Both the political and medical
worlds have been abuzz with the experimental
antibody cocktail that President Donald Trump received to combat his coronavirus
disease 2019 (COVID-19) infection earlier this month.
So, is the cocktail ready to treat
society at large?
In trials, the antibody therapy,
REGN-COV2—produced by the biotechnology firm Regeneron—led
to quick reduction in levels of the virus and reduced symptoms in infected non-hospitalized
patients with mild to moderate disease. The trial is also separately studying
the effectiveness of REGN-COV2 for the treatment of hospitalized patients and
prevention of infection in those exposed to the virus.
The antibody cocktail includes two
proteins that mimic the antibodies that are produced by the body’s own immune
system during an infection; these lab-created antibodies are expected to bind
to the virus and prevent it from entering cells, thus inhibiting infection. In
the trial, the greatest positive effects of therapy were seen in patients who
had not mounted their own immune response, which means the treatment could be an
effective substitute for a naturally occurring immune response.
“This potentially would be helpful for patients that
wouldn’t respond—either they have a problem with their immune system, something
called primary deficiency, or cancer, transplant patients that may not be
necessarily candidates for a regular vaccine—this potentially would offer some
benefit in protecting them,” Gary Kleiner, MD, an allergy & immunology
specialist at the University of Miami Miller School of Medicine, said at an expert
panel discussion with trial site doctors and the American Medical Association.
“We’re performing a preventive trial there with this combination used for
household contacts in the hope of decreasing transmission in these subjects.”
Regeneron's monoclonal antibody cocktail is just one of many
clinical trials currently underway with regard to prevention and treatment of
COVID-19. A majority of the trials, understandably, are focused on producing an
A new vaccine for coronavirus disease 2019 (COVID-19) just entered
clinical trials at the end of September.
The vaccine is a recombinant vector that uses a nonvirulent human
adenovirus to express the SARS-CoV-2 spike protein in cells. “This particular
vaccine is using Adenovirus 26, it’s a type of respiratory virus that we
commonly see, but it is genetically modified to have the coronavirus part of
the genome in it, and it’s a non-replicating virus,” Dushyahtha Jayaweera, MD,
explained at the panel. Jayaweera is an infectious disease specialist and
professor of clinical medicine at the University of Miami, and is working on
the vaccine trial. “So, once you inject it, it gets into the cell and introduces
this genetic material and then the immune system will recognize it and produce
The spike protein, also called the S protein, is an
ideal target for COVID-19 immunotherapy, since antibodies directed against
it play a key role in countering coronavirus infection, and have been shown to
be effective at inhibiting virus entry into host cells. By eliciting a
polyclonal antibody response, the S protein effectively neutralizes SARS-CoV-2
entry into cells. It showed complete or
near-complete protection against the virus in rhesus macaques.
The spike protein is a good molecular target for vaccines
because the virus attaches to human cells through it; the protein binds to a
protein on the human cell surface, following which, the viral membrane fuses
with the human cell membrane, allowing entry of the viral genome into the host cell.
The fourth large-scale COVID-19 vaccine trial in the US, it
will evaluate if the vaccine can prevent symptomatic COVID-19 after a single
dose regimen. The trial is being funded by Janssen Pharmaceutical Companies, of
Johnson & Johnson, which developed the vaccine, the National Institute of
Allergy and Infectious Diseases (NIAID), and the Biomedical Advanced Research
and Development Authority (BARDA) —part of the U.S. Department of Health and
The Janssen vaccine has shown promise in early-stage testing.
If it can demonstrate effective protection after a single dose, it can be especially
useful in controlling the pandemic. It can also be rapidly produced.
“One of the advantages of this vaccine is that their
platform can have rapid operationalization and create one billion vaccine doses
over the next year,” Jayaweera said. “So that’s one of the advantages, provided
the study shows that it works.”
Treatments like Regeneron’s antibody cocktail and Janssen’s
vaccine give us hope at a time when COVID-19 cases continue to rise.
As Susan Bailey, MD, President of the American Medical
Association noted at the panel, “There are over a hundred vaccines that are in
the preclinical stage of investigation. There are about a half a dozen vaccines
that are in phase 3 trials, three of which are going on in the U.S., three in
other parts of the world, and others that are in various stages in the
pipeline. So, there's an incredible amount of activity that’s going on in this
area, which I think is just absolutely amazing.”