Year-Long Phase 3 Study Confirms Tocilizumab Biosimilar Comparability With Actemra

CT-P47, a biosimilar candidate to tocilizumab, has shown promising results in the treatment of rheumatoid arthritis (RA), according to findings from a phase 3 clinical trial conducted at 22 centers in Poland.1

Over the course of a year, CT-P47 demonstrated comparable efficacy, safety, and immunogenicity to the reference product (Actemra/RoActemra), including among patients who transitioned from the originator biologic. The findings, published in Clinical Drug Investigation, may strengthen payer and provider confidence in switching to biosimilars as a cost-effective alternative for RA care.

Tocilizumab’s Role and the Biosimilar Landscape

Tocilizumab, an interleukin-6 (IL-6) receptor inhibitor, has played a central role in RA management for over a decade. RA is a chronic autoimmune disease marked by inflammation and joint destruction, driven in part by elevated IL-6 activity.

The US and European markets for tocilizumab biosimilars are experiencing rapid growth. In the US, the FDA has approved several tocilizumab biosimilars, including Biogen's Tofidence (tocilizumab-bavi) in September 2023, Fresenius Kabi's Tyenne (tocilizumab-aazg) in March 2024, and most recently, Celltrion's CT-P47 (Avtozma; tocilizumab-anoh) in January 2025.2 Similarly, the European Commission has granted marketing authorization for multiple biosimilars, including Tyenne in November 2023, Tofidence in June 2024, and Avtozma in February 2025.

Despite the effectiveness of these biosimilars, the high cost of biologics like tocilizumab has limited access for some patients and driven interest in lower-cost biosimilar options.2

Although biosimilars are increasingly entering the market, long-term data remain essential to validate their clinical equivalence. The European League Against Rheumatism (EULAR) has endorsed the use of biosimilars when supported by evidence of comparable efficacy and safety, but real-world data on switching remain limited. This trial aims to address that gap.

The multicenter, randomized, double-blind study enrolled adult patients (aged 18-75 years) with moderate to severe RA of at least 24 weeks’ duration, all of whom were on stable methotrexate therapy for at least 12 weeks prior to enrollment. Participants were randomized 1:1 to receive either CT-P47 or the reference product intravenously at a dose of 8 mg/kg every 4 weeks over the initial 20-week treatment phase.

At week 24, patients receiving CT-P47 continued treatment, while those on Actemra were rerandomized to either continue the reference product or switch to the biosimilar. All patients were then treated through week 48 and followed through week 52. Outcomes assessed included disease activity, radiographic progression, pharmacokinetics (PK), safety, and immunogenicity.

Among the 444 patients who completed the first treatment phase, 225 continued on CT-P47, 109 continued on Actemra, and 110 switched from Actemra to CT-P47. Efficacy, measured by the mean change from baseline in Disease Activity Score in 28 joints using erythrocyte sedimentation rate (DAS28-ESR), remained consistent through week 52 across all groups (CT-P47, −4.279; Actemra, −4.231; switch group, −4.376).

Radiographic progression, assessed using the modified total Sharp score, was minimal. More than 81% of patients in all groups showed no radiographic progression over the study period. Serum drug concentration levels remained stable, indicating similar PK profiles across treatment arms.

The incidence of antidrug antibodies was low (< 5%), and the safety profile was consistent with historical data for tocilizumab. No new safety concerns were identified in patients who switched to the biosimilar.

The results support CT-P47 as a viable biosimilar alternative for RA treatment and provide reassurance regarding the safety and efficacy of switching from the originator biologic. For clinicians, these findings add to the growing body of evidence supporting biosimilar use in rheumatology.

With rising biologic costs and growing RA prevalence, biosimilars such as CT-P47 may expand treatment access and relieve financial pressure on health systems. Broader uptake will depend on continued evidence generation, physician and patient education, and favorable reimbursement policies. Further real-world studies are needed to confirm these findings and support wider adoption.

References

1. Burmester G, Trefler J, Racewicz A, et al. Efficacy and safety of biosimilar CT-P47 versus reference tocilizumab: 1-year results of a randomised, active-controlled, double-blind, phase iii study in patients with rheumatoid arthritis. Clin Drug Investig. 2025;45(8):551-563. doi:10.1007/s40261-025-01453-8

2. Biosimilar approvals. The Center for Biosimilars®. Updated August 5, 2025. Accessed August 5, 2025. https://www.centerforbiosimilars.com/biosimilar-approvals