Celltrion Healthcare presented positive results from the Phase III CT-P17 3.1 trial comparing the efficacy and safety of biosimilar adalimumab,Yuflyma™, with reference adalimumab in patients with active rheumatoid arthritis (RA) at the Annual European Congress of Rheumatology 2021 (EULAR Virtual Congress 2021). The trial met its primary and secondary endpoints, demonstrating that the efficacy, pharmacokinetics (PK), safety and immunogenicity of CT-P17, a high-concentration (100mg/mL), low-volume and citrate-free adalimumab biosimilar, is comparable to reference adalimumab in the treatment of patients with moderate-to-severe active RA up to one year. The abstract has been published in an official supplement of the Annals of Rheumatic Diseases (ARD). The randomised, double-blind, Phase III study has demonstrated therapeutic equivalence of CT-P17 to reference adalimumab in 648 patients with active moderate-to-severe RA, despite methotrexate treatment, who were randomised (1:1) to receive either 40mg of CT-P17 or reference adalimumab every two weeks up to week 24.2 Prior to dosing at week 26, 608 patients were randomised again to either maintaining their treatment or being switched from reference adalimumab to CT-P17. After the second randomisation, 303 patients continued with CT-P17, 153 patients continued with reference adalimumab and 151 patients were switched from reference adalimumab to CT-P17 up to week 48. Results demonstrated comparable efficacy in terms of ACR20/50/70 response rates, both in patients receiving maintenance therapy and in patients switched from reference adalimumab to CT-P17 up to week 52. With respect to PK, mean Ctrough levels were maintained after week 24 in all three treatment groups with the observed mean Ctrough levels recorded within the reported therapeutic ranges of reference adalimumab trough levels (5-8 µg/ml) in RA patients. The safety profile among the three treatment groups was comparable, with the most common treatment-emergent adverse event (TEAE) being neutropenia and similar proportions seen across all treatment groups experiencing at least one TEAE: injection site reactions, hypersensitivity/allergic reactions and infections. Anti-drug antibody (ADA) and neutralising antibody (NAb) results were also similar among the three treatment groups; the proportions of patients who had ADA/NAbs were 28.4%/24.8% in CT-P17 maintenance, 27.0%/24.3% in reference adalimumab maintenance and 28.3%/26.3% in switched to CT-P17 groups.