SB16 versus reference denosumab in postmenopausal women with osteoporosis: 18-month outcomes of a phase III randomized clinical trial

Purpose: This study evaluated the efficacy, safety, pharmacodynamics (PD), pharmacokinetics (PK), and immunogenicity of SB16 versus reference denosumab (DEN) up to 18 months in postmenopausal osteoporosis (PMO) patients, and assessed outcomes after switching from DEN to SB16 compared to those who continued with DEN or SB16.

Methods: 457 PMO patients were initially randomized, with 407 re-randomized at Month 12 to either continue DEN (DEN+DEN), switch to SB16 (DEN+SB16), or continue SB16 (SB16 + SB16) through Month 18. Efficacy was assessed by the percent change from baseline in bone mineral density (BMD) at the lumbar spine, total hip, and femoral neck. Safety, PD, PK, and immunogenicity were evaluated throughout the study period.

Results: Mean percent changes from baseline in lumbar spine, total hip, and femoral neck BMD at Month 18 were comparable across treatment groups, indicating comparable efficacy between SB16 and DEN. The mean percent change in lumbar spine BMD was 6.8 % (SB16 + SB16), 6.2 % (DEN+SB16), and 6.8 % (DEN+DEN). Total hip BMD increased by 4.4 %, 3.5 %, and 4.0 %, and femoral neck BMD by 3.4 %, 3.1 %, and 2.7 % for SB16 + SB16, DEN+SB16, and DEN+DEN, respectively. Safety profiles were similar among groups, with no new safety concerns identified after switching. Only one patient in the DEN+SB16 group developed non-neutralizing anti-drug antibodies by Month 18, indicating a low immunogenicity risk for SB16.

Conclusion: Switching from DEN to SB16 demonstrated comparable efficacy, safety, PD, PK, and immunogenicity in PMO patients relative to those who continued DEN. SB16 was well tolerated over 18 months, demonstrating comparable outcomes to DEN.