Health workers prepare doses of the Pfizer-BioNTech Covid-19 vaccine at Coors Field in Denver, Colorado, on Feb. 20.
Photographer: Chet Strange / Bloomberg
Photographer: Chet Strange / Bloomberg
Pfizer Inc. said he has begun human safety testing of a new pill to treat the coronavirus that could be used at the first sign of illness.
If successful in trials, the pill may be prescribed early infection to block viral replication before patients become very ill. The drug binds to an enzyme called protease to prevent the virus from reproducing. Protease inhibitor drugs have been successful in treating other types of viruses, such as HIV and hepatitis C.
“Given the way SARS-CoV-2 is mutating and the continued global impact of Covid-19, it seems likely to be critical to have access to therapeutic options both now and outside the pandemic,” said Mikael Dolsten, head of Pfizer Scientific Officer, in a statement.
In an interview, Dolsten said that so far no unexpected problems had been seen in the study and that it could generate results in a few weeks.
The new protease inhibitor is the second drug Pfizer has introduced in human trials to treat Covid-19. Pfizer is testing another administered intravenously to hospitalized virus patients.
Shares of Pfizer fell 1.3% to $ 35.55 at 12:36 in New York. Over the past year, shares have risen 32%.
Easy-to-use treatments are lacking for patients with early-stage Covid-19. While antibody therapies of Eli Lilly & Co. i Regeneron Pharmaceuticals Inc. is authorized in the United States for Covid patients who have not yet been hospitalized, but who are at high risk of developing severe symptoms; they should be infused in a hospital or doctor’s office.
This has created logistical challenges that have limited its use. Other therapies are intended for sick people: Gilead Sciences Inc. antiviral drug remdesivir it should be infused for several days and should only be approved for hospitalized patients.
Among the leading drug manufacturers, Merck & Co. has one of the few coronavirus pills that is far behind in human testing. Its experimental antiviral drug, molnupiravir, works by a different mechanism than the Pfizer drug and is in end-stage human trials. Merck is developing its drug in collaboration with Ridgeback Biotherapeutics LP.
Combined test
If all goes well, Pfizer could begin a much larger combined Phase 2 and Phase 3 trial in the early second quarter, Dolsten said, which would possibly allow it to apply for Food Emergency Authorization and Drug Administration later this year, depending on how the pandemic evolves.
The drug is likely to be given twice a day for about five days, he said.
“This is really a potential game changer,” Dolsten said.
Although initial efficacy testing will focus on people with early infections, Pfizer also plans to explore whether the drug works to protect healthy people who have been exposed to the coronavirus, such as family members or roommates living with someone sick.
Dolsten said the Pfizer oral protease inhibitor, codenamed PF-07321332, had a number of potential benefits. In laboratory tests, it worked against many coronaviruses, including the original SARS virus and MERS. In addition, the coronavirus protease does not mutate much, which means the therapy is likely to work just as well against numerous variant strains, he said.
In theory, the protease inhibitor could also be combined with other antiviral drugs, such as the one Merck is developing, Dolsten said.
Pfizer said it plans to share more data on the compound at the American Chemical Society meeting on April 6.
(Updates with Merck Partner Name in the ninth paragraph)