Synthesis and Anti-HCV Activity of Sugar-Modified Guanosine Analogues: Discovery of <b>AL-611</b> as an HCV NS5B Polymerase Inhibitor for the Treatment of Chronic Hepatitis C

Abstract

Chronic hepatitis C (CHC) is a major liver disease caused by the hepatitis C virus. The current standard of care for CHC can achieve cure rates above 95%; however, the drugs in current use are administered for a period of 8-16 weeks. A combination of safe and effective drugs with a shorter treatment period is highly desirable. We report synthesis and biological evaluation of a series of 2',3'- and 2',4'-substituted guanosine nucleotide analogues. Their triphosphates exhibited potent inhibition of the HCV NS5B polymerase with IC₅₀ as low as 0.13 μM. In the HCV replicon assay, the phosphoramidate prodrugs of these analogues demonstrated excellent activity with EC₅₀ values as low as 5 nM. A lead compound <b>AL-611</b> showed high levels of the nucleoside 5'-triphosphate in vitro in primary human hepatocytes and in vivo in dog liver following oral administration.