title: Activity and the metabolic activation pathway of the potent and selective hepatitis C virus pronucleotide inhibitor PSI-353661.
abstract: PSI-353661, a phosphoramidate prodrug of 2'-deoxy-2'-fluoro-2'-C-methylguanosine-5'-monophosphate, is a highly active inhibitor of genotype 1a, 1b, and 2a HCV RNA replication in the replicon assay and of genotype 1a and 2a infectious virus replication. PSI-353661 is active against replicons harboring the NS5B S282T or S96T/N142T amino acid alterations that confer decreased susceptibility to nucleoside/tide analogs as well as mutations that confer resistance to non-nucleoside inhibitors of NS5B. Replicon clearance studies show that PSI-353661 was able to clear cells of HCV replicon RNA and prevent a rebound in replicon RNA. PSI-353661 showed no toxicity toward bone marrow stem cells or mitochondrial toxicity. The metabolism to the active 5'-triphosphate involves hydrolysis of the carboxyl ester by cathepsin A (Cat A) and carboxylesterase 1 (CES1) followed by a putative nucleophilic attack on the phosphorus by the carboxyl group resulting in the elimination of phenol and the alaninyl phosphate metabolite, PSI-353131. Histidine triad nucleotide-binding protein 1 (Hint 1) then removes the amino acid moiety, which is followed by hydrolysis of the methoxyl group at the O(6)-position of the guanine base by adenosine deaminase-like protein 1 (ADAL1) to give 2'-deoxy-2'-fluoro-2'-C-methylguanosine-5'-monophosphate. The monophosphate is phosphorylated to the diphosphate by guanylate kinase. Nucleoside diphosphate kinase is the primary enzyme involved in phosphorylation of the diphosphate to the active triphosphate, PSI-352666. PSI-352666 is equally active against wild-type NS5B and NS5B containing the S282T amino acid alteration.
authors: Pharmasset, Inc., Princeton, NJ 08540, USA. phillip.furman@pharmasset.com
authors: Phillip A
authors: PA
authors: Furman
authors: Eisuke
authors: E
authors: Murakami
authors: Congrong
authors: C
authors: Niu
authors: Angela M
authors: AM
authors: Lam
authors: Christine
authors: C
authors: Espiritu
authors: Shalini
authors: S
authors: Bansal
authors: Haiying
authors: H
authors: Bao
authors: Tatiana
authors: T
authors: Tolstykh
authors: Holly
authors: H
authors: Micolochick Steuer
authors: Meg
authors: M
authors: Keilman
authors: Veronique
authors: V
authors: Zennou
authors: Nigel
authors: N
authors: Bourne
authors: Ronald L
authors: RL
authors: Veselenak
authors: Wonsuk
authors: W
authors: Chang
authors: Bruce S
authors: BS
authors: Ross
authors: Jinfa
authors: J
authors: Du
authors: Michael J
authors: MJ
authors: Otto
authors: Michael J
authors: MJ
authors: Sofia
references: J Hepatol. 2009 Oct;51(4):787-91
references: 19665816
references: Antimicrob Agents Chemother. 2008 Sep;52(9):3327-38
references: 18559648
references: J Biol Chem. 2002 Feb 15;277(7):5453-9
references: 11741981
references: Antimicrob Agents Chemother. 2003 Nov;47(11):3525-30
references: 14576112
references: Antimicrob Agents Chemother. 2008 Oct;52(10):3523-31
references: 18694956
references: Antimicrob Agents Chemother. 2008 Feb;52(2):458-64
references: 17999967
references: J Virol. 2003 Oct;77(19):10689-94
references: 12970456
references: Antivir Chem Chemother. 1998 Nov;9(6):473-9
references: 9865385
references: Proc Natl Acad Sci U S A. 2006 Feb 14;103(7):2310-5
references: 16461899
references: J Virol. 2006 Jun;80(12):6146-54
references: 16731953
references: J Submicrosc Cytol Pathol. 1989 Apr;21(2):275-9
references: 2752360
references: J Biol Chem. 2003 Dec 5;278(49):49164-70
references: 12966103
references: J Virol. 2007 Jan;81(2):588-98
references: 17079281
references: Bioorg Med Chem Lett. 2010 Aug 15;20(16):4850-4
references: 20637609
references: Hum Pathol. 2001 Jul;32(7):734-40
references: 11486172
references: Drug Saf. 2000 Dec;23(6):467-81
references: 11144657
references: Antimicrob Agents Chemother. 2010 Aug;54(8):3187-96
references: 20516278
references: J Virol. 2003 Mar;77(5):3181-90
references: 12584342
references: Nat Rev Drug Discov. 2003 Oct;2(10):812-22
references: 14526384
references: J Virol. 2003 Dec;77(24):13225-31
references: 14645579
references: J Virol. 2003 Mar;77(5):3007-19
references: 12584326
references: Antivir Chem Chemother. 2006;17(2):79-87
references: 17042329
references: Antivir Chem Chemother. 1998 Mar;9(2):109-15
references: 9875382
references: Antimicrob Agents Chemother. 2008 May;52(5):1604-12
references: 18285474
references: ACS Med Chem Lett. 2010 Dec 17;2(2):130-5
references: 24900291
references: Virology. 2006 Aug 1;351(2):349-59
references: 16713611
references: Bioorg Med Chem Lett. 2006 Mar 15;16(6):1712-5
references: 16368235
references: J Med Chem. 2010 Oct 14;53(19):7202-18
references: 20845908
references: Biochem Pharmacol. 2006 Apr 28;71(9):1370-6
references: 16513094
references: Mol Pharm. 2007 Mar-Apr;4(2):208-17
references: 17217311
references: J Biol Chem. 2010 Nov 5;285(45):34337-47
references: 20801890
references: Antimicrob Agents Chemother. 2002 Dec;46(12):3854-60
references: 12435688
references: Antimicrob Agents Chemother. 2007 Feb;51(2):503-9
references: 17101674