P139 Rituximab in a large UK centre during the COVID-19 pandemic: the effects of employing a reduced dosing regimen on clinical response in Rheumatoid Arthritis patients

Background/Aims When the COVID-19 pandemic began, steps were taken to minimise risk to those vulnerable to severe outcomes. For immunosuppressed patients with rheumatoid arthritis (RA), consideration was given to reducing risk whilst mindful of compromising control of their underlying condition. At Leeds Teaching Hospitals NHS Trust, patients receiving rituximab (RTX) were considered for a reduced dose regimen. A retrospective study, using real-world data, was undertaken to assess the impact of lower doses of RTX on response to treatment. Methods The clinical records of all patients with RA who had received RTX between March 2020 and March 2021 were reviewed. Demographics and previous RTX exposure were recorded. The dose of RTX given during the specified period was noted. Response to treatment was recorded pragmatically by physicians as good, partial or none, based on patient reported VAS for disease activity and swollen and tender joint counts, given the limitations placed on face-to-face patient review due to the pandemic. The time to subsequent RTX treatment and the need for steroid treatment for flares was also studied. Results The number of patients treated with RTX was 282, of whom 89 patients received full dose (1g x 2 infusions), 192 patients received half dose (500mg x 2 infusions). The mean age was 61 years. 77% were female. 9% were RTX-naive, 80% had previously had full dose. Follow-up data were available for 185/192 of the group receiving 1g and 88/89 of the group receiving 2g. Clinical outcomes were as follows for the two groups (1g RTX vs 2g RTX): no response 10.3% vs 9.1%; partial response:34.9% vs 20% %; good response: 54.8% vs 70.9%. The mean length of response was 7.5 months in the patients receiving 1g of RTX compared to 8.6 months in the group receiving 2g of RTX. Similar number of patients required steroid for a flare after receiving Ig of RTX (23.9%) compare to those receiving 2g of RTX (25.8%). Conclusion A majority of patients receiving RTX for RA at either standard or reduced dose reported clinical response. Those receiving lower dose RTX were more likely to report a partial response whilst those receiving full dose were more likely to report a good response. Duration of response and need for steroid therapy for flare of RA between treatments did not significantly differ between groups. Further analysis of factors that may influence clinical response to lower dose RTX is ongoing, which could guide tailored therapy regimens should the need arise again. Disclosure J. McLorinan: None. M. Slade: None. C. Leong: None. J. Baker: None. L. Bailey: None. J. Nam: None. L. Bissell: None. P. Emery: None. S. Dass: None. B. Saleem: None.