimeSecondary· Baseline, Week 40, 64, 160
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 (sever
Change at Week 40
Group
Value
95% CI
Burosumab Q2W
1.60
± 0.13
Burosumab Q4W Then Q2W
1.34
± 0.13
Change at Week 64
Group
Value
95% CI
Burosumab Q2W
1.57
± 0.104
Burosumab Q4W Then Q2W
1.53
± 0.099
Change at Week 160
Group
Value
95% CI
Burosumab Q2W
2.01
± 0.106
Burosumab Q4W Then Q2W
1.85
± 0.118
RGI-C Wrist Scores Over TimeSecondary· Baseline, Week 40, 64, 160
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 (sever
Change at Week 40
Group
Value
95% CI
Burosumab Q2W
1.64
± 0.14
Burosumab Q4W Then Q2W
1.45
± 0.14
Change at Week 64
Group
Value
95% CI
Burosumab Q2W
1.65
± 0.153
Burosumab Q4W Then Q2W
1.55
± 0.124
Change at Week 160
Group
Value
95% CI
Burosumab Q2W
1.78
± 0.133
Burosumab Q4W Then Q2W
1.83
± 0.132
Change From Baseline in Growth Velocity Over TimeSecondary· Baseline, Week 40, 64, 160
Week 0 to Week 40: Change from Baseline
Group
Value
95% CI
Burosumab Q2W
0.96
± 1.677
Burosumab Q4W Then Q2W
0.39
± 2.559
Week 0 to Week 64: Change from Baseline
Group
Value
95% CI
Burosumab Q2W
0.73
± 1.399
Burosumab Q4W Then Q2W
0.37
± 2.164
Week 64 to Week 112: Change from Baseline
Group
Value
95% CI
Burosumab Q2W
0.29
± 2.284
Burosumab Q4W Then Q2W
0.09
± 2.523
Week 112 to Week 160: Change from Baseline
Group
Value
95% CI
Burosumab Q2W
0.67
± 2.318
Burosumab Q4W Then Q2W
0.54
± 3.158
Change From Baseline in Standing Height Z Score Over TimeSecondary· Baseline, Week 40, 64, 160
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 to Week 40
Group
Value
95% CI
Burosumab Q2W
0.17
± 0.042
Burosumab Q4W Then Q2W
0.10
± 0.051
Change to Week 64
Group
Value
95% CI
Burosumab Q2W
0.19
± 0.051
Burosumab Q4W Then Q2W
0.12
± 0.061
Change to Week 160
Group
Value
95% CI
Burosumab Q2W
0.35
± 0.084
Burosumab Q4W Then Q2W
0.19
± 0.089
Change From Baseline in Growth (Standing Height) Over TimeSecondary· Baseline, Week 40, 64, 160
Change at Week 40
Group
Value
95% CI
Burosumab Q2W
5.03
± 1.232
Burosumab Q4W Then Q2W
4.49
± 1.455
Change at Week 64
Group
Value
95% CI
Burosumab Q2W
7.48
± 1.934
Burosumab Q4W Then Q2W
6.98
± 1.594
Change at Week 160
Group
Value
95% CI
Burosumab Q2W
18.38
± 2.958
Burosumab Q4W Then Q2W
17.22
± 2.653
Adverse events — posted to ClinicalTrials.gov
Time frame: Up to 216 weeks.
Reporting threshold: 5%.
Adverse-event reports describe events observed during the trial — not all are caused by the drug.
Burosumab Q2W
Serious: 0/26 (0%)
Deaths: 0/26
Burosumab Q4W Then Q2W
Serious: 1/26 (4%)
Deaths: 0/26
Serious adverse events (3 terms)
Reaction
System
Burosumab Q2W
Burosumab Q4W Then Q2W
Pyrexia
General disorders
—
—
Myalgia
Musculoskeletal and connective tissue disorders
—
—
Headache
Nervous system disorders
—
—
Other adverse events (107 terms — click to expand)
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
Publications & conference data
8 peer-reviewed publications reference this trial (live from Europe PMC):
NCT02915705 — Efficacy and Safety of Burosumab Versus Oral Phosphate and Active Vitamin D Treatment in Pediatric Patients With XLH
· Phase 3
· completed
NCT02537431 — Open Label Study of KRN23 on Osteomalacia in Adults With X-linked Hypophosphatemia (XLH)
· Phase 3
· completed
NCT02526160 — Study of KRN23 in Adults With X-linked Hypophosphatemia (XLH)
· Phase 3
· completed
Other recruiting trials for X-linked Hypophosphatemia
Currently open trials in the same condition.
NCT06525636 — A First-in-human Study of KK8123 in Adults With X-linked Hypophosphatemia
· Phase 1, PHASE2
· recruiting
Other Kyowa Kirin, Inc. trials
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NCT03703102 — Study of an Anti-OX40 Monoclonal Antibody (KHK4083) in Subjects With Moderate to Severe Atopic Dermatitis
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Publications: Europe PMC API search by NCT ID, retrieved 10 June 2026
Drug + disease cross-links: matched in real time against Drug Landscape's normalised drug + company + condition tables
Sponsor: as reported to ClinicalTrials.gov by Kyowa Kirin, Inc.
Last refreshed: 6 May 2024
Drug Landscape aggregates and links these public records for informational use only. Always verify against the primary source before clinical or regulatory decisions. Canonical URL: https://druglandscape.com/trial/NCT02163577.