Protease Inhibitor Promising Against SARS-CoV-2 in Midstage Trial

By Reuters Staff

March 03, 2022

(Reuters) - An experimental oral drug being developed by Redhill Biopharma Inc interrupts a process that helps the coronavirus infect cells and might keep COVID-19 patients from becoming seriously ill, the company said.

The virus co-opts serine proteases and uses them to prepare its spike to break into cells and infect them. The drug, RHB-107, blocks the proteins' activity.

The new findings come from a small trial to confirm the safety of the drug in recently infected, symptomatic but non-hospitalized COVID-19 patients. While a larger study is needed to demonstrate efficacy, Redhill said that among the 61 adults in the trial, no one taking once-daily RHB-107 (upamostat) needed to be hospitalized, compared to 15% of those in a placebo group. Rates of new-onset severe symptoms were 2.4% with RHB-107 and 20% with the placebo.

Because RHB-107 acts against human proteins that are involved in preparing the virus spike for cell entry, rather than acting against the spike itself, the researchers said they expect it could be effective against new variants despite mutations in the spike.

A larger randomized trial is underway but results are not yet available. Pfizer's Paxlovid pill, which has emergency use authorization for patients with early COVID-19, is also a protease inhibitor.

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