Efficacy of romosozumab for osteoporosis in a patient with osteogenesis imperfecta: A case report

The efficacy of romosozumab for severe osteoporosis is uncertain in patients with osteogenesis imperfecta (OI). This report introduced a severe osteoporotic case of OI to examine the effect of romosozumab on bone fragility. A 64-year-old man with OI was referred to our department for finding out the cause of his repeated fractures. He was medicated with alendronate for only 1 year, 8 years ago, but it did not prevent repeated fractures, and thus, he had not received any treatments for osteoporosis since then. However, recently, the frequency of fractures had increased. At presentation, his lumbar and bilateral total hip bone mineral density (BMD) values were severely decreased to 0.546 and 0.209 g/cm(2), respectively. Because of his severe osteoporosis, we started romosozumab treatment with eldecalcitol. Romosozumab (210 mg) was injected subcutaneously every month. At 12 months after drug initiation, his lumbar and total hip BMD increased by 22.0% and 136.4% versus pre-treatment levels, respectively. Bone formation markers increased, and bone resorption markers decreased at 12 months of the therapy. Neither hypocalcaemia nor any other severe adverse effects were observed in this severe osteoporotic case. This study revealed good responses of BMD and bone turnover markers to romosozumab treatment, which can be considered as an effective treatment option for osteoporotic OI patients.