Comparable efficacy and safety observed in patients switched to biosimilar CT-P10

Rituximab is a monoclonal antibody that targets the CD20 protein that is primarily found on B lymphocytes. Through depletion of CD20-positive B cells in the peripheral blood and bone marrow, rituximab is effective for treating some haematological malignancies and immune-mediated diseases such as rheumatoid arthritis (RA). CT-P10 (Truxima) is a biosimilar of the rituximab reference product. It is the first biosimilar to receive market authorization from the European Medicines Agency and is approved in Europe for all indications for which RTX is licensed [1]. A phase I randomized controlled trial (RCT) in patients with RA demonstrated pharmacokinetic equivalence of CT-P10 and reference rituximab over 24 weeks of treatment [2], and comparable efficacy and safety of these two drugs has recently been demonstrated over an extended treatment duration from the same trial [3]. With biosimilars typically being less expensive than originator biologicals [4], it is of interest to know whether patients treated with an originator biological can be switched to a biosimilar to save healthcare costs and increase access without affecting treatment efficacy or safety. An open-label extension (OLE) study that enrolled patients who had completed the aforementioned phase I RCT has been published [5]. The study has demonstrated comparable efficacy and safety profiles in patients who switched from the reference rituximab to CT-P10 and those maintained on CT-P10 throughout treatment [5].

In this single-arm, open-label extension, 87 patients who had completed up to 72 weeks of treatment with CT-P10 or reference rituximab during the preceding phase I trial were enrolled. Of these, 58 and 29 patients had previously received CT-P10 or reference rituximab, respectively. Thirty-eight and 20 of these patients were treated in the OLE, comprising the maintenance and switch groups, respectively, and received CT-P10 for up to two years or after switching from reference rituximab.

Efficacy endpoints included the mean change in disease activity measured by DAS28-ESR and DAS28-CRP compared with baseline (week 0 of the preceding RCT) and the proportion of patients with good, moderate or no response, defined according to European League Against Rheumatism (EULAR) response criteria based on Disease Activity Score for 28 joints, including erythrocyte sedimentation rate (DAS28-ESR) and DAS28-C-Reactive Protein (DAS28-CRP). All efficacy endpoints were comparable between the maintenance and switch groups, including improvements in DAS28, which did not differ between the two groups, see Figure 1. Moreover, switching from reference rituximab to CT-P10 was not associated with any safety issues. Long-term treatment with CT-P10 was efficacious and well tolerated by patients, supporting the results of the phase I RCT [3].

It is common for countries to recommend the least expensive drug be used for treating conditions such as RA [6]. Therefore, studies that examine whether patients can be switched from the reference product to a biosimilar are crucial for making informed clinical decisions that may result in reducing healthcare costs without compromising efficacy and safety.

Conflict of interest
Several of the authors of the research paper [5] reported conflicts of interest, including having received consulting fees and grants from, or being an employee of, Celltrion. For full details of the authors’ conflict of interest, see the research paper [5].

Abstracted by Professor Dae Hyun Yoo, Hanyang University Hospital for Rheumatic Diseases, Seoul, Republic of Korea (medical writing support provided by Louise Niven, DPhil, and funded by Celltrion Healthcare).

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References
1. GaBI Online - Generics and Biosimilars Initiative. Biosimilars approved in Europe [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2017 Sep 22]. Available from: www.gabionline.net/Biosimilars/General/Biosimilars-approved-in-Europe
2. Yoo DH, Suh C, Shim SC, et al. A multicentre randomised controlled trial to compare the pharmacokinetics, efficacy and safety of CT-P10 and innovator rituximab in patients with rheumatoid arthritis. Ann Rheum Dis. 2017;76(3):566-70.
3. Yoo DH, Suh C, Shim SC, et al. Efficacy, safety and pharmacokinetics of up to two courses of the rituximab biosimilar CT-P10 versus innovator rituximab in patients with rheumatoid arthritis: Results up to week 72 of a phase I randomized controlled trial. BioDrugs. 2017 Jun 13. doi: 10.1007/s40259-017-0232-7. [Epub ahead of print]
4. IMS Health. Shaping the biosimilars opportunity: a global perspective on the evolving biosimilars landscape. December 2011 [homepage on the Internet]. [cited 2017 Sep 22]. Available from: http://weinberggroup.com/pdfs/Shaping_the_biosimiliars_opportunity_A_global_perspective_on_the_evolving_biosimiliars_landscape.pdf
5. Park W, Suh CH, Shim SC, et al. Efficacy and Safety of Switching from Innovator Rituximab to Biosimilar CT-P10 Compared with Continued Treatment with CT-P10: Results of a 56-Week Open-Label Study in Patients with Rheumatoid Arthritis. BioDrugs. 2017 Jun 9. doi: 10.1007/s40259-017-0233-6. [Epub ahead of print]
6. National Institute for Health and Care Excellence. Adalimumab, etanercept, infliximab, certolizumab pegol, golimumab, tocilizumab and abatacept for rheumatoid arthritis not previously treated with DMARDs or after conventional DMARDs only have failed. NICE technology appraisal guidance (TA375). 26 January 2016 [homepage on the Internet]. [cited 2017 Sep 22]. Available from: https://www.nice.org.uk/guidance/TA375/chapter/1-Recommendations

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