Shionogi’s respiratory syncytial virus (RSV) antiviral for adults has proven its ability to reduce viral load in a phase 2 trial.
The study saw 114 healthy adults inoculated with the virus and then given the antiviral, dubbed S-337395, or placebo for five days. Individuals treated with S-337395 showed a “statistically significant reduction in viral load compared to the placebo group,” hitting the study’s primary endpoint.
The Japanese biopharma singled out the cohort that received the highest dose of S-337395. These individuals saw a 88.94% reduction in viral load as well as a “statistically significant improvement in clinical symptom scores,” the company said in a Jan. 30 release.
When it came to safety, there were no serious or severe adverse events and “no dose-dependent increase in incidence or severity of adverse events,” Shionogi added.
S-337395 is designed to inhibit the activity of the L protein, which is required for the virus to replicate. The tech was developed in collaboration with Japanese chemical company UBE, which is responsible for developing and manufacturing the antiviral’s pharmaceutical ingredient.
While a lot of recent development in the RSV space from the likes of Merck & Co.’s preventive antibody have focused on children, Shionogi used this morning’s release to highlight that recent years have seen “growing awareness that RSV also causes high rates of hospitalization and mortality amongst individuals aged 60 and older.”
This morning's data are similar to those posted by Enanta Pharmaceuticals in September, which showed that its own antiviral EDP-323 lowered viral load by 85% at the high dose and 87% at the low dose compared to placebo.
Both Enanta and Shionogi are looking to enter a market already served by RSV vaccines that can prevent infection and, in doing so, reduce the number of people who may need an antiviral. However, Enanta previously explained that it sees an ongoing need for antivirals in both the pediatric and adult populations, pointing to low vaccine use in adults.
In its release this morning, Shionogi made a similar point, noting that “effective antiviral treatment options for RSV remain limited, and there continues to be a significant unmet medical need in this area.”