Holy Grail treatment for COVID-19 remains out of reach. But options exist
Monoclonal antibody drugs are promising, but they're also expensive and logistically challenging
A COVID-19 treatment showing early signs of promise is at risk of being overshadowed by the vaccine rollout.
Monoclonal antibody treatments have been used by doctors in the United States on people like President Donald Trump, who fought COVID-19 in October, and on others in an effort to try to keep people with the coronavirus out of hospital. Health Canada has authorized one such drug from Eli Lilly, pending the results of trials to verify its benefits to patients.
Our immune system naturally makes antibodies to fight off the coronavirus. But it can take several weeks to gain full protection and some patients go downhill too quickly to wait. The aim of giving a one-time monoclonal antibody treatment is to seize a window of opportunity early in the course of COVID-19.
Dr. Srinivas Murthy, an infectious disease physician and a clinical associate professor in pediatrics at the University of British Columbia in Vancouver, said a treatment that's simple and works to prevent COVID-19 from becoming severe is "the Holy Grail right now."
"The challenge with any of those treatments is that you have to give it to a lot of people to prevent hospitalizations or severe disease because a lot of people have mild-COVID," Murthy said. "Whatever you give has to be safe and convenient otherwise people won't take it."
The two monoclonal antibody treatments at the forefront of COVID-19 studies are Eli Lilly's product, bamlanivimab, and a cocktail from Regeneron Pharmaceuticals that Trump received.
Dr. Saahir Khan, a clinical professor in infectious diseases at the University of Southern California in Los Angeles, is a co-principal investigator of a clinical trial evaluating bamlanivimab.
"The goal of this trial is to find treatment that prevents these patients with what we call mild-to-moderate disease progressing to severe disease that would require hospitalization," Khan said in an interview.
About 79 million cases have been reported worldwide. And the need for such drugs is especially pressing as the number of cases continues to climb.
"Unfortunately, as bad as it is now, it's almost a foregone conclusion that it's going to get worse for the next month," Khan said.
Vaccines offer hope, but health officials caution they won't be widely available to the general public in Canada for a few months.
In the meantime, effective treatments could help reduce the severity of disease and hospitalization rates, lower death rates and flatten the curve so health systems aren't overwhelmed.
The oldest way to apply antibody treatments is to use the plasma from blood of people who've naturally recovered from COVID-19 and give those antibodies to a patient in need. That's known as convalescent serum or polyclonal antibodies.
But convalescent serum includes a range of antibodies to various infections, such as influenza, as well as the virus that causes COVID-19, called SARS-CoV-2.
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Monoclonal antibodies are synthetic, purer than convalescent serum and recognize a specific target, such as the proteins that SARS-CoV-2 uses to make copies of itself.
Before COVID-19 upended lives worldwide, other monoclonal antibody treatments were used to treat rheumatoid arthritis and Crohn's disease, including those with injections given at home using an auto-injector-type device.
For a treatment showing early promise, there hasn't been much pick up of monoclonal antibodies in COVID-19.
UBC's Murthy, who also co-chairs the World Health Organization's clinical research committee on COVID-19, said monoclonal antibodies haven't really been embraced in Canada yet because of access and feasibility questions.
To conduct the trial in southern California for instance, Khan's hospital set up a special tent outside, similar to COVID assessment centres at some Canadian hospitals. The site is staffed by health-care workers wearing full personal protective equipment to minimize the risk of people coming to participate in the trial spreading COVID-19 to any patients or staff.
What's more, current monoclonal antibody treatments for COVID-19 need to be given by infusion, similar to some chemotherapy agents. Khan said it takes an hour for patients to receive the monoclonal antibodies and then staff need to closely monitor them for another hour to check for any allergic reactions.
By mid-December in the U.S., less than 20 per cent of the doses of monoclonal antibodies that the federal government allocated had been used. Red tape, staff shortages, testing delays and skepticism are keeping patients and doctors from using the drugs. Evidence on their effectiveness is also thin so far.
Competition from vaccines
Meanwhile, hospitals and health-care systems in Canada and the U.S. are devoting more attention and resources to the vaccine rollout.
Dr. Donald Vinh, an infectious disease specialist and medical microbiologist at the McGill University Health Centre in Montreal, said monoclonal antibodies could help people who test positive and who need to keep their blood levels of oxygen up, while staying out of hospital.
Vinh, who advises the federal government's COVID-19 Therapeutics Task Force, said to his knowledge, monoclonal antibodies aren't being used in Canada to treat COVID. In contrast, Pfizer-BioNtech's vaccine is going into arms across the country.
"These vaccines are extremely effective in stimulating people to produce polyantibodies that protect you against COVID," Vinh said.
Matthew Miller, an associate professor at the Institute for Infectious Disease Research at McMaster University in Hamilton, about 70 kilometres southwest of Toronto, said logistical and economic issues are hindering the use of monoclonal antibodies to treat COVID-19.
Before the treatments can be given, people need to be diagnosed with COVID-19 quickly, Miller said. And he estimated monoclonal antibodies are about 1,000 times more expensive than a vaccine.
The U.S. has paid $1,250 US per dose for 950,000 doses of Lilly's bamlanivimab. Eli Lilly Canada signed an agreement with the federal government to supply 26,000 initial doses of bamlanivimab, also at $1,250 per dose, between December 2020 and February 2021, pending the results of trials to verify its clinical benefits.
To maximize the potential of monoclonal antibodies and to take advantage of when they work best, Miller suggested using them to prevent infection, rather than treat it.
"The sort of obvious settings where these would be really useful is nursing homes, because obviously those people are at a really high risk of dying and that population is usually a population that's quite hard to vaccinate," Miller said.
Other people who could potentially receive the preventive option include employees at meat-packing plants with outbreaks, or households with confirmed COVID-19 cases.
With files from Associated Press and Reuters