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PF-07321332, an investigational oral antiviral, cut COVID-related hospitalizations and deaths by nearly 90% in patients at high risk for severe disease, manufacturer .

The company is apparently so confident in the product they already have a proposed trade name -- Paxlovid.

In an interim analysis of a phase II/III randomized trial, 0.8% of patients in the PF-07321332 group who received the drug within 3 days of symptom onset were hospitalized through day 28 (three hospitalizations, no deaths) compared to 7.0% of patients who received placebo in this time frame (27 hospitalizations and seven deaths).

Results were similar among patients treated within 5 days of symptoms (1.0% vs 6.7%, respectively).

Importantly, there were no deaths in the intervention group by day 28 versus 10 in the placebo group, the manufacturer noted.

Based on this interim analysis, an independent data monitoring board suggested enrollment in the trial be stopped, Pfizer said, adding that it has applied to the FDA for emergency use authorization (EUA).

This is the second oral antiviral to show efficacy in a late-stage clinical trial. In October, Merck and Ridgeback Therapeutics' said their oral antiviral molnupiravir cut the risk of hospitalization or death in half when taken within 5 days of symptom onset. The FDA's Antimicrobial Drugs Advisory Committee to discuss an EUA for molnupiravir.

Pfizer noted that PF-07321332 is a "specifically designed SARS-CoV-2-3CL protease inhibitor," which is the first of its kind, and is especially potent when boosted with a low-dose of ritonavir. They speculated the drug could be used both in early treatment for COVID-19, as well as potentially for post-exposure prophylaxis. In vitro studies showed the drug to be active against variants of concern, Pfizer said, and could even be used to potentially treat other coronaviruses.

Not surprisingly, Pfizer Chairman and CEO Albert Bourla called these data a "game-changer."

"Our oral antiviral candidate, if approved or authorized by regulatory authorities, has the potential to save patients' lives, reduce the severity of COVID-19 infections, and eliminate up to nine out of ten hospitalizations," he said in a statement.

The phase II/III trial -- EPIC-HR (Evaluation of Protease Inhibition for COVID-19 in High-Risk Patients) -- evaluated data from 1,219 adults across multiple continents, with 45% of patients in the U.S. The trial began enrolling in July and was stopped at 70% of its target enrollment on September 29. Patients had laboratory-confirmed SARS-CoV-2 within 5 days of symptom onset, mild to moderate symptoms, and at least one underlying medical condition that put them at risk of severe COVID. They were randomized 1:1 to receive one pill every 12 hours for a 5-day treatment course.

A safety cohort of 1,881 adults found comparable rates of adverse events between the intervention and placebo groups (19% vs 21%, respectively), and most were mild, Pfizer said. More patients in the placebo group had serious treatment-emergent adverse events, they added.

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