Tixagevimab/cilgavimab for the prevention of COVID-19 in vaccine-refractory patients with autoimmune diseases: a prospective cohort study.

OBJECTIVES: To investigate the effects of passive immunization with the anti-SARS-CoV-2 monoclonal antibodies tixagevimab/cilgavimab on humoral responses and on COVID-19 outcomes in vaccine-refractory patients with immune-mediated inflammatory diseases (IMID) at high risk of severe COVID-19. METHODS: A prospective cohort study was performed on a cohort of high-risk vaccine-refractory IMID patients treated with a single dose of tixagevimab/cilgavimab (150 mg/150 mg). COVID-19 outcomes as well as serum and salivary anti-SARS-CoV-2 IgG were assessed at baseline and for at least 6 months. Results were compared with an untreated high-risk vaccine-refractory IMID population. Standardised incidence ratios (SIR) of COVID-19 compared with the general population were calculated for both groups. RESULTS: 38 high-risk IMID patients received tixagevimab/cilgavimab and were compared with 114 untreated high-risk IMID controls. Serum anti-Spike IgG increased to 6.6 OD (SD: ±0.8) at day one and remained positive up to month 6 (6.3 ± 1.4 OD). Salivary anti-Spike IgG peaked at month 2 (1.6 ± 1.1 OD)) and decreased from month 3 (0.8 ± 0.3 OD)). No severe or extended infection was observed in the tixagevimab/cilgavimab group. Compared with the general population, the SIR of COVID-19 in treated patients was 0.76 (95% CI: 0.24-1.58) despite the increased risk profile. The SIR of the control group was 1.51 (1.07-2.02), corresponding to a significantly increased incidence. CONCLUSIONS: Passive immunization with tixagevimab/cilgavimab is safe and effective in inducing anti-SARS-CoV-2 immunity and potentially in preventing COVID-19 in high-risk vaccine-refractory IMID patients. These data provide a proof of concept for the use of monoclonal antibodies as a preventative strategy against SARS-CoV-2 in vulnerable populations.