In rheumatoid arthritis (RA), the safety and efficacy of biosimilar CT-P17 and reference adalimumab were comparable after 1 year of treatment, even among participants who switched from adalimumab to CT-P17 after 24 weeks, according to phase 3 study results published in Rheumatology.

CT-P17 is a citrate-free biosimilar of adalimumab (100 mg/mL) approved by the European Commission for use in patients with RA. An earlier report suggested similar efficacy between biosimilar CT-P17 and reference adalimumab at 24 weeks.

The current double-blind phase 3 study (ClinicalTrials.gov Identifier: NCT03789292) was conducted to compare the efficacy and safety of adalimumab CT-P17 vs the reference product. Researchers specifically reported on the safety and efficacy of switching from reference adalimumab to the biosimilar CT-P17 from week 26 to 52.


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During the first part of the study (treatment period 1, week 0-24), participants were assigned randomly to receive 40 mg (100 mg/mL) adalimumab reference or CT-P17 subcutaneously every 2 weeks. During the treatment period 2 that commenced at week 26, patients in the adalimumab group were randomly assigned to continue to receive the adalimumab reference or switch to CT-P17 until week 52. Patients in the original CT-P17 group continued to receive their treatment. All patients received concomitant methotrexate and folic acid throughout the study.

Endpoints included improvements in the American College of Rheumatology (ACR) criteria from baseline (ACR20, ACR50, and ACR70 criteria indicates a 20%, 50%, and 70% improvement, respectively) and joint damage progression, using the modified total Sharp score.

Pharmacokinetics were assessed by measuring mean adalimumab trough concentrations. Safety and immunogenicity were also evaluated.

Treatment period 2 included 607 patients, among whom 303 continued to receive the biosimilar CT-P17, 153 continued to receive adalimumab, and 151 switched from the reference adalimumab to CT-P17.

The ACR20 response rates were 80.5% in the group that continued CT-P17, 77.8% in the group that continued reference adalimumab, and 82.2% in the group that switched to CT-P17. Joint damage progression was minimal. Pharmacokinetics and safety were similar among the treatment groups. Immunogenicity was also similar between the groups, with antidrug antibody positivity observed in 28.4% in the group that continued CT-P17, 27.0% in the group that continued reference adalimumab, and 28.3% in the group that switched to CT-P17.

Study limitations included a relatively small number of participants in the group that switched from reference adalimumab to CT-P17 and the use of post hoc statistical analyses. In addition, the COVID-19 pandemic affected the latter half of the study period and required protocol adjustments, including remote visits for some participants.

Researchers concluded, “After 52 weeks of treatment, CT-P17 was comparable to reference adalimumab in terms of efficacy, [pharmacokinetics], safety and immunogenicity. Efficacy, safety, and immunogenicity following the switch from reference adalimumab to CT-P17 were comparable to findings with continued treatment with reference adalimumab or CT-P17. Thus, this study affirms the biosimilarity of CT-P17 to reference adalimumab and provides clinical evidence for switching from reference adalimumab to CT-P17.”

Disclosure: This study was supported by Celltrion, Inc. (Incheon, Republic of Korea). Please see the original reference for a full list of the authors’ disclosures.

Reference

Furst DE, Jaworski J, Wojciechowski R, et al. Efficacy and safety of switching from reference adalimumab to CT-P17 (100 mg/ml): 52 week randomized study in rheumatoid arthritis. Rheumatology (Oxford). Published online June 17, 2021. doi:10.1093/rheumatology/keab460