Lumicitabine (formerly called ALS-8176), a first-in-class orally administered nucleoside analogue is being developed by Alios BioPharma for the treatment of respiratory syncytial virus infections. Lumicitabine converts to plasma-circulating ALS-8112, and then to the 5'-active nucleoside triphosphate (NTP) form within host cells. Extensive and rapid RSV reduction occurred after lumicitabine treatment (EC50 = 1.79 uM), with >99% viral inhibition at 2 h after loading dose. Clinical trials of Lumicitabine for the treatment of respiratory syncytial virus infection are ongoing.