The history of Dengue drug development highlights the challenges posed in the field as a whole. Despite being the most studied mosquito-borne viral infection, with decades of intense vaccine and therapeutic development efforts, the global incidence of Dengue has grown 30-fold over the past 50 years, and the virus currently infects more people than all other mosquito-borne viral infections combined.

In terms of prevention, the world’s first approved Dengue vaccine was introduced by Sanofi in late 2015, but its efficacy has been limited and large-scale immunization programs were recently halted after reports of potentially deadly outcomes for certain populations (namely, those who have not been previously infected with the virus).

In terms of treatment, there are currently no approved therapies and very few Dengue antiviral drug candidates in human clinical trials. Those that have made it to trial have had limited success and sub-optimal outcomes. As a result, today’s standard treatment options for Dengue infections remain merely supportive, focused on reducing symptoms as opposed to stopping the virus. The same is the case for Zika and other mosquito-borne viral infections.

Another prominent case recently gaining attention is Yellow Fever, particularly in Brazil where there is an ongoing outbreak. While a Yellow Fever vaccine exists, global supplies are limited and a large fraction of the population has not been vaccinated. The recent outbreak highlights the urgent, unmet need to develop effective treatments. These issues become all the more pressing when considering that many mosquito-borne viruses co-circulate in the same geographical regions and infected patients often present similar clinical symptoms that make differential diagnosis difficult. A broadly effective treatment solution, such as the one TSG is developing, would solve these challenges in one fell swoop.