Endocrine Abstracts

JOINT524

Objectives: To evaluate the effectiveness and safety of treatment with burosumab in pediatric X-linked hypophosphatemia (XLH) patients.

Methods: In this retrospective case study, six pediatric XLH patients treated with burosumab admitted to Beijing Children’s Hospital, Capital Medical University from July 2022 to December 2024 were selected as the study objects. We colleceted clinical characteristics, biochemical indicators, imaging data of patients, treatment and follow-up (follow-up every three months until December 2024), and analyzed the clinical outcomes and adverse drug reactions after treatment.

Results: Among the 6 patients, there were 3 males and 3 female, aged 1.58 - 11.67 years. 4 patients had previously received treatment with phosphate supplements and active vitamins, but their wadding gait and lower limb deformities did not improve significantly, neither did their imaging changes of active richets. The initial dose of burosumab in 6 patients was 0.68 - 1.03 mg/kg, administered subcutaneously every two weeks, with a treatment period of 0.75 - 2.25 years. After treatment, gait abnormalities were improved in all 6 children, and the Knee width was reduced from 3.6 ± 2.5cm to 1.3 ± 1.5cm. The fasting serum phosphorus and TmP/GFR of 6 patients before treatment were 0.87±0.10 mmol/l and 0.81±0.11 mmol/l, respectively. After 3months of treatment with burosumab, both the fasting serum phosphorus and TmP/GFR levels increased (serum phosphorus 1.07±0.11 mmol/l, TmP/GFR 1.02±0.10 mmol/l). During the treatment, only 1patient reached the normal values of fasting serum phosphorus, while 3 patients had normal TmP/GFR). At the last follow-up, the serum phosphorus and TmP/GFR were 1.00 ± 0.14mmol/l and 0.90 ± 0.11mmol/l, respectively. After treatment, the alkaline phosphatase levels of all patients gradually decreased, from 574.83 ± 96.12U/l to 364.33 ± 107.69U/l. At the last visit, 4 patients returned normal level of ALP. At the last follow-up, only one child had elevated parathyroid hormone levels. The severity score of rickets decreased from 1.38 ± 1.47 points to 1.33 ± 1.21 points. One patients showed nephrocalcinosis, while the other patients did not experience any adverse drug reactions such as nephrocalcinosis, local skin injection reaction, hyperphosphatemia, or vitamin D deficiency were observed.

Conclusion: Treatment with brosuzumab can improve clinical symptoms in children with XLH, and no adverse drug reactions have been observed.