Last summer, Synairgen’s stock soared 300% in a study that showed that its inhaled form of interferon beta-1a being developed to treat COVID-19 decreased the chance that patients would progress to a severe form of the virus.
But there was a big shadow hanging over the results: interferon is known to increase levels of the ACE2 cell surface protein, which serves as an entry point for SARS-CoV-2, the virus that causes COVID-19. This raised fears that interferon-based treatments would eventually fail to treat coronavirus.
Now researchers led by the University of Southampton, which is collaborating with Synairgen in the development of its drug, have found that interferon increases levels of an abbreviated form of ACE2 that does not allow SARS-CoV-2 to enter cells. In fact, it may have a protective effect, the team reported in the journal Nature Genetics.
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The abbreviated form of ACE2 that researchers in the United Kingdom found does not have a specific binding site that SARS-CoV-2 needs to enter healthy cells. As this short version of the protein increases in response to interferons – but not SARS-CoV-2 – the researchers believe it is somehow involved in the body’s natural immune response to viruses.
“We are excited to discover a new form of ACE2 and are even more interested when [realized] which can be protective against SARS-CoV-2 in the airways, rather than an entry point for infection, ”said University of Southampton professor Jane Lucas, MD, Ph.D., in a statement. Two of the study’s co-authors, Donna Davies, Ph.D., and Ratko Djukanovic, MD, are co-founders and shareholders of Synairgen, which was spun off from the university.
Investors applauded Synairgen when preliminary data from their 101-patient study showed that its interferon, SNG001, reduced the risk of progression to severe COVID-19 by 79% over placebo. An update of these results raised the company’s stock by 30% in November, when the company reported that 75% of patients who took SNG001 showed clinical improvement on 15/16, as measured by a key World Health Organization scale.
The discovery of the short ACE2 may have implications for more than just Synairgen, the authors argued in the new study. The researchers’ ability to distinguish between the two versions of the protein may generate ideas for more sophisticated treatments for the coronavirus, they said.
The team led by the University of Southampton is now planning additional studies to investigate the implications of short ACE2 for managing COVID-19.
In December, Synairgen announced that it had started a phase 3 trial of SNG001 in the UK and that the FDA granted the drug fast-track status and released it for studies in the United States.