A handful of companies may have a lock on COVID-19 vaccines, but competition is heating up in antivirals targeting the novel coronavirus.

One of the latest entrants is Pardes Biosciences (Carlsbad, Calif.), which recently announced a Phase 1 trial for PBI-0451, an oral antiviral targeting SARS-CoV-2.

Other companies developing antivirals for COVID-19 include Pfizer as well as Merck and its partner Ridgeback Biotherapeutics. In addition, Gilead Sciences scored the first FDA approval for COVID-19 with its broad-spectrum IV-based antiviral Remdesivir, which it first envisioned as an Ebola treatment.

PBI-0451 inhibits viral main protease (Mpro).

Researchers have validated viral proteases over the years for viruses such as hepatitis C and human immunodeficiency virus.

Given their mode of action, oral antivirals could also be effective against variants of concern.

Mpro is common across SARS-CoV-2 variants as well as multiple other coronaviruses. The antiviral also is potentially effective against SARS and MERS.

Preclinical studies indicate that PBI-0451 can inhibit replication of an array of coronaviruses, including SARS-CoV-2, in multiple in vitro models.

Dr. Uri Lopatin

Pardes also reports that data from toxicity studies have been positive.

“We believe oral antiviral therapies have the potential to address the significant global public health challenges of both COVID-19 as well as future pandemics,” said Dr. Uri A. Lopatin, CEO of Pardes Biosciences, in a statement.

The company’s Phase 1 trial will be placebo-controlled, blinded and randomized. In addition, it will evaluate the dosing of PBI-0451 as a once or twice-a-day pill.

Pardes aims to enroll up to 110 participants for the trial.

It expects data from the trial to be available in the fourth quarter of the year.