LAUSR

Background Recent in-vitro data have shown that the activity of monoclonal antibodies (mAbs) targeting SARS-CoV-2 varies according to the Variant of Concern (VOC). No studies have compared the clinical efficacy of different mAbs against Omicron VOC. Methods The MANTICO trial is a non-inferiority randomised controlled trial comparing the clinical efficacy of bamlanivimab/etesevimab, casirivimab/imdevimab, and sotrovimab in outpatients aged 50 or older with early COVID-19. As the patient enrolment was interrupted for possible futility after the onset of the Omicron wave, the analysis was performed according to the SARS-CoV-2 VOC. The primary outcome was COVID-19 progression (hospitalisation, need of supplemental oxygen therapy, or death through day 14). Secondary outcomes included the time to symptom resolution, assessed using the product-limit method. Kaplan-Meier estimator and Cox proportional hazard model were used to assess the association with predictors. Log rank test was used to compare survival functions. Results Overall, 319 patients were included. Among 141 patients infected with Delta, no disease progression was recorded and the time to symptom resolution did not differ significantly between treatment groups (Log-rank Chi-square 0.22, p 0.895). Among 170 patients infected with Omicron (80.6% BA.1, 19.4% BA.1.1), two disease progressions were recorded in the bamlanivimab/etesevimab group and the median time to symptom resolution was 5 days shorter in the sotrovimab group compared to bamlanivimab/etesevimab and casirivimab/imdevimab (HR 0.526 and HR 0.451, 95% CI 0.359 - 0.77 and 95% CI 0.303 - 0.669, p 0.001 and 0.0001, respectively). Conclusions These results confirm the in-vitro data of superiority of sotrovimab versus casirivimab/imdevimab and bamlanivimab/etesivamab in reducing the time to recovery in patients infected with Omicron BA.1 and BA.1.1, while no difference was detected in Delta infections. Casirivimab/imdevimab seems to maintain a role in preventing severe COVID-19 in the Omicron population. Adaptive clinical trials comparing mAbs by VOC should be pursued to promptly inform clinical recommendations.