Pfizer initiated a Phase 2/3 study of an investigational oral antiviral with a low dose of ritonavir to prevent COVID-19 illness, the company announced Monday. The treatment is aimed to slow viral replication after exposure to tamp down symptomatic disease and infection onset in others.
"With the continued impact of COVID-19 around the world, we believe 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," Dr. Mikael Dolsten, PhD., chief scientific officer and president, worldwide research, development and medical of Pfizer, said in a news release posted Monday. "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."
The Phase 2/3 study called EPIC-PEP, (Evaluation of Protease Inhibition for COVID-19 in Post-Exposure Prophylaxis), is a randomized, double-blind, placebo-controlled trial, set to enroll up to 2,660 healthy adults ages 18 and older living with a household member with a confirmed symptomatic COVID-19 infection. Study participants will be randomly assigned to receive PF-07321332/ritonavir or a placebo twice each day for five or 10 days, per the news release. The treatment is designed to be administered early (such as the first sign or infection or awareness of exposure) while ritonavir is intended to slow the metabolism of the PF-07321332 antiviral to help fight the virus for a longer period of time.
"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," Dolsten said.
The company intends to evaluate the candidate's safety and efficacy in preventing confirmed SARS-CoV-2 infection and symptoms through two weeks, Pfizer said, noting that an early stage trial suggested the oral antiviral was safe and well tolerated. The global program involves other ongoing studies, like COVID-infected patients at high-risk of poor outcomes while another trial includes patients at a standard risk, which began in July and August, respectively.