Efficacy and Safety of Denosumab vs Zoledronic Acid in OI Adults: A Prospective, Open-Label, Randomized Study

The comparative effectiveness of denosumab and zoledronic acid for adult patients with osteogenesis imperfecta (OI) has not been established.

To evaluate the efficacy and safety of denosumab and zoledronic acid in adult patients with OI.

This was a prospective, open-label study. Patients were randomized to receive denosumab 60 mg every 6 months or zoledronic acid 5 mg once for 12 months. Pathogenic mutations of OI were identified by next-generation sequencing and confirmed by Sanger sequencing. Percentage changes in the areal bone mineral density (aBMD), trabecular bone score (TBS), and bone turnover biomarkers (BTMs) from baseline to 6 and 12 months of treatment, as well as safety, were evaluated.

A total of 51 adults with OI (denosumab: 25, zoledronic acid: 26) were included, of whom 49 patients had identified pathogenic mutations. At 12 months, aBMD at the lumbar spine and total hip significantly increased by 4.34% (P = .005) and 1.45% (P = .023) in the denosumab group and by 4.92% (P = .006) and 2.02% (P = .016) in the zoledronic acid group, respectively. TBS showed an increasing trend by 1.39% and 2.70% in denosumab and zoledronic acid groups, respectively. Serum levels of β-isomerized carboxy-telopeptide of type I collagen and alkaline phosphatase markedly decreased after denosumab treatment. Percentage changes in aBMD, TBS, and BTMs during the treatment were similar between the 2 groups. Patients with OI with milder phenotypes showed a significantly higher increase in the TBS after 12 months of denosumab treatment than those with more severe phenotypes (P = .030). During the study period, the denosumab group had fewer adverse events than the zoledronic acid group.

Denosumab effectively increases aBMD in adults with OI, with similar efficacy to zoledronic acid. Long-term and large-sample studies are needed to confirm the antifracture efficacy and safety of denosumab in adult patients with OI.