Switching between adalimumab and biosimilar adalimumab-atto shows similar pharmacokinetics in plaque psoriasis

INTRODUCTION: ABP 501, now approved as AMJEVITA (adalimumab-atto, USA)/AMGEVITA (adalimumab, EU), is a biosimilar to adalimumab reference product (RP, Humira) indicated for the treatment of various chronic inflammatory conditions. This multicenter, randomized, double-blind study aimed to investigate the impact of multiple switches between adalimumab RP and ABP 501 as compared with continued-use of adalimumab RP. METHODS: This study (NCT05073315) consisted of a 12-week lead-in period where adults with moderate-to-severe plaque psoriasis received adalimumab RP subcutaneously every 2 weeks (Q2W), followed by a double-blind, two-parallel arm period in which patients were randomized to either the continued-use group (adalimumab RP Q2W, weeks 12-28) or switching group (ABP 501, weeks 12 and 14; adalimumab RP, weeks 16 and 18; ABP 501 Q2W, weeks 20-28). The primary pharmacokinetic (PK) endpoints were area under the serum concentration-time curve (AUC) and maximum observed serum concentration (C) between weeks 28 and 30. Secondary endpoints included additional PK assessments and measures of safety, immunogenicity, and efficacy. RESULTS: A total of 425 patients were enrolled across 85 centers. Adherence to dosing protocol and completion/discontinuation rates were similar between groups. The ratio of geometric least squares means (90% confidence interval; CI) between the continued-use group and switching group for AUC was 1.0516 (0.9010, 1.2273) and for C was 1.0044 (0.8717, 1.1574); 90% CIs were contained within the prespecified similarity margin (0.8, 1.25). Secondary endpoints were comparable between groups. There were no new or concerning safety signals. CONCLUSION: This study demonstrates PK similarity in patients with plaque psoriasis who underwent three treatment switches between adalimumab RP and ABP 501 as compared with those who received continuous treatment with adalimumab RP. Safety, immunogenicity, and efficacy profiles were comparable. Overall, results support the interchangeability designation of ABP 501 with adalimumab RP, consistent with the US Food and Drug Administration (2019) guidelines. TRIAL REGISTRATION: This study was registered as NCT05073315.