For postmenopausal women with osteoporosis, romosozumab increases bone formation and decreases bone resorption, according to a study published online June 24 in the Journal of Bone and Mineral Research.
Pascale Chavassieux, M.D., from the Université de Lyon in France, and colleagues examined the effects of romosozumab on bone tissue in postmenopausal women with osteoporosis. Transiliac bone biopsies were performed in a subset of women from the multicenter, phase 3, randomized clinical trial after two (34 women) or 12 (73 women) months of treatment with 210 mg once monthly romosozumab or placebo.
The researchers found that after two months, there were significant increases in dynamic parameters of formation for romosozumab (median ratio of mineralizing surface to bone surface [BS]: 1.51 and 5.64 percent at baseline and month two, respectively) versus placebo (1.60 and 2.31 percent at baseline and month two, respectively). Compared with placebo, rosozumab correlated with a significant decrease in resorption parameters in cancellous bone (median eroded surface [ES]/BS: romosozumab 1.8 percent and placebo 3.4 percent) and endocortical bone (median ES/BS: romosozumab 1.6 percent and placebo 6.3 percent). Cancellous bone formation was significantly lower in romosozumab versus placebo at 12 months; the lower values for resorption endpoints seen at month two persisted, indicating reduced bone turnover. At month 12, there was an increase in bone mass and trabecular thickness with improved trabecular connectivity, without significant modification of cortical porosity.
“This dual but opposite effect suggests a transient absence of coupling between resorption and formation early in the initiation of treatment, with bone formation potentially occurring without prior resorption, consistent with a modeling process,” the authors write.