A. Rebeca Hernandez-Hernandez1, Evert van Velsen2, A. Bosman3, N. M. Appelman?Dijkstra4, A. M. Boot5, M. H. de Borst6, A. C. van de Ven7, R. T. de Jongh8, A. Bökenkamp9, J. P. van den Bergh10, B. C. J. van der Eerden11, M. Carola Zillikens12
(1) Erasmus MC Bone Center, Erasmus University Medical Center/Internal Medicine, Rotterdam , Netherlands . (2) Erasmus MC Bone Center, Erasmus University Medical Center/Internal Medicine, Rotterdam , Netherlands . (3) Erasmus MC,Erasmus University Medical Center/Internal Medicine, Rotterdam , Netherlands . (4) Leiden University Medical Center/Internal Medicine,, Leiden, Netherlands . (5) University Medical Center Groningen, University of Groningen/Pediatrics, Groningen, Netherlands . (6) University Medical Center Groningen, University of Groningen/Internal Medicine, Groningen, Netherlands . (7) Radboud University MedicalCenter/Internal Medicine, Nijmegen, Netherlands. (8) Amsterdam University Medical Center, Vrije Universiteit/Internal Medicine, Amsterdam, Netherlands. (9) Amsterdam University Medical Center, Emma Children’s Hospital/Pediatric Nephrology, Amsterdam, Netherlands . (10) VieCuri Medical Center/Internal Medicine, Venlo, Netherlands . (11) Erasmus MC Bone Center, Erasmus University Medical Center/Internal Medicine, Rotterdam , Netherlands . (12) Erasmus MC Bone Center, Erasmus University MedicalCenter/Internal Medicine, Rotterdam , Netherlands .
X-linked hypophosphatemia (XLH) caused by pathogenic variants in the PHEX gene, leads to increased circulating fibroblast growth factor 23 (FGF23) levels, resulting in renal phosphate wasting and decreased intestinal phosphate absorption. Classical presentation involves symptoms related to rickets (in children) and osteomalacia (in adults), with progressive bowing of lower limbs, disproportionate short stature, bone pains, muscle weakness and impairment of physical function. Conventional treatment for XLH consists of supplementing phosphate and active vitamin D analogues. Recently, an anti-FGF23 antibody (burosumab) has become available; first for children and later also for adults. Clinical trials showed that burosumab is able to normalize serum phosphate levels and quality of life (QoL), but real-world data is lacking. In the Netherlands, a treatment indication committee evaluates indication for Burosumab treatment in adults, initially for 18 months with option to restart. In the present study we focused on the clinical effects of burosumab treatment in adult Dutch XLH patients.
We included patients from the Dutch registry for chronic hypophosphatemia named ORPHOS-NED. We assessed the effects of burosumab on serum phosphate levels, QoL questionnaires, and physical function.
A total of 14 (9 females; mean age 48 years) patients were included. During treatment with burosumab, serum phosphate levels normalized in the majority of patients after 6 and 12 months. Additionally, an improvement in both QoL and physical function was observed at these moments in time.
In conclusion:
This real-world Dutch study showed that burosumab is an effective treatment option for adult XLH patients meeting indication committee criteria