Pfizer starts Phase 2/3 study of oral antiviral drug for adults after COVID-19 exposure

Pfizer Inc. is starting the Phase 2/3 Evaluation of Protease Inhibition for COVID-19 in Post-Exposure Prophylaxis (EPIC-PEP) study to evaluate the investigational novel oral antiviral candidate PF-07321332, co-administered with a low dose of ritonavir, for the prevention of COVID-19 infection.

This Phase 2/3 trial is part of a global clinical research program and is enrolling individuals who are at least 18 years old and live in the same household as an individual with a confirmed symptomatic SARS-CoV-2 infection.

Mikael Dolsten, MD, PhD, chief scientific officer and president, Worldwide Research, Development and Medical of Pfizer, said that with the continued impact of COVID-19 around the world, Pfizer believes that tackling the virus will require effective treatments for people who contract, or have been exposed to, the virus, complementing the impact that vaccines have had in helping quell infections.

“If successful, we believe this therapy could help stop the virus early – before it has had a chance to replicate extensively – potentially preventing symptomatic disease in those who have been exposed and inhibiting the onset of infection in others,” Dolsten said. “Given the continued emergence and evolution of SARS-CoV-2 variants and their immense impact, we continue to work diligently to develop and study new ways that our investigational oral antiviral candidate could potentially lower the impact of COVID-19, not only on patients’ lives, but also the lives of their families and household members.”

The Phase 2/3 EPIC-PEP trial is a randomly assigned, double-blind, placebo-controlled study and will enroll up to 2,660 healthy adult participants aged 18 and older.

According to Pfizer, participants will be randomly assigned (1:1:1) to receive PF-07321332/ritonavir or placebo orally twice daily for 5 or 10 days.

The primary objective will assess safety and efficacy for the prevention of confirmed SARS-CoV-2 infection and its symptoms through Day 14.

PF-07321332 is an oral antiviral SARS-CoV-2-3CL protease inhibitor, which has an encouraging pre-clinical profile, including potent in vitro antiviral SARS-CoV-2 and broad coronavirus activity.

Results from the Phase 1 clinical trial demonstrated that PF-07321332 was safe and well tolerated.

In addition to this study, the global EPIC program consists of multiple ongoing clinical trials, including one in SARS-CoV-2 infected patients who are at high risk of severe illness (including hospitalization or death), which began in July 2021, and another in infected patients who are at standard risk (i.e., do not have risk factors for severe illness), which began in August 2021.

For more information on the EPIC Phase 2/3 clinical trials for PF-07321332, visit clinicaltrials.gov.