denosumab treatment of severe disuse osteoporosis in a boy with spinal muscular atrophy

Denosumab is a fully human recombinant monoclonal antibody to the receptor activator of nuclear factor-κb ligand. denosumab is used in the treatment of postmenopausal osteoporosis and cancer-related bone disorders. there are only very scarce data on denosumab treatment in children. 14-year-old boy with spinal muscular atrophy (sma) and severe disuse osteoporosis (spinal bone mineral density l1-l4 bmd-6.2sd z-score) and two prevalent fragility fractures was treated with denosumab. he received 60 mg subcutaneous injection at the baseline and seven months later. six months after the initial injection there was a 19% increase in l1-l4 bmd. the injections were well tolerated without any adverse reactions. calcemia remained stable (2.3-2.4 mmol/l). he was scheduled for the third denosumab injection six months later. prior to this date, he acquired pneumonia and died due to respiratory failure, which is a frequent cause of death in patients with sma. there was no relation to the denosumab treatment. in conclusion, one dose of denosumab significantly increased bmd in a child with severe osteoporosis.