292 Switching to biosimilar rituximab: a real world study

Abstract

Background: Since the introduction of anti-TNF biosimilars in routine clinical practice, there has been a drive to implement the switch programme for all biosimilars at the point of availability. Rituximab biosimilar was granted marketing authorisation by the EMA in February 2017. Our Trust was one of the first centres to receive a CQUIN which required adoption of biosimilar within three months for new patients and one year for switchers. We report our early experience of introducing rituximab biosimilar in people with RA. Methods: A list of all patients prescribed rituximab was extracted through our database. A switch letter was drafted and sent to all patients including Truxima information sheet. Patients were given the opportunity to contact nurse helpline for information or if disease control worsened/adverse effects developed. We reviewed all relevant records and collected data on any adverse events and disease outcome on either side of the switch. Patients were reviewed as originally planned by their respective clinicians. Results: 44 patients were identified established on rituximab. Four had stopped treatment prior to switching. One female had it for GPA and was continued on the innovator. All 39 agreed to switch and were on 2g dose six-monthly. Until October 2017, 24/39 (61.5%) had switched to biosimilar. Median age of switchers was 60 (range 26-80 years). Three were men and remaining 21 (87.5%) were women. Seven (29%) were Asian, one Afro-Caribbean and the rest 16 (66%) were White Caucasian. DAS28 scores were available for all prior to the switch (median 3.0, range 0.6-5.1). However only nine had been reviewed face-to-face following the switch with DAS28 calculated. Their median DAS28 prior to the switch was 3.1 (range 1.6-4.5). Following the switch it was 2.9 (range 1.6-5.5). Amongst these nine, 5/ 24 (20%) had severe serum sickness reaction within the first week of the second dose with loss of efficacy. Two required admission to ED (<24 hrs) for further management. Four decided against further biosimilar and requested to return to the originator. No obvious precipitating factors were identified. Conclusion: Our experience of switching rituximab patients is certainly not as smooth as it was for infliximab and etanercept. All were happy to switch after receiving a letter and having the opportunity to contact if necessary. Substantial annual cost savings of £156,659.10 would have been achievable once all 39 patients have switched. At group level there were no major differences in disease outcomes and 80% reported no issues. However, 20% had severe serum sickness with loss of efficacy and loss of confidence in the drug. We support the routine switching from originator to biosimilar rituximab however close monitoring is required certainly in the first week of dose adminstration.