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.