INX-08189, a Phosphoramidate Prodrug of 6-
            <i>O</i>
            -Methyl-2′-
            <i>C</i>
            -Methyl Guanosine, Is a Potent Inhibitor of Hepatitis C Virus Replication with Excellent Pharmacokinetic and Pharmacodynamic Properties

Vernachio, John; Bleiman, Blair; Bryant, K. Dawn; Chamberlain, Stanley D.; Hunley, Damound; Hutchins, Jeff; Ames, Brenda; Gorovits, Elena L.; Ganguly, Babita; Hall, Andrea; Kolykhalov, Alexander A.; Liu, Yule; Muhammad, Jerry; Raja, Nicholas; Walters, C. Robin; Wang, Jin; Williams, Karen; Patti, Joseph M.; Henson, Geoffrey; Madela, Karolina; Aljarah, Mohamed; Gilles, Arnaud; McGuigan, Christopher

doi:10.1128/aac.01335-10

Cited by 79 publications

(74 citation statements)

References 34 publications

(52 reference statements)

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“…For HCV, INX-08189 was tested in combination with ribavirin in the presence or absence of pegylated interferon (PEG-IFN) in HCV patients; unfortunately, adverse effects (heart and renal toxicity) were observed (37). This was not too surprising, as INX-08189 showed similar toxicological findings when administered as monotherapy (38). For HIV, a CTP synthase inhibitor (3=-deazauridine) strongly potentiated the anti-HIV-1 activity of a 5=-triphosphate of the cytidine analog lamivudine (3TC) and a 2,3=-dideoxycytidine (ddC) in cell culture (39).…”

Section: Discussionmentioning

confidence: 95%

Synergistic Suppression of Dengue Virus Replication Using a Combination of Nucleoside Analogs and Nucleoside Synthesis Inhibitors

Yeo

Chen

et al. 2015

Antimicrob Agents Chemother

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Dengue virus (DENV) is the most prevalent mosquito-borne viral pathogen in humans. Currently, there is no clinically approved vaccine or antiviral for DENV. Combination therapy is a common practice in antiviral treatment and a potential approach to search for new treatments for infectious pathogens. In this study, we performed a combination treatment in cell culture by using three distinct classes of inhibitors, including ribavirin (a guanosine analog with several antiviral mechanisms), brequinar (a pyrimidine biosynthesis inhibitor), and INX-08189 (a guanosine analog). The compound pairs were evaluated for antiviral activity by use of a DENV-2 luciferase replicon assay. Our result indicated that the combination of ribavirin and INX-08189 exhibited strong antiviral synergy. This result suggests that synergy can be achieved with compound pairs in which one compound suppresses the synthesis of the nucleoside for which the other compound is a corresponding nucleoside analog. In addition, we found that treatment of cells with brequinar alone could activate interferon-stimulated response elements (ISREs); furthermore, brequinar and NITD-982 (another pyrimidine biosynthesis inhibitor) potentiated interferon-induced ISRE activation. Compared to treatment with brequinar, treatment of cells with ribavirin alone could also induce ISRE activation, but to a lesser extent; however, when cells were cotreated with ribavirin and beta interferon, ribavirin did not augment the interferoninduced ISRE activation. O ver 2.5 billion people worldwide are at risk of dengue virus (DENV) infection, with 390 million human infections and 96 million cases with disease manifestations each year (1). DENV is endemic throughout tropical and subtropical climates and is found mostly in urban and semiurban areas. This positive-sense single-stranded RNA virus is transmitted mainly by the Aedes aegypti mosquito and is classified under the genus Flavivirus in the family Flaviviridae. Other notable viruses in this group include yellow fever virus, Japanese encephalitis virus, West Nile virus, and tick-borne encephalitis virus. Currently, neither an antiviral nor a vaccine is approved for DENV. Care for hospitalized dengue patients is supportive, mainly through optimal replenishment of body fluids. Treatment is intensive for those who succumb to the severe forms of the disease, i.e., dengue shock syndrome (DSS) and dengue hemorrhagic fever (DHF).Multiples approaches have been taken to identify inhibitors of DENV (2, 3). Small-molecule inhibitors have been reported to target various DENV proteins, including capsid (4, 5), envelope (6), protease (7, 8), nonstructural protein (NS) 4B (9, 10), methyltransferase (2, 11), and RNA-dependent RNA polymerase (12-16). Inhibition of host factors important for viral replication and of compounds with immunomodulation activities, including imino sugars (17), cholesterol inhibitors (18), chloroquine (19), and prednisolone (20), has also been pursued for potential treatment of DENV infections.Ribavirin is a drug with a...

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Section: Discussionmentioning

confidence: 95%

Synergistic Suppression of Dengue Virus Replication Using a Combination of Nucleoside Analogs and Nucleoside Synthesis Inhibitors

Yeo

Chen

et al. 2015

Antimicrob Agents Chemother

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“…PSI-7977 (prodrug of 2=-F-2=-C-methyluridine monophosphate) (38), PSI-352938 (prodrug of 2=-F-2=-C-methylguanosine monophosphate) (34), PSI-6130 (2=-F-2=-C-methylcytidine) (40), R1479 (4=-azidocytidine) (13), IDX-184 and INX-189 (prodrugs of 2=-C-meth-ylguanosine monophosphate) (43,48), NS5B nonnucleoside inhibitors NNI-1 (an indole analog), NNI-2 (a thiophene analog), NNI-3 (a benzothiadiazine analog), and HCV-796 (a benzofuran analog or NNI-4) (39), NS3 protease inhibitors telaprevir and RG7227 (ITMN-191) (21,22), NS3/4a inhibitor ACH-806 (46), and NS5A inhibitor BMS-790052 (8) were synthesized at Pharmasset and shown to be Ͼ95 to 99% pure by proton nuclear magnetic resonance, mass spectroscopy, and highperformance liquid chromatography analysis. Ribavirin was obtained from Sigma-Aldrich.…”

Section: Methodsmentioning

confidence: 99%

“…To determine if this was also a requirement for other classes of nucleoside/tide analogs, representative JFH-1 GT 2a replicon variants were examined for their susceptibility to PSI-6130 (2=-F-2=-C-methylcytidine nucleoside analog of RG-7128) and to INX-189 and IDX-184 (both prodrugs of 2=-C-methylguanosine monophosphate). It has previously been reported that PSI-6130, INX-189, and IDX-184 were less active against GT 1b S282T replicons (26,40,43). In addition, we included in these studies PSI-352938, a prodrug of 2=-F-2=-C-methylguanosine monophosphate that remains active against GT 1b replicons with the S282T change (16).…”

Section: Figmentioning

confidence: 99%

Genotype and Subtype Profiling of PSI-7977 as a Nucleotide Inhibitor of Hepatitis C Virus

Lam¹,

Espiritu²,

Bansal³

et al. 2012

Antimicrob Agents Chemother

222

186

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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. Hepatitis C virus (HCV) currently infects more than 170 million people worldwide and is the leading cause of chronic liver disease and liver transplantation in the United States. HCV is a single plus-strand RNA virus about 9.6 kb in genome size and contains one open reading frame that encodes 10 structural and nonstructural (NS) proteins. The structural proteins (core, E1, and E2), which constitute the viral capsid and envelope proteins, are located at the amino terminus, followed by p7, which oligomerizes to form an ion channel critical for viral assembly, and the nonstructural proteins (NS2, NS3, NS4A, NS4B, NS5A, and NS5B), which are responsible for viral replication (35). Recently, two antiviral agents have been approved, in combination with pegylated alpha interferon and ribavirin (Peg-IFN/RBV), to treat patients infected with genotype (GT) 1 HCV. Both of these compounds, boceprevir (Victrelis) and telaprevir (Incivek), target the NS3/4A protease and inhibit HCV replication by blocking processing of NS3, NS4A/B, and NS5A/B (25, 33). These treatments showed improvement over Peg-IFN/RBV; however, patients may develop additional side effects corresponding to each of these antiviral compounds (4). Furthermore, viral resistance against these compounds has emerged both in vitro and in vivo as a result of the high genetic diversity of HCV and error-prone nature of the HCV NS5B RNA-dependent RNA polymerase (12). Therefore, research...

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“…In contrast, a higher barrier of resistance exists for NS5B nucleoside analogs (17). To date, only two mutations within HCV NS5B have been found to be associated with decreased susceptibility to nucleoside/-tide analogs: S96T, which confers resistance to 4Ј-azidocytidine (R1479) (13), and S282T, which confers resistance to 2Ј-Cmethyl-modified nucleoside/-tides (e.g., IDX184 and INX-08189) (18,29; J. F. McCarville et al, presented at the 5th International Workshop on Hepatitis C-Resistance and New Compounds, Boston, MA, 24 to 25 June 2010) and 2Ј-F-2Ј-Cmethyl pyrimidine nucleoside/-tide analogs (e.g., RG7128 and PSI-7977) (1,26). Since these are highly conserved residues, replicons containing the S96T or S282T amino acid change are severely impaired for replication (1,18).…”

mentioning

confidence: 99%

Hepatitis C Virus Nucleotide Inhibitors PSI-352938 and PSI-353661 Exhibit a Novel Mechanism of Resistance Requiring Multiple Mutations within Replicon RNA

Lam¹,

Espiritu²,

Bansal³

et al. 2011

J Virol

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PSI-352938, a cyclic phosphate nucleotide, and PSI-353661, a phosphoramidate nucleotide, are prodrugs of ␤-D-2-deoxy-2-␣-fluoro-2-␤-C-methylguanosine-5-monophosphate. Both compounds are metabolized to the same active 5-triphosphate, PSI-352666, which serves as an alternative substrate inhibitor of the NS5B RNA-dependent RNA polymerase during HCV replication. PSI-352938 and PSI-353661 retained full activity against replicons containing the S282T substitution, which confers resistance to certain 2-substituted nucleoside/nucleotide analogs. PSI-352666 was also similarly active against both wild-type and S282T NS5B polymerases. In order to identify mutations that confer resistance to these compounds, in vitro selection studies were performed using HCV replicon cells. While no resistant genotype 1a or 1b replicons could be selected, cells containing genotype 2a JFH-1 replicons cultured in the presence of PSI-352938 or PSI-353661 developed resistance to both compounds. Sequencing of the NS5B region identified a number of amino acid changes, including S15G, R222Q, C223Y/H, L320I, and V321I. Phenotypic evaluation of these mutations indicated that single amino acid changes were not sufficient to significantly reduce the activity of PSI-352938 and PSI-353661. Instead, a combination of three amino acid changes, S15G/C223H/V321I, was required to confer a high level of resistance. No cross-resistance exists between the 2-F-2-C-methylguanosine prodrugs and other classes of HCV inhibitors, including 2-modified nucleoside/-tide analogs such as PSI-6130, PSI-7977, INX-08189, and IDX-184. Finally, we determined that in genotype 1b replicons, the C223Y/H mutation failed to support replication, and although the A15G/C223H/V321I triple mutation did confer resistance to PSI-352938 and PSI-353661, this mutant replicated at only about 10% efficiency compared to the wild type.According to the World Health Organization, hepatitis C virus (HCV) currently infects more than 170 million people worldwide. The majority of these patients develop chronic liver disease, with a 20% rate of liver cirrhosis and fibrosis, and up to 5% could progress to hepatocellular carcinoma. There is no vaccine available, and the current standard of care (SOC), which combines pegylated alpha interferon (peg-IFN-␣) and ribavirin, has limited efficacy and may be associated with a number of side effects (3,5). Efforts to develop direct-acting antiviral agents (DAA) have focused on compounds that target viral proteins critical for HCV replication. Recently, two DAA targeting the NS3/4A protease, boceprevir (Victrelis) and telaprevir (Incivek), in combination with the SOC have been approved as treatment for hepatitis C. Other antiviral compounds currently in clinical development include NS5A inhibitors, nucleoside/nucleotide analogs, and nonnucleoside inhibitors that target the NS5B polymerase. While DAA strategies have shown promising results in reducing viral load, viral breakthrough related to the emergence of resistance has been observed and has since become a majo...

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INX-08189, a Phosphoramidate Prodrug of 6- O -Methyl-2′- C -Methyl Guanosine, Is a Potent Inhibitor of Hepatitis C Virus Replication with Excellent Pharmacokinetic and Pharmacodynamic Properties

Cited by 79 publications

References 34 publications

Synergistic Suppression of Dengue Virus Replication Using a Combination of Nucleoside Analogs and Nucleoside Synthesis Inhibitors

Synergistic Suppression of Dengue Virus Replication Using a Combination of Nucleoside Analogs and Nucleoside Synthesis Inhibitors

Genotype and Subtype Profiling of PSI-7977 as a Nucleotide Inhibitor of Hepatitis C Virus

Hepatitis C Virus Nucleotide Inhibitors PSI-352938 and PSI-353661 Exhibit a Novel Mechanism of Resistance Requiring Multiple Mutations within Replicon RNA

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