By Peter Loftus, Jared S. Hopkins and Jenny Strasburg
AstraZeneca PLC said Wednesday an independent committee is
reviewing the potential safety concern that led to a pause of its
clinical trials of an experimental Covid-19 vaccine, and the trials
could restart depending on the outcome.
The company paused testing of the vaccine, which it licensed
from the University of Oxford, after a person in a U.K. study
developed an unexplained illness.
It is unclear what happened to the trial subject, a woman from
the U.K. who had received the experimental vaccine, according to a
person familiar with the matter. Doctors are conducting tests to
determine the cause, the person said.
The suspension threatens the progress of one of the most
advanced Covid-19 vaccine candidates in development.
AstraZeneca had just started a large, late-stage trial in the
U.S. that aims to enroll up to 30,000 people to test whether the
vaccine safely protects people from Covid-19. AstraZeneca also had
been testing the vaccine in countries including South Africa and
Brazil.
The candidate was on track to be approved for use before year's
end, if it proved to work safely in late-stage testing. Now, the
timetable for its development is uncertain, though AstraZeneca
expressed confidence the trials could resume.
The independent committee will guide AstraZeneca "as to when the
trials could restart, so that we can continue our work at the
earliest opportunity to provide this vaccine broadly, equitably and
at no profit during this pandemic," AstraZeneca Chief Executive
Pascal Soriot said.
AstraZeneca's American depositary receipts declined 1.2%
Wednesday. Shares of other Covid-19 vaccine makers with shots in
human testing rose on the news.
Many vaccines come with side effects, including injection-site
soreness and low-grade fevers, according to the Centers for Disease
Control and Prevention. Subjects in Covid-19 vaccine studies have
had adverse events such as injection-site pain or flu-like
symptoms.
Pauses in vaccine clinical trials aren't uncommon, according to
vaccine researchers. Many times, they said, further examination
reveals that the vaccine candidate didn't cause the safety event
and the trial resumes.
"It's quite common for serious adverse events to occur, most not
relevant to the vaccine," especially in a 30,000-person trial, said
Peter Hotez, dean of the National School of Tropical Medicine at
Baylor College of Medicine. "It's a reason why we do big trials,
and a reason why we shouldn't skip these important steps."
Researchers conduct trials partly to look for safety issues, and
studies like AstraZeneca's are often overseen by committees of
outside experts known as data safety monitoring boards, which look
for any troubling signs.
To protect subjects, the boards can suspend trials to explore
any serious safety signal and assess whether the drug or vaccine
under study was the cause and whether the trial should restart or
shut down.
"This is what happens in clinical trials. That's why we do
them," said Naor Bar-Zeev, a pediatric infectious diseases
physician and epidemiologist at Johns Hopkins Bloomberg School of
Public Health.
The U.K. study of the vaccine was paused once before, in July,
according to an Oxford spokesman. The university declined to
discuss specifics, other than that there were no ongoing concerns
as a result of it.
One volunteer in the trials of the AstraZeneca/Oxford vaccine
developed symptoms of transverse myelitis, or inflammation in the
spinal cord, according to a form for trial participants from July
that is posted on an international registry of clinical trials.
The cause was uncertain, the document said.
An updated information sheet from August said a volunteer
developed neurological symptoms that caused the study to pause
while a safety review took place. The volunteer was later diagnosed
with an "unrelated neurological illness," according to the updated
document.
William Schaffner, professor of preventive medicine and
infectious diseases at Vanderbilt University Medical Center, said
doctors don't know for sure what causes transitive myelitis but
that there is a one in a million chance of contracting it in the
general population.
If the myelitis occurred within a couple of days of receiving an
experimental shot, the case could be coincidental, Dr. Shaffner
said. It could be related to the vaccine and a cause for concern if
it happened a week or more afterward, he said.
The pause of AstraZeneca's trials could prompt potential
volunteers to seek out trials of other vaccines, Evercore ISI
analyst Umer Raffat said on a webinar with investors discussing the
suspension.
Moderna Inc. said it isn't aware of any impact the AstraZeneca
news will have on a large ongoing study of its coronavirus vaccine.
Johnson & Johnson said studies of its vaccine are ongoing, and
it still expects to start large, late-stage trials later this
month.
Pfizer Inc. is tracking and evaluating safety of its two-dose
vaccine, including review by an external, independent
data-monitoring panel of vaccine experts, according to a Pfizer
spokeswoman.
As the vaccine candidates move closer to use, health
authorities, researchers and industry officials have begun trying
to ease the safety and other concerns of sizable percentages of
people who in polls and surveys express hesitance to take the shots
when cleared for use.
This week, nine pharmaceutical companies developing Covid-19
vaccines sought to address concerns and issued a pledge promising
not to file for regulatory approval or authorization of their
experimental jabs until the shots have been shown to work safely
though late-stage clinical testing.
Spokespeople for the Food and Drug Administration and the
National Institute of Allergy and Infectious Diseases declined to
comment on the AstraZeneca testing pause. NIAID is funding the U.S.
trial of the AstraZeneca/Oxford vaccine, and the FDA monitors
safety in clinical trials.
Also on Wednesday, Pfizer Inc. and partner BioNTech SE said they
finished "exploratory talks" with the European Commission to supply
200 million doses of their experimental Covid-19 vaccine, with an
option for the commission to purchase an additional 100 million
doses. The companies said they expected to begin contract
negotiations.
The amount of doses is the largest so far the companies have
announced with governments and double the number the U.S. agreed to
purchase. Financial details weren't disclosed, although the
separate U.S. agreement priced the shot at $19.50 per dose.
More than 25,000 volunteers have enrolled in a late-stage
clinical trial testing the vaccine and seeking to enroll 30,000
people.
Write to Peter Loftus at peter.loftus@wsj.com, Jared S. Hopkins
at jared.hopkins@wsj.com and Jenny Strasburg at
jenny.strasburg@wsj.com
(END) Dow Jones Newswires
September 09, 2020 14:17 ET (18:17 GMT)
Copyright (c) 2020 Dow Jones & Company, Inc.
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