Pharmacokinetics and Safety of Intravenous Candidate Biosimilar CT‐P47 and Reference Tocilizumab: A Randomized, Double‐Blind, Phase 1 Study

CT-P47 is a candidate biosimilar of tocilizumab. This 12-week, randomized, double-blind, parallel-design, phase 1 study aimed to demonstrate pharmacokinetic (PK) equivalence of CT-P47 and reference tocilizumab. Participants were healthy Japanese adults aged 18-55 years. Participants were randomized (1:1:1) to receive a single intravenous dose (8 mg/kg) of CT-P47, EU-approved tocilizumab (EU-tocilizumab), or US-licensed tocilizumab (US-tocilizumab). Primary PK endpoints were area under the concentration-time curve (AUC) from time zero to infinity, AUC from time zero to the last quantifiable concentration, and maximum serum concentration. Additional PK variables, safety, and immunogenicity were evaluated. The study was conducted from January 20 to May 26, 2023, in three centers in Japan. In total, 133 male participants were randomized (n = 45 to CT-P47, n = 44 to EU-tocilizumab, and n = 44 to US-tocilizumab). For all primary PK variables, 90% confidence intervals of the ratio of geometric least squares means were within the predefined equivalence margin of 0.80-1.25. Secondary PK variables were similar across groups. The most common treatment-emergent adverse event (TEAE) was neutrophil count decreased, occurring in 15 (33.3%), 13 (30.2%), and 12 (27.3%) participants in the CT-P47, EU-tocilizumab, and US-tocilizumab groups, respectively. There were no serious TEAEs, deaths, or study drug discontinuations due to TEAEs. Few participants were anti-drug antibody (ADA)- or neutralizing antibody (NAb)-positive. At the end of study, four (8.9%), one (2.3%), and two (4.5%) participants in the CT-P47, EU-tocilizumab, and US-tocilizumab groups, respectively, were ADA-positive; two (4.4%), zero (0%), and one (2.3%) in the respective groups were NAb-positive. CT-P47 demonstrated PK equivalence and comparable safety to EU- and US-tocilizumab.