Adults 1 to 4, 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 at Week 40 in Serum PhosphorusPrimary· Baseline, Week 40
The Generalized Estimation Equation (GEE) model includes the change from baseline as the dependent variable, time as the categorical variable and adjusted for baseline measurement, with exchangeable covariance structure.
Group
Value
95% CI
Burosumab Q2W
0.96
± 0.117
Number of Participants With Adverse Events (AEs), Treatment Emergent AEs (TEAEs), Serious TEAEs, and TEAEs Leading to DiscontinuationPrimary· From first dose of study drug through the end of the study (Week 160). Maximum duration of exposure to study drug was 160 weeks.
An AE was defined as any untoward medical occurrence associated with the use of a drug, whether or not considered drug related. A serious AE was defined as an AE that at any dose, in the view of either the Investigator or Sponsor, results in any of the following outcomes: death, a life-threatening AE, inpatient hospitalization or prolongation of existing hospitalization, persistent or significant incapacity or disability, a congenital anomaly/birth defect, or other important medical events (according to the investigator). An AE was considered a TEAE if it occurred on or after the first dose an
Adverse Event Starting during Screening Period
Group
Value
95% CI
Burosumab Q2W
5
TEAEs
Group
Value
95% CI
Burosumab Q2W
13
Related TEAEs
Group
Value
95% CI
Burosumab Q2W
5
Serious TEAEs
Group
Value
95% CI
Burosumab Q2W
1
Serious Related TEAEs
Group
Value
95% CI
Burosumab Q2W
0
Grade 3 or 4 TEAE
Group
Value
95% CI
Burosumab Q2W
2
TEAE Leading to Study Discontinuation
Group
Value
95% CI
Burosumab Q2W
0
TEAE Leading to Treatment Discontinuation
Group
Value
95% CI
Burosumab Q2W
0
Radiographic Global Impression of Change (RGI-C) Score at Week 40Secondary· Week 40
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
Group
Value
95% CI
Burosumab Q2W
2.21
± 0.071
RGI-C Score at Week 64Secondary· Week 64
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
Group
Value
95% CI
Burosumab Q2W
2.23
± 0.111
Change From Baseline in Rickets at Week 40 as Assessed by the RSS Total ScoreSecondary· Baseline, Week 40
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.The ANCOVA model
Group
Value
95% CI
Burosumab Q2W
-1.75
± 0.116
Change From Baseline in Rickets at Week 64 as Assessed by the RSS Total ScoreSecondary· Baseline, Week 64
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, with a total possible score of 4 points for the wrists and 6 points for the knees. Higher scores indicate greater rickets severity. The GEE model includes the change from base
Group
Value
95% CI
Burosumab Q2W
-2.02
± 0.115
RGI-C Lower Limb Deformity Score at Week 40Secondary· Week 40
Changes in the severity of lower extremity skeletal abnormalities 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 = ve
Group
Value
95% CI
Burosumab Q2W
1.21
± 0.155
RGI-C Lower Limb Deformity Score at Week 64Secondary· Week 64
Changes in the severity of lower extremity skeletal abnormalities 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 = ve
Group
Value
95% CI
Burosumab Q2W
1.51
± 0.123
Change From Baseline Over Time in Recumbent Length/Standing HeightSecondary· Baseline, Weeks 12, 24, 40, 64, 88, 112, 136, 160
Week 12
Group
Value
95% CI
Burosumab Q2W
1.44
± 2.009
Week 24
Group
Value
95% CI
Burosumab Q2W
2.52
± 1.518
Week 40
Group
Value
95% CI
Burosumab Q2W
4.29
± 2.451
Week 64
Group
Value
95% CI
Burosumab Q2W
7.22
± 3.157
Week 88
Group
Value
95% CI
Burosumab Q2W
10.30
± 3.400
Week 112
Group
Value
95% CI
Burosumab Q2W
13.25
± 3.724
Week 136
Group
Value
95% CI
Burosumab Q2W
15.41
± 3.699
Week 160
Group
Value
95% CI
Burosumab Q2W
18.96
± 4.206
Change From Baseline Over Time in Recumbent Length/Standing Height as Assessed by Height-for-Age Z-ScoresSecondary· Baseline, Weeks 12, 24, 40, 64, 88, 112, 136, 160
Recumbent length/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.
Week 12
Group
Value
95% CI
Burosumab Q2W
-0.082
± 0.4964
Week 24
Group
Value
95% CI
Burosumab Q2W
-0.208
± 0.4540
Week 40
Group
Value
95% CI
Burosumab Q2W
-0.276
± 0.6647
Week 64
Group
Value
95% CI
Burosumab Q2W
-0.264
± 0.8755
Week 88
Group
Value
95% CI
Burosumab Q2W
-0.212
± 0.9115
Week 112
Group
Value
95% CI
Burosumab Q2W
-0.174
± 0.9273
Week 136
Group
Value
95% CI
Burosumab Q2W
-0.321
± 0.9123
Week 160
Group
Value
95% CI
Burosumab Q2W
-0.172
± 0.9048
Change From Baseline Over Time in Recumbent Length/Standing Height as Assessed by PercentilesSecondary· Baseline, Weeks 12, 24, 40, 64, 88, 112, 136, 160
Week 12
Group
Value
95% CI
Burosumab Q2W
-0.006
± 11.6149
Week 24
Group
Value
95% CI
Burosumab Q2W
-4.940
± 13.1323
Week 40
Group
Value
95% CI
Burosumab Q2W
-5.283
± 20.1675
Week 64
Group
Value
95% CI
Burosumab Q2W
-4.980
± 23.4412
Week 88
Group
Value
95% CI
Burosumab Q2W
-4.155
± 23.9126
Week 112
Group
Value
95% CI
Burosumab Q2W
-3.000
± 24.7569
Week 136
Group
Value
95% CI
Burosumab Q2W
-7.026
± 24.8583
Week 160
Group
Value
95% CI
Burosumab Q2W
-3.628
± 25.5113
Change From Baseline Over Time in Serum Alkaline Phosphatase (ALP)Secondary· Baseline, Weeks 4, 12, 20, 40, 48, 56, 64, 76, 88, 100, 112, 124, 136, 148, 160
The GEE model includes the change from baseline as the dependent variable, time as the categorical variable and adjusted for baseline measurement, with exchangeable covariance structure.
Week 4
Group
Value
95% CI
Burosumab Q2W
-82.91
± 23.348
Week 12
Group
Value
95% CI
Burosumab Q2W
-83.84
± 45.263
Week 20
Group
Value
95% CI
Burosumab Q2W
-161.38
± 12.924
Week 40
Group
Value
95% CI
Burosumab Q2W
-214.99
± 13.628
Week 48
Group
Value
95% CI
Burosumab Q2W
-226.58
± 11.491
Week 56
Group
Value
95% CI
Burosumab Q2W
-216.45
± 16.165
Week 64
Group
Value
95% CI
Burosumab Q2W
-216.76
± 12.705
Week 76
Group
Value
95% CI
Burosumab Q2W
-231.22
± 15.964
Adverse events — posted to ClinicalTrials.gov
Time frame: From first dose of study drug through the end of the study (at Week 160). Maximum duration of exposure to study drug was 160 weeks..
Reporting threshold: 5%.
Adverse-event reports describe events observed during the trial — not all are caused by the drug.
Burosumab Q2W
Serious: 1/13 (8%)
Deaths: 0/13
Serious adverse events (1 terms)
Reaction
System
Burosumab Q2W
Tooth Abscess
Infections and infestations
—
Other adverse events (131 terms — click to expand)
The primary objectives of the study are to:
* Establish the safety profile of KRN23 for the treatment of XLH in children between 1 and 4 years old
* Determine the PD effects of KRN23 treatment on serum phosphorus and other PD markers that reflect the status of phosphate homeostasis in children between 1 and 4 years old with XLH
Publications & conference data
8 peer-reviewed publications reference this trial (live from Europe PMC):
NCT05509595 — Burosumab for Fibroblast Growth Factor-23 Mediated Hypophosphatemia in Fibrous Dysplasia
· Phase 2
· completed
NCT05181839 — A Study to Describe the Lived Experience of XLH for Adolescents at End of Skeletal Growth
· completed
NCT04695860 — Anti-FGF23 (Burosumab) in Adult Patients With XLH
· Phase 3
· completed
NCT04188964 — Study to Assess the Safety, Tolerability, Pharmacokinetics and Efficacy of Burosumab in Patients Less Than 1 Year of Age
· Phase 1, PHASE2
· completed
NCT03920072 — Study of the Anti-FGF23 Antibody, Burosumab, in Adults With XLH
· Phase 3
· completed
Other recruiting trials for X-Linked Hypophosphatemia
Currently open trials in the same condition.
NCT03745521 — Study of Longitudinal Observation for Patient With X-linked Hypophosphatemic Rickets/Osteomalacia in Collaboration With
· active not recruiting
NCT03193476 — Registry for Patients With X-Linked Hypophosphatemia
· recruiting
Other Kyowa Kirin, Inc. trials
Trials by the same sponsor.
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· Phase 1
· completed
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· Phase 1
· completed
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· Phase 1
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NCT04147910 — Phase 1, Open-label Study of the Absorption, Metabolism, and Excretion of [14C]-KW-6356
· Phase 1
· completed
NCT03703102 — Study of an Anti-OX40 Monoclonal Antibody (KHK4083) in Subjects With Moderate to Severe Atopic Dermatitis
· Phase 2
· completed
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/NCT02750618.