Five hundred twenty-seven postmenopausal women with osteoporosis were randomized to receive either biosimilar denosumab GP2411 (n=263) or reference denosumab (n=264), with doses administered at baseline and week 26. At week 52, participants initially treated with reference denosumab were re-randomized to continue reference denosumab or switch to GP2411. The primary outcome was the percent change from baseline in lumbar spine bone mineral density (LS-BMD) at week 52. Secondary outcomes included changes in femoral neck (FN-BMD) and total hip bone mineral density (TH-BMD), pharmacokinetic and pharmacodynamic parameters, immunogenicity, and safety. Outcomes were assessed through 78 weeks. Overall, the results of the study revealed that GP2411 was equivalent to reference denosumab in efficacy, PK, PD, and safety, with no clinically meaningful differences. These findings suggest that GP2411 is a viable biosimilar alternative for the treatment of postmenopausal osteoporosis.