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A New Flu Drug Works Astoundingly Well—By Not Targeting the Flu at All

Vasculotide buys the immune system time, which may be all it needs.
Image: Warren Lee Lab

Dying from the flu, whether it's a standard-issue seasonal flu preying on the elderly and otherwise immunocompromised or a superstrain we don't even know about yet, mostly comes in the form of respiratory failure. This is what the virus (usually) targets: airways and lungs. As an influenza infection turns dire, the thin layer of cells known as the microvascular endothelium that form the barrier between the circulatory system and the respiratory system become damaged and the result is leakage of fluids in sometimes large volumes, the result of which is known as acute respiratory distress syndrome (ARDS). Flu-death is sort of like drowning.


For the most part, there's no great treatment for the flu. There's the yearly crapshoot of flu vaccines and there's better-than-nothing Tamiflu, but beating back the virus in its more advanced and potentially-lethal stages is more a matter of supportive care and the efforts of the body's own immune system. It's not ideal.

A new treatment known as Vasculotide offers a fundamentally different approach to fighting viruses—not fighting them in the first place. Instead, it concentrates on stopping fluid from leaking into the lungs, buying the body's immune system some crucial time and perhaps even enough to outlast the virus and recover. So, yes, it turns out that "just treating the symptoms" isn't always as wrongheaded as it's made out to be. The new drug is described in Scientific Reports.

"Whether as an agent of pandemics or as a seasonal pathogen, the influenza virus exacts a heavy toll on global public health," the study notes. "Despite vaccination programs and antiviral drugs, seasonal influenza alone causes millions of cases of severe illness and hundreds of thousands of deaths annually."

"There are concerns that ongoing mutation will lead to a novel strain of the virus that is both highly transmissible and highly virulent, as occurred in the 1918 pandemic leading to the deaths of 50 million people," it continues.

The Vasculotide research comes courtesy of a large team based primarily at the University of Toronto and led by respirology researcher/clinician Warren L Lee. Several of the authors, including Lee, have filed for a patent on the new treatment.


Image: Warren Lee Lab

Vasculotide is a "Tie2-agonist tetrameric peptide." Its efficacy doesn't have to do with the production of additional healthy lung cells but rather the inhibition of the programmed cell death, known as apotosis, that's triggered by the influenza virus. This cell death has to do in large part with the removal of Tie2, a protein that Vasculotide acts as an "agonist" for, e.g. stimulates the production of. And with Tie2 back on the scene, lung cells stop self-destructing and fluids stop leaking in.

Lee and his group tested Vasculotide using three different flu strains, administered in lethal doses, infecting two different species of mice.

"Prior to receiving Vasculotide, mice displayed typical signs of progressive illness such as arterial hypoxemia, hypothermia, and declining body weight; these features are apparent as early as 48–72 hours after infection," Lee and co. report. "Vasculotide treatment started at 72 hours post-infection is able to rescue a significant subset of infected mice."

What makes the treatment interesting—aside from, you know, working really well—is that it's not an immune system booster. Its effects inhibit "downstream" effects of the illness and the body's innate immune responses. The immune system doesn't get stronger, it just gets more time. It could be all the difference.