One pill could be home cure for COVID-19
Pfizer’s newest labour has been its quietest
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 the virus will become available later this year. The U.K. prime minister announced the formation of an “Antivirals Taskforce” last week specifically to invest in such products.
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 SARSCOV-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 U.K. 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, 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.
Pfizer is keeping quiet 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 PF07321332 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 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 Daily Telegraph in London 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 Feb. 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.”
Those who have signed up for the trial are in for an intensive few months.
The trial is split into three phases and will run for 145 days, with another 28 days added for “screening and dosing.” For all participants, there will be several overnight stays.
“You are here today as a possible participant in a drug research study sponsored by Pfizer Incorporated,” say the briefing documents.
“Taking part in this study is voluntary ... If you are not completely honest about your health history, you may be harmed by being in this study.”
The “randomized, doubleblind, placebo-controlled, single- and multiple-dose escalation study” is designed to see how well or otherwise different dosing regimens are tolerated in humans while the active compound is maintained in the body.
PF-07321332 will be administered in combination with low doses of ritonavir, an antiviral used to treat HIV. It acts as a “booster” to increase PF-07321332 in participants’ blood.
Phase 1 of the trial is designed to see how it “is tolerated as the dose is increased, alone or with ritonavir, if there are significant side effects, and how people feel after taking it”, say the documents.
Phase 2 will do the same but with “multiple doses”, while in Phase 3, tablet and liquid forms of the drug will be administered and tested, as will the impact of eating on top of it.
Every detail has been specified in advance. In Phase 3, for example, a highfat breakfast is defined as: “2 eggs fried in butter, 2 strips of pork bacon, 2 slices of toast with butter, 4 oz. of hash brown potatoes, and 8 oz. of whole milk ... eaten in 20 minutes”.
Bringing a new drug to market is a long and difficult process and even if PF07321332 is found to be well tolerated in humans, formal Phase 3 trials would need to follow to establish whether the drug worked against people exposed to SARSCOV-2.