AstraZeneca, GSK's COVID-19 Therapies Lose Efficacy Against Omicron's Subvariants

The FDA authorized an increased dose in the case of AstraZeneca Plc's AZN pre-exposure prophylaxis drug Evusheld (tixagevimab and cilgavimab).

"Based on the most recent information and data available, Evusheld may be less active against certain Omicron subvariants. The dosing regimen was revised because available data indicate that a higher dose of Evusheld may be more likely to prevent infection by the COVID-19 Omicron subvariants BA.1 and BA.1.1 than the originally authorized Evusheld dose," the FDA said in a statement.

The revised EUA doubles the initial authorized dose to 300 mg of tixagevimab and 300 mg of cilgavimab. 

The FDA recommends that patients who previously received Evusheld get additional doses ASAP as nonclinical data indicate that the neutralizing activity of Evusheld decreases 12- to 424- fold against the Omicron subvariants BA.1 and BA.1.1.

Meanwhile, earlier in the week, the FDA updated its fact sheet for GlaxoSmithKline Plc GSK and Vir Biotechnology Inc's VIR sotrovimab.

Omicron subvariant BA.2 is 16-fold less susceptible to sotrovimab than against the original SARS-CoV-2 virus. The agency added that it is unknown whether the reduced potency will impact its effectiveness.

In addition, the updated document adds the vague language that sotrovimab is not authorized as a COVID-19 treatment in geographic regions where the infection is likely to have been caused by a non-susceptible SARS-Cov-2 variant. 

Related: Preprint Suggests, Vir-GSK's COVID-19 Antibody Can Evade Omicron Sub-Variant.

Price Action: AZN shares are up 3.75% at $60.31, and GSK stock is up 3.67% at $42.70 during the market session on the last check Friday.