Pfizer begins Phase 1 study of oral antiviral therapeutic for use against SARS-CoV-2

Encouraged by its success against SARS-CoV-2 and other coronaviruses in test-tube studies, Pfizer Inc. has launched a phase one study of healthy adults to determine if multiple ascending doses of an oral antiviral therapeutic could be effective against COVID-19.

PF-07321332 is a protease inhibitor, meaning it binds to a viral enzyme to prevent viruses from replicating in cells. Generally, such therapeutics lack toxicity as well, making them well-tolerated. This would be the first orally administered protease inhibitor for coronavirus-specific cases, if successful, though it follows another Pfizer protease inhibitor, which is intravenously administered. That therapeutic is currently being evaluated in a Phase 1b multi-dose study in hospitalized clinical trial participants.

“Given the way that SARS-CoV-2 is mutating and the continued global impact of COVID-19, it appears likely that it will be critical to have access to therapeutic options both now and beyond the pandemic,” said Dr. Mikael Dolsten, chief scientific officer and president of Worldwide Research, Development, and Medical for Pfizer. “We have designed PF-07321332 as a potential oral therapy that could be prescribed at the first sign of infection, without requiring that patients are hospitalized or in critical care. At the same time, Pfizer’s intravenous antiviral candidate is a potential novel treatment option for hospitalized patients. Together, the two have the potential to create an end to end treatment paradigm that complements vaccination in cases where disease still occurs.”

The oral therapeutic will be tested in a randomized, double-blind trial, consisting of single and multi-dose escalation. The therapeutic has, however, shown previous success in single-dose efforts. Pfizer intends to present pre-clinical data on the therapeutic at a shared COVID-19 session of the Spring American Chemical Society on April 6, 2021.