Difficulties Of Single Monoclonal Antibody Treatment Of SARS-CoV-2: The Sotrovimab Experience In Australia

The SARS-CoV-2 Omicron variant has spread around the globe at unprecedented speed. Neither prior infection nor multiple vaccinations impede transmission. One hope was that early treatment with monoclonal antibodies for those most susceptible to serious disease would reduce hospitalization and death. Unfortunately, Omicron has proved to be resistant to most FDA-approved monoclonal antibody treatments. Laboratory experiments suggested that at least one monoclonal antibody, sotrovimab retained significant activity. Unfortunately, recent data from Australia raises serious issues of sotrovimab as a stand-alone treatment. RockettĀ et al. demonstrate that resistance to sotrovimab as a monotherapy rises rapidly in treated patients. Moreover, they worry that such viable variants may also be highly resistant to existing vaccines.

Rockett et al. determined the sequence of virus isolated from patients treated with sotrovimab. A patient cohort of 100 received sotrovimab at a treatment center in New South Wales, Australia. The treatment was a single 500mg dose targeted at patients within five days of symptom onset thought to be at risk for severe disease progression. Of the initial 100 patients, 23 tested positive for SARS-CoV-2 infection at least 10 days post-infusion, and of these, the pre- and post-infusion respiratory tract samples of eight were collected. Of these eight, seven were hospitalized, six were partially vaccinated or unvaccinated, and four were given additional antibody treatment (Table 1).

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© William A. Haseltine, PhD. All Rights Reserved.