Classed as a ‘protease inhibitor’, it has been formulated to attack the “spine” of the SARS-CoV-2 virus and stop it replicating in our nose, throats and lungs.
At two anonymous Pfizer buildings, one in the U.S. and one in Belgium, a remarkable experiment is under way. Up to 60 volunteers, all clean-living adults aged between 18 and 60, are being given the first pill specifically designed to stop Covid-19.
If the trial is successful, it is just possible a home cure for Covid-19 will become available later this year. U.K. Prime Minister Boris Johnson, who announced the formation of an “Antivirals Taskforce” last week specifically to invest in such products, will no doubt be scanning his text messages for early updates.
The molecule being tested is a bespoke antiviral code-named PF-07321332. Classed as a “protease inhibitor”, it has been formulated to attack the “spine” of the SARS-CoV-2 virus and stop it replicating in our nose, throats and lungs.
It was protease inhibitors that turned the tide on the spread of HIV in the UK and around the world. Now researchers hope they may be on the brink of a similar pandemic-busting breakthrough.
“If they have moved to this stage they will be quietly optimistic,” said Penny Ward, a visiting professor in pharmaceutical medicine at King’s College London and a pioneer in the development of Tamiflu, an antiviral that combats seasonal and pandemic flu. “The question will be about how the drug is tolerated… They will be going like the clappers”.
The antiviral pill was developed from scratch during the current pandemic, Dafydd Owen, director of medicinal chemistry at Pfizer, told a private symposium of the Division of Medicinal Chemistry last month.
The first seven milligrams of the compound – no more than a raindrop — were made in late July 2020. By late October, they’d made 100 grams.
Just two weeks later, they had more than a kilogram in the bag. It took 210 researchers to do it, said Owen.
If they have moved to this stage they will be quietly optimistic
Pfizer is keeping schtum about the detail of the lab tests it has completed but says it has demonstrated “potent in vitro antiviral activity against SARS-CoV-2”, as well as activity against other coronaviruses, raising the prospect of a cure for the common cold as well as future pandemic threats.
“We have designed PF-07321332 as a potential oral therapy that could be prescribed at the first sign of infection, without requiring that patients are hospitalised or in critical care”, said Mikael Dolsten, chief scientific officer and president of worldwide research, development and medical at Pfizer, in a statement released last month.
According to Ward, Pfizer’s scientists will have most likely established the drug’s “potent” action against SARS-CoV-2 by deploying it against infected human tissue cultures, including lung tissue, in a laboratory. “Once you know it works in vitro, it’s all about establishing its tolerance in animals and then humans,” she said.
The Sunday Telegraph has obtained copies of the documents given to participants who are now entering the first human trials.
“To date, the study drug has not been administered to humans,” say the documents which were formally approved on February 8 this year.
“The safety of the study drug has been studied in animals. In these animal studies, no significant risks or safety events of concern were identified, and the study drug did not cause side effects at any of the dose levels that will be used in clinical studies.”