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Antimicrob Agents Chemother. 2019 Mar 27;63(4). pii: e02143-18. doi: 10.1128/AAC.02143-18. Print 2019 Apr.

CMCdG, a Novel Nucleoside Analog with Favorable Safety Features, Exerts Potent Activity against Wild-Type and Entecavir-Resistant Hepatitis B Virus.

Author information

1
Department of Refractory Viral Infections, National Center for Global Health & Medicine Research Institute, Tokyo, Japan.
2
Department of Virology & Liver Unit, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
3
Experimental Retrovirology Section, HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
4
Faculty of Pharmaceutical Sciences, Sojo University, Kumamoto, Japan.
5
Biostatistics and Data Management Section, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
6
Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA.
7
Department of Refractory Viral Infections, National Center for Global Health & Medicine Research Institute, Tokyo, Japan hiroaki.mitsuya2@nih.gov.
8
Department of Clinical Sciences, Kumamoto University Hospital, Kumamoto, Japan.

Abstract

We designed, synthesized, and characterized a novel nucleoside analog, (1S,3S,5S)-3-(2-amino-6-oxo-1,6-dihydro-9H-purin-9-yl)-5-hydroxy-1-(hydroxymethyl)-2-methylene-cyclopentanecarbonitrile, or 4'-cyano-methylenecarbocyclic-2'-deoxyguanosine (CMCdG), and evaluated its anti-hepatitis B virus (anti-HBV) activity, safety, and related features. CMCdG's in vitro activity was determined using quantitative PCR and Southern blotting assays, and its cytotoxicity was determined with a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay, while its in vivo activity and safety were determined in human liver-chimeric mice infected with wild-type HBV genotype Ce (HBVWT Ce) and an entecavir (ETV)-resistant HBV variant containing the amino acid substitutions L180M, S202G, and M204V (HBVETV-R L180M/S202G/M204V). CMCdG potently inhibited HBV production in HepG2.2.15 cells (50% inhibitory concentration [IC50], ∼30 nM) and HBVWT Ce plasmid-transfected Huh7 cells (IC50, 206 nM) and efficiently suppressed ETV-resistant HBVETV-R L180M/S202G/M204V (IC50, 2,657 nM), while it showed no or little cytotoxicity (50% cytotoxic concentration, >500 μM in most hepatocytic cells examined). Two-week peroral administration of CMCdG (1 mg/kg of body weight/day once a day [q.d.]) to HBVWT Ce-infected human liver-chimeric mice reduced the level of viremia by ∼2 logs. CMCdG also reduced the level of HBVETV-R L180M/S202G/M204V viremia by ∼1 log in HBVETV-R L180M/S202G/M204V-infected human liver-chimeric mice, while ETV (1 mg/kg/day q.d.) completely failed to reduce the viremia. None of the CMCdG-treated mice had significant drug-related changes in body weights or serum human albumin levels. Structural analyses using homology modeling, semiempirical quantum methods, and molecular dynamics revealed that although ETV triphosphate (TP) forms good van der Waals contacts with L180 and M204 of HBVWT Ce reverse transcriptase (RT), its contacts with the M180 substitution are totally lost in the HBVETV-R L180M/S202G/M204V RT complex. However, CMCdG-TP retains good contacts with both the HBVWT Ce RT and HBVETV-R L180M/S202G/M204V RT complexes. The present data warrant further studies toward the development of CMCdG as a potential therapeutic for patients infected with drug-resistant HBV and shed light on the further development of more potent and safer anti-HBV agents.

KEYWORDS:

anti-HBV drugs; drug-resistant HBV variants; human liver-chimeric mice; molecular modeling; nucleoside/nucleotide reverse transcriptase inhibitors

PMID:
30670420
PMCID:
PMC6437475
[Available on 2019-09-27]
DOI:
10.1128/AAC.02143-18

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