AstraZeneca’s Evusheld (tixagevimab co-packaged with cilgavimab), a long-acting antibody combination for the prevention of COVID-19, retained neutralising activity against the Omicron SARS-CoV-2 variant (B.1.1.529), according to new preclinical data.
In this study, Evusheld’s Inhibitory Concentration 50 (IC50), a measure of neutralising potency of an antibody, was 171 ng/ml and 277 ng/ml in two confirmatory tests, which is within the range of neutralising titres found in someone who has been previously infected with coronavirus. Evusheld’s IC50 for the original strain of SARS-CoV-2, previously referred to as the Wuhan strain, was approximately 1.3 ng/ml and 1.5 ng/ml, respectively.
The early data, generated by pseudovirus testing of the full Omicron variant spike against the combination of tixagevimab with cilgavimab, the antibodies that comprise Evusheld, add to the growing body of preclinical evidence demonstrating that Evusheld retains activity against all tested variants of concern to date.
The study was performed independently by investigators at the US Food and Drug Administration (FDA), Center for Biologics Evaluation and Research. The work was supported by US government research funds.
Mene Pangalos, Executive Vice President, BioPharmaceuticals R&D, AstraZeneca, said: “This study shows Evusheld retains neutralisation activity against the Omicron variant. By combining two potent antibodies with different and complementary activities against the virus, Evusheld was designed to evade potential resistance with the emergence of new SARS-CoV-2 variants. Evusheld is the first long-acting antibody to receive emergency use authorisation in the US for pre-exposure prophylaxis of COVID-19, in addition to authorisations in other countries, and we are working with regulators on applications for the use of Evusheld in treating COVID-19.”
The Omicron variant was not in circulation during the Evusheld clinical trials. The Company is continuing to collect further data to better understand the implications of this observation in clinical practice. Additional analyses to evaluate Evusheld against the Omicron variant are being conducted by AstraZeneca and third-party laboratories, with data anticipated very soon.
Evusheld received Emergency Use Authorization (EUA) in the US in December 2021 for pre-exposure prophylaxis (prevention) of COVID-19 in people with moderate to severe immune compromise due to a medical condition or immunosuppressive medications and who may not mount an adequate immune response to COVID-19 vaccination, as well as those individuals for whom COVID-19 vaccination is not recommended. The first doses are expected to become available within days.
About 2% of the global population is considered at increased risk of an inadequate response to a COVID-19 vaccine. Emerging evidence indicates that protecting vulnerable populations from getting COVID-19 could help prevent viral evolution that is an important factor in the emergence of variants.
Additionally, the TACKLE Phase III outpatient treatment trial of Evusheld showed it reduced the risk of developing severe COVID-19 or death (from any cause) by 50% compared to placebo in non-hospitalised patients with mild to moderate COVID-19 who had been symptomatic for seven days or less.
Evusheld, formerly known as AZD7442 is a combination of two LAABs - tixagevimab (AZD8895) and cilgavimab (AZD1061) - derived from B-cells donated by convalescent patients after SARS-CoV-2 virus. Discovered by Vanderbilt University Medical Center and licensed to AstraZeneca in June 2020, the human monoclonal antibodies bind to distinct sites on the SARS-CoV-2 spike protein and were optimised by AstraZeneca with half-life extension and reduced Fc receptor and complement C1q binding.
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