E054 Rituximab dose minimisation in rheumatoid arthritis, a retrospective outcome analysis

Abstract Background/Aims Rituximab was originally developed as a non-Hodgkin lymphoma treatment and rheumatology adopted the same dosing for rheumatoid arthritis(RA); two 1000mg doses two weeks apart for each maintenance cycle. UHSussex utilises self-referral for maintenance rituximab dosing once disease control lessens. Evidence demonstrates patients treated with lower dose rituximab still enjoy good disease control with less immunosuppression, reduced hospital attendance and reduction in drug expenditure. Following one two-dose cycle, stable RA patients were prescribed a single 1000mg dose from 2020 onwards. A retrospective outcome analysis was completed in August 2022; however, results were highly impacted by Covid-19 and a repeat analysis was required. Aim: to assess impact of a single 1000mg dose rituximab regime on patient sustained outcomes, dose intervals, Disease Activity Scores (DAS) and drug expenditure. Methods The pharmacy database was used to identify RA patients receiving rituximab from March 2020 to August 2023. Patients received at least one standard two-dose cycle before switching to a single infusion. Patients were excluded if lost to follow up (under care of rheumatology for less than a year following dose switching) or considered clinically unstable. Patient letters and departmental records were accessed for disease scores and treatment intervals. Results Table1: Results from the two analysis periods From the original cohort (31/59)53% remained on single dosing. Switch back tended to occur within 18 months of switching. DAS scores were not collected reliably and were omitted. Conclusion Covid-19 impacted services and attitudes during the initial study period. Many patients stopped treatment, particularly rituximab, due to the prolonged duration of effect, excluding them from analysis. The dose-interval increase during the first analysis was considered a result of the pandemic. Patients and clinicians delayed infusions; minimising immunosuppression due to perceived increased risk of Covid-19. The continued interval increase in the second analysis may identify a patient cohort in deep remission eligible for therapy review. The study highlights poor practice in collecting and recording DAS scores and appropriate patient-clinician interaction opportunities. 53% of patients remained on single infusions in August 2023 resulting in resource savings, reduced hospital attendance, immunosuppression and significant cost savings demonstrating the rationale for this option. Disclosure S. Butler: Honoraria; Abbvie, Janssen. H. Smith: Honoraria; Novartis, Abbvie.