Background The etanercept biosimilar SB4 was introduced in Sweden in early 2016. SB4 has been shown in a randomized controlled trial to be equivalent to its etanercept reference product (ERP) in terms of efficacy and safety in subjects with active rheumatoid arthritis (RA) (1). In light of this, and the fact that biosimilars offer considerable cost savings, all patients being treated with ERP at our clinic were switched to treatment with SB4 in april 2016.
Objectives To describe the clinical experiences of switching patients on treatment with ERP to SB4 at our clinic.
Methods All patients using ERP 50 mg at our clinic were identified using the Swedish Rheumatology Quality Register (SRQ). The patients were issued prescriptions for SB4 50 mg and were sent a letter encouraging them to switch to SB4 when they ran out of ERP. The process of switching was started 21st. However, the actual date of starting treatment with SB4 might have been 0–90 days from April 20th for individual patients, as prescriptions are written in 3 month increments.
Patients were followed up clinically and in the SRQ as planned at the last visit before switching.
For RA and psoriatic arthritis (PsA) patients DAS28 values from the last visit preceding the switch and the last visit after the switch registered up to January 2017 were collected from the SRQ. The paired T-test was used to compare mean DAS28 before and after switching.
Results Before the switch, 147 patients were on treatment with ERP. Indications for treatment were RA (N=76), PsA (N=28), other spondyloarthritis (N=13), ankylosing spondylitis (N=12), unspecified arthritis (N=10) and juvenile arthritis (N=8).
At the end of January 2017, 126 patients (86%) were still on SB4.
Since the switch, 9 patients have requested to be switched back to ERP, 2 made the request before initiating therapy with SB4. No objective evidence for lack of efficacy was seen in these 9 patients. Seven patients have stopped treatment with SB4 because of inactive disease. Five patients have been switched to a non-etanercept biologic because of lack of efficacy, these patients also had lack of efficacy when on ERP.
The 76 RA patients had a mean disease duration of 17 years and had been on ERP for a mean duration of 4.7 years. As of January 2017, 60 of the RA patients have been on a follow-up visit and 54 of these had available DAS28 data from both the last visit before and after switching. For the RA patients DAS28 was 2.80 before and 2.79 after switching, p=0.960. Complete DAS28 data was available for 23 of the 28 PsA patients, mean DAS28 was 2.54 before switching and 2.06 after, p=0.161. The mean duration since switching at follow-up was 22 weeks for the RA and PsA patients.
Conclusions Switching from the etanercept reference product to the biosimilar SB4 was acceptable to most of our patients. Low mean disease activity has been maintained in the RA and PsA group after the switch.
Emery P, Vencovsky J, Sylwestrzak A, Leszczynski P, Porawska W, Baranauskaite A, et al. A phase III randomised, double-blind, parallel-group study comparing SB4 with etanercept reference product in patients with active rheumatoid arthritis despite methotrexate therapy. Annals of the Rheumatic Diseases. 2017;76(1):51–7.
Disclosure of Interest None declared