Discovery and Synthesis of a Phosphoramidate Prodrug of a Pyrrolo2,1-ftriazin-4-amino Adenine C-Nucleoside (GS-5734) for the Treatment of Ebola and Emerging Viruses

= 86 nM in macrophages as the clinical candidate. Structure activity relationships established that the 1'-CN group and C-linked nucleobase were critical for optimal anti-EBOV potency and selectivity against host polymerases. A robust diastereoselective synthesis provided sufficient quantities of 4b to enable preclinical efficacy in a non-human-primate EBOV challenge model. Once-daily 10 mg/kg iv treatment on days 3-14 postinfection had a significant effect on viremia and mortality, resulting in 100% survival of infected treated animals Nature 2016 , 531 , 381 - 385 . A phase 2 study (PREVAIL IV) is currently enrolling and will evaluate the effect of 4b on viral shedding from sanctuary sites in EBOV survivors.