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Phase 3 study comparing the efficacy and safety of proposed biosimilar RGB-14-P with denosumab in postmenopausal women with osteoporosis: results from the transition (switch) phase

Ferrari S, Seefried L, Páll D, Viapiana O, Rosa J, Supronik J, Nestorova Licheva R, Kiefer J et al.

Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA, 2026

188 participants

Abstract

Osteoporosis is a chronic condition requiring long-term management of fracture risk. Biosimilars provide the possibility of continuous use of well-established compounds. Proposed denosumab biosimilar RGB-14-P demonstrated equivalent efficacy and similar pharmacodynamics, immunogenicity, and safety to the reference denosumab. Transitioning from reference denosumab to RGB-14-P was associated with continued effectiveness and safety.

Purpose: To establish the therapeutic equivalence of RGB-14-P and reference denosumab (RD) in postmenopausal women with osteoporosis through demonstrating equivalent efficacy and similar safety, pharmacodynamics (PD), and immunogenicity when transitioning from RD to RGB-14-P.

Methods: Patients (n = 188) who had received two 60-mg doses of RGB-14-P or RD (day 1 and week 26) in a randomised, blinded, controlled phase 3 study were re-randomised 1:1:1 at week 52 to continue RGB-14-P (n = 63) or RD (n = 63) or transition from RD to RGB-14-P (n = 62) and followed to week 78.

Results: Gains in lumbar spine, hip, and femoral neck bone mineral density (BMD) observed in the first 52 weeks of treatment were further improved up to week 78 in all three groups, including patients who transitioned from RD to RGB-14-P. Incidences of new fragility fractures were comparable. Changes from baseline in serum PD markers (serum C-telopeptide of type I collagen and procollagen type I N-terminal propeptide) were maintained. The transition did not induce a discernible…

How strong is the evidence?

Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design. Reported size: 188 participants or records.

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