A Comparison of the Immunogenicity of Intravenous BAT1806, a Tocilizumab Biosimilar, and Its Reference Product

INTRODUCTION: Biosimilars need to demonstrate similarity in terms of quality, pharmacokinetics (PK), efficacy, safety, and immunogenicity. Here, we report the outcome of a comprehensive evaluation of the immunogenicity of the biosimilar BAT1806 compared with the tocilizumab reference product (TCZ). METHODS: We conducted a post hoc analysis of study BAT1806-001-CR, a comparative PK study in healthy male volunteers (n = 129), and BAT1806-002-CR, a phase III, 52-week trial in patients with rheumatoid arthritis (n = 621). Anti-drug antibodies (ADA), ADA titers, and neutralizing ADA were measured, and their impact on PK, safety, and efficacy parameters were assessed. RESULTS: In BAT1806-001-CR, treatment-induced ADA were observed in 37.8% of participants for the BAT1806 group, 28.6% for the EU-sourced TCZ group, and 31.0% for the US-sourced TCZ group, without an impact on PK and safety. In BAT1806-002-CR after 52 weeks, 28.2% of participants in the BAT1806 group developed treatment-induced ADA, compared with 24.0% in the TCZ group and 19.7% of participants who initiated TCZ and switched to BAT1806 at week 24. ADA-positive participants reported lower geometric mean serum tocilizumab trough concentrations than ADA-negative participants in all treatment groups. ADA-positive participants achieved similar efficacy outcomes to ADA-negative participants in all treatment groups. ADA were not associated with an incremental risk of treatment-emergent adverse events or hypersensitivity in any of the treatment groups. CONCLUSIONS: The results of these post hoc analyses did not indicate any clinically relevant differences in the immunogenicity profile of intravenously administered BAT1806 compared with TCZ. TRIAL REGISTRATION: ClinicalTrials.gov identifiers, NCT03606876, NCT03830203.