New York-based Siga said that it expects the results from the study to be used as one of the two animal models required for the FDA’s “animal efficacy rule” which allows animal studies in cases where human trials cannot be ethically conducted.
The study was conducted under Biosafety Level 4 conditions at the US Army Medical Research Institute of Infectious Diseases. Strain 13 guinea pigs were challenged with a lethal dose of Lassa virus and treated with ST-193 once a day for 14 days.
Siga said that administration with ST-193 resulted in significant reduction in mortality at the two doses tested, 80mg/kg and 25mg/kg (71% of the animals survived at the low dose), whereas all of the control animals and those treated with ribavirin succumbed to the disease within 20 days of the challenge.
Dr Dennis Hruby, Siga’s chief scientific officer, said: “This study should provide the basis for advancing this lead candidate into IND-enabling activities in the near future.”
Lassa fever is both a current world health threat, as it is prevalent in parts of West Africa (the CDC reports estimates of as many as 300,000 new cases each year), and a bioterror threat, due to its previous history as an object of weaponization research. Development of this Lassa antiviral is supported by the National Institutes of Health, which awarded Siga a $6 million grant in September 2006.