#3767 THE IMPACT OF COVID-19 PANDEMICS ON THE OUTCOME OF 24 CHINESE PATIENTS DIAGNOSED OF MEMBRANOUS NEPHROPATHY RECEIVING RITUXIMAB THERAPY

Abstract Background and Aims Rituximab has been considered as the first-line immunosuppressive therapy in membranous nephropathy. Anti-CD20 depleting therapy is associated with prolonged B-cell depletion and has been reported to increase risk of severe COVID-19 infection in several rheumatic and neurologic diseases. However, few studies reported the impact of COVID-19 infection on membranous nephropathy in the status of B-cell depletion. Our study aimed to describe the impact of prior rituximab therapy on clinical outcomes of a group of Chinese membranous nephropathy within 6-month follow-up during COVID-19 pandemics. Method We prospectively conducted a cohort study of adult patients diagnosed of membranous nephropathy receiving rituximab therapy from Aug 1st to Nov 30th in 2022, in one tertiary hospital, in Beijing. Patients’ baseline characteristics (including demographic data, serum albumin, serum creatinine, 24-hour proteinuria, serum IgG level, peripheral lymphocyte subsets, medications, past medical history, prior COVID-19 vaccination history), clinical outcomes were recorded. We followed up all the patient regularly until Jan 31st, 2023. Results We included 24 patients with median age of 55 (27, 83) years old. 13 (54.2%) patients were on chronic immunosuppression with corticosteroids, calcineurin inhibitors, and/or mycophenolate mofetil. We followed up the patients within median 4.6 months since last rituximab infusion at the dose of 1 gram. During follow-up, 18 (75%) patients got COVID-19 infection including 16 non-severe cases and two severe cases requiring hospitalization and receiving intravenous dexamethasone. The overall COVID-19 vaccination rate was 33%. In subgroup analysis, the baseline characteristics were comparable between COVID-19 infection group and non-infection group. Vaccination rate in COVID-19 infection group was lower than that in non-infection group insignificantly (28% vs 50%, P=0.362), and the two cases of severe infection were unvaccinated with severe hypoimmunoglobulinemia. Circulating natural killer cell counts were significantly different between the two groups (365(63, 745) vs 194(23, 928)/μl, P=0.019), while neither CD4+T cells nor CD8+T cells counts showed statistically difference between the counterparts (CD4+T cells: 632 (227, 1231) vs 407 (230, 571)/μl, P=0.05; CD8+T cells: 496 (134, 1815) vs 306 (127, 728)/μl, P=0.179). No relapse of membranous nephropathy was observed after infection during follow-up. Conclusion COVID-19 infection was common in Chinese membranous nephropathy receiving recent administration of rituximab during COVID-19 pandemics. Low vaccination rate and prolonged B-cell depletion after rituximab infusion in this population may attenuate the protective effect of COVID-19 vaccine. Nature killer cells may play a key role in antiviral immunity. Patients should continue to maintain a high adherence to preventive measures against COVID-19.