THU0192 Retention rates for etanercept: comparing the original with a biosimilar
Authors: A. Strangfeld, L. Baganz, P. Herzer, J. Braun, A. Gräßler, A. Zink
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Since the first approval of a biosimilar in 2015, the number of biosimilars approved for the treatment of rheumatoid arthritis (RA) in Germany has been increasing. Until now, there are just a few analyses investigating retention rates of biosimilars and the respective originators. <h3>Objectives</h3> To compare treatment survival on SB4 to the originator etanercept (oETN) using real-world data. <h3>Methods</h3> We used data gathered until December 2017 from the prospective, longitudinal RABBIT (<b><i>R</i></b>heumatoid <b><i>A</i></b>rthritis: O<b><i>b</i></b>servation of <b><i>bi</i></b>ologic <b><i>t</i></b>herapy) cohort. RA patients are enrolled in RABBIT when they start a biologic, biosimilar or new csDMARD treatment. For comparative analyses, patients starting SB4 either at enrollment or during follow-up were compared to patients enrolled with oETN since 2015. The drug survival rates during the first six months were analysed in biologic naive patients prior to enrollment using Kaplan-Meier curves. <h3>Results</h3> Overall, 283 patients were included in the register starting SB4 and 369 with oETN. Another 355 patients who had already been enrolled in RABBIT switched to SB4 during follow up. Compared to oETN patients, those enrolled with SB4 had slightly lower disease duration (8 vs. 9 years) and significantly fewer patients had three or more comorbidities (40% vs. 47%, p=0.04). 88% (n=250) of patients enrolled with SB4% and 86% (n=317) enrolled with oETN were bionaive. Out of all patients who started SB4 during follow up, 40% had been treated with oETN, and 39% with another biologic before switching. 21% had received csDMARD or no drug treatment before treatment start. Kaplan-Meier curves show comparable retention rates over 6 months for SB4 and oETN (figure 1). Adjusting the curves for disease duration and comorbidities had no significant influence on the results. 8% (n=20) of bionaive SB4 patients and 17% (n=54) of bionaive oETN patients stopped treatment during the first 90 days. Additional 6% (n=14, SB4)/15% (n=46, oETN) stopped the treatment within 180 days after enrolment. The reasons for discontinuation of both treatments were adverse events (AE) in 59% (n=20, SB4)/49% (n=49, oETN) and loss of response in 26% (n=9, SB4)/31% (n=31, oETN). The most common cause for discontinuation within 180 days due to AE were skin reactions at the injection site in 35% (7 of 20)of SB4, and 49% (24 of 49) of oETN patients). <h3>Conclusions</h3> The retention rates for bionaive patients starting either the biosimilar SB4 or the originator oETN were similar. The distribution of adverse events was also comparable. A selection bias cannot fully be ruled out since patients on oETN had more comorbidities. <h3>Acknowledgements</h3> <b>Disclosure:</b> RABBIT is supported by a joint, unconditional grant from AbbVie, Bristol-Myers Squibb, Celltrion, Hexal, Lilly, MSD Sharp and Dohme, Pfizer, Roche, Samsung Bioepis, Sanofi-Aventis und UCB. <h3>Disclosure of Interest</h3> A. Strangfeld Speakers bureau: AbbVie, BMS, Lilly, MSD, Pfizer, Roche and UCB, L. Baganz: None declared, P. Herzer Speakers bureau: Pfizer, J. Braun: None declared, A. Gräßler: None declared, A. Zink Speakers bureau: BMS, Lilly, Pfizer, Roche, UCB