POS1097 RATES OF RELAPSES AND SERIOUS ADVERSE EVENTS IN PATIENTS WITH GPA OR MPA RECEIVING RITUXIMAB FOR MAINTENANCE THERAPY: A MULTICENTRE, RETROSPECTIVE STUDY
Authors: C. G. Gialouri, A. Chalkia, C. Koutsianas, K. Chavatza, E. Argyriou, A. Panagiotopoulos, A. Karamanakos, A. Dimouli, P. Orfanos, P. Lagiou, K. Thomas, C. Tsalapaki, G. Katsikas, K. Boki, D. Boumpas, D. Petras, D. Vassilopoulos
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> There are limited real-life data regarding relapses and serious adverse event (SAEs) rates in patients with microscopic polyangiitis (ΜPA) and granulomatosis with polyangiitis (GPA) receiving rituximab (RTX) for remission-maintenance. <h3>Objectives:</h3> To estimate the incidence of relapses and SAEs as well the factors associated with the time to relapse in MPA/GPA patients under RTX-maintenance. <h3>Methods:</h3> Retrospective study of newly diagnosed/relapsing GPA/MPA patients who received RTX-maintenance (≥1 RTX-cycle with ≥6 months follow-up) after complete-remission (BVASv3=0 plus prednisolone ≤7.5mg/day) with induction regimens had been achieved. Relapses (BVASv3&gt;0) were defined as major/minor, while SAEs included serious infections (SI), COVID-19-associated hospitalizations, deaths, cardiovascular events (CVE), malignancies and hypogammaglobulinemia. Incidence rates (IR) and relapse-free survival by Kaplan-Meier method were estimated while Cox-regression analysis was performed to investigate for factors associated with the time to first relapse. <h3>Results:</h3> Overall, 101 patients were included; GPA: 69%, 48% females, 53% newly diagnosed, median age: 63 years, C-/PR3-ANCA positive: 52% and p-/MPO-ANCA positive: 41%. During follow-up (294.5 patient-years, median [IQR] 3 [2-6] RTX-cycles), we identified 30 relapses in 24 patients (24%, IR 10.2/100 patient-years, 57% major). Up to the 3rd year from the first RTX-maintenance course, ~25% of patients had relapsed, while ~15% had experienced a major relapse (Figure 1). By Cox-regression analysis, renal involvement (adjusted-Hazard-Ratio-HR [95% Confidence-Interval]: 0.23 [0.06-0.78], p=0.019) and a higher number of RTX-administered cycles (adjusted-HR [95% CI]: 0.20 [0.09-0.44], p&lt;0.001) were independently associated with a lower risk of relapses. We also recorded 17 SIs in 14 patients (14%, IR 5.8/100 patient-years), 11 COVID-19-associated hospitalizations (IR 3.7/100 patient-years), 4 malignancies (IR 1.4/100 patient-years), 6 CVE (IR 2/100 patient-years) and 10 deaths (10%, IR 3.4/100 patient-years). Among patients with available IgG data (n=53), 41 (77%) had normal IgG levels at baseline, of which 8 (20%) developed hypogammaglobulinemia. The rate of SIs did not differ significantly between those who developed hypogammaglobulinaemia (2/8, 25%) and those who did not (6/33, 18%, p=0.642). <h3>Conclusion:</h3> In this real-life study, relapses occurred in approximately one quarter of GPA/MPA patients under RTX-maintenance. The time to first relapse was longer in those with renal involvement and those who received &gt;3 RTX cycles while a high rate of COVID19-associated hospitalizations was observed. Whether or not, longer duration of RTX maintenance therapy is required in these patients, needs to be examined in a randomized controlled trial. <h3>REFERENCES:</h3> [1] Delestre F et al. Rituximab as maintenance therapy for ANCA-associated vasculitides: pooled analysis and long-term outcome of 277 patients included in the MAINRITSAN trials. Ann Rheum Dis. 2023. [2] Smith RM et al. Rituximab versus azathioprine for maintenance of remission for patients with ANCA-associated vasculitis and relapsing disease: an international randomized controlled trial. Ann Rheum Dis. 2023;82(7):937-44. <h3>Acknowledgements:</h3> This work was supported in part by the Special Account for Research Grants, National and Kapodistrian University of Athens, Athens, Greece (DV #12085, 12086) and is conducted as a Master Thesis in Epidemiology – Research Methodology in biomedical sciences, clinical practice and public health (CG), Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine, National and Kapodistrian University of Athens. This study has been accepted to be granted by EULAR with a Research Voucher for publication support. <h3>Disclosure of Interests:</h3> <b>None declared.</b>