Background: This Phase I study compared the pharmacokinetic (PK) and pharmacodynamic (PD) similarity of GP2411 proposed denosumab biosimilar to reference denosumab (a monoclonal antibody for specific pro-resorptive conditions).
Research design and methods: Healthy males (28-65 years, 50-90 kg) were randomized to a single sub-therapeutic subcutaneous injection of 35 mg GP2411, EU-Xgeva® or US-Xgeva®, and followed for 39 weeks. The primary endpoints were AUCinf, AUClast, and Cmax.
Results: Four hundred ninety-two participants completed treatment. The 90% confidence intervals (CIs) (AUCinf, AUClast, and Cmax) and 95% CI of the geometric mean ratios of AUEC of % change from baseline in serum CTX were fully contained within the prespecified equivalence margins (0.80, 1.25), demonstrating similarity. The occurrence of treatment-emergent adverse events (TEAEs) with GP2411, EU-Xgeva® and US-Xgeva® was similar (72.9%, 76.0%, and 71.0% of participants, respectively). Most were Grade 1 or 2, <30% were treatment-related, and there was only one TEAE-related study discontinuation. Rates of positive anti-drug antibodies (ADAs) were similar (57.8%, 64.9%, and 69.1% of participants respectively), but immunogenicity was only borderline detectable and of very low magnitude. Ninety-nine percent of positive ADAs were transient.
Conclusion: GP2411 demonstrated similarity with EU-Xgeva® and US-Xgeva® in PK, PD, safety, and immunogenicity in this population.
Clinical trial registration: EudraCT 2019-001651-39.
Keywords: Biosimilar; GP2411; denosumab; immunogenicity; pharmacodynamics; pharmacokinetics; phase I; safety.
Denosumab is a biological treatment that inhibits bone degradation. It is very effective in conditions characterized by elevated bone degradation, such as osteoporosis in women who have gone through the menopause, and in the treatment of specific bone cancers. However, the cost of the original patented denosumab (‘reference denosumab’) treatment may result in fewer eligible patients receiving denosumab treatment. A biosimilar is highly similar to the original treatment but at a lower price, enabling more patients to benefit.GP2411 is being developed as a proposed biosimilar to denosumab. This Phase I clinical trial was the first clinical trial to compare GP2411 to the EU and US versions of the reference denosumab (EU-Xgeva® and US-Xgeva®). All three products were given at a dose of 35 mg to 502 healthy males. The dose was lower than the dose that would be used in clinical practice to provide a more sensitive evaluation of similarity. Healthy males were chosen because they have fewer hormonal fluctuations than females, and are considered the most appropriate population for detecting differences in pharmacological effects of denosumab.The results demonstrate that GP2411 proposed denosumab biosimilar is highly similar to the reference products in absorption, distribution, and elimination, and other outcomes, including bone turnover. The incidence of adverse events was also comparable, most adverse events were very mild, and GP2411 was not associated with a higher rate of immune reactions.These results support its continued development and GP2411 may, in future, enable more patients to benefit from denosumab treatment.