title: Genotype and subtype profiling of PSI-7977 as a nucleotide inhibitor of hepatitis C virus.
abstract: PSI-7977, a prodrug of 2'-F-2'-C-methyluridine monophosphate, is the purified diastereoisomer of PSI-7851 and is currently being investigated in phase 3 clinical trials for the treatment of hepatitis C. In this study, we profiled the activity of PSI-7977 and its ability to select for resistance using a number of different replicon cells. Results showed that PSI-7977 was active against genotype (GT) 1a, 1b, and 2a (strain JFH-1) replicons and chimeric replicons containing GT 2a (strain J6), 2b, and 3a NS5B polymerase. Cross-resistance studies using GT 1b replicons confirmed that the S282T change conferred resistance to PSI-7977. Subsequently, we evaluated the ability of PSI-7977 to select for resistance using GT 1a, 1b, and 2a (JFH-1) replicon cells. S282T was the common mutation selected among all three genotypes, but while it conferred resistance to PSI-7977 in GT 1a and 1b, JFH-1 GT 2a S282T showed only a very modest shift in 50% effective concentration (EC(50)) for PSI-7977. Sequence analysis of the JFH-1 NS5B region indicated that additional amino acid changes were selected both prior to and after the emergence of S282T. These include T179A, M289L, I293L, M434T, and H479P. Residues 179, 289, and 293 are located within the finger and palm domains, while 434 and 479 are located on the surface of the thumb domain. Data from the JFH-1 replicon variants showed that amino acid changes within the finger and palm domains together with S282T were required to confer resistance to PSI-7977, while the mutations on the thumb domain serve to enhance the replication capacity of the S282T replicons.
authors.affiliation: Pharmasset, Inc, Princeton, New Jersey, USA. angela.lam.al1@roche.com
authors.forename: Angela M
authors.initials: AM
authors.lastname: Lam
authors.forename: Christine
authors.initials: C
authors.lastname: Espiritu
authors.forename: Shalini
authors.initials: S
authors.lastname: Bansal
authors.forename: Holly M
authors.initials: HM
authors.lastname: Micolochick Steuer
authors.forename: Congrong
authors.initials: C
authors.lastname: Niu
authors.forename: Veronique
authors.initials: V
authors.lastname: Zennou
authors.forename: Meg
authors.initials: M
authors.lastname: Keilman
authors.forename: Yuao
authors.initials: Y
authors.lastname: Zhu
authors.forename: Shuiyun
authors.initials: S
authors.lastname: Lan
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Otto
authors.forename: Phillip A
authors.initials: PA
authors.lastname: Furman
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D002460:Cell Line; D005838:Genotype; D016174:Hepacivirus / Q000187:drug effects* / Q000235:genetics*; D006801:Humans; D012093:Replicon / Q000187:drug effects / Q000235:genetics; D000069474:Sofosbuvir; D014542:Uridine Monophosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D014779:Virus Replication / Q000187:drug effects
chemical_list: D000998:Antiviral Agents; D014542:Uridine Monophosphate; D000069474:Sofosbuvir