LAUSR

Background The etanercept (ETN) biosimilar SB4 was introduced in Sweden in 2016 at a lower price than the reference product etanercept (RPE). Now the reverse is true, as the price of RPE dropped. Switching ETN-treated patients to the lowest priced ETN available is economically favourable. The safety of multiple switches between RPE and biosimilar has been adressed in a psoriasis trial(,1 finding no indications of harm. No reports on outcomes of multiswitching in a rheumatology setting are available. Objectives To describe the impact of a clinic-wide switch from RPE to SB4 and then back to RPE on disease activity and drug-survival, relating outcomes to a historical cohort of RPE-treated patients. Methods Observational study of 145 patients switched from RPE to SB4 (day 0=20/4/2016) and back to RPE (day 544=16/10/2017) for economical reasons. Letters were mailed to patients on day 0 and 544, informing them that prescriptions had been changed from RPE to SB4 and from SB4 to RPE respectively. During days 1–543, clinicians were allowed to switch patients back to RPE if requested by the patient or if medically indicated. Disease activity data was entered into the Swedish Rheumatology Quality Register (SRQ) at visits. The SRQ was searched retrospectively for data from day −365 to 771 (May 31, 2018). Visits were categorised into visits occurring a) on days −365 to day 0, b) on days 1–543 and c) on days 544–771. A reference cohort of all RPE-treated patients on April 20, 2013 at the clinic was used for comparison. Results Numbers and proportions of patients discontinuing SB4 during days 1–543 in the switching cohort and RPE in the historical cohort are shown in the table 1. On day 544, the 97 patients still treated with SB4 were switched back to RPE. In the switching cohort, DAS28 and CRP did not change significantly when comparing data from visits occurring before the switch from RPE to SB4 to data from visits that occurred on days 1–543 and days 544–636 (figure 1). Data from 5 months of additional follow-up, up until day 771 will be presented at the congress. Among the 24 patients that discontinued SB4 during days 1–543 and went back to RPE, no worsening of disease activity parameters was seen during SB4 treatment. Switching cohort, n=145 Historical RPE-treated cohort, n=98 p Disontinued SB4/RPE, total* 48 (33) 15 (15) 0.002 ‡Back to RPE 24 (17) Not applicable N/A ‡No biologic 14 (10) 6 (6) 0.32 ‡Non ETN biologic 10 (7) 9 (9) 0.52 On ETN (SB4 or RPE) at day 544 121 (83) 83 (85) 0.80 *During days 1–543 ‡ Treatment after discontinuation of SB4/RPEAbstract THU0222 – Figure 1 Mean DAS28 and CRP with 95% CI for 145 patients in the switching cohort according to timepoint of visit..n:s refer to number of visits contributing to data during each period. Conclusions The strategy of multiswitching ETN-treated patients has thus far not impacted disease activity negatively in our population. An additional 5 months of follow-up data after the second switch will be presented at the congress. A high proportion of patients discontinued SB4 after the initial switch, as no worsening in disease activity measures was seen in the data we believe this to have been due to nocebo effects. Reference [1] Gerdes S, Thaci D, Griffiths CEM, Arenberger P, Poetzl J, Wuerth G, et al. Multiple switches between GP2015, an etanercept biosimilar, with originator product do not impact efficacy, safety and immunogenicity in patients with chronic plaque-type psoriasis: 30-week results from the phase 3, confirmatory EGALITY study. Journal of the European Academy of Dermatology and Venereology: JEADV2017. Disclosure of Interest None declared