Repeated Switching Between CT-P17 and EU Reference Adalimumab in Patients with Moderate-to-Severe Chronic Plaque Psoriasis: A Randomized, Double-Blind, Active-Controlled, Phase 3, Interchangeability Study

Introduction: This study aimed to demonstrate the interchangeability of biosimilar CT-P17 and European Union reference adalimumab (EU-adalimumab) in a repeated-switch scenario. Methods: In this ongoing, randomized, double-blind, active-controlled, phase 3 study, adults with moderate-to-severe plaque psoriasis received 80 mg EU-adalimumab on day 1, then 40 mg 1 week later and every other week until week 11. At week 13, patients were randomized (1:1, via an interactive web response system) to continue EU-adalimumab (“continuous” group) or undergo repeated switches between CT-P17 and EU-adalimumab (“switching” group). Dosing was via subcutaneous administration. The primary endpoints were area under the concentration–time curve and maximum serum concentration between weeks 25 and 27 (AUC_tau,W25–27 and C_max,W25–27, respectively). Secondary endpoints comprised additional pharmacokinetic (PK) parameters, efficacy, safety, and immunogenicity. Week 27 findings are presented. Results: The first patient provided signed informed consent on November 7, 2022. Week 27 visits were completed by August 14, 2023. Of 367 patients enrolled, 346 were randomized (switching group, n = 172; continuous group, n = 174). The ratios of least squares means between groups and associated 90% confidence intervals (CIs) for AUC_tau,W25–27 and C_max,W25–27 were 99.45% (94.11–105.08%) and 100.45% (95.03–106.17%), respectively. For both endpoints, 90% CIs fell within the predefined equivalence margin of 80–125% and criteria were greater than calculated t values, satisfying bioequivalence. Additional PK endpoints and efficacy, safety, and immunogenicity findings were similar between groups. Safety profiles were in line with those previously reported. Conclusions: Week 27 primary PK results demonstrated bioequivalence, and the overall study results supported the interchangeability of CT-P17 and EU-adalimumab. Trial Registration: ClinicalTrials.gov, NCT05495568.