Purpose <p>This Phase 1 study evaluated the pharmacokinetics (PK), pharmacodynamics (PD), immunogenicity, and safety of INTP23.1, a proposed denosumab biosimilar, compared with US- and EU-licensed reference denosumab (Xgeva®) in healthy male volunteers.</p> Methods <p>This randomized, double-blind, three-arm, 36&#xa0;week, parallel-group trial (CTRI/2020/09/027619), assessed a single 35&#xa0;mg subcutaneous dose of INTP23.1, Xgeva (US), or Xgeva (EU), administered in the upper arm. PK endpoints were statistically compared using geometric least-squares means (LSM) and 90% confidence intervals (CIs). PD markers were evaluated, immunogenicity and safety were assessed through validated assays, and adverse events (AEs) were monitored.</p> Results <p>A total of 234 healthy male volunteers were enrolled. Baseline demographics were similar across the three treatment sequence groups. PK equivalence was demonstrated, with all geometric LSM ratios and 90% CIs for maximum serum concentration, area under the concentration–time curve (AUC) from time zero to the last measurable concentration, and AUC from time zero to infinity falling within the predefined bioequivalence range of 80.00% to 125.00%. PD responses showed comparable suppression of C-terminal telopeptide (CTX) and procollagen type 1 N-terminal propeptide (P1NP) across treatment groups. Immunogenicity profiles were similar, with low anti-drug antibody incidence and no neutralizing antibodies detected. AEs were generally mild or moderate in intensity, and no unexpected safety signals were observed.</p> Conclusions <p>INTP23.1 demonstrated comparable PK, PD, immunogenicity, and safety to US- and EU-licensed denosumab reference products in healthy male volunteers. These findings support further clinical development of INTP23.1 as a denosumab biosimilar for approved indications.</p> Trial registration number <p>CTRI/2020/09/027619; Registered 07/09/2020.</p>