Hepatitis: Lin K

Lin K, Vickery J. · Center for Primary Care, Prevention and Clinical Partnerships, Agency for Healthcare Research and Quality, Rockville, Maryland 20850, USA. · Ann Intern Med. · Pubmed #19528566 No free full text.

Abstract: BACKGROUND: Screening for hepatitis B virus (HBV) infection in pregnant women to identify newborns who will require prophylaxis against perinatal infection is a well-established, evidence-based standard of current medical practice. In 2004, the U.S. Preventive Services Task Force (USPSTF) recommended universal screening of pregnant women for HBV infection at the first prenatal visit. PURPOSE: To search for large, high-quality studies related to hepatitis B screening in pregnancy that have been published since the 2004 USPSTF recommendation. DATA SOURCES: English-language studies indexed in PubMed and the Cochrane Database of Systematic Reviews and published between 1 January 2001 and 5 March 2008. STUDY SELECTION: For benefits of screening and newborn prophylaxis, we included systematic reviews; meta-analyses; and randomized, controlled trials. For harms of screening, we included systematic reviews; meta-analyses; randomized, controlled trials; cohort studies; case-control studies; and case series of large, multisite databases. Abstracts and full articles were independently reviewed for inclusion by both reviewers. DATA EXTRACTION: Data on the benefits of screening, including benefits of hepatitis B immune globulin and hepatitis B vaccine prophylaxis of newborns of hepatitis B surface antigen-positive mothers, were extracted by 1 reviewer. DATA SYNTHESIS: No new studies met inclusion criteria. A 2006 systematic review of randomized, controlled trials found that newborn prophylaxis reduced perinatal transmission of HBV infection; all relevant trials were published in 1996 or earlier. LIMITATION: The focused search strategy, which was restricted to English-language articles, may have missed some smaller studies or new research published in languages other than English. CONCLUSION: No new evidence was found on the benefits or harms of screening for HBV infection in pregnant women. Previously published randomized trials support the 2004 USPSTF recommendation for screening.

Mathy JE, Ma S, Compton T, Lin K. · Novartis Institutes for Biomedical Research, Inc, Cambridge, Massachusetts 02139, USA. · Antimicrob Agents Chemother. · Pubmed #18591281 links to  free full text

Abstract: Chronic hepatitis C virus (HCV) infection remains a major global health burden while current interferon-based therapy is suboptimal. Efforts to develop more effective antiviral agents mainly focus on two viral targets: NS3-4A protease and NS5B polymerase. However, resistant mutants against these viral specific inhibitors emerge quickly both in vitro and in patients, particularly in the case of monotherapy. An alternative and complementary strategy is to target host factors such as cyclophilins that are also essential for viral replication. Future HCV therapies will most likely be combinations of multiple drugs of different mechanisms to maximize antiviral activity and to suppress the emergence of resistance. Here, the effects of combining a host cyclophilin inhibitor NIM811 with other viral specific inhibitors were investigated in vitro using HCV replicon. All of the combinations led to more pronounced antiviral effects than any single agent, with no significant increase of cytotoxicity. Moreover, the combination of NIM811 with a nucleoside (NM107) or a non-nucleoside (thiophene-2-carboxylic acid) polymerase inhibitor was synergistic, while the combination with a protease inhibitor (BILN2061) was additive. Resistant clones were selected in vitro with these inhibitors. Interestingly, it was much more difficult to develop resistance against NIM811 than viral specific inhibitors. No cross-resistance was observed among these inhibitors. Most notably, NIM811 was highly effective in blocking the emergence of resistance when used in combination with viral protease or polymerase inhibitors. Taken together, these results illustrate the significant advantages of combining inhibitors targeting both viral and host factors as key components of future HCV therapies.

Perni RB, Chandorkar G, Cottrell KM, Gates CA, Lin C, Lin K, Luong YP, Maxwell JP, Murcko MA, Pitlik J, Rao G, Schairer WC, Van Drie J, Wei Y. · Vertex Pharmaceuticals, Inc., 130 Waverly Street, Cambridge, MA 02139, USA. · Bioorg Med Chem Lett. · Pubmed #17482818 No free full text.

Abstract: Reversible tetrapeptide-based compounds have been shown to effectively inhibit the hepatitis C virus NS3.4A protease. Inhibition of viral replicon RNA production in Huh-7 cells has also been demonstrated. We show herein that the inclusion of hydrogen bond donors on the P4 capping group of tetrapeptide-based inhibitors result in increased binding potency to the NS3.4A protease. The capping groups also impart significant effects on the pharmacokinetic profile of these inhibitors.

Ma S, Boerner JE, TiongYip C, Weidmann B, Ryder NS, Cooreman MP, Lin K. · Novartis Institutes for Biomedical Research, Inc., 500 Technology Square, Cambridge, MA 02139, USA. · Antimicrob Agents Chemother. · Pubmed #16940091 links to  free full text

Abstract: Host factors involved in viral replication are potentially attractive antiviral targets that are complementary to specific inhibitors of viral enzymes, since resistant mutations against the latter are likely to emerge during long-term treatment. It has been reported recently that cyclosporine, which binds to a family of cellular proteins, cyclophilins, inhibits hepatitis C virus (HCV) replication in vitro. Here, the activities of various cyclosporine derivatives were evaluated in the HCV replicon system. There was a strong correlation between the anti-HCV activity and cyclophilin-binding affinity of these compounds. Of these, NIM811 has been selected as a therapeutic candidate for HCV infection, since it binds to cyclophilins with higher affinity than cyclosporine but is devoid of the significant immunosuppressive activity associated with cyclosporine. NIM811 induced a concentration-dependent reduction of HCV RNA in the replicon cells with a 50% inhibitory concentration of 0.66 microM at 48 h. Furthermore, a greater than three-log(10) viral RNA reduction was achieved after treating the cells with as little as 1 microM of NIM811 for 9 days. In addition, the combination of NIM811 with alpha interferon significantly enhanced anti-HCV activities without causing any increase of cytotoxicity. Taken together, these promising in vitro data warrant clinical investigation of NIM811, an inhibitor of novel mechanism, for the treatment of hepatitis C.

Lin K, Perni RB, Kwong AD, Lin C. · Vertex Pharmaceuticals Incorporated, 130 Waverly Street, Cambridge, MA 02139, USA. · Antimicrob Agents Chemother. · Pubmed #16641454 links to  free full text

Abstract: The NS3-4A serine protease of hepatitis C virus (HCV) is essential for viral replication and therefore has been one of the most attractive targets for developing specific antiviral agents against HCV. VX-950, a highly selective, reversible, and potent peptidomimetic inhibitor of the HCV NS3-4A protease, is currently in clinical development for the treatment of hepatitis C. In this report, we describe the in vitro characterization of anti-HCV activities of VX-950 in subgenomic HCV replicon cells. Incubation with VX-950 resulted in a time- and dose-dependent reduction of HCV RNA and proteins in replicon cells. Moreover, following a 2-week incubation with VX-950, a reduction in HCV RNA levels of 4.7 log(10) was observed, and this reduction resulted in elimination of HCV RNA from replicon cells, since there was no rebound in replicon RNA after withdrawal of the inhibitor. The combination of VX-950 and alpha interferon was additive to moderately synergistic in reducing HCV RNA in replicon cells with no significant increase in cytotoxicity. The benefit of the combination was sustained over time: a 4-log(10) reduction in HCV RNA level was achieved following a 9-day incubation with VX-950 and alpha interferon at lower concentrations than when either VX-950 or alpha interferon was used alone. The combination of VX-950 and alpha interferon also suppressed the emergence of in vitro resistance mutations against VX-950 in replicon cells.

Perni RB, Almquist SJ, Byrn RA, Chandorkar G, Chaturvedi PR, Courtney LF, Decker CJ, Dinehart K, Gates CA, Harbeson SL, Heiser A, Kalkeri G, Kolaczkowski E, Lin K, Luong YP, Rao BG, Taylor WP, Thomson JA, Tung RD, Wei Y, Kwong AD, Lin C. · Vertex Pharmaceuticals Incorporated, 130 Waverly Street, Cambridge, Massachusetts 02139, USA. · Antimicrob Agents Chemother. · Pubmed #16495249 links to  free full text

Abstract: VX-950 is a potent, selective, peptidomimetic inhibitor of the hepatitis C virus (HCV) NS3-4A serine protease, and it demonstrated excellent antiviral activity both in genotype 1b HCV replicon cells (50% inhibitory concentration [IC50] = 354 nM) and in human fetal hepatocytes infected with genotype 1a HCV-positive patient sera (IC50 = 280 nM). VX-950 forms a covalent but reversible complex with the genotype 1a HCV NS3-4A protease in a slow-on, slow-off process with a steady-state inhibition constant (K(i)*) of 7 nM. Dissociation of the covalent enzyme-inhibitor complex of VX-950 and genotype 1a HCV protease has a half-life of almost an hour. A >4-log10 reduction in the HCV RNA levels was observed after a 2-week incubation of replicon cells with VX-950, with no rebound of viral RNA observed after withdrawal of the inhibitor. In several animal species, VX-950 exhibits a favorable pharmacokinetic profile with high exposure in the liver. In a recently developed HCV protease mouse model, VX-950 showed excellent inhibition of HCV NS3-4A protease activity in the liver. Therefore, the overall preclinical profile of VX-950 supports its candidacy as a novel oral therapy against hepatitis C.

Baker DP, Lin EY, Lin K, Pellegrini M, Petter RC, Chen LL, Arduini RM, Brickelmaier M, Wen D, Hess DM, Chen L, Grant D, Whitty A, Gill A, Lindner DJ, Pepinsky RB. · BiogenIdec Inc., 14 Cambridge Center, Cambridge, Massachusetts 02142, USA. · Bioconjug Chem. · Pubmed #16417267 No free full text.

Abstract: PEGylation of IFN-alpha has been used successfully to improve the pharmacokinetic properties and efficacy of the drug. To prepare a PEGylated form of human interferon-beta-1a (IFN-beta-1a) suitable for testing in vivo, we have synthesized 20 kDa mPEG-O-2-methylpropionaldehyde and used it to modify the N-terminal alpha-amino group of the cytokine. The PEGylated protein retained approximately 50% of the activity of the unmodified protein and had significantly improved pharmacokinetic properties following intravenous administration in rats. The clearance and volume of distribution at steady state were reduced approximately 30-fold and approximately 4-fold, respectively, resulting in a significant increase in systemic exposure as determined by the area under the curve. The elimination half-life of the PEGylated protein was approximately 13-fold greater than for the unmodified protein. The unmodified and PEGylated proteins were tested for their ability to inhibit the formation of radially oriented blood vessels entering the periphery of human SK-MEL-1 melanoma tumors in athymic nude homozygous (nu/nu) mice. In a single dose comparison study, administration of 1 x 10(6) units of unmodified IFN-beta-1a resulted in a 29% reduction in vessel number, while 1 x 10(6) units of PEGylated IFN-beta-1a resulted in a 58% reduction. Both treatments resulted in statistically significant reductions in mean vessel number as compared to the vehicle (control)-treated mice, with the PEGylated IFN-beta-1a-treated mice showing a statistically significantly greater reduction in mean vessel number as compared to the unmodified IFN-beta-1a-treated mice. In a multiple versus single dose comparison study, daily administration of 1 x 10(6) units of unmodified IFN-beta-1a for 9 days resulted in a 51% reduction in vessel number, while a single dose of 1 x 10(6) units of the PEGylated protein resulted in a 66% reduction. Both treatments resulted in statistically significant reductions in mean vessel number as compared to the vehicle-treated mice, with the PEGylated IFN-beta-1a-treated mice showing a statistically significantly greater reduction in mean vessel number as compared to the unmodified IFN-beta-1a-treated mice. Therefore, the improved pharmacokinetic properties of the modified protein translated into improved efficacy. Since unmodified IFN-beta is used for the treatment of multiple sclerosis and hepatitis C virus infection, a PEGylated form of the protein such as 20 kDa mPEG-O-2-methylpropionaldehyde-modified IFN-beta-1a may serve as a useful adjunct for the treatment of these diseases. In addition, the antiangiogenic effects of PEGylated IFN-beta-1a may be harnessed for the treatment of certain cancers, either as a sole agent or in combination with other antitumor drugs.

Lin C, Gates CA, Rao BG, Brennan DL, Fulghum JR, Luong YP, Frantz JD, Lin K, Ma S, Wei YY, Perni RB, Kwong AD. · Vertex Pharmaceuticals Incorporated, Cambridge, Massachusetts 02139, USA. · J Biol Chem. · Pubmed #16087668 links to  free full text

Abstract: VX-950 is a potent, small molecule, peptidomimetic inhibitor of the hepatitis C virus (HCV) NS3.4A serine protease and has recently been shown to possess antiviral activity in a phase I trial in patients chronically infected with genotype 1 HCV. In a previous study, we described in vitro resistance mutations against either VX-950 or another HCV NS3.4A protease inhibitor, BILN 2061. Single amino acid substitutions that conferred drug resistance (distinct for either inhibitor) were identified in the HCV NS3 serine protease domain. The dominant VX-950-resistant mutant (A156S) remains sensitive to BILN 2061. The major BILN 2061-resistant mutants (D168V and D168A) are fully susceptible to VX-950. Modeling analysis suggested that there are different mechanisms of resistance for these mutations induced by VX-950 or BILN 2061. In this study, we identified mutants that are cross-resistant to both HCV protease inhibitors. The cross-resistance conferred by substitution of Ala(156) with either Val or Thr was confirmed by characterization of the purified enzymes and reconstituted replicon cells containing the single amino acid substitution A156V or A156T. Both cross-resistance mutations (A156V and A156T) displayed significantly diminished fitness (or replication capacity) in a transient replicon cell system.

Lin K, Kwong AD, Lin C. · Vertex Pharmaceuticals Incorporated, Cambridge, Massachusetts 02139, USA. · Antimicrob Agents Chemother. · Pubmed #15561857 links to  free full text

Abstract: The present standard of care for hepatitis C virus (HCV) infection is pegylated alpha interferon (IFN-alpha) in combination with ribavirin. However, specific antivirals such as HCV NS3-NS4A protease inhibitors are now in clinical development, and these agents can potentially be used in combination with the present treatments. Therefore, it is important to investigate the potential benefits or adverse effects of these new combinations by using available in vitro HCV culture systems first. In the present study we demonstrate that the combination of a specific HCV NS3-NS4A protease inhibitor and IFN-alpha synergistically inhibits HCV RNA replication in replicon cells, with little or no increase in cytotoxicity. Furthermore, the benefit of the combination was sustained over time, such that a greater than 3-log reduction in HCV RNA levels was achieved following 9 days of treatment. The viral RNA appeared to be cleared from the replicon cells after 14 days of treatment, and no viral RNA rebound was observed upon withdrawal of the inhibitors. In each case, the antiviral effects obtained with higher concentrations of either the protease inhibitor alone or IFN-alpha alone can be achieved by a combination of both agents at lower concentrations, which may potentially reduce the risk of possible adverse effects associated with high doses of either agent.

Perni RB, Farmer LJ, Cottrell KM, Court JJ, Courtney LF, Deininger DD, Gates CA, Harbeson SL, Kim JL, Lin C, Lin K, Luong YP, Maxwell JP, Murcko MA, Pitlik J, Rao BG, Schairer WC, Tung RD, Van Drie JH, Wilson K, Thomson JA. · Vertex Pharmaceuticals Inc., 130 Waverly Street, Cambridge, MA 02139, USA. · Bioorg Med Chem Lett. · Pubmed #15050632 No free full text.

Abstract: We recently described the identification of an optimized alpha-ketoamide warhead for our series of HCV NS3.4A inhibitors. We report herein a series of HCV protease inhibitors incorporating 3-alkyl-substituted prolines in P(2). These compounds show exceptional enzymatic and cellular potency given their relatively small size. The marked enhancement of activity of these 3-substituted proline derivatives relative to previously reported 4-hydroxyproline derivatives constitutes additional evidence for the importance of the S(2) binding pocket as the defining pharmacophore for inhibition of the NS3.4A enzyme.

Perni RB, Pitlik J, Britt SD, Court JJ, Courtney LF, Deininger DD, Farmer LJ, Gates CA, Harbeson SL, Levin RB, Lin C, Lin K, Moon YC, Luong YP, O'Malley ET, Rao BG, Thomson JA, Tung RD, Van Drie JH, Wei Y. · Vertex Pharmaceuticals Inc., 130 Waverly Street, Cambridge, MA 02139, USA. · Bioorg Med Chem Lett. · Pubmed #15006379 No free full text.

Abstract: The alpha-ketoamide warhead (e.g., 15) was found to be a practical replacement for aliphatic aldehydes in a series of HCV NS3.4A protease inhibitors. Structure-activity relationships and prime side optimization are discussed.

Lin C, Lin K, Luong YP, Rao BG, Wei YY, Brennan DL, Fulghum JR, Hsiao HM, Ma S, Maxwell JP, Cottrell KM, Perni RB, Gates CA, Kwong AD. · Vertex Pharmaceuticals Inc., Cambridge, Massachusetts 02139, USA. · J Biol Chem. · Pubmed #14766754 links to  free full text

Abstract: We have used a structure-based drug design approach to identify small molecule inhibitors of the hepatitis C virus (HCV) NS3.4A protease as potential candidates for new anti-HCV therapies. VX-950 is a potent NS3.4A protease inhibitor that was recently selected as a clinical development candidate for hepatitis C treatment. In this report, we describe in vitro resistance studies using a subgenomic replicon system to compare VX-950 with another HCV NS3.4A protease inhibitor, BILN 2061, for which the Phase I clinical trial results were reported recently. Distinct drug-resistant substitutions of a single amino acid were identified in the HCV NS3 serine protease domain for both inhibitors. The resistance conferred by these mutations was confirmed by characterization of the mutant enzymes and replicon cells that contain the single amino acid substitutions. The major BILN 2061-resistant mutations at Asp(168) are fully susceptible to VX-950, and the dominant resistant mutation against VX-950 at Ala(156) remains sensitive to BILN 2061. Modeling analysis suggests that there are different mechanisms of resistance to VX-950 and BILN 2061.