2′-Deoxy-4′-azido Nucleoside Analogs Are Highly Potent Inhibitors of Hepatitis C Virus Replication Despite the Lack of 2′-α-Hydroxyl Groups

• Published in: The Journal of biological chemistry Vol. 283; no. 4; p. 2167
• Main Authors: Klaus Klumpp, Genadiy Kalayanov, Han Ma, Sophie Le Pogam, Vincent Leveque, Wen-Rong Jiang, Nicole Inocencio, Anniek De Witte, Sonal Rajyaguru, Ezra Tai, Sushmita Chanda, Michael R. Irwin, Christian Sund, Anna Winqist, Tatiana Maltseva, Staffan Eriksson, Elena Usova, Mark Smith, Andre Alker, Isabel Najera, Nick Cammack, Joseph A. Martin, Nils Gunnar Johansson, David B. Smith
• Format: Journal Article
• Language: English
• Published: American Society for Biochemistry and Molecular Biology 25.01.2008
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M708929200

RNA polymerases effectively discriminate against deoxyribonucleotides and specifically recognize ribonucleotide substrates most likely through direct hydrogen bonding interaction with the 2′-α-hydroxy moieties of ribonucleosides. Therefore, ribonucleoside analogs as inhibitors of viral RNA polymerases have mostly been designed to retain hydrogen bonding potential at this site for optimal inhibitory potency. Here, two novel nucleoside triphosphate analogs are described, which are efficiently incorporated into nascent RNA by the RNA-dependent RNA polymerase NS5B of hepatitis C virus (HCV), causing chain termination, despite the lack of α-hydroxy moieties. 2′-Deoxy-2′-β-fluoro-4′-azidocytidine (RO-0622) and 2′-deoxy-2′-β-hydroxy-4′-azidocytidine (RO-9187) were excellent substrates for deoxycytidine kinase and were phosphorylated with efficiencies up to 3-fold higher than deoxycytidine. As compared with previous reports on ribonucleosides, higher levels of triphosphate were formed from RO-9187 in primary human hepatocytes, and both compounds were potent inhibitors of HCV virus replication in the replicon system (IC 50 = 171 ± 12 n m and 24 ± 3 n m for RO-9187 and RO-0622, respectively; CC 50 >1 m m for both). Both compounds inhibited RNA synthesis by HCV polymerases from either HCV genotypes 1a and 1b or containing S96T or S282T point mutations with similar potencies, suggesting no cross-resistance with either R1479 (4′-azidocytidine) or 2′-C-methyl nucleosides. Pharmacokinetic studies with RO-9187 in rats and dogs showed that plasma concentrations exceeding HCV replicon IC 50 values 8-150-fold could be achieved by low dose (10 mg/kg) oral administration. Therefore, 2′-α-deoxy-4′-azido nucleosides are a new class of antiviral nucleosides with promising preclinical properties as potential medicines for the treatment of HCV infection.