GlaxoSmithKline and Vir Biotechnology have taken a big step toward authorization of an intramuscular formulation of their anti-SARS-CoV-2 antibody sotrovimab. The partners have filed for FDA emergency use authorization of a more convenient form of one of the few antibodies to hold up against omicron.
Intramuscular delivery is seen as a way to increase use of antibody treatments of COVID-19, which were shown to be effective at preventing hospitalization and death—at least in the pre-omicron era—but were used relatively rarely earlier in the pandemic amid issues including the need for intravenous delivery. Regeneron received authorization of a subcutaneous formulation over the summer, but omicron has affected its efficacy.
The shortcomings of anti-SARS-CoV-2 antibodies from Regeneron and Eli Lilly against omicron have put more focus on sotrovimab, the only product of its type that is available in the U.S. and expected to work against the variant.
GSK and Vir set the stage for the authorization of a more convenient formulation of the antibody last year by running a clinical trial that compared the existing intravenous product to a new intramuscular dose. The intramuscular shot held its own in high-risk, non-hospitalized patients with mild to moderate COVID-19.
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The rates of hospitalization for more than 24 hours or death were 2.7% in the intramuscular arm and 1.3% in the intravenous cohort. The 95% confidence interval for the adjusted difference between the two groups was -1.3% to 3.4%. As the upper bound is below the 3.5% non-inferiority margin, the study hit its primary endpoint.
With low rates of serious adverse events in both arms, GSK and Vir think they have the data to support the expansion of the FDA emergency authorization to cover the intramuscular formulation and the intravenous version that received the regulatory green light in May.