ESPE Abstracts (2022) 95 FC2.5

ESPE2022 Free Communications Bone, Growth Plate and Mineral Metabolism (6 abstracts)

Effects of burosumab treatment on mineral homeostasis in children and adolescents with X-linked hypophosphatemia: lessons from the German XLH Registry

Annika Ewert 1 , Mirko Rehberg 2 , Olaf Hiort 3 , Gerhard Binder 4 , Carmen Schröder 5 , Norbert Jorch 6 , Annette Richter-Unruh 7 , Clemens Freiberg 8 , Karl Peter Schlingmann 9 , Dieter Haffner 1 & Dirk Schnabel 10

1Department of Pediatric Nephrology, Hannover Medical School, Hannover, Germany; 2Department of Pediatrics, University of Cologne, Cologne, Germany; 3University Children’s Hospital Lübeck, Lübeck, Germany; 4Pediatric Endocrinology, University Children’s Hospital, Tübingen, Germany; 5Pediatric Endocrinology, University Children’s Hospital, Greifswald, Germany; 6Evangelisches Klinikum Bethel, Pediatric Endocrinology, Bielefeld, Germany; 7Pediatric Endocrinology, University Children’s Hospital, Bochum, Germany; 8Department of Pediatrics, Universitätsmedizin Göttingen, Göttingen, Germany; 9Department of Pediatrics, Pediatric Nephrology, University Children’s Hospital, Münster, Germany; 10Center for Chronically Sick Children, Pediatric Endocrinology, University Medicine, Charitè, Berlin, Germany

Introduction: Burosumab was approved for treatment of pediatric patients with X-linked hypophosphatemia (XLH). However, data on its efficacy in adolescents (age > 12 years) and in real-world settings are lacking.

Material and methods: Here we assess the effects of 12 months burosumab treatment on mineral homeostasis in 77 pediatric XLH patients (50 children, 27 adolescents) enrolled in the German XLH Registry. Age and sex related SD scores (SDS) were calculated for serum phosphate and alkaline phosphatase (ALP) levels, and renal tubular reabsorption of phosphate per glomerular filtration rate (TmP/GFR).

Results: At baseline, all patients presented with profound hypophosphatemia (-4.5 SDS), reduced TmP/GFR (-6.5 SDS), and elevated ALP (2.7 SDS, each P<0.001 vs healthy children) suggesting persisting rickets despite long-term therapy with oral phosphate and active vitamin D. Burosumab treatment resulted in rapid increases in mean serum phosphate and TmP/GFR by approx. 0.3 mmol/l amounting to -2.2 SDS and -2.5 SDS at 12 months, respectively (each P<0.001 vs baseline). This was paralleled by a continuous decrease in serum ALP (1.3 SDS, P<0.001 vs baseline). Serum phosphate, TmP/GFR, and ALP values were normalized in approximately 40%, 30% and 80% of patients, respectively. Two patients had transient hyperphosphatemia due to a dosing error. At 12 months, the median burosumab dosage amounted to 0.8 mg/kg (range 0.6-1.2). Serum phosphate levels at 12 months were comparable between children (-2.3 SDS) and adolescents (-2.1 SDS) and associated with parathyroid hormone (PTH) levels. Serum ALP z-scores were associated with PTH levels in adolescents but not in children.

Conclusions: In this real world setting 12 months burosumab treatment was effective to normalize serum ALP levels in children and adolescents with XLH suggesting healing of rickets despite persisting mild hypophosphatemia in about half of patients. Elevated PTH levels are a risk factor for failure to normalize mineral homeostasis.

Volume 95

60th Annual ESPE (ESPE 2022)

Rome, Italy
15 Sep 2022 - 17 Sep 2022

European Society for Paediatric Endocrinology 

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