Class A capsid assembly modulator apoptotic elimination of hepatocytes with high HBV core antigen level in vivo is dependent on de novo core protein translation.

Capsid assembly is critical in the hepatitis B virus (HBV) life cycle, mediated by the viral core protein. Capsid assembly is the target for new anti-viral therapeutics known as capsid assembly modulators (CAMs) of which the CAM-aberrant (CAM-A) class induces aberrant shaped core protein structures and leads to hepatocyte cell death. This study aimed to identify the mechanism of action of CAM-A modulators leading to HBV-infected hepatocyte elimination where CAM-A-mediated hepatitis B surface antigen (HBsAg) reduction was evaluated in a stable HBV replicating cell line and in AAV-HBV-transduced C57BL/6, C57BL/6 SCID, and HBV-infected chimeric mice with humanized livers. Results showed that in vivo treatment with CAM-A modulators induced pronounced reductions in hepatitis B e antigen (HBeAg) and HBsAg, associated with a transient alanine amino transferase (ALT) increase. Both HBsAg and HBeAg reductions and ALT increase were delayed in C57BL/6 SCID and chimeric mice, suggesting that adaptive immune responses may indirectly contribute. However, CD8+ T cell depletion in transduced wild-type mice did not impact antigen reduction, indicating that CD8+ T cell responses are not essential. Transient ALT elevation in AAV-HBV-transduced mice coincided with a transient increase in endoplasmic reticulum stress and apoptosis markers, followed by detection of a proliferation marker. Microarray data revealed antigen presentation pathway (major histocompatibility complex class I molecules) upregulation, overlapping with the apoptosis. Combination treatment with HBV-specific siRNA demonstrated that CAM-A-mediated HBsAg reduction is dependent on de novo core protein translation. To conclude, CAM-A treatment eradicates HBV-infected hepatocytes with high core protein levels through the induction of apoptosis, which can be a promising approach as part of a regimen to achieve functional cure. IMPORTANCE: Treatment with hepatitis B virus (HBV) capsid assembly modulators that induce the formation of aberrant HBV core protein structures (CAM-A) leads to programmed cell death, apoptosis, of HBV-infected hepatocytes and subsequent reduction of HBV antigens, which differentiates CAM-A from other CAMs. The effect is dependent on the de novo synthesis and high levels of core protein.

Identification of NK Cell Subpopulations That Differentiate HIV-Infected Subject Cohorts with Diverse Levels of Virus Control.

HIV infection is controlled immunologically in a small subset of infected individuals without antiretroviral therapy (ART), though the mechanism of control is unclear. CD8+ T cells are a critical component of HIV control in many immunological controllers. NK cells are also believed to have a role in controlling HIV infection, though their role is less well characterized. We used mass cytometry to simultaneously measure the levels of expression of 24 surface markers on peripheral NK cells from HIV-infected subjects with various degrees of HIV natural control; we then used machine learning to identify NK cell subpopulations that differentiate HIV controllers from noncontrollers. Using CITRUS (cluster identification, characterization, and regression), we identified 3 NK cell subpopulations that differentiated subjects with chronic HIV viremia (viremic noncontrollers [VNC]) from individuals with undetectable HIV viremia without ART (elite controllers [EC]). In a parallel approach, we identified 11 NK cell subpopulations that differentiated HIV-infected subject groups using k-means clustering after dimensionality reduction by t-neighbor stochastic neighbor embedding (tSNE) or linear discriminant analysis (LDA). Among these additional 11 subpopulations, the frequencies of 5 correlated with HIV DNA levels; importantly, significance was retained in 2 subpopulations in analyses that included only cohorts without detectable viremia. By comparing the surface marker expression patterns of all identified subpopulations, we revealed that the CD11b+ CD57- CD161+ Siglec-7+ subpopulation of CD56dim CD16+ NK cells are more abundant in EC and HIV-negative controls than in VNC and that the frequency of these cells correlated with HIV DNA levels. We hypothesize that this population may have a role in immunological control of HIV infection.IMPORTANCE HIV infection results in the establishment of a stable reservoir of latently infected cells; ART is usually required to keep viral replication under control and disease progression at bay, though a small subset of HIV-infected subjects can control HIV infection without ART through immunological mechanisms. In this study, we sought to identify subpopulations of NK cells that may be involved in the natural immunological control of HIV infection. We used mass cytometry to measure surface marker expression on peripheral NK cells. Using two distinct semisupervised machine learning approaches, we identified a CD11b+ CD57- CD161+ Siglec-7+ subpopulation of CD56dim CD16+ NK cells that differentiates HIV controllers from noncontrollers. These cells can be sorted out for future functional studies to assess their potential role in the immunological control of HIV infection.

Toll-Like Receptor 7 Agonist GS-9620 Induces HIV Expression and HIV-Specific Immunity in Cells from HIV-Infected Individuals on Suppressive Antiretroviral Therapy.

Antiretroviral therapy can suppress HIV replication to undetectable levels but does not eliminate latent HIV, thus necessitating lifelong therapy. Recent efforts to target this persistent reservoir have focused on inducing the expression of latent HIV so that infected cells may be recognized and eliminated by the immune system. Toll-like receptor (TLR) activation stimulates antiviral immunity and has been shown to induce HIV from latently infected cells. Activation of TLR7 leads to the production of several stimulatory cytokines, including type I interferons (IFNs). In this study, we show that the selective TLR7 agonist GS-9620 induced HIV in peripheral blood mononuclear cells (PBMCs) from HIV-infected individuals on suppressive antiretroviral therapy. GS-9620 increased extracellular HIV RNA 1.5- to 2-fold through a mechanism that required type I IFN signaling. GS-9620 also activated HIV-specific T cells and enhanced antibody-mediated clearance of HIV-infected cells. Activation by GS-9620 in combination with HIV peptide stimulation increased CD8 T cell degranulation, production of intracellular cytokines, and cytolytic activity. T cell activation was again dependent on type I IFNs produced by plasmacytoid dendritic cells. GS-9620 induced phagocytic cell maturation and improved effector-mediated killing of HIV-infected CD4 T cells by the HIV envelope-specific broadly neutralizing antibody PGT121. Collectively, these data show that GS-9620 can activate HIV production and improve the effector functions that target latently infected cells. GS-9620 may effectively complement orthogonal therapies designed to stimulate antiviral immunity, such as therapeutic vaccines or broadly neutralizing antibodies. Clinical studies are under way to determine if GS-9620 can target HIV reservoirs.IMPORTANCE Though antiretroviral therapies effectively suppress viral replication, they do not eliminate integrated proviral DNA. This stable intermediate of viral infection is persistently maintained in reservoirs of latently infected cells. Consequently, lifelong therapy is required to maintain viral suppression. Ultimately, new therapies that specifically target and eliminate the latent HIV reservoir are needed. Toll-like receptor agonists are potent enhancers of innate antiviral immunity that can also improve the adaptive immune response. Here, we show that a highly selective TLR7 agonist, GS-9620, activated HIV from peripheral blood mononuclear cells isolated from HIV-infected individuals with suppressed infection. GS-9620 also improved immune effector functions that specifically targeted HIV-infected cells. Previously published studies on the compound in other chronic viral infections show that it can effectively induce immune activation at safe and tolerable clinical doses. Together, the results of these studies suggest that GS-9620 may be useful for treating HIV-infected individuals on suppressive antiretroviral therapy.

Antiviral Activity of Bictegravir (GS-9883), a Novel Potent HIV-1 Integrase Strand Transfer Inhibitor with an Improved Resistance Profile.

Bictegravir (BIC; GS-9883), a novel, potent, once-daily, unboosted inhibitor of HIV-1 integrase (IN), specifically targets IN strand transfer activity (50% inhibitory concentration [IC50] of 7.5 ± 0.3 nM) and HIV-1 integration in cells. BIC exhibits potent and selective in vitro antiretroviral activity in both T-cell lines and primary human T lymphocytes, with 50% effective concentrations ranging from 1.5 to 2.4 nM and selectivity indices up to 8,700 relative to cytotoxicity. BIC exhibits synergistic in vitro antiviral effects in pairwise combinations with tenofovir alafenamide, emtricitabine, or darunavir and maintains potent antiviral activity against HIV-1 variants resistant to other classes of antiretrovirals. BIC displayed an in vitro resistance profile that was markedly improved compared to the integrase strand transfer inhibitors (INSTIs) raltegravir (RAL) and elvitegravir (EVG), and comparable to that of dolutegravir (DTG), against nine INSTI-resistant site-directed HIV-1 mutants. BIC displayed statistically improved antiviral activity relative to EVG, RAL, and DTG against a panel of 47 patient-derived HIV-1 isolates with high-level INSTI resistance; 13 of 47 tested isolates exhibited >2-fold lower resistance to BIC than DTG. In dose-escalation experiments conducted in vitro, BIC and DTG exhibited higher barriers to resistance than EVG, selecting for HIV-1 variants with reduced phenotypic susceptibility at days 71, 87, and 20, respectively. A recombinant virus with the BIC-selected M50I/R263K dual mutations in IN exhibited only 2.8-fold reduced susceptibility to BIC compared to wild-type virus. All BIC-selected variants exhibited low to intermediate levels of cross-resistance to RAL, DTG, and EVG (<8-fold) but remained susceptible to other classes of antiretrovirals. A high barrier to in vitro resistance emergence for both BIC and DTG was also observed in viral breakthrough studies in the presence of constant clinically relevant drug concentrations. The overall virologic profile of BIC supports its ongoing clinical investigation in combination with other antiretroviral agents for both treatment-naive and -experienced HIV-infected patients.

Faldaprevir and deleobuvir for HCV genotype 1 infection.

BACKGROUND: Interferon-free regimens would be a major advance in the treatment of patients with chronic hepatitis C virus (HCV) infection. METHODS: In this phase 2b, randomized, open-label trial of faldaprevir (a protease inhibitor) and deleobuvir (a nonnucleoside polymerase inhibitor), we randomly assigned 362 previously untreated patients with HCV genotype 1 infection to one of five groups: faldaprevir at a dose of 120 mg once daily and deleobuvir at a dose of 600 mg three times daily, plus ribavirin, for 16, 28, or 40 weeks (TID16W, TID28W, or TID40W, respectively); faldaprevir at a dose of 120 mg once daily and deleobuvir at a dose of 600 mg twice daily, plus ribavirin, for 28 weeks (BID28W); or faldaprevir at a dose of 120 mg once daily and deleobuvir at a dose of 600 mg three times daily, without ribavirin, for 28 weeks (TID28W-NR). The primary end point was a sustained virologic response 12 weeks after the completion of therapy. RESULTS: The primary end point was met in 59% of patients in the TID16W group, 59% of patients in the TID28W group, 52% of patients in the TID40W group, 69% of patients in the BID28W group, and 39% of patients in the TID28W-NR group. The sustained virologic response 12 weeks after the completion of therapy did not differ significantly according to treatment duration or dosage among ribavirin-containing regimens. This response was significantly higher with TID28W than with TID28W-NR (P=0.03). Rates of a sustained virologic response 12 weeks after the completion of therapy were 56 to 85% among patients with genotype 1b infection versus 11 to 47% among patients with genotype 1a infection and 58 to 84% among patients with IL28B CC versus 33 to 64% with non-CC genotypes. Rash, photosensitivity, nausea, vomiting, and diarrhea were the most common adverse events. CONCLUSIONS: The rate of a sustained virologic response 12 weeks after the completion of therapy was 52 to 69% among patients who received interferon-free treatment with faldaprevir in combination with deleobuvir plus ribavirin. (Funded by Boehringer Ingelheim; SOUND-C2 ClinicalTrials.gov number, NCT01132313.).

STARTVerso1: A randomized trial of faldaprevir plus pegylated interferon/ribavirin for chronic HCV genotype-1 infection.

BACKGROUND & AIMS: The efficacy and tolerability of faldaprevir, a potent hepatitis C virus (HCV) NS3/4A protease inhibitor, plus peginterferon (PegIFN) and ribavirin (RBV) was assessed in a double-blind, placebo-controlled phase 3 study of treatment-naïve patients with HCV genotype-1 infection. METHODS: Patients were randomly assigned (1:2:2) to PegIFN/RBV plus: placebo (arm 1, n = 132) for 24 weeks; faldaprevir (120 mg, once daily) for 12 or 24 weeks (arm 2, n = 259); or faldaprevir (240 mg, once daily) for 12 weeks (arm 3, n = 261). In arms 2 and 3, patients with early treatment success (HCV-RNA <25 IU/ml at week 4 and undetectable at week 8) stopped all treatment at week 24. Other patients received PegIFN/RBV until week 48 unless they met futility criteria. The primary endpoint was sustained virologic response 12 weeks post-treatment (SVR12). RESULTS: SVR12 was achieved by 52%, 79%, and 80% of patients in arms 1, 2, and 3, respectively (estimated difference for arms 2 and 3 vs. arm 1: 27%, 95% confidence interval 17%-36%; and 29%, 95% confidence interval, 19%-38%, respectively; p < 0.0001 for both). Early treatment success was achieved by 87% (arm 2) and 89% (arm 3) of patients, of whom 86% and 89% achieved SVR12. Adverse event rates were similar among groups; few adverse events led to discontinuation of all regimen components. CONCLUSIONS: Faldaprevir plus PegIFN/RBV significantly increased SVR12, compared with PegIFN/RBV, in treatment-naïve patients with HCV genotype-1 infection. No differences were seen in responses of patients given faldaprevir once daily at 120 or 240 mg.

Aza follow-ups to BI 207524, a thumb pocket 1 HCV NS5B polymerase inhibitor. Part 1: Mitigating the genotoxic liability of an aniline metabolite.

A series of heterocyclic aza-analogs of BI 207524 (2), a potent HCV NS5B polymerase thumb pocket 1 inhibitor, was investigated with the goal to reduce the liability associated with the release of a genotoxic aniline metabolite in vivo. Analog 4, containing a 2-aminopyridine aniline isostere that is negative in the Ames test was identified, and was found to provide comparable GT1a/1b potency to 2. Although the cross-species PK profile, poor predicted human liver distribution of analog 4 and allometry principles projected high doses to achieve a strong antiviral response in patients, this work has provided a path forward toward the design of novel thumb pocket 1 NS5B polymerase inhibitors with improved safety profiles.

A prodrug strategy for the oral delivery of a poorly soluble HCV NS5B thumb pocket 1 polymerase inhibitor using self-emulsifying drug delivery systems (SEDDS).

A prodrug approach was developed to address the low oral bioavailability of a poorly soluble (<0.1µg/mL in pH 6.8 buffer) but highly permeable thumb pocket 1 HCV NS5B polymerase inhibitor. Bioconversion rates of structurally diverse prodrug derivatives were evaluated in a panel of in vitro assays using microsomes, from either liver or intestinal tissues, simulated intestinal fluids, simulated gastric fluids or plasma. In vivo bioconversion of promising candidates was evaluated following oral administration to rats. The most successful strategy involved modification of the parent drug carboxylic acid moiety to glycolic amide esters which improved solubility in lipid-based self-emulsifying drug delivery systems (SEDDS). Crystalline prodrug analog 36 (mp 161°C) showed good solubility in individual SEDDS components (up to 80mg/mL) compared to parent 2 (<3mg/mL; mp 267°C) and cross-species bioconversions which correlated with in vitro stability in liver microsomes.

Multi-parameter optimization of aza-follow-ups to BI 207524, a thumb pocket 1 HCV NS5B polymerase inhibitor. Part 2: Impact of lipophilicity on promiscuity and in vivo toxicity.

We describe our efforts to identify analogs of thumb pocket 1 HCV NS5B inhibitor 1 (aza-analog of BI 207524) with improved plasma to liver partitioning and a predicted human half-life consistent with achieving a strong antiviral effect at a reasonable dose in HCV-infected patients. Compounds 3 and 7 were identified that met these criteria but exhibited off-target promiscuity in an in vitro pharmacology screen and in vivo toxicity in rats. High lipophilicity in this class was found to correlate with increased probability for promiscuous behavior and toxicity. The synthesis of an 8×11 matrix of analogs allowed the identification of C3, an inhibitor that displayed comparable potency to 1, improved partitioning to the liver and reduced lipophilicity. Although C3 displayed reduced propensity for in vitro off-target inhibition and the toxicity profile in rats was improved, the predicted human half-life of this compound was short, resulting in unacceptable dosing requirements to maintain a strong antiviral effect in patients.

Molecular mechanism by which a potent hepatitis C virus NS3-NS4A protease inhibitor overcomes emergence of resistance.

Although optimizing the resistance profile of an inhibitor can be challenging, it is potentially important for improving the long term effectiveness of antiviral therapy. This work describes our rational approach toward the identification of a macrocyclic acylsulfonamide that is a potent inhibitor of the NS3-NS4A proteases of all hepatitis C virus genotypes and of a panel of genotype 1-resistant variants. The enhanced potency of this compound versus variants D168V and R155K facilitated x-ray determination of the inhibitor-variant complexes. In turn, these structural studies revealed a complex molecular basis of resistance and rationalized how such compounds are able to circumvent these mechanisms.

Restoration of HCV-specific CD8+ T cell function by interferon-free therapy.

BACKGROUND & AIMS: Chronic hepatitis C virus (HCV) infection is characterised by a failure of virus-specific CD8+ T cells that is mainly caused by viral escape and T cell exhaustion. Constant antigen stimulation has been suggested to contribute to HCV-specific CD8+ T cell exhaustion. However, IFN-based therapies failed to recover HCV-specific CD8+ T cell function suggesting that the damage to CD8+ T cells may be permanent even after antigen removal. It was therefore the objective of this study to analyse the impact of inhibition of ongoing viral replication by IFN-free therapy with direct acting antivirals (DAA) on the phenotype and function of HCV-specific CD8+ T cells. METHODS: Virus-specific CD8+ T cells obtained from a patient cohort of 51 previously untreated chronically infected patients undergoing IFN-free therapy with a combination of faldaprevir (a protease inhibitor) and deleobuvir (a non-nucleoside polymerase inhibitor) with or without ribavirin were analysed ex vivo and after in vitro expansion at baseline, wk4, wk 12, and after treatment. RESULTS: Our results show the rapid restoration of proliferative HCV-specific CD8+ T cells in the majority of patients with SVR12 within 4 weeks of therapy suggesting that IFN-free therapy mediated antigen removal may restore CD8+ T cell function. CONCLUSIONS: This study indicates a specific restoration of proliferative HCV-specific CD8+ T cells under IFN-free therapy. This is in contrast to PegIFN-based therapies that have been shown not to restore T cell function during and after chronic infection.

Baseline hepatitis C virus (HCV) NS3 polymorphisms and their impact on treatment response in clinical studies of the HCV NS3 protease inhibitor faldaprevir.

A challenge to the treatment of chronic hepatitis C with direct-acting antivirals is the emergence of drug-resistant hepatitis C virus (HCV) variants. HCV with preexisting polymorphisms that are associated with resistance to NS3/4A protease inhibitors have been detected in patients with chronic hepatitis C. We performed a comprehensive pooled analysis from phase 1b and phase 2 clinical studies of the HCV protease inhibitor faldaprevir to assess the population frequency of baseline protease inhibitor resistance-associated NS3 polymorphisms and their impact on response to faldaprevir treatment. A total of 980 baseline NS3 sequences were obtained (543 genotype 1b and 437 genotype 1a sequences). Substitutions associated with faldaprevir resistance (at amino acid positions 155 and 168) were rare (<1% of sequences) and did not compromise treatment response: in a phase 2 study in treatment-naive patients, six patients had faldaprevir resistance-associated polymorphisms at baseline, of whom five completed faldaprevir-based treatment and all five achieved a sustained virologic response 24 weeks after the end of treatment (SVR24). Among 13 clinically relevant amino acid positions associated with HCV protease resistance, the greatest heterogeneity was seen at NS3 codons 132 and 170 in genotype 1b, and the most common baseline substitution in genotype 1a was Q80K (99/437 [23%]). The presence of the Q80K variant did not reduce response rates to faldaprevir-based treatment. Across the three phase 2 studies, there was no significant difference in SVR24 rates between patients with genotype 1a Q80K HCV and those without Q80K HCV, whether treatment experienced (17% compared to 26%; P = 0.47) or treatment naive (62% compared to 66%; P = 0.72).

CD160 isoforms and regulation of CD4 and CD8 T-cell responses.

BACKGROUND: Coexpression of CD160 and PD-1 on HIV-specific CD8+ T-cells defines a highly exhausted T-cell subset. CD160 binds to Herpes Virus Entry Mediator (HVEM) and blocking this interaction with HVEM antibodies reverses T-cell exhaustion. As HVEM binds both inhibitory and activatory receptors, our aim in the current study was to assess the impact of CD160-specific antibodies on the enhancement of T-cell activation. METHODS: Expression of the two CD160 isoforms; glycosylphosphatidylinositol-anchored (CD160-GPI) and the transmembrane isoforms (CD160-TM) was assessed in CD4 and CD8 primary T-cells by quantitative RT-PCR and Flow-cytometry. Binding of these isoforms to HVEM ligand and the differential capacities of CD160 and HVEM specific antibodies to inhibit this binding were further evaluated using a Time-Resolved Fluorescence assay (TRF). The impact of both CD160 and HVEM specific antibodies on enhancing T-cell functionality upon antigenic stimulation was performed in comparative ex vivo studies using primary cells from HIV-infected subjects stimulated with HIV antigens in the presence or absence of blocking antibodies to the key inhibitory receptor PD-1. RESULTS: We first show that both CD160 isoforms, CD160-GPI and CD160-TM, were expressed in human primary CD4+ and CD8+ T-cells. The two isoforms were also recognized by the HVEM ligand, although this binding was less pronounced with the CD160-TM isoform. Mechanistic studies revealed that although HVEM specific antibodies blocked its binding to CD160-GPI, surprisingly, these antibodies enhanced HVEM binding to CD160-TM, suggesting that potential antibody-mediated HVEM multimerization and/or induced conformational changes may be required for optimal CD160-TM binding. Triggering of CD160-GPI over-expressed on Jurkat cells with either bead-bound HVEM-Fc or anti-CD160 monoclonal antibodies enhanced cell activation, consistent with a positive co-stimulatory role for CD160-GPI. However, CD160-TM did not respond to this stimulation, likely due to the lack of optimal HVEM binding. Finally, ex vivo assays using PBMCs from HIV viremic subjects showed that the use of CD160-GPI-specific antibodies combined with blockade of PD-1 synergistically enhanced the proliferation of HIV-1 specific CD8+ T-cells upon antigenic stimulation. CONCLUSIONS: Antibodies targeting CD160-GPI complement the blockade of PD-1 to enhance HIV-specific T-cell responses and warrant further investigation in the development of novel immunotherapeutic approaches.

Faldaprevir combined with pegylated interferon alfa-2a and ribavirin in treatment-naïve patients with chronic genotype 1 HCV: SILEN-C1 trial.

UNLABELLED: Faldaprevir (BI 201335) is a potent, hepatitis C virus (HCV) NS3/4A protease inhibitor with pharmacokinetic properties supportive of once-daily (QD) dosing. Four hundred and twenty-nine HCV genotype (GT)-1 treatment-naïve patients without cirrhosis were randomized 1:1:2:2 to receive 24 weeks of pegylated interferon alfa-2a and ribavirin (PegIFN/RBV) in combination with placebo, faldaprevir 120 mg QD with 3 days of PegIFN/RBV lead-in (LI), 240 mg QD with LI, or 240 mg QD without LI, followed by an additional 24 weeks of PegIFN/RBV. Patients in the 240 mg QD groups achieving maintained rapid virologic response (mRVR; viral load [VL] <25 IU/mL at week 4 and undetectable at weeks 8-20) were rerandomized to cease all treatment at week 24 or continue receiving PegIFN/RBV up to week 48. VL was measured by Roche TaqMan. Sustained virologic response (SVR) rates were 56%, 72%, 72%, and 84% in the placebo, faldaprevir 120 mg QD/LI, 240 mg QD/LI, and 240 mg QD groups. Ninety-two percent of mRVR patients treated with faldaprevir 240 mg QD achieved SVR, irrespective of PegIFN/RBV treatment duration. Eighty-two percent of GT-1a patients who received faldaprevir 240 mg QD achieved SVR versus 47% with placebo. Mild gastrointestinal disorders, jaundice resulting from isolated unconjugated hyperbilirubinemia, and rash or photosensitivity were more common in the active groups than with placebo. Discontinuations resulting from adverse events occurred in 4%, 11%, and 5% of patients treated with 120 mg QD/LI, 240 mg QD/LI, and 240 mg QD of faldaprevir versus 1% with placebo. CONCLUSION: Faldaprevir QD with PegIFN/RBV achieved consistently high SVR rates with acceptable tolerability and safety at all dose levels. The 120 and 240 mg QD doses are currently undergoing phase 3 evaluation. (HEPATOLOGY 2013;57:2143-2154).

Faldaprevir combined with peginterferon alfa-2a and ribavirin in chronic hepatitis C virus genotype-1 patients with prior nonresponse: SILEN-C2 trial.

UNLABELLED: Faldaprevir (BI 201335) is a potent, hepatitis C virus (HCV) NS3/4A protease inhibitor. In all, 290 noncirrhotic HCV genotype (GT)-1 patients with prior null (<1 log10 viral load [VL] drop at any time on treatment) or partial response (≥1 log10 VL drop but never undetectable on treatment) were randomized 2:1:1 to receive 48 weeks of peginterferon alfa-2a and ribavirin (PegIFN/RBV) in combination with faldaprevir 240 mg once daily (QD) with 3 days PegIFN/RBV lead-in (LI), 240 mg QD without LI, or 240 mg twice daily (BID) with LI. Patients in the 240 mg QD/LI group achieving maintained rapid virologic response (mRVR; VL <25 IU/mL [Roche TaqMan] at week 4 and undetectable at weeks 8 to 20) were rerandomized to cease all treatment at week 24 or continue PegIFN/RBV up to week 48. Sustained virologic response (SVR) rates were 32%, 50%, and 42% in prior partial responders, and 21%, 35%, and 29% in prior null responders in the faldaprevir 240 mg QD/LI, 240 mg QD, and 240 mg BID/LI groups, respectively. In the 240 mg QD/LI group, a significantly higher proportion of mRVR patients rerandomized to 48 weeks' treatment achieved SVR compared with those assigned to 24 weeks treatment (72% versus 43%; P = 0.035). Rates of gastrointestinal disorders, jaundice, dry skin, and photosensitivity were increased at 240 mg BID compared with the 240 mg QD dose. Faldaprevir discontinuations owing to adverse events occurred in 6%, 4%, and 23% of patients in the 240 mg QD/LI, 240 mg QD, and 240 mg BID/LI groups, respectively. CONCLUSION: Faldaprevir 240 mg QD with PegIFN/RBV was safe and tolerable and produced substantial SVR rates in prior null and partial responders. The 240 mg QD dose is currently undergoing phase 3 evaluation.

Derivatives of imidazotriazine and pyrrolotriazine C-nucleosides as potential new anti-HCV agents.

Previous investigations identified 2'-C-Me-branched ribo-C-nucleoside adenosine analogues, 1, which contains a pyrrolo[2,1-f][1,2,4]triazin-4-amine heterocyclic base, and 2, which contains an imidazo[2,1-f][1,2,4]triazin-4-amine heterocyclic base as two compounds with promising anti-HCV in vitro activity. This Letter describes the synthesis and evaluation of a series of novel analogues of these compounds substituted at the 2-, 7-, and 8-positions of the heterocyclic bases. A number of active new HCV inhibitors were identified but most compounds also demonstrated unacceptable cytotoxicity. However, the 7-fluoro analogue of 1 displayed good potency with a promising cytotherapeutic margin.

Identification of a potent and specific retinoic acid-inducible gene 1 pathway activator as a Hepatitis B Virus antiviral through a novel cell-based reporter assay.

Chronic Hepatitis B Virus (HBV) infection remains a global burden. To identify small molecule RIG-I agonists as antivirals against HBV, we developed an HBV-pgRNA-based interferon-ß (IFN-ß) luciferase reporter assay with high level of assay sensitivity, specificity and robustness. Through HTS screening, lead compound (JJ#1) was identified to activate RIG-I signaling pathway by inducing TBK1 phosphorylation. Knockdown experiments demonstrated that JJ#1-induced retinoic acid-inducible gene 1 (RIG-I) signaling pathway activation was MAVS-dependent. Furthermore, JJ#1 exhibited HBV antiviral potency in HBV-infected cell models by reducing HBV DNA and antigens (HBsAg and HBeAg).

Viral resistance in hepatitis C virus genotype 1-infected patients receiving the NS3 protease inhibitor Faldaprevir (BI 201335) in a phase 1b multiple-rising-dose study.

Faldaprevir (BI 201335) is a selective NS3/4A protease inhibitor under development for the treatment of chronic hepatitis C virus (HCV) infection. NS3/4A genotyping and NS3 protease phenotyping analyses were performed to monitor the emergence of resistance in patients with HCV genotype 1 infection receiving faldaprevir alone or combined with pegylated interferon alfa 2a and ribavirin (PegIFN-RBV) during a phase 1b study. Among all baseline variants, a maximum 7-fold reduction in in vitro sensitivity to faldaprevir was observed for a rare NS3 (V/I)170T polymorphism. During faldaprevir monotherapy in treatment-naive patients, virologic breakthrough was common (77%, 20/26) and was associated with the emergence of resistance mutations predominantly carrying NS3 substitutions R155K in GT1a and D168V in GT1b. D168V conferred a greater reduction in faldaprevir sensitivity (1,800-fold) than R155K (330-fold); however, D168V was generally less fit than R155K in the absence of selective drug pressure. Treatment-experienced patients treated with faldaprevir-PegIFN-RBV triple therapy showed higher viral load reductions, lower rates of breakthrough (8%, 5/62), and less frequent emergence of resistance-associated variants compared with faldaprevir monotherapy. (This study has been registered at ClinicalTrials.gov under registration no. NCT00793793.).

Antiviral effect, safety, and pharmacokinetics of five-day oral administration of Deleobuvir (BI 207127), an investigational hepatitis C virus RNA polymerase inhibitor, in patients with chronic hepatitis C.

Deleobuvir (BI 207127) is an investigational oral nonnucleoside inhibitor of hepatitis C virus (HCV) NS5B RNA polymerase. Antiviral activity, virology, pharmacokinetics, and safety were assessed in HCV genotype 1-infected patients receiving 5 days' deleobuvir monotherapy. In this double-blind phase 1b study, treatment-naive (TN; n = 15) and treatment-experienced (TE; n = 45) patients without cirrhosis received placebo or deleobuvir at 100, 200, 400, 800, or 1,200 mg every 8 h (q8h) for 5 days. Patients with cirrhosis (n = 13) received deleobuvir at 400 or 600 mg q8h for 5 days. Virologic analyses included NS5B genotyping and phenotyping of individual isolates. At day 5, patients without cirrhosis had dose-dependent median HCV RNA reductions of up to 3.8 log10 (with no placebo response); patients with cirrhosis had median HCV RNA reductions of approximately 3.0 log10. Three patients discontinued due to adverse events (AEs). The most common AEs were gastrointestinal, nervous system, and skin/cutaneous tissue disorders. Plasma exposure of deleobuvir was supraproportional at doses ≥ 400 mg q8h and approximately 2-fold higher in patients with cirrhosis than in patients without cirrhosis. No virologic breakthrough was observed. NS5B substitutions associated with deleobuvir resistance in vitro were detected in 9/59 patients; seven encoded P495 substitutions, including P495L, which conferred 120- to 310-fold-decreased sensitivity to deleobuvir. P495 variants did not persist in follow-up without selective drug pressure. Deleobuvir monotherapy was generally well tolerated and demonstrated dose-dependent antiviral activity against HCV genotype 1 over 5 days.

Evaluation of phosphatidylinositol-4-kinase IIIα as a hepatitis C virus drug target.

Phosphatidylinositol-4-kinase IIIα (PI4KIIIα) is an essential host cell factor for hepatitis C virus (HCV) replication. An N-terminally truncated 130-kDa form was used to reconstitute an in vitro biochemical lipid kinase assay that was optimized for small-molecule compound screening and identified potent and specific inhibitors. Cell culture studies with PI4KIIIα inhibitors demonstrated that the kinase activity was essential for HCV RNA replication. Two PI4KIIIα inhibitors were used to select cell lines harboring HCV replicon mutants with a 20-fold loss in sensitivity to the compounds. Reverse genetic mapping isolated an NS4B-NS5A segment that rescued HCV RNA replication in PIK4IIIα-deficient cells. HCV RNA replication occurs on specialized membranous webs, and this study with PIK4IIIα inhibitor-resistant mutants provides a genetic link between NS4B/NS5A functions and PI4-phosphate lipid metabolism. A comprehensive assessment of PI4KIIIα as a drug target included its evaluation for pharmacologic intervention in vivo through conditional transgenic murine lines that mimic target-specific inhibition in adult mice. Homozygotes that induce a knockout of the kinase domain or knock in a single amino acid substitution, kinase-defective PI4KIIIα, displayed a lethal phenotype with a fairly widespread mucosal epithelial degeneration of the gastrointestinal tract. This essential host physiologic role raises doubt about the pursuit of PI4KIIIα inhibitors for treatment of chronic HCV infection.