Efficacy of Bamlanivimab/Etesevimab and Casirivimab/Imdevimab in Preventing Progression to Severe COVID-19 and Role of Variants of Concern.

ABSTRACT

INTRODUCTION: The aim of this study was to evaluate the risk of hospitalization or death in patients infected by SARS-CoV2 variants of concern (VOCs) receiving combinations of monoclonal antibodies (mAbs), bamlanivimab/etesevimab or casirivimab/imdevimab. METHODS: Observational prospective study conducted in two Italian hospitals (University Hospital of Pisa and San Donato Hospital, Arezzo) including consecutive outpatients with COVID-19 who received bamlanivimab/etesevimab or casirivimab/imdevimab from March 20th to May 10th 2021. All patients were at high risk of COVID-19 progression according to FDA/AIFA recommendations. Patients were divided into two study groups according to the infecting viral strain (VOCs) Alpha and Gamma group. The primary endpoint was a composite of hospitalization or death within 30 days from mAbs infusion. A Cox regression multivariate analysis was performed to identify factors associated with the primary outcome in the overall population. RESULTS: The study included 165 patients 105 were infected by the VOC Alpha and 43 by the VOC Gamma. In the Alpha group, no differences in the primary endpoint were observed between patients treated with bamlanivimab/etesevimab or casirivimab/imdevimab. Conversely, in the Gamma group, a higher proportion of patients treated with bamlanivimab/etesevimab met the primary endpoint compared to those receiving casirivimab/imdevimab (55% vs. 17.4%, p = 0.013). On multivariate Cox-regression analysis, the Gamma variant and days from symptoms onset to mAbs infusion were factors independently associated with higher risk of hospitalization or death, while casirivimab/imdevimab was protective (HR 0.33, 95% CI 0.13-0.83, p = 0.019). CONCLUSIONS: In patients infected by the SARS-CoV-2 Gamma variant, bamlanivimab/etesevimab should be used with caution because of the high risk of disease progression.