Systematic review of the clinical effectiveness of Tixagevimab/Cilgavimab for prophylaxis of COVID-19 in immunocompromised patients

Background and aimsImmunocompromised patients have a reduced ability to generate antibodies after COVID-19 vaccination and are at higher risk of SARS-CoV-2 infection, complications and mortality. Tixagevimab/Cilgavimab (Evusheld) is a monoclonal antibody combination which bind to the SARS-CoV-2 spike protein, preventing the virus entering human cells. The phase III PROVENT trial reported that immunocompromised patients given Tixagevimab/Cilgavimab had a significantly reduced risk of COVID-19 infection. However, PROVENT was conducted before the SARS-CoV-2 Omicron became prevalent. This systematic review provides an updated summary of real-world clinical evidence of Tixagevimab/Cilgavimab effectiveness in immunocompromised patients. MethodsTwo independent reviewers conducted PubMed and medRxiv searches for the period of 01/01/2021 to 01/10/2022. Clinical studies which reported the primary outcome of breakthrough COVID-19 infections after Tixagevimab/Cilgavimab administration were included in the review. COVID-19-related hospitalisations, ITU admissions and mortality were assessed as secondary outcomes. Clinical effectiveness was determined using the case-control clinical effectiveness methodology. The GRADE tool was used to ascertain the level of certainty for the primary outcome in each study. Results17 clinical studies were included, comprising 24,773 immunocompromised participants of whom 10,775 received Tixagevimab/Cilgavimab. Most studies reported clinical outcomes during the SARS-CoV-2 Omicron wave. Six studies compared a Tixagevimab/Cilgavimab intervention group to a control group. Overall, the clinical effectiveness of prophylactic Tixagevimab/Cilgavimab against COVID-19 breakthrough infection, hospitalisation and ITU admission were 40.47%, 69.23% and 87.89%, respectively. For prevention of all-cause and COVID-19-specifc mortality, overall clinical effectiveness was 81.29% and 86.36%, respectively. ConclusionsThere is a growing body of real-world evidence validating the original PROVENT phase III study regarding the clinical effectiveness of Tixagevimab/Cilgavimab as prophylaxis for immunocompromised patients, notably demonstrating effectiveness during the Omicron wave. This review demonstrates the clinical effectiveness of prophylactic Tixagevimab/Cilgavimab at reducing COVID-19 infection, hospitalisation, ITU admission and mortality for immunosuppressed individuals. It is important that ongoing larger-scale and better-controlled real world studies are initiated and evaluated to provide ongoing certainty of the clinical benefit of prophylactic antibody treatment for immunocompromised patients in the face of new variants.