Bone Abstracts

Background: Denosumab (DMAB) is used in adults for the treatment of osteoporosis, giant cell tumour of bone, and cancer metastases. There are little data on paediatric use with clinical decision making reliant on adult data and clinical experience.

Presenting problem: We have treated 33 children with DMAB: Perthes disease (n=9), avascular necrosis (n=17), osteoporosis (n=1), aneurysmal bone cyst (n=4) and giant cell tumour (n=2). Treatment protocols have varied between conditions and over time with growing clinical experience. There have been five cases of hypercalcaemia, and one case of osteonecrosis of the jaw.

Patient 1: 11-year-old female with Perthes disease (PD) treated with DMAB (1 mg/kg) 12 weekly, incidental finding of serum calcium 3.29 mmol/l before 4th dose of DMAB.

Patient 2: 16-year-old male with avascular necrosis treated with DMAB (1 mg/kg) 12 weekly for 12 months followed by oral risedronate. Nausea and vomiting 3 weeks after stopping DMAB. Serum calcium 3.70 mmol/l.

Patient 3: 10-year-old male with PD treated with 8 weekly DMAB (1 mg/kg) for 12 months followed by two doses of zoledronic acid (ZA). 12 weeks post DMAB, 4 weeks after first ZA, incidental finding of serum calcium 3.61 mmol/l.

Patient 4: 15-year-old male with giant cell tumour of maxilla, treated with 4 weekly DMAB (1 mg/kg) for 18 months. 8 weeks post DMAB, 4 weeks after first ZA, incidental finding of serum calcium 3.87 mmol/l.

Patient 5: 14-year-old male with an aneurysmal bone cyst of 3rd cervical vertebra. Treated with 4 weekly DMAB (60 mg) for 18 months, followed by two doses of ZA. Spontaneous osteonecrosis of the mandible after 18 months of DMAB therapy. Symptomatic hypercalcaemia 3 months post final ZA (6 months post final DMAB). Serum calcium 3.60 mmol/l.

Clinical management: Hypercalcaemia treated with intravenous rehydration and ZA without sequalae. Osteonecrosis of the jaw healing spontaneously.

Discussion: DMAB is a potent inhibitor of bone resorption, leading to excessive metaphyseal bone retention. Its potent action has the potential to improve outcome in paediatric bone disorders, but the optimal regimen to prevent complications is still to be determined. Our DMAB protocol continues to be revised to minimize hypercalcaemia risk.

Disclosure: The authors declared no competing interests.