SNG001: Synairgen's COVID-19 Antiviral for the Immunocompromised

At more than 2 years into the COVID-19 pandemic, there have been significant advances in treatment and prevention options. COVID-19 mRNA vaccination is highly effective against severe disease and death, but highly infectious variants like Omicron BA.1 and BA.2 are causing breakthrough infections, leading cases to rise once again.

To prevent older or otherwise immunocompromised people from severe or fatal infection, Synairgen is developing SNG001, an inhalable COVID-19 treatment for hospitalized persons.

Dr. Phillip Monk, the Chief Scientific Officer at Synairgen, joined Contagion to discuss the SNG001 trial data Synairgen presented at the American Thoracic Society 2022 International Conference, held in San Francisco last month.

SNG001 is a formulation of Interferon-beta (IFN-β), a naturally occurring protein that catalyzes the body’s antiviral response. SARS-CoV-2 suppresses this protein, so the inhalable IFN-β directly targets the lungs, the primary site of the COVID-19 viral reservoir.

SNG001 may retain some efficacy against the Omicron variant. As a host-directed antiviral, Monk says, SNG001 has “broad spectrum antiviral potential.” “We have in the lab actually shown the antiviral activity of IFN-β against Omicron as we have against other variants”

The phase 3 SPRINTER trial (SG018; NCT04732949) was a global, randomized, placebo-controlled, double-blind clinical study. The trial evaluated inhaled SNG001 to treat adults hospitalized with COVID-19 who required supplemental oxygen. SPRINTER included 624 participants, randomly assigned to either SNG001 (n = 309) or placebo (n = 314) in addition to standard of care.

In February 2022, Synairgen announced that SPRINTER did not meet its primary endpoints of hospital discharge and illness recovery. Monk says that this can be partially attributed to the standard-of-care COVID-19 treatments improving so much that SNG001 had to demonstrate a greater significance of disease reduction. “Because patients are doing so much better, it’s much more difficult to show treatment effect on things like hospital discharge,” Mock explained.

Despite the efficacy of vaccines and other antivirals, there are still COVID-19 mortalities. Monk says over 2000 patients are being hospitalized in the US each day, and about 200 people a day are dying of COVID-19.

Among the trial participants given SNG001, there was a signal in reduction in the relative risk of progression to severe disease or death within 35 days. Monk said that the greatest treatment benefits were observed in older patients, patients with comorbidities, and especially in people who had poor respiratory function at baseline.

“These are people who are having to breathe faster or have low oxygen saturation despite being on oxygen,” Monk said, noting that this treatment population saw a relative risk reduction of 70% for severe disease.