Healthcare professionals prepare doses of the Pfizer-BioNTech Covid-19 vaccine at Coors Field in Denver, Colorado, on February 20.
Photographer: Chet Strange / Bloomberg
Photographer: Chet Strange / Bloomberg
Pfizer Inc. said it began human safety testing of a new pill to treat coronavirus, which can be used at the first sign of the disease.
If the tests are successful, the pill can be prescribed at the beginning of an infection to block viral replication before patients become very sick. The drug binds to an enzyme called protease to prevent the virus from replicating. Protease inhibitor drugs have been successful in treating other types of viruses, including HIV and hepatitis C.
“Given the way in which SARS-CoV-2 is changing and the continued global impact of Covid-19, it seems likely that it will be critical to have access to therapeutic options now and after the pandemic,” said Mikael Dolsten, Pfizer Chief Scientific Officer , in a statement.
In an interview, Dolsten said that no unexpected problems were seen in the study so far and that it could deliver results in weeks.
The new protease inhibitor is the second drug of its kind that Pfizer has brought in for human testing to treat Covid-19. Pfizer is testing another one administered intravenously to patients with hospitalized viruses.
Pfizer shares fell 1.3% to $ 35.55 at 12:36 pm in New York. Last year, the stock rose 32%.
Easy-to-use treatments for early-stage Covid-19 patients are lacking. While antibody therapies of Eli Lilly & Co. and Regeneron Pharmaceuticals Inc. is authorized in the USA for patients at Covid who have not yet been hospitalized, but are at high risk of developing severe symptoms, they must be infused in the hospital or in a doctor’s office.
This created logistical challenges that limited its use. Other therapies are aimed at the sickest people: The antiviral drug remdesivir from Gilead Sciences Inc. must be infused over several days and is approved only for hospitalized patients.
Among the main pharmaceutical companies, Merck & Co. has one of the few coronavirus pills that is well advanced in human testing. Its experimental antiviral drug, molnupiravir, works by a different mechanism than Pfizer and is in the final stages of testing in humans. Merck is developing its medicine in collaboration with Ridgeback Biotherapeutics LP.
Combined Test
If all continues to go well, Pfizer could begin a much larger phase 2 phase 3 combined study early in the second quarter, Dolsten said, potentially allowing it to apply for emergency use authorization from the Food and Drug Administration by the end of this year, depending on the evolution of the pandemic.
The drug should be administered twice a day for about five days, he said.
“This is really a potential game changer,” said Dolsten.
Although the initial effectiveness test focuses 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 who live with someone who has fallen ill.
Dolsten said Pfizer’s oral protease inhibitor, codenamed PF-07321332, has a number of potential advantages. In laboratory tests, it worked against many coronaviruses, including the original SARS virus and MERS. In addition, the coronavirus protease does not mutate much, meaning that the therapy is likely to work equally well against several variant strains, he said.
In theory, the protease inhibitor could also be combined with other antiviral drugs, such as the one Merck is developing, said Dolsten.
Pfizer said it plans to share more data about the compound at the American Chemical Society meeting on April 6.
(Updates with the name of the Merck partner in the 9th paragraph)