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Sustained efficacy and seroconversion with the Toll-like receptor 7 agonist GS-9620 in the Woodchuck model of chronic hepatitis B….Treatment with a TLR7 Agonist Induces Transient Viremia in SIV-Infected ART-Suppressed Monkeys…..
http://www.natap.org/2015/CROI/croi_37.htm
Preclinical Characterization of GS-9620, A Potent and Selective Oral TLR7 Agonist…..
http://www.natap.org/2011/EASL/EASL_57.htm
The Antiviral Response to the Toll-Like Receptor 7 Agonist GS-9620 in Preclinical Models of Chronic Hepatitis B Is Associated With an Intrahepatic Cytotoxic T Cell Transcriptional Signature…...
http://www.natap.org/2014/AASLD/AASLD_140.htmTLR7 Agonist GS-9620 Activates HIV-1 in PBMCs from HIV-Infected Patients on cART…..http://www.natap.org/2015/CROI/croi_25.htmCytokines Induced by a Toll-Like Receptor 7 Agonist Potently Inhibit HBV RNA, DNA, and Antigen Levels in Primary Human Hepatocytes…..http://www.natap.org/2014/AASLD/AASLD_139.htm
The Antiviral Response to the Toll-Like Receptor 7 Agonist GS-9620 in Preclinical Models of Chronic Hepatitis B is Associated With an Intrahepatic Cytotoxic T Cell Transcriptional Signature…..http://www.natap.org/2014/AASLD/AASLD_148.htm
Targeting Innate Immunity [GS-9620]: A New Step in the Development of Combination Therapy for Chronic Hepatitis B …...http://www.natap.org/2014/HBV/010515_06.htm
Journal of Hepatology 2015
"In summary, short duration treatment with GS-9620 induced a sustained antiviral response and anti-WHs antibody seroconversion in the woodchuck model of CHB. These data suggest that GS-9620 may have the potential to therapeutically induce sustained immunological control of chronic HBV infection in patients…….GS-9620 treatment induced marked, sustained reductions in serum WHV DNA noted as early as the first week of treatment. GS-9620 induced reductions in viremia occurred in nearly all GS-9620-treated woodchucks by week 4 (Fig. 3 and Table 2)…...In this group (group 5), GS-9620 treatment caused statistically significant reductions in viral load compared to pretreatment and the placebo control group at weeks 2–35 (all p <0.05) with a mean maximal viral load reduction of 6.1 log10 and a sustained mean 5.0 log10 viral load reduction at the end of the study (week 35). Strikingly, after completion of only 4 or 8 weeks of GS-9620 treatment, suppression of viral load was sustained through the end of the study (week 35) in all woodchucks in group 3 (QOD × 4 weeks), and in 4 of 5 woodchucks in group 5 (QW × 8 weeks) that completed treatment (Fig. 3C and E)…...The incidence of HCC was markedly reduced in GS-9620-treated woodchucks (Table 2). In placebo-treated WHV-infected woodchucks, HCC occurred in 5 of the 7 (71%) woodchucks, consistent with the previous observation that nearly all chronic WHV carriers develop HCC over time [[url=]22[/url]]. In contrast, for all GS-9620-treated woodchucks that completed treatment and had a viral load reduction in response to treatment, the incidence was 2 of 15 (13%). Importantly, in GS-9620-treated woodchucks that had a sustained reduction in viral load, the incidence of HCC was only 1 of 12 (8%) (Table 2).
The results demonstrate that short duration treatment with GS-9620 can induce a durable therapeutic antiviral immune response during chronic hepadnavirus infection. In a previous study in chimpanzees chronically infected with HBV, GS-9620 treatment caused a sustained, albeit less marked reduction in viral load and HBsAg [[url=]10[/url]]. While studies are ongoing to define the cellular and molecular characteristics of the antiviral response to GS-9620, it likely involves local induction of IFN-α, as well as induction of antiviral NK and CD8+ T cell responses [[url=][8][/url], [url=][31][/url], [url=][32][/url]]. In addition, direct activation of B cells by GS-9620 may also be an important mechanism that contributes to viral clearance [[url=]33[/url]].
The antiviral responses induced by GS-9620 are clearly differentiated from those observed with nucleos(t)ides evaluated in the woodchuck model of CHB. While the duration of viral load reduction was markedly longer with GS-9620 compared to similar treatment with nucleos(t)ides, the most important finding was that, in contrast to GS-9620, nucleos(t)ide treatment induced a sustained loss of WHsAg in only a small minority of WHV-infected woodchucks and induction of anti-WHsAb was rare [[url=][3][/url], [url=][14][/url]]. Other therapeutic strategies in this model have included therapeutic vaccination, IL-12 gene therapy and inhibition of PD-L1 [[url=][24][/url], [url=][25][/url], [url=][26][/url]]. Although, in some instances, these therapies have yielded transient reductions in viral load, WHsAg and induction of anti-WHsAb, no single agent has been reported to induce a comparable antiviral response to GS-9620. Most notably, while treatment of chronically infected woodchucks with recombinant woodchuck IFN-α strongly reduced serum WHV DNA and WHsAg in some treated animals, this was a transient response that was not accompanied by anti-WHsAb seroconversion in most woodchucks (Menne S, unpublished data).
Treatment of WHV-infected woodchucks with GS-9620 resulted in rapid, marked and sustained antiviral response. GS-9620 pharmacodynamic responses were consistent with activation of TLR7 and correlated statistically with antiviral efficacy. Importantly, the magnitude of ISG induction in chronically infected woodchucks was similar to that induced in humans at well tolerated doses (Supplementary Table 1) [[url=]11[/url]]. Strikingly, in most chronically infected animals GS-9620 induced a multi-log reduction in viral load, WHsAg loss and anti-WHs antibody seroconversion, and reduced cccDNA levels and HCC incidence. Specifically, reductions in viral load occurred in 15 of 19 woodchucks that completed treatment (regardless of regimen) and viral load reductions were sustained through the end of the study in 12 of these 15 woodchucks. Sustained WHsAg loss occurred in 13 of 15 woodchucks that completed treatment. Importantly, in 8 of 13 treated woodchucks with WHsAg loss, induction of WHsAb occurred and persisted. In GS-9620-treated woodchucks that had a sustained reduction in viral load, the incidence of HCC was less than 10% compared to a rate of over 70% in the placebo group."
Sustained efficacy and seroconversion with the Toll-like receptor 7 agonist GS-9620 in the Woodchuck model of chronic hepatitis BJournal of Hepatology 2015
Stephan Menne1,⇑,
, Daniel B. Tumas2,
, Katherine H. Liu3, Linta Thampi1, Dalal AlDeghaither1, Betty H. Baldwin3, Christine A. Bellezza3, Paul J. Cote1, Jim Zheng4, Randall Halcomb5, Abigail Fosdick6, Simon P. Fletcher2, Stephane Daffis2, Li Li7, Peng Yue7, Grushenka H.I. Wolfgang6, Bud C. Tennant3
1Department of Microbiology and Immunology, Georgetown University Medical Center, Washington, DC 20057, United States; 2Department of
Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, United States; 3Department of Clinical Sciences, Gastrointestinal Unit,
College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, United States; 4Department of Drug Metabolism, Gilead Sciences, Inc., 333
Lakeside Drive, Foster City, CA 94404, United States; 5Department of Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404,
United States; 6Department of Drug Safety Evaluation, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, United States;
7Department of Biomarkers, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, United States
Background & AimsNew therapies for chronic hepatitis B (CHB) are urgently needed since current treatments rarely lead to cure. We evaluated whether the oral small molecule toll-like receptor (TLR7) agonist GS-9620 could induce durable antiviral efficacy in woodchucks chronically infected with woodchuck hepatitis virus (WHV), a hepadnavirus closely related to human hepatitis B virus (HBV).
MethodsAfter evaluating the pharmacokinetics, pharmacodynamics and tolerability of oral GS-9620 in uninfected woodchucks, adult woodchucks chronically infected with WHV (n = 7 per group) were dosed with GS-9620 or placebo for 4 or 8 weeks with different treatment schedules.
ResultsGS-9620 treatment induced rapid, marked and sustained reduction in serum viral DNA (mean maximal 6.2 log10 reduction), and hepatic WHV DNA replicative intermediates, WHV cccDNA and WHV RNA, as well as loss of detectable serum WHV surface antigen (WHsAg). GS-9620 treatment also induced a sustained antibody response against WHsAg in a subset of animals. Strikingly, treatment reduced the incidence of hepatocellular carcinoma (HCC) from 71% in the placebo group to 8% in GS-9620-treated woodchucks with sustained viral load reduction. GS-9620 treatment was associated with reversible increases in serum liver enzymes and thrombocytopenia, and induced intrahepatic CD8+ T cell, NK cell, B cell and interferon response transcriptional signatures.
ConclusionsThe data demonstrate that short duration, finite treatment with the oral TLR7 agonist GS-9620 can induce a sustained antiviral response in the woodchuck model of CHB, and support investigation of this compound as a therapeutic approach to attain a functional cure in CHB patients.
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