Increased reporting of venous and arterial thromboembolic events reported with tixagevimab–cilgavimab for coronavirus disease 2019

OBJECTIVES: As two phase three clinical trials indicated a disproportion in the number of thromboembolic events in the tixagevimab/cilgavimab group than in the placebo group, there has been a cardiovascular safety concern with the use of anti–SARS-CoV-2 monoclonal antibody (mAb). Whether tixagevimab/cilgavimab use in real life increases the risk of thromboembolic events is unclear. METHODS: We used VigiBase, WHO's individual case safety reports database, to assess the risk of reporting arterial or venous thromboembolic events in patients with COVID-19 (aged ≥12 years) exposed to tixagevimab/cilgavimab compared with patients with COVID-19 exposed to other anti–SARS-CoV-2 mAbs, including casirivimab/imdevimab, bamlanivimab/etesevimab and sotrovimab. RESULTS: Among the 8952 reports of patients with an anti–SARS-CoV-2 mAb, 31 reports of thromboembolic events were associated with tixagevimab/cilgavimab, mainly deep vein thrombosis (10), pulmonary embolism (8) and myocardial infarction (7). Compared with other anti–SARS-CoV-2 mAbs, the use of tixagevimab/cilgavimab was associated with an increased risk of reporting arterial thromboembolic events (reporting OR 3.25; 95% CI 1.73, 6.10). Concerning venous thromboembolic events, a significant increase in the risk of reporting was observed with the use of tixagevimab/cilgavimab (reporting OR 3.59; 95% CI 2.16, 5.96). DISCUSSION: This observational study corroborates in a real-world setting in which the cardiovascular safety signal has already been found for tixagevimab/cilgavimab in two clinical trials. Owing to these thromboembolic safety concerns and considering the lack of clinical trials supporting protection against the omicron variant, there is an urgent need to improve knowledge on the effectiveness of tixagevimab/cilgavimab with new COVID-19 variants.