Efficacy of once-weekly teriparatide in patients with glucocorticoid-induced osteoporosis: the TOWER-GO study.

Abstract

Bisphosphonates are the standard treatment for glucocorticoid-induced osteoporosis (GIOP) with teriparatide being another option. While daily teriparatide has been shown to be effective in increasing bone mineral density (BMD), the efficacy of once-weekly teriparatide (56.5µg) has not yet been evaluated. The TOWER-GO study, a 72-week, multicenter, open-label, randomized controlled trial, was conducted in patients with GIOP to compare the effects of once-weekly teriparatide and once-weekly alendronate 35mg on BMD. Patients (N = 180) with GIOP for whom drug treatment was indicated according to the 2004 guidelines in Japan were randomized to receive once-weekly teriparatide (n = 89) or once-weekly alendronate (n = 91). The primary endpoint was the non-inferiority of percentage change in lumbar spine BMD at final follow-up. The secondary endpoints were the percentage change in BMD from baseline, incidence of bone fractures, and changes in bone turnover markers. While the non-inferiority of teriparatide to alendronate was not confirmed, BMD increased significantly from baseline with teriparatide and alendronate by 5.09% and 4.04%, respectively (both p < 0.05), at 72weeks. The incidence of vertebral and non-vertebral fractures was similar in both groups. Bone formation markers increased in the teriparatide group and decreased in the alendronate group. The non-inferiority of once-weekly teriparatide versus once-weekly alendronate in BMD change at 72weeks was not shown, but the increase in bone formation markers over time and the increase of BMD in GIOP patients treated with once-weekly teriparatide were confirmed.