Synairgen's inhalable therapy has failed in late-stage trial testing in patients hospitalized with COVID-19, wiping out over 85% of the British drugmaker's stock value on Monday after the blow to the development of its key product.
SNG001, an inhalable formulation containing the broad-spectrum antiviral protein interferon beta, was being tested for whether it reduced patients' hospital stay and how rapidly they recovered when given the drug along with standard treatment.
The therapy did not show any meaningful change in those parameters compared with a placebo.
"While we are disappointed by the overall outcome, SNG001 has been administered to hospitalized patients on top of standard of care which changed substantially between our Phase 2 and Phase 3 trials," Chief Executive Richard Marsden said.
"This improvement in patient care may have compromised the potential of SNG001," he said, adding that the company was now analyzing the full dataset from the "Sprinter" trial.
Synairgen, founded by three University of Southampton professors in 2003, stands to lose about 342 million pounds ($466.2 million) of its market value at Monday's low of 11.12 pence per share if the losses hold.
Its shares, which had surged about 36% in 2021, pared some losses to trade 86% lower at 23.70 pence by 0841 GMT after earlier tumbling as much as 93.5%.
Interferon beta is a naturally occurring protein instrumental to the body's antiviral responses, and studies have shown the COVID-causing SARS-CoV-2 virus can suppress its production in the body.
SNG001, delivered directly into the lungs using a mesh nebulizer, is also being tested in a late-stage COVID-19 trial for at-home use, sponsored by the U.S. National Institutes of Health. Results from that trial are yet to be announced.
As part of Sprinter, 623 patients were given SNG001 or a placebo on top of the standard treatment at random.