Effects of Burosumab Treatment on Mineral Metabolism in Children and Adolescents With X-linked Hypophosphatemia.
J Clin Endocrinol Metab 2023;
108:e998-e1006. [PMID:
37097907 DOI:
10.1210/clinem/dgad223]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 04/05/2023] [Accepted: 04/13/2023] [Indexed: 04/26/2023]
Abstract
CONTEXT
Burosumab has been approved for the treatment of children and adults with X-linked hypophosphatemia (XLH). Real-world data and evidence for its efficacy in adolescents are lacking.
OBJECTIVE
To assess the effects of 12 months of burosumab treatment on mineral metabolism in children (aged <12 years) and adolescents (aged 12-18 years) with XLH.
DESIGN
Prospective national registry.
SETTING
Hospital clinics.
PATIENTS
A total of 93 patients with XLH (65 children, 28 adolescents).
MAIN OUTCOME MEASURES
Z scores for serum phosphate, alkaline phosphatase (ALP), and renal tubular reabsorption of phosphate per glomerular filtration rate (TmP/GFR) at 12 months.
RESULTS
At baseline, patients showed hypophosphatemia (-4.4 SD), reduced TmP/GFR (-6.5 SD), and elevated ALP (2.7 SD, each P < .001 vs healthy children) irrespective of age, suggesting active rickets despite prior therapy with oral phosphate and active vitamin D in 88% of patients. Burosumab treatment resulted in comparable increases in serum phosphate and TmP/GFR in children and adolescents with XLH and a steady decline in serum ALP (each P < .001 vs baseline). At 12 months, serum phosphate, TmP/GFR, and ALP levels were within the age-related normal range in approximately 42%, 27%, and 80% of patients in both groups, respectively, with a lower, weight-based final burosumab dose in adolescents compared with children (0.72 vs 1.06 mg/kg, P < .01).
CONCLUSIONS
In this real-world setting, 12 months of burosumab treatment was equally effective in normalizing serum ALP in adolescents and children, despite persistent mild hypophosphatemia in one-half of patients, suggesting that complete normalization of serum phosphate is not mandatory for substantial improvement of rickets in these patients. Adolescents appear to require lower weight-based burosumab dosage than children.
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