530. Bamlanivimab (BAM) for SARS-CoV-2 Infection: Rates and Risk Factors for Hospitalization after Monoclonal Antibody Administration in a High-Risk Population

BACKGROUND: In response to the ongoing COVID-19 pandemic, an emergency use authorization (EUA) was issued for neutralizing antibody therapies including BAM. Licensing trials suggest that use of BAM reduces hospitalizations when compared with placebo (1.6% vs 6.3%). However, the real world impact of BAM is not well-described. In this study, risk factors, outcomes, and hospitalization rates among high-risk outpatients presenting with mild-to-moderate COVID-19 who received BAM were examined. METHODS: This is a single center retrospective analysis of all patients who received BAM monotherapy between 11/11/2020 and 3/16/2021. Electronic health records were reviewed for baseline demographics, EUA indications, comorbidities, and outcomes to include infusion reactions, hospitalizations, and deaths occurring within 29 days of BAM administration. Moderate COVID-19 was defined as having any infiltrate on chest imaging prior to BAM administration. Chi-squared or Fisher’s exact tests were used to compare categorical values as appropriate, and Mann-Whitney U for continuous variables. RESULTS: Of the 101 patients who received BAM (median age 64 years; 21% black; 4% Hispanic; 55% male), 13 were subsequently admitted. 22 patients (22%) had moderately severe disease as evidenced by abnormal imaging. Severity on presentation, number of indications for therapy, hypertension, stroke, diabetes, and number of co-morbidities were significantly associated with subsequent admission (table 1). No patients had adverse infusion reactions. Of those hospitalized, 8 (61.5%) were for COVID-19, the median duration of hospitalization was 2 days, and 4 received guideline-directed treatment for COVID-19 (table 2). Table 1. Factors Associated with Hospitalization Following Bamlanivimab (BAM) Administration [Image: see text] Table 1. (Continued) Factors Associated with Hospitalization Following Bamlanivimab (BAM) Administration [Image: see text] Table 2: Characteristics and Resource Utilization of Patients Hospitalized After Bamlanivimab Therapy (n=13) [Image: see text] CONCLUSION: In a high-risk population, hospitalization rates were higher than those observed in clinical trials, with 8% of subjects being admitted for COVID-19. Disease severity on presentation, multiple indications for therapy, and the presence of multiple co-morbidities were all associated with subsequent admission. Reassuringly, BAM was well tolerated, and in those requiring admission, hospitalizations were short, resource utilization was low, and there were no deaths. DISCLOSURES: Benjamin L. Custer, M.D., Alexion Pharmaceuticals (Shareholder)Armata Pharmaceuticals (Shareholder)Biomarin Pharmaceutical (Shareholder)Crispr Therapeutics (Shareholder)CVS Health Corp (Shareholder)Editas Medicine (Shareholder)Gilead (Shareholder)Glaxo Smith Kline (Shareholder)Hologic Inc (Shareholder)Merck (Shareholder)Mesoblast LTD (Shareholder)Pfizer (Shareholder)Sanofi (Shareholder)Unitedhealth Group (Shareholder)Vertex Pharmaceuticals (Shareholder) Dana M. Blyth, MD, Nothing to disclose