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Changes of the lower limb deformity in children with FGF23-related hypophosphatemic rickets treated with Burosumab: a
Kenta Sawamura1,2, Takashi Hamajima3, Masako Izawa3
1Department of Orthopaedic Surgery, Aichi Children's Health and Medical Center, Obu.
Insights
Burosumab treatment improved lower limb deformities in children with Fibroblast Growth Factor 23 (FGF23)-related hypophosphatemic rickets (HPR). Younger patients with severe deformities showed the most significant improvement after 12 months.
Area of Science:
- Pediatric Endocrinology
- Skeletal Dysplasias
- Medical Imaging
Background:
- Fibroblast Growth Factor 23 (FGF23)-related hypophosphatemic rickets (HPR) presents with excess FGF23, low serum phosphorus, and skeletal deformities, particularly in children's lower limbs.
- Current management strategies for HPR aim to address the underlying biochemical abnormalities and their skeletal consequences.
Purpose of the Study:
- To prospectively evaluate the impact of burosumab, an FGF23-neutralizing antibody, on lower limb deformities in pediatric patients with HPR.
- To assess changes in radiological parameters of lower limb alignment over a 12-month treatment period with burosumab.
Main Methods:
- Prospective study including 5 pediatric patients (15 years or younger) with diagnosed HPR receiving burosumab.
- Radiological assessment of lower limb alignment using anteroposterior and lateral radiographs at baseline and 3, 6, 9, and 12 months post-treatment.
- Classification of outcome as 'improvement', 'no change', or 'deterioration' after 12 months.
Main Results:
- Overall, 6 out of 10 limbs showed improvement, and 4 showed no change; no limbs demonstrated deterioration after 12 months of burosumab treatment.
- Significant improvement in lower limb malalignment was observed in younger patients with initially severe deformities.
- Older patients with milder deformities exhibited less pronounced improvement.
Conclusions:
- Burosumab therapy demonstrates a favorable effect on lower limb malalignment in children with FGF23-related HPR.
- Treatment efficacy appears to be influenced by patient age and the severity of initial lower limb deformities.
Abstract:
Fibroblast growth factor 23 (FGF23)-related hypophosphatemic rickets (HPR) are characterized by excess circulating FGF23 and low concentrations of serum phosphorus, leading to skeletal manifestations of rickets, including lower limb deformities in children. The objective of this study was to prospectively evaluate whether treatment with burosumab, a monoclonal antibody neutralizing FGF23, changes lower limb deformities in HPR. Patients who were 15 years of age or younger with a documented clinical diagnosis of HPR, receiving burosumab treatment, and had a minimum follow-up period of one year were included in the study. Various radiological parameters were measured from anteroposterior and lateral radiographs of the bilateral lower limbs taken before administration of burosumab and at 3, 6, 9, and 12 months after treatment for evaluation of lower limb alignment. Outcome was classified as 'improvement', 'no change', or 'deterioration' after 12 months treatment. Five patients (10 limbs), with a mean age of 7.2 years were included in this study. The outcome was 'improvement' in six limbs and 'no change' in four limbs. There were no limbs of 'deterioration'. The improvement in deformities after treatment was more significant in younger patients who originally showed severe lower limb deformities. Older patients with milder deformities, on the other hand, showed less improvement. Burosumab therapy favorably changed lower-limb malalignment in children with FGF23-related HPR.
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