Clinical and Virological Outcome of Monoclonal Antibody Therapies Across SARS-CoV-2 Variants in 245 Immunocompromised Patients: A Multicenter Prospective Cohort Study

Background: Immunocompromised patients (ICPs) have an increased risk for a severe and prolonged COVID-19. SARS-CoV-2 monoclonal antibodies (mAbs) were extensively used in these patients, but data from randomized trials that focus on ICPs are lacking. We evaluated the clinical and virological outcome of COVID-19 in ICPs treated with mAbs across SARS-CoV-2 variants.

Methods: In this multicenter prospective cohort study, we enrolled B-cell- and/or T-cell-deficient patients treated with casirivimab/imdevimab, sotrovimab, or tixagevimab/cilgavimab. SARS-CoV-2 RNA was quantified and sequenced weekly, and time to viral clearance, viral genome mutations, hospitalization, and death rates were registered.

Results: Two hundred and forty five patients infected with the Delta (50%) or Omicron BA.1, 2, or 5 (50%) variant were enrolled. Sixty-seven percent were vaccinated; 78 treated as outpatients, of whom 2 required hospital admission, but both survived. Of the 159 patients hospitalized at time of treatment, 43 (27%) required mechanical ventilation or died. The median time to viral clearance was 14 days (interquartile range, 7-22); however, it took >30 days in 15%. Resistance-associated spike mutations emerged in 9 patients in whom the median time to viral clearance was 63 days (95% confidence interval, 57-69; P < .001). Spike mutations were observed in 1 of 42 (2.4%) patients after treatment with 2 active mAbs, in 5 of 34 (14.7%) treated with actual monotherapy (sotrovimab), and 3 of 20 (12%) treated with functional monotherapy (ie, tixagevimab/cilgavimab against tixagevimab-resistant variant).

Conclusions: Despite treatment with mAbs, morbidity and mortality of COVID-19 in ICPs remained substantial. Combination antiviral therapy should be further explored and may be preferred in severely ICPs.