On Apr. 6, 2020, Mateon Therapeutics announced an update on its rapid antiviral response program targeting coronaviruses, initially targeting COVID-19. OT-101 continued to show significant activity against coronaviruses and in the new testing results, two additional therapeutic oligonucleotides designed to target COVID-19 also demonstrated potent anti-viral activity.

The candidates were all designed to work synergistically to avoid resistant mutations frequently seen with viral infections. OT-101 and the other candidates work by inhibiting virus binding to its target, thereby stopping the virus from replicating itself and stopping viral induced pneumonia, which often leads to patient complications.