Efficacy of denosumab in two cases with multiple-system atrophy and osteoporosis

Off-label uses of denosumab in metabolic bone diseases

Denosumab (Dmab), a monoclonal antibody against the receptor activator of nuclear factor-κB (RANK) ligand (RANKL) which substantially suppresses osteoclast activity, has been approved for the treatment of common metabolic bone diseases, including postmenopausal osteoporosis, male osteoporosis, and glucocorticoid-induced osteoporosis, in which the pathway of the RANK/RANKL/osteoprotegerin is dysregulated. However, the imbalance of RANKL/RANK/osteoprotegerin is also implicated in the pathogenesis of several other rare metabolic bone diseases, including Juvenile Paget disease, fibrous dysplasia, Hajdu Cheney syndrome and Langerhans cell histiocytosis, thus rendering Dmab a potential treatment option for these diseases. Dmab has been also administered off-label in selected patients (e.g., with Paget's disease, osteogenesis imperfecta, aneurysmal bone cysts) due to contraindications or unresponsiveness to standard treatment, such as bisphosphonates. Moreover, Dmab was administered to improve hypercalcemia induced by various diseases, including primary hyperparathyroidism, tuberculosis and immobilization. The aim of this review is to summarize existing evidence on off-label uses of Dmab in metabolic bone diseases and provide opinion for or against its use, which should be always considered on an individual basis.

Efficacy and Safety of Denosumab Therapy for Osteogenesis Imperfecta Patients with Osteoporosis-Case Series

Osteogenesis imperfecta (OI) is a connective tissue disorder that is characterized by low bone density leading to recurrent fractures. The efficacy of the anti-resorption drug denosumab for OI with osteoporosis is still largely unknown. We herein describe the clinical outcomes of eight osteoporotic cases of OI to examine the effects and safety of denosumab. This retrospective, consecutive case series included eight patients respectively aged 42, 40, 14, 22, 3, 51, 37, and 9 years. We measured the bone mineral density (BMD) of the lumbar 1⁻4 spine (L-BMD) and bilateral hips (H-BMD), bone-specific alkaline phosphatase, urinary type I collagen amino-terminal telopeptide, and tartrate-resistant acid phosphatase 5b before and during denosumab therapy. Despite multiple pretreatment fractures in the cohort, no fractures or severe side effects, such as hypocalcemia, were observed during the observational period apart from a fracture in a young pediatric girl. Both L-BMD and H-BMD were increased by denosumab in seven of eight cases. Bone turnover markers were inhibited in most cases by denosumab therapy. Denosumab treatment could generally raise BMD without any adverse effects. The agent therefore represents a good therapeutic option for OI with osteoporosis.