Background Rituximab is a safe and effective treatment in RA, however the current treatment regimen requires to wait for a clinical relapse before a new course of treatment. The interval between two courses of treatment varies from one patient to another and remains unknown prior to the treatment. Our aim was to evaluate the utility of following-up different B cells subtypes depletion as a tool to foresee RA clinical relapse.
Objectives To assess the usefulness of periodical B cell analysis to determine if it may predict clinical relapse of RA in patients treated with rituximab.
Methods Prospective single-center observational study of 39 patients with RA treated with rituximab 1g twice 15 days apart. Patients were monitored clinically and biologically every 2 months until retreatment. Clinical assessment consisted of RA activity and report of adverse event, biological assessment consisted of inflammatory parameters, antibodies, gammaglobulins titers and B cell analysis. The clinician was blinded of the B cell analysis results. Chi 2 test was used for comparison between B cell population before and after treatment, and univariate logistic regression was used to determine relative risk of clinical relapse if B cell are detected in peripheral blood.
Results 39 patients were included from March 2010 to December 2011 with a follow-up until December 2012. 7 patients had two course of treatment and a total of 46 cycles of rituximab were analysed. At baseline mean DAS 28 was 5,35 ; 33 patients were RF and/or anti-CCP2 antibody positive. At 6 months, 44 patients (96%) had a good-to-moderate clinical response according to the EULAR criteria. The mean treatment duration was 13 months.
After the two infusions, total number of CD19+ cells decreased (0.155G/l vs 0.0002G/l, p<0.0001) with a complete depletion for all patients in the memory (CD19+27+) and transitional subtypes (CD19+CD38++CD24++) (p<0.0001). At relapse B cells had return in 36 patients, p=0.03. When transitional and memory B cell repopulation is detected risk of relapsing in the four months that follow is 10 times higher, RR 10.2 [1.35-76.93] p=0.01.
Conclusions Presence of transitional and memory B cell predicts a relapse in the four months that follows repopulation.
Disclosure of Interest: None Declared