Sequential therapy with once-weekly teriparatide injection followed by alendronate versus monotherapy with alendronate alone in patients at high risk of osteoporotic fracture: final results of the Japanese Osteoporosis Intervention Trial-05

Summary In this randomized, controlled trial, sequential therapy with once-weekly subcutaneous injection of teriparatide for 72 weeks, followed by alendronate for 48 weeks resulted in a significantly lower incidence of morphometric vertebral fracture than monotherapy with alendronate for 120 weeks in women with osteoporosis at high risk of fracture. Purpose To determine whether the anti-fracture efficacy of sequential therapy with teriparatide, followed by alendronate is superior to that of monotherapy with alendronate, a prospective, randomized, open-label, blinded-endpoint trial was performed. Methods Japanese women aged at least 75 years were eligible for the study, if they had primary osteoporosis and if they were at high risk of fracture. Patients were randomly assigned (1:1) to receive the sequential therapy (once-weekly subcutaneous injection of teriparatide 56.5 μg for 72 weeks, followed by alendronate for 48 weeks) or monotherapy with alendronate for 120 weeks. The primary endpoint in the final analysis was the incidence of morphometric vertebral fracture during the 120-week follow-up period. Results Between October 2014 and June 2020, 505 patients in the sequential therapy group and 506 in the monotherapy group were enrolled. Of these, 489 and 496, respectively, were included in the main analysis. The incidence of morphometric vertebral fracture during the 120-week follow-up period in the sequential therapy group (64 per 627.5 person-years, annual incidence rate 0.1020) was significantly lower than that in the monotherapy group (126 per 844.2 person-years, annual incidence rate 0.1492), with a rate ratio of 0.69 (95% confidence interval 0.54 to 0.88, P < 0.01). After 72 weeks, no patient had a severe adverse event that was considered related to the study drug. Conclusion Once-weekly injection of teriparatide, followed by alendronate resulted in a significantly lower incidence of morphometric vertebral fracture than alendronate monotherapy in women with osteoporosis who were at high risk of fracture. Trial registration number, date of registration jRCTs031180235 and UMIN000015573, March 12, 2019