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A drug aimed at curbing severe COVID-19 is stirring excitement among scientists, given the limited treatments left to beat back serious infections — but some doubt it will ever reach patients.
Canadian research on the drug, called pegylated interferon lambda, is just the latest chapter in a years-long saga to find effective COVID treatments, one that’s been filled with promising prospects, regulatory roadblocks, and ultimately a series of dead-ends as many drugs proved powerless against this ever-evolving virus.
Monoclonal antibodies, once considered life-saving, no longer work against new variants — leaving Pfizer’s antiviral, multi-pill drug Paxlovid as one of the last tools in the toolbox.
Researchers’ renewed hope centres on a different type of drug based on a specific type of interferon — a substance typically made by the body’s own cells to help the immune system fight infections — which appears to hold up against various variants of SARS-CoV-2.
A study from researchers at McMaster University in Hamilton and the University Health Network (UHN) in Toronto, published this week in the New England Journal of Medicine, found the drug reduced the risk of hospitalization.
The randomized clinical trial involved close to 2,000 participants, mostly from Brazil and some from Toronto, and took place between June and March 2021.
The bulk of subjects, around 84 per cent, were previously vaccinated against COVID-19.
“What we saw is that a single dose of the treatment reduced the probability of people who are at high risk for severe COVID ending up requiring hospitalization with their illness by about 50 per cent in people who were vaccinated,” said UHN researcher Dr. Jordan Feld.
“And in people who were not vaccinated, the effect was greater — almost 90 per cent reduction.”
Dr. Donald Vinh, an infectious diseases specialist with McGill University, called the drug’s potential “amazing” during an e-mail exchange with CBC News, “because it shows that we can harness the power of the immune system, and augment it to provide protection against infection, and to do it with relatively few side effects.”
The drug would also be straightforward to administer, as it’s just one single injection into the skin, much like an insulin shot — something patients could even do themselves, if necessary.
What’s far less clear is whether any patients will actually get the drug in the first place.
Drug features lung-targeting interferon
The specific type of interferon studied by the Canadian research team uses a receptor that’s only found in certain parts of the body, primarily the lungs and liver, Feld said. (His interest in the drug stems from his primary work as a liver disease researcher.)
That’s what makes it different from prior studies looking at the impact of other, broader interferons, which operate throughout the body. Those also ramp up an immune response, but can stimulate dangerous inflammation as well.
For instance, another team backed by the World Health Organization conducted a study earlier in the pandemic on hospitalized COVID patients, which found a different interferon was actually associated with worse outcomes, said B.C.-based clinician-scientist Dr. Srinivas Murthy, who helped with that research.
“We need to make sure that it’s the right interferon and the right patient population, and so the availability and the accessibility of this product is an important consideration,” he added.
Right now, the interferon showing potential against COVID, pegylated interferon lambda, isn’t actually available to give to Canadian patients. It’s been studied previously in the context of hepatitis viruses, Feld noted, but it’s “not actually approved for use for other indications.”
Feld is hopeful the drug may one day wind its way through the regulatory process to gain approval for use.
Murthy, however, is more “skeptical.”
“It’s not really a used drug in Canada, or USA, or anywhere else,” he said. “And so what needs to happen is that — compared to the other drugs that we thought about for COVID-19, that were repurposed — this needs to go through all of the approval mechanisms and so on.”
FDA didn’t authorize for emergency use
That’s where things get tricky. Late last year, regulators at the U.S. Food and Drug Administration (FDA) told the company behind the drug, Eiger Biopharmaceuticals — which helped fund the new study into its use against COVID — that they were “not prepared to authorize it for emergency use,” the New York Times recently reported.
“The regulators suggested that only a large clinical trial conducted at least in part in the United States and with more involvement from the company would suffice, Eiger executives said, a scenario that would require several years and considerably more funding,” the Times story continued.
Dr. Paul Sax, clinical director of infectious diseases at Brigham and Women’s Hospital and a professor of Medicine at Harvard Medical School, said regulatory discussions around the drug became “total silence” for several months.
“I was kind of worried it was left to languish,” he said, “and then this study appeared.”
Health Canada, Murthy said, usually “doesn’t deviate too far” from the FDA’s approach.
“Typically, for new drugs, we would need a couple of trials with reliable endpoints,” he said.
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High-risk individuals may seek new treatment options
There’s also an argument to be made that at this point in the pandemic — given access to vaccines that can largely prevent serious disease in the first place — there just isn’t the same level of need for an additional treatment, given the shrinking rate of people requiring major hospitalization for COVID, Murthy said.
Sax, however, stressed that high-risk individuals are still seeking new options.
A single shot could be easier, for some people, than Paxlovid’s multi-day pill regimen. And an interferon immune-based therapy may provide a variant-proof treatment, unlike monoclonal antibodies which targeted the virus’ spike protein — rendering them ineffective as that area continues to mutate.
For now, pegylated interferon lambda remains a promising possibility, even though “we can’t give this therapy to anybody tomorrow,” Feld said.
“Some people… they saw the publication and asked me, ‘Can we get this?'” he said. “And I said, unfortunately, not yet. I hope soon — but not yet.”
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