Purpose: In the pivotal fracture trial of denosumab in postmenopausal women with osteoporosis (FREEDOM), treatment with denosumab, a RANK ligand (RANKL) inhibitor, resulted in a lower subject incidence of falls not associated with fracture (log rank P‑value = 0.02) compared with placebo [1]. In addition to its role in osteoporosis, the RANK/RANKL pathway has also been shown to play a role in muscle strength in a murine model [2]. In an ad hoc exploratory analysis, we pooled data from additional placebo-controlled trials of denosumab to determine the consistency across trials of the reduction in the incidence of falls.
Methods: Five placebo-controlled trials that contributed data to the FDA approval of denosumab for the bone loss indication were analyzed. These included: trials in postmenopausal women with osteoporosis (FREEDOM, Trial 1, NCT00089791, [1]) and low bone mass (Trial 2, NCT00091793, [3]), men with osteoporosis (Trial 3, NCT00980174, [4]), women receiving adjuvant aromatase inhibitors for breast cancer (Trial 4, NCT00089661, [5]), and men receiving androgen deprivation therapy for prostate cancer (Trial 5, NCT00089674, [6]). The analysis was stratified by trial and only included data from the placebo-controlled period of each trial. A time-to-event analysis of first fall and exposure‑adjusted subject incidence rates of falls (data not shown) were analyzed. Falls were reported as adverse events and not prospectively collected.
Results: Kaplan-Meier estimates showed that falls occurred in 6.5% of subjects in the placebo groups (N = 5006), compared to 5.2% in denosumab-treated subjects (N = 5030), with an HR (95% CI) of 0.78 (0.66, 0.93), P-value 0.0053. The forest plot of time-to-first occurrence of fall is shown for both the individual studies and overall (Figure).
Conclusions: Denosumab may reduce the risk of falls in postmenopausal women with osteoporosis, in addition to the established fracture risk reduction in these patients.