Comparative Study Assessing Multiple Switches Between Biosimilar ABP 501 (adalimumab-atto) and Adalimumab Reference Product in Patients with Plaque Psoriasis

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. 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 (AUCtau) and maximum observed serum concentration (Cmax) between weeks 28 and 30. Secondary endpoints included additional PK assessments and measures of safety, immunogenicity, and efficacy. 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 AUCtau was 1.0516 (0.9010, 1.2273) and for Cmax 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. 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. This study was registered as NCT05073315 Adalimumab is a medication used to treat various chronic inflammatory conditions. Adalimumab-atto (AMJEVITA®, USA/AMGEVITA®, EU; Amgen Inc.), also known as ABP 501, is an approved biosimilar to adalimumab (HUMIRA®, AbbVie Inc.). Biosimilars are medications that are highly similar to an approved biologic reference product. Approval of ABP 501 was based on the totality of evidence, including comparative clinical trials in patients with moderate-to-severe plaque psoriasis and rheumatoid arthritis, both of which demonstrated similarity of efficacy, safety, and immunogenicity to the reference product. This study aimed to show that switching between adalimumab reference product and ABP 501 is just as effective and safe as continual use of adalimumab reference product without switching. The study included 425 patients with moderate-to-severe plaque psoriasis. During the study, one group continued using adalimumab reference product every 2 weeks, while the other group switched between adalimumab and ABP 501 at specified intervals, starting at week 12. Researchers measured the concentration of the medications in the blood and checked for changes in clinical severity of psoriasis, immune responses, and safety. The results showed that the levels of medication in the blood were similar between the two treatment groups. In addition, both treatment groups experienced comparable improvements in psoriasis severity using standardized clinical scoring methods, and comparable safety with no new safety concerns emerging during the study. Taken together, these results support the interchangeability, which refers to the ability to substitute one investigational product for the other, of ABP 501 and adalimumab reference product.