AstraZeneca’s Evusheld (tixagevimab co-packaged with cilgavimab), a long-acting antibody combination for the prevention of COVID-19, retained neutralizing 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 neutralizing potency of an antibody, was 171 ng/ml and 277 ng/ml in two confirmatory tests, which is within the range of neutralizing titers found in someone who has been previously infected with COVID-19. 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 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 neutralization 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 authorization in the US for pre-exposure prophylaxis of COVID-19, in addition to authorizations 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.