Background: Denosumab is a human monoclonal antibody that binds to RANKL, preventing activation of its receptor RANK on the surface of osteoclasts and inhibiting osteoclastic bone resorption. This study was conducted to support demonstration of biosimilarity by evaluating similarity in pharmacokinetics (PK), pharmacodynamics (PD), safety, and immunogenicity between GP2411, a proposed Sandoz denosumab biosimilar, and reference denosumab in healthy male subjects. Methods: This double-blind, three-arm, parallel-group, PK and PD study was conducted at two centres in Germany. Participants were randomised (1:1:1) to receive a single 35 mg s.c. dose of either GP2411, EU-authorised reference denosumab, or US-licensed reference denosumab and were followed-up for 39 weeks. A sub-therapeutic dose was chosen since it is more sensitive than therapeutic doses to detect potential PK and PD differences; PK and PD similarity established at the 35 mg dose supports extrapolation to therapeutic doses. The study enrolled 502 healthy male subjects, aged 28–65 years, with a body weight range of 50–90 kg. PK endpoints included the area under the serum concentration-time curve measured from the time of dosing and extrapolated to infinity (AUC_inf), or to the last measurable concentration (AUC_last), and maximum observed serum concentration (C_max). PD endpoints were the area under the effect-time curve (AUEC) of the percentage change from baseline (%CfB) in serum carboxy-terminal crosslinked telopeptide of type I collagen (CTX), and CTX and procollagen I N-terminal propeptide (PINP) serum concentration per visit. Results: Overall, 499 healthy volunteers received one of the three treatments. PK and PD similarity was demonstrated between GP2411 and its reference biologic (EU-authorised and US-licensed), as the 90% CIs and 95% CIs of the geometric mean ratios for PK and PD parameters were fully contained within the prespecified equivalence margins [0.80, 1.25]. Changes from baseline to Week 39 in serum concentrations of CTX and PINP were similar between groups. Conclusions: PK and PD similarity between GP2411, a proposed Sandoz denosumab biosimilar, and reference denosumab were demonstrated in healthy male subjects.

PE, point estimate.