Abaloparatide Increases Lumbar Spine and Hip BMD in Japanese Patients With Osteoporosis: The Phase 3 ACTIVE-J Study

CONTEXT: Abaloparatide reduced fracture risk in postmenopausal women with osteoporosis in the Abaloparatide Comparator Trial In Vertebral Endpoints (ACTIVE). Its effect in Japanese patients remains unexamined. OBJECTIVE: This work aimed to determine the efficacy and safety of abaloparatide in increasing bone mineral density (BMD) in Japanese patients with osteoporosis at high fracture risk. METHODS: This was a randomized, double-blind, placebo-controlled study conducted in Japan. Postmenopausal women and men with osteoporosis with high fracture risk were given daily subcutaneous 80 µg abaloparatide or placebo for 78 weeks (18 months). The primary end point was percentage change in lumbar spine (LS) BMD from baseline at the last visit. Secondary end points included time-course changes in LS, total hip (TH), and femoral neck (FN) BMDs and bone turnover markers, and cumulative number of fractures. RESULTS: Abaloparatide increased LS, TH, and FN BMDs (mean [95% CI]) by 12.5% (10.3%-14.8%; P < .001), 4.3% (3.3%-5.3%), and 4.3% (2.9%-5.6%), respectively, vs placebo. Serum procollagen type I N-terminal propeptide increased rapidly to ~ 140% above baseline at 6 weeks and gradually decreased but was approximately 25% higher than baseline at 78 weeks. Serum carboxy-terminal cross-linking telopeptide of type I collagen gradually increased to 50% above baseline at 24 weeks and decreased gradually to the placebo-group level from 60 weeks. Four vertebrae of 3 participants in the placebo group, but none in the abaloparatide group, developed new vertebral fractures. The safety profile was similar to that in the ACTIVE study. CONCLUSION: In Japanese patients with postmenopausal and male osteoporosis with high fracture risk, abaloparatide for 78 weeks robustly increased LS, TH, and FN BMDs, suggesting a similar efficacy in Japanese patients vs the ACTIVE study population.