6795 Romosozumab improves bone mineral density and markers of bone resorption in a patient with osteogenesis imperfecta

Abstract Disclosure: M.K. Shakir: None. C.M. Godar: None. R. Piech: None. T.D. Hoang: None. The efficacy of romosozumab for improving osteoporosis and preventing skeletal fractures is uncertain in patients with osteogenesis imperfecta (OI). In this case report we describe the beneficial effect of romosozumab on markers of bone turnover and bone density in a patient with OI. A 64-year-old man with OI was referred to endocrinology for evaluation of repeated fractures. The patient had a few fractures as a child (2 collar bones and wrist, oldest at age 14); and he recovered well. He reports that he has had a short stature and blue sclera but was otherwise asymptomatic. His son was also diagnosed with OI based on bone biopsy showing abnormalities suggestive of OI type II or IV. This son has had multiple fractures, 10 shoulder dislocations, and 2 hip replacements. He has another son with a history of multiple fractures but no formal diagnosis of OI. His third son has no findings. The patient’s brother has been diagnosed clinically with OI type 4, and had genetic testing showing a COL1A1 pathogenic variant (c. 976G>C, p.Gly326Arg) . Genetic testing in our patient revealed a COL1A1 pathogenic variant (c. 976G>C, p.Gly326Arg) confirming the diagnosis of OI type 4. 8 years ago, he was treated with alendronate for 12 months, which did not prevent recurrent fractures, and all therapies were discontinued. However, recently, the frequency of fractures involving multiple sites had increased. At presentation, his lumbar and bilateral total hip bone mineral density (BMD) values were severely decreased to 0.725 and 0.566 g/cm2, (T scores -3.3 and -3.1) respectively. Because of severe osteoporosis, he was treated with romosozumab 210 mg every month. After 12 months of treatment, his lumbar and total hip BMD increased by 28.3% and 7.2 % respectively. Additionally, bone formation markers increased, and bone resorption markers decreased at 12 months of therapy. He did not develop any fractures after treatment with romosumab. No severe adverse drug effects were observed. At the end of 12 months he received 5 mg zoledronic acid IV. This case 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. Studies involving large number of patients are required. Presentation: 6/2/2024