SAT0144 UNDERSTANDING THE LONG-TERM OUTCOME OF RITUXIMAB – IMPLICATIONS FOR MANAGEMENT
Authors: Leticia Garcia-Montoya, MD Yuzaiful MD Yusof, Jean Baptiste Candelier, Andrew Rawstron, Edward Vital, Paul Emery
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> In patients with rheumatoid arthritis (RA), rituximab (RTX) is often prescribed after loss of response to TNF inhibitors; however, little is known about the long-term outcome of patients receiving treatment with RTX. Previous work [1,2] has shown that aiming for "complete B-cell depletion with clinical response" (CD-R) leads to an optimal management of the disease but unfortunately not all patients maintain this status. Whether CD-R can be regained with RTX retreatment remains unclear. <h3>Objectives:</h3> To assess the outcome of RA patients treated with consecutive cycles of RTX, focusing on those who achieved complete B-cell depletion with clinical response. <h3>Methods:</h3> A prospective 12 year observational study was conducted in RA patients who were treated with RTX in Leeds. Consecutive cycles of RTX consisting of 2 infusions of 1000mg were administered either on clinical relapse or a 6-monthly basis. B-cells were measured using highly sensitivity flow cytometry at 0 and 2 weeks post-RTX. Complete depletion (CD) was defined by total B-cell count &lt;0.0001x10<sup>9/</sup>L at week 2. Clinical response was defined by EULAR response criteria and CD-R was seen as the optimal outcome. <h3>Results:</h3> 755 patients participated in the study of which 723 had complete data (see fig.1). The mean (range) number of RTX cycles administered was 3.8 (1-14). 76% (549/723) of patients reached CD-R at some stage during therapy while 24% (174/723) never did. The latter patients had a shorter period of RTX treatment vs CD-R with an OR of 7.98 after adjusting for age, gender, prior therapy with TNF-I and concomitant DMARDs (95% CI 5.86-10.86); p&lt;0.001 (see fig.2). 84% of those who were retreated with RTX recovered CD-R (77% of them did it in the following cycle). Half of the patients that reached CD-R maintained it in prospective cycles but 47% lost it subsequently. A third of the patients that lost either clinical response or B-cell depletion were switched to other medication without receiving further cycles. Overall, at the end of the study, 55% of all patients treated with RTX (400/723) remained in CD-R. <h3>Conclusion:</h3> Most patients treated with RTX will achieve CD-R, but approximately half of them will lose this optimal status at some point. In patients who achieve CD-R but subsequently lose it, retreatment with RTX appears to be an effective strategy since 80% of them will regain it and will maintain long-term treatment with therapy <h3>References</h3> [1] Md Yusof, et al. EULAR2016 [2] Garcia-Montoya, et al. EULAR2018 <h3>Acknowledgement:</h3> Shouvik Dass Maya Buch Sarah Bingham <h3>Disclosure of Interests:</h3> Leticia Garcia-Montoya: None declared, Md Yuzaiful Md Yusof: None declared, Jean Baptiste Candelier: None declared, Andrew Rawstron: None declared, Edward Vital Grant/research support from: He has received honoraria and research grant support from Roche, GSK and AstraZeneca., Paul Emery Grant/research support from: Pfizer, MSD, AbbVie, Bristol-Myers Squibb, Roche, Consultant for: Pfizer, MSD, AbbVie, Bristol-Myers Squibb, UCB, Roche, Novartis, Gilead,Samsung, Sandoz and Lilly