527. A Descriptive, Retrospective Analysis of COVID-19 Antibody Therapy and its Effects on Morbidity and Mortality in Patients Receiving B-cell Depleting Therapies

Abstract Background Patients receiving B-cell-depleting therapies (BCDT) are at an increased risk for severe COVID-19. Passive antibody therapy (PAT), including COVID-19 convalescent plasma (CCP) and monoclonal antibodies (MAB), is hypothesized to be an effective treatment in this population. However, real-world data on their effectiveness is limited. Methods We conducted a retrospective chart review of patients who contracted COVID-19 within a year from their last BCDT treatment and later received PAT (Table 1). Response to treatment was assessed by 90-day COVID-related mortality and all-cause morbidity, defined through number of hospitalizations (Figure 1).Table 1.Inclusion and exclusion criteria.Figure 1.Patient flow. Sixty-five patients met initial criteria. Five were excluded from analysis due to non-COVID related death within 90 days from COVID diagnosis. Cause of death was established in the chart and confirmed by review of two investigators. Results From 60 included patients, the majority were Caucasians (97%), females (57%), and vaccinated (67%) (Table 2). Most patients received rituximab (53%) for treatment of a hematological malignancy (37%) or multiple sclerosis (37%) (Figure 2). Overall morbidity (3/39, 7.7%) and mortality (3/60, 5%) were low. All hospitalized and deceased patients were elderly Caucasian males receiving rituximab for underlying hematological malignancy. All deceased patients received inpatient treatment, 2 with CCP and one with MAB (Figure 3).Table 2.Basic characteristics of passive antibody therapy recipients. Demographics, vaccination status and number of comorbidities excluding the condition which is the indication for B-cell depleting therapy.Figure 2.Type of B-cell depleting therapy and indication for use.Evaluated B-cell depleting therapies are rituximab (n=32), ocrelizumab (n=21), obinutuzumab (n=6), ofatumumab (n=1). Evaluated underlying indications for B-cell depleting therapy are hematological malignancy (n=22), multiple sclerosis (n=22); rheumatoid arthritis (n=9) and others (n=7). Others include scleroderma (n=1), systemic lupus (n=2), granulomatosis with polyangiitis (n=4).Figure 3:Treatment location and type of passive antibody therapy.All patients treated outpatient (39) received monoclonal antibodies. Of inpatients (21), 14 received COVID-19 convalescent plasma. Of patients treated as outpatient, 3 were hospitalized, with only 1 hospitalized for a COVID-related illness. Conclusion COVID-19 patients undergoing B