Denosumab is associated with a greater increase in lumbar spine bone mineral density at 12 months compared with ibandronate as a sequential treatment after 12 months of romosozumab therapy, according to study findings published in Bone.
“The present study directly compared the efficacy of ibandronate and denosumab on BMD changes in postmenopausal osteoporosis as a continuous sequential therapy following 12-month treatment with romosozumab in a real-world randomized controlled trial,” Yukio Nakamura, MD, PhD, associate professor at Shinshu University in Matsumoto, Japan, and colleagues wrote. “While significant increases in BMD after 12-month sequential therapy with either ibandronate or denosumab following romosozumab treatment for 12 months were observed, this study revealed a significantly superior ability of denosumab over ibandronate to increase BMD, especially at the lumbar spine. Therefore, denosumab may be considered a preferable option for ongoing osteoporosis management following romosozumab in postmenopausal women.”
Researchers conducted a randomized controlled trial enrolling 124 postmenopausal women with osteoporosis and a severe risk for fractures. After receiving 12 months of romosozumab-aqqg (Evenity, Amgen), participants were randomly assigned to 100 mg ibandronate monthly or 60 mg denosumab (Prolia, Amgen) subcutaneously every 6 months for an additional 12 months. BMD was assessed through DXA scans. The primary outcomes were the change in BMD with ibandronate or denosumab at 18 and 24 months at the lumbar spine, total hip and femoral neck. Enzyme immunoassays were used to measure the serum bone turnover markers procollagen type 1 N-terminal propeptide 1 (P1NP) and tartrate-resistant acid phosphatase isoform 5b.
At the end of the romosozumab phase at 12 months, the ibandronate group and denosumab group had similar areal BMD increases of 12% and 12.4%, respectively. The denosumab group had a larger increase in lumbar spine BMD at 18 months (16.6% vs. 12.8%; P < .05) and 24 months (18% vs. 14.6%; P < .05) compared with the ibandronate group. The denosumab group had an 8.9% total hip BMD gain and the ibandronate group had an 8.4% BMD increase at 24 months. The increases were significant compared with baseline, but not between the two groups. Femoral neck BMD increased 8.6% with denosumab and 7.1% with ibandronate at 24 months. Similar to the total hip, the figures were a significant increase from baseline, but there was no difference between the two therapies.
The ibandronate group had a large decrease in P1NP of 75.5% at 18 months and 76.9% at 24 months. The denosumab group had similar large decreases in P1NP of 64.1% at 18 months and 71.9% at 24 months. Decreases in tartrate-resistant acid phosphatase isoform 5b that began during the romosozumab phase continued in both the ibandronate and denosumab groups, with no difference between the two therapies.
There were 10 adverse events in the ibandronate group and five in the denosumab group, all of which were considered minor. None resulted in treatment discontinuation.
“The discontinuation of romosozumab may trigger the promotion of bone resorption,” the researchers wrote. “Therefore, it appears reasonable to use such antiresorptive agents as bisphosphonate and denosumab for continuing treatment. It will be increasingly necessary for physicians to devise a long-term strategy for osteoporosis treatment agents and approaches as the average life expectancy increases worldwide.”