A Canadian clinical trial plans to test if virus-fighting antibodies in plasma can help the sick
Canadian researchers are planning clinical trials for the potential treatment for COVID-19 will use blood plasma transfusions from people who have recovered from the disease.
the blood plasma of patients was cured – the so-called “plasma cured,” is expected to be rich in immune molecules called antibodies against the virus, which is produced by the body in response to infection.
Dr. Dana Devine, Chief Scientist with Canadian Blood Services to Quirks & Quarks host Bob McDonald that there might be a key moment in the disease when it may be most useful.
“We think it is most likely effective is when you have a patient who obviously sick with a virus but the body’s own immune system does not have a chance to make antibodies yet.”
Fighting plagues with the blood of the recovered
The use of recovered plasma medicine dates behind before the discovery of antibiotics. It is used to fight the epidemic of Spanish flu in 1918 and has been used sporadically since, perhaps most recently when the World Health Organization provides guidelines to be used in the Ebola epidemic.
In the current pandemic, blood plasma has been used in a small number of critical cases, Devine said, but this was done in less than ideal conditions.
“China, South Korea, and Singapore have actually used the plasma recovered patients to treat, but they’ve not done a comparison between the use of recovered plasma and so we could not really believe that the therapy works.”
Devine and his colleagues at Canadian Blood Services are currently working with researchers at several locations across the country to develop a protocol for a clinical trial to surrender Health Canada.
Canadian Blood Services will handle the collection of plasma from donors, said Devine. An important step will be the screening of donors who have recovered from COVID-19.
“We will check before we gather that the plasma ensures that there are enough of the right antibodies there and then we will collect plasma and give it to clinical trials that operate at several sites in Canada.
How antibodies are produced to fight the virus
Antibodies are small molecules produced by immune cells. They can recognize and stick to parts of the virus – usually part of its protein coat. Often, the antibody binds precisely the parts of the virus that the virus itself uses to bind to the cells it infects.
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This allows the antibody to perform multiple functions. They can only block the virus from being able to bind and infect cells. They can also attract white blood cells of the immune system to destroy the virus. “They are a sign of how the immune system’s destruction of things,” said Devine.
Once a person has been cleared of infection, antibodies remain in the bloodstream. This is what researchers hope to harvest in blood plasma, and used to treat those whose immune systems have not mounted a strong defense.
Donations of plasma will be important
Canadian Blood Services for the hearing will deal with the collection of plasma from donors, said Devine. An important step will be the screening of donors who have recovered from COVID-19. “We will check before we gather that the plasma ensures that there are enough of the right antibodies there and then we will collect plasma and give it to clinical trials that operate at several sites in Canada.”
Donors must be matched by blood group, such as for a blood transfusion. For clinical trials, only a small number of donors will be needed. But if the experiment is successful, a much larger pool of donors must be recruited.
Despite the success, the key issue in this trial will be safe. Devine said investigators will be watching for a phenomenon called “antibody-dependent enhancement” that can trigger a harmful immune overreaction in patients who are already very sick.
“When you give a patient the other person is plasma sometimes you can actually make the disease worse.”
The next step in antibody therapy
“We hope that we are actually up and running within the next four weeks or so and then it’ll probably take about four months total to run the study,” said Devine. “We hope we know sometime this summer what the answer is.”
But plasma therapy is probably not the end-point in this kind of antibody treatment.
“We anticipate that there’s an immediate need for this convalescent plasma but that eventually, it will start to be replaced by other therapies — things like growing up antibodies in the laboratory,” said Devine.
Indeed a Vancouver based company called AbCellara has received funding to do exactly that. They’ll be working to isolate the antibodies that COVID-19 patients are using to fight the virus. These could then be incorporated into a drug to treat coronavirus infections.
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