A multicenter, randomized, rater-blinded, parallel-group, phase 3 study to compare the efficacy, safety, and immunogenicity of biosimilar RGB-10 and reference once-daily teriparatide in patients with osteoporosis

SUMMARY: The efficacy and safety of RGB-10 and reference teriparatide were evaluated in a randomized 52-week study in 250 patients with osteoporosis at high risk of fracture. RGB-10 was equivalent to reference teriparatide in efficacy and had a comparable safety profile. INTRODUCTION: RGB-10 is the first biosimilar teriparatide authorized in the European Union. This multicenter, randomized, rater-blinded, parallel-group phase 3 study evaluated equivalence in efficacy and compared safety between RGB-10 and reference teriparatide in patients with osteoporosis at high risk of fracture for registration in Japan. METHODS: Ambulatory postmenopausal women and men (≥ 55 years of age) with osteoporosis at high risk of fracture were randomized 1:1 to receive either RGB-10 or reference teriparatide 20 μg once daily via subcutaneous self-injection for 52 weeks. The primary efficacy endpoint was the percent change from baseline to 52 weeks in lumbar spine (L2–L4) bone mineral density (BMD). Safety outcomes and immunogenicity were also assessed. RESULTS: In total, 250 patients (125 in each group) were randomized. The percent change from baseline to 52 weeks in lumbar spine (L2–L4) BMD (mean ± standard deviation) was 8.94% ± 6.19% in the RGB-10 group and 9.65% ± 6.22% in the reference teriparatide group. The estimated between-group difference (95% confidence interval) was − 0.65% (− 2.17% to − 0.87%) within the pre-specified equivalence margin (± 2.8%), which indicates equivalence in efficacy between the two groups. Changes in BMD at lumbar spine (L1–L4), femoral neck, and total hip and serum procollagen type I amino-terminal propeptide were also similar between the groups. Safety profiles, including immunogenicity, were comparable. CONCLUSIONS: The therapeutic equivalence of RGB-10 to reference teriparatide was demonstrated. RGB-10 had comparable safety profile to that of reference teriparatide. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s00198-019-05038-y) contains supplementary material, which is available to authorized users.