Purpose: There are limited data on patients transitioning from denosumab (DMAb) to bisphosphonates (BPs). The Denosumab Adherence Preference Satisfaction (DAPS) study (NCT00518531) reported that alendronate (ALN) could maintain the gains in bone mineral density (BMD) achieved with 1 year of DMAb (Freemantle Osteoporos Int 2012). Here, we further evaluate BMD responses after transitioning from DMAb to ALN.
Methods: DAPS was a 24-month, open-label, randomized, cross-over study designed to compare adherence to 12 months of DMAb treatment (60 mg Q6M SC) with ALN (70 mg QW PO) in treatment-naïve postmenopausal women with a T-score ≤─2.0 to ≥─4.0 at the lumbar spine (LS), total hip (TH), or femoral neck (FN). BMD was measured at baseline and months (M) 12 and 24. A 3% BMD least significant change threshold identified subjects who lost, maintained, or gained BMD from M12 to M24 (change ≤─3%, >─3% and <3%, or ≥3%, respectively). Subject characteristics were summarized using descriptive statistics.
Results: Of 126 subjects randomized to DMAb, 115 (91%) transitioned to ALN at M12. At baseline, mean age was 65 years and mean BMD T-scores were ─1.6 to ─2.0. BMD increased by 5.6%, 3.2%, and 3.1% with DMAb from M0 to M12 at the LS, TH, and FN, respectively, and changed by 0.6%, 0.4%, and –0.1% with ALN from M12 to M24. After transitioning to ALN, most subjects showed maintained or increased BMD, regardless of baseline characteristics or alendronate adherence (Table); 15.9%, 7.6%, and 21.7% lost BMD at the LS, TH, and FN, respectively, and only 1 subject (1.2%) lost BMD at all sites.
Conclusion: ALN can maintain the BMD gains accrued after 1 year of DMAb in most subjects regardless of subject characteristics. These data highlight the need for oral BP therapy following DMAb cessation and BMD monitoring of patients transitioning from DMAb to ALN.