Pre-exposure prophylaxis with tixagevimab/cilgavimab for coronavirus disease 2019 (COVID-19) during the Omicron BA.5 wave at a single institution in Japan.

Pre-exposure prophylaxis with tixagevimab/cilgavimab was considered a useful strategy to protect immunocompromised patients from COVID-19 based on the phase 3 PROVENT trial conducted between November 2020 and March 2021. However, after late 2021, the dominant substrains of COVID-19 changed to Omicron substrains, which showed resistance to tixagevimab/cilgavimab. Therefore, it is important to re-evaluate the real-world efficacy of tixagevimab/cilgavimab for the prevention of COVID-19 in the Omicron era. To this end, we retrospectively evaluated the efficacy and safety of tixagevimab/cilgavimab prophylaxis for COVID-19 during the Omicron BA.5 wave in Japan. A total of 240 consecutive patients with hematologic malignancies received tixagevimab/cilgavimab at our institution from October 18, 2022, to January 31, 2023. Among them, the cumulative incidence of COVID-19 at 90 days was 6.4%. A total of 10/14 (71.4%) had mild infection, and 4/14 (28.5%) had severe infection. No patient died due to COVID-19. Adverse events consisted of deep vein thrombosis in 2 patients. Our analysis indicated that pre-exposure prophylaxis with tixagevimab/cilgavimab might have clinical effectiveness in reducing the severity of COVID-19 in Japanese HM patients, even in the Omicron BA.5 surge. It also suggested that tixagevimab/cilgavimab may be associated with cardiovascular complications.