At two anonymous Pfizer buildings, one in the US 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 SARS-CoV-2.
If the trial is successful, it is just possible that a home cure for Covid-19 will become available later this year. The Prime Minister, who announced the formation of a UK 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 codenamed 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 noses, 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 Prof Penny Ward, 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 anti-viral pill was developed from scratch during the current pandemic, Dafydd Owen, the director of medicinal chemistry at Pfizer, told a private symposium of the Division of Medicinal Chemistry last month.
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 cure to 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 hospitalized or in critical care,”said Mikael Dolsten, chief scientific officer and president, worldwide research, development and medical of Pfizer in an official statement released last month.
According to Prof 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.