2'-deoxy-4'-azido nucleoside analogs are highly potent inhibitors of hepatitis C virus replication despite the lack of 2'-alpha-hydroxyl groups.
RNA polymerases effectively discriminate against deoxyribonucleotides and specifically recognize ribonucleotide substrates most likely through direct hydrogen bonding interaction with the 2'-alpha-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 alpha-hydroxy moieties. 2'-deoxy-2'-beta-fluoro-4'-azidocytidine (RO-0622) and 2'-deoxy-2'-beta-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 nM and 24 +/- 3 nM for RO-9187 and RO-0622, respectively; CC(50) >1 mM 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'-alpha-deoxy-4'-azido nucleosides are a new class of antiviral nucleosides with promising preclinical properties as potential medicines for the treatment of HCV infection.
Klumpp
Klaus
K
Roche Palo Alto LLC, Palo Alto, California 94304, USA. Klaus.klumpp@roche.com
Kalayanov
Genadiy
G
Ma
Han
H
Le Pogam
Sophie
S
Leveque
Vincent
V
Jiang
Wen-Rong
WR
Inocencio
Nicole
N
De Witte
Anniek
A
Rajyaguru
Sonal
S
Tai
Ezra
E
Chanda
Sushmita
S
Irwin
Michael R
MR
Sund
Christian
C
Winqist
Anna
A
Maltseva
Tatiana
T
Eriksson
Staffan
S
Usova
Elena
E
Smith
Mark
M
Alker
Andre
A
Najera
Isabel
I
Cammack
Nick
N
Martin
Joseph A
JA
Johansson
Nils Gunnar
NG
Smith
David B
DB
D000818:Animals; D000998:Antiviral Agents / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use; D002478:Cells, Cultured; D004285:Dogs; D004791:Enzyme Inhibitors / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use; D005838:Genotype; D016174:Hepacivirus / Q000201:enzymology* / Q000235:genetics; D006526:Hepatitis C / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000821:virology; D022781:Hepatocytes / Q000201:enzymology / Q000821:virology; D006801:Humans; D012367:RNA, Viral / Q000096:biosynthesis / Q000235:genetics; D012324:RNA-Dependent RNA Polymerase / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012263:Ribonucleosides / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use; D014779:Virus Replication / Q000187:drug effects* / Q000502:physiology
D000998:Antiviral Agents; D004791:Enzyme Inhibitors; D012367:RNA, Viral; D012263:Ribonucleosides; D012324:RNA-Dependent RNA Polymerase