Pharmacokinetics and safety of candidate biosimilar CT-P55 versus reference secukinumab: a three-arm, randomized, double-blinded, single-dose, multicenter, Phase I study

Background This first-in-human study compared the pharmacokinetics, safety, and immunogenicity of candidate biosimilar CT-P55 to both European Union (EU)-approved and United States (US)-licensed secukinumab in healthy participants.Research design and methods Three-arm, double-blinded, parallel-group, single-dose, Phase 1 study conducted across four centers in Japan over 22 weeks. Healthy adult males were randomized (1:1:1) to a single 150-mg subcutaneous dose of CTP55, EU-approved, or US-licensed secukinumab. Primary endpoints were area under the concentration – time curve from time zero to infinity (AUC0–inf) and maximum serum drug concentration (Cmax).Results Baseline characteristics were comparable across groups (CT-P55 [n = 57], EU-approved secukinumab [n = 59], and US-licensed secukinumab [n = 56]). The 90% confidence intervals for the geometric least squares mean ratios of AUC0–inf and Cmax were within the equivalence margin (80–125%). Safety profiles were comparable. 218 treatment-emergent adverse events were reported for 110 (65.5%) participants; most were Grade 1/2. One serious adverse event was reported (US-licensed secukinumab group). The low immunogenic profile of CT-P55 was comparable to both reference secukinumab groups, with no neutralizing antibodies detected.Conclusions CT-P55 exhibited equivalent pharmacokinetics as well as comparable safety and immunogenicity to both EU-approved and US-licensed secukinumab in healthy Japanese males. Generalizability may be limited beyond Asian males.Trial registration The study is registered at Clinicaltrials.gov (NCT07054970).