Efficacy of Zoledronic Acid in Maintaining Areal and Volumetric Bone Density after Combined Denosumab and Teriparatide Administration: DATA-HD Study Extension.

Abstract

Combined teriparatide and denosumab rapidly and substantially increases bone mineral density (BMD) at all anatomic sites. Discontinuation of denosumab however, results in high-turnover bone loss and increased fracture risk. The optimal way to prevent this bone loss remains undefined. This study is a pre-planned extension of the DATA-HD study, where postmenopausal women with osteoporosis were randomized to receive 9 months of either 20-μg or 40-μg of teriparatide daily overlapping with denosumab (60-mg administered at months 3 and 9). At the completion of this 15-month study, women were invited to enroll in the DATA-HD Extension where they received a single dose of zoledronic acid (5-mg) 24-35 weeks after the last denosumab dose. Areal BMD and bone turnover markers were measured at month 27 and 42 (12 and 27 months after zoledronic acid, respectively) and spine and hip volumetric bone density by quantitative CT was measured at month 42. Fifty-three women enrolled in the DATA-HD Extension. At the femoral neck and total hip, the mean 5.6% and 5.1% gains in BMD achieved from month 0-15 were maintained both 12 and 27 months after zoledronic acid administration. At the spine, the mean 13.6% gain in BMD achieved from month 0-15 was maintained for the first 12 months but modestly decreased thereafter resulting in a 3.0% reduction (95% CI -4.0 to -2.0%, P<0.0001) 27 months after zoledronic acid. The pattern of BMD changes between months 15-42 were qualitatively similar in the 20-μg and 40-μg groups. A single dose of zoledronic acid effectively maintains the large and rapid total hip and femoral neck BMD increases achieved with combination teriparatide/denosumab therapy for at least 27 months following the transition. Spine BMD was also largely, though not fully, maintained during this period. These data suggest that the DATA-HD Extension regimen may be an effective strategy in the long-term management of patients at high risk of fragility fracture.