The US government spent more than $18 billion last year funding
drugmakers to make a COVID vaccine, an effort that led to at least five highly
effective shots in record time. Now it is pouring more than $3 billion on a
neglected area of research: developing pills to fight the virus early in the
course of infection, potentially saving many lives in the years to come.
اضافة اعلان
The new program, announced Thursday by the Department of Health
and Human Services, will speed up the clinical trials of a few promising drug
candidates. If all goes well, some of those first pills could be ready by the
end of the year. The Antiviral Program for Pandemics will also support research
on entirely new drugs — not just for the coronavirus, but for viruses that
could cause future pandemics.
A number of other viruses, including influenza, HIV and
hepatitis C, can be treated with a simple pill. But despite more than a year of
research, no such pill exists to treat someone with a coronavirus infection
before it wreaks havoc. Operation Warp Speed, the Trump administration’s
program for accelerating COVID-19 research, invested far more money in the
development of vaccines than of treatments, a gap that the new program will try
to fill.
Dr Anthony Fauci, director of the National Institute of Allergy
and Infectious Diseases and a key backer of the program, said he looked forward
to a time when COVID-19 patients could pick up antiviral pills from a pharmacy
as soon as they tested positive for the coronavirus or develop COVID-19
symptoms.
“I wake up in the morning, I don’t feel very well, my sense of
smell and taste go away, I get a sore throat,” Fauci said in an interview. “I
call up my doctor, and I say, ‘I have COVID, and I need a prescription.’”
Fauci’s support for research on antiviral pills stems from his
own experience fighting AIDS three decades ago. In the 1990s, his institute
conducted research that led to some of the first antiviral pills for HIV, “protease
inhibitors” that block an essential virus protein and can keep the virus at bay
for a lifetime.
In the early 2000s, researchers found that an antiviral called
sofosbuvir could cure hepatitis C close to 100 percent of the time. Tamiflu, an
over-the-counter pill for influenza, can cut the time it takes to recover from
an infection and reduce the chances that a bout of the flu will land someone in
the hospital.
At the start of the pandemic, researchers began testing existing
antivirals in people hospitalized with severe COVID-19. But many of those
trials failed to show any benefit from the antivirals. In hindsight, the choice
to work in hospitals was a mistake. Scientists now know that the best time to
try to block the coronavirus is in the first few days of the disease, when the
virus is replicating rapidly and the immune system has not yet mounted a
defense.
Many people crush their infection and recuperate, but in others,
the immune system misfires and starts damaging tissues instead of viruses. It
is this self-inflicted damage that sends many people with COVID-19 to the
hospital as the coronavirus replication is tapering off. So a drug that blocks
replication early in an infection might very well fail in a trial on patients
who have progressed to later stages of the disease.
So far, only one antiviral has demonstrated a clear benefit to
people in hospitals: remdesivir. Originally investigated as a potential cure
for Ebola, the drug seems to shorten the course of COVID-19 when given
intravenously to patients. In October, it became the first — and so far, the
only — antiviral drug to gain full FDA approval to treat the disease.
Yet remdesivir’s performance has left many researchers
underwhelmed. In November, the World Health Organization recommended against
using the drug.
Remdesivir might work more effectively if people could take it
earlier in the course of COVID-19 as a pill. But in its approved formulation,
the compound does not work orally. It cannot survive the passage from the mouth
to the stomach to the circulatory system.
Researchers from around the world are testing other antivirals
already known to work in pill form. One such compound, called molnupiravir, was
developed in 2003 by researchers at Emory University and has been tested
against viruses including influenza and dengue.
In partnership with Ridgeback Biotherapeutics of Miami, the
Emory team carried out experiments in mice that were so impressive that Merck
approached them to bring the drug into human clinical trials for COVID-19.
“We thought this molecule was really amazing,” said Daria
Hazuda, vice president of infectious disease and vaccine research at Merck.
The companies began a second study last fall, this time testing
the drug on people recently diagnosed with COVID-19. That trial is continuing,
and Merck is recruiting volunteers with a higher risk of infection, such as
older people with obesity and diabetes. Hazuda said the trial should deliver
clear results by October.
Last year, the government’s funding of COVID-19 treatments
focused on a handful of candidates, such as monoclonal antibodies and
remdesivir. Many other studies on antivirals were small and underfunded. In
January, the incoming Biden administration began designing a new program
dedicated to antiviral pills.
Last week saw the first results of this planning. The Department
of Health and Human Services announced that it would purchase from Merck 1.7
million doses of molnupiravir at a cost of $1.2 billion, provided that the
current trial leads to authorization by the Food and Drug Administration. The
government may seek similar deals for two other antivirals far along in
clinical trials, according to Dr. David Kessler, chief science officer of the
Biden administration’s COVID-19 response team.
The hope “is that we can get an antiviral by the end of the fall
that can help us close out this chapter of the epidemic,” Kessler said in an
interview.
One of the drugs the government is considering is AT-527,
developed by Atea Pharmaceuticals. The compound has already proved safe and
effective as a treatment for hepatitis C, and early studies suggested it might
also work against COVID-19. Roche has partnered with Atea to test it in people,
and the companies are currently running a late-stage clinical trial.
The other drug on the government’s radar was created by
scientists at Pfizer, adapted from a molecule initially designed in the early
2000s as a potential drug for
SARS, or severe acute respiratory syndrome. That
drug had sat on the shelf for years, but last spring, the scientists decided to
modify its structure so that it would work against the new coronavirus’s
protease. More than 200 Pfizer researchers joined forces on the effort on the
molecule, known for now as PF-07321332.
The drug had been designed to be taken intravenously, but the
Pfizer researchers succeeded in altering its structure to work as a pill. When
mice were given the drug orally, it reached high enough levels in the body to
block the coronavirus.
Pfizer launched a clinical trial in March to study its
safety in people and expects to move to later-stage testing next month.
Kessler acknowledged that there will be challenges in using such
pills to drive down hospitalizations and deaths from
COVID-19. People will need
to gain access to the drugs as soon as they test positive. “Your testing
programs are going to have to be linked to your treatment,” he said.
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