Search

Background: Temsavir (TMR), the active agent of the gp120-directed attachment inhibitor fostemsavir (FTR), the CD4-directed attachment inhibitor ibalizumab (IBA), and the CCR5 antagonist maraviroc (MVC) are antiretroviral agents that target steps in HIV-1 viral entry. Although mechanisms of inhibition of the three agents are different, it is important to understand whether there is potential for cross-resistance between these agents, as all involve interactions with gp120. Methods: Envelopes derived from plasma samples from participants in the BRIGHTE study who experienced protocol-derived virologic failure (PDVF) and were co-dosed with FTR and either IBA or MVC were analyzed for susceptibility to the agents. Also, CCR5-tropic MVC-resistant envelopes from the MOTIVATE trials were regenerated and studies were performed to understand whether susceptibility to multiple agents were linked. Results: The cloned envelopes exhibited reduced susceptibility to TMR and resistance to the co-dosed agent. At PDVF, emergent or preexisting amino acid substitutions were present at TMR positions of interest. When amino acid substitutions at these positions were reverted to the consensus sequence, full susceptibility to TMR was restored without effecting resistance to the co-dosed agent. In addition, five envelopes from MOTIVATE were regenerated and exhibited R5-tropic-MVC-resistance. Only one exhibited reduced susceptibility to TMR and it contained an M426L polymorphism. When reverted to 426M, full sensitivity for TMR was restored, but it remained MVC resistant. Conclusion: The data confirm that decreased susceptibility to TMR and resistance to IBA or MVC are not linked and that there is no cross-resistance between either of these two agents and FTR.

The cosignal molecule B7-H3 is gaining attention due to its abnormal expression and abundant signal transduction in many types of malignancies. B7-H3-induced signaling includes at least three cascades: PI3K/AKT, JAK2/STAT3, and Raf/MEK/ERK1/2, which are also involved in epidermal growth factor receptor- (EGFR-) triggered signaling in lung adenocarcinoma cells. However, the correlation between B7-H3-induced signaling and EGFR signaling, and between B7-H3-targeted immunotherapy and EGFR-targeted therapy in lung adenocarcinoma, remains to be elucidated. Herein we find that knockout of B7-H3 gene decreased cell survival and increased EGFR-tyrosine kinase inhibitor gefitinib susceptibility of both H3255 and HCC827 cells, two lung adenocarcinoma cell lines harboring EGFR L858R (exon 21) and Del E746-A750 (exon 19) mutations, respectively. B7-H3 deletion resulted in dramatic reduction of phosphorylation level of AKT and STAT3 in H3255 cells while having mild-to-moderate suppression on AKT, STAT3, and ERK1/2 in HCC827 cells. Gefitinib had similar effects with B7-H3 deletion both in H3255 and HCC827 cells. Furthermore, B7-H3 ablation had significant synergistic effects with gefitinib in HCC827 cells. Collectively, our study reveals B7-H3-induced signaling in lung adenocarcinoma cell lines with divergent EGFR mutations, and a translational potential of combined targeted therapy of B7-H3 and EGFR in lung adenocarcinoma with EGFR Del E746-A750 mutation.

Silent hypoxia has emerged as a unique feature of coronavirus disease 2019 (COVID-19). In this study, we show that mucins are accumulated in the bronchoalveolar lavage fluid (BALF) of COVID-19 patients and are upregulated in the lungs of severe respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected mice and macaques. We find that induction of either interferon (IFN)-β or IFN-γ upon SARS-CoV-2 infection results in activation of aryl hydrocarbon receptor (AhR) signaling through an IDO-Kyn-dependent pathway, leading to transcriptional upregulation of the expression of mucins, both the secreted and membrane-bound, in alveolar epithelial cells. Consequently, accumulated alveolar mucus affects the blood-gas barrier, thus inducing hypoxia and diminishing lung capacity, which can be reversed by blocking AhR activity. These findings potentially explain the silent hypoxia formation in COVID-19 patients, and suggest a possible intervention strategy by targeting the AhR pathway.

Entecavir (ETV) is a first‐line therapy for chronic hepatitis B virus (HBV), demonstrating potent suppression of HBV DNA and a high barrier to viral resistance. Previous studies revealed that ETV‐resistant (ETVr) HBV DNA resulted from substitutions in the HBV reverse transcriptase (RT) at positions rtT184, rtS202, or rtM250 in combination with lamivudine resistance (LVDr) substitutions rtM204I/V±rtL180M. In vitro, viral variants exhibit varying degrees of ETV susceptibility and replication capacity depending on specific resistance substitutions. To explore the potential for additional pathways to ETVr, HBV RT sequences from 982 evaluable patients enrolled in 17 ETV clinical studies were analyzed. Thirty novel emergent substitutions at amino acid positions not previously associated with HBV nucleos(t)ide drug resistance were observed in at least 2 patients and were identified in patient‐derived HBV with a wild‐type, LVDr, or ETVr RT sequence. Phenotypic analysis of these substitutions indicated that they had no effect on ETV susceptibility. Phenotypic analysis was also performed on patient‐derived HBV RT sequences from 10 LVD‐naive and 13 LVD‐experienced patients with virologic breakthrough and emergent novel substitutions while on ETV treatment. One LVD‐experienced patient‐derived HBV RT harboring LVDr substitutions rtL180M+rtM204V with rtA181C displayed reduced ETV susceptibility (122‐fold greater than wild‐type HBV) and remained susceptible to adefovir and tenofovir. HBV harboring the rtA181C substitution without LVDr substitutions rtL180M+rtM204V remained susceptible to inhibition by ETV, adefovir, and tenofovir, although cross‐resistance to LVD and telbivudine was observed. Conclusion: An integrated genotypic analysis of HBV RT sequences from patients with chronic HBV treated with ETV led to the discovery of the novel ETVr substitution rtA181C. This substitution was always detected in combination with LVDr substitutions rtL180M+rtM204V in ETV‐treated patients.

Background Viral myocarditis is a widespread cardiac disease associated with inflammation and myocardial injury and is predominantly caused by coxsackievirus B3 (CVB3) infection in humans as well as in mice. CVB3-induced myocarditis shows sexually dimorphic sensitivity and is more prevalent in male mice. Our previous studies showed that natural killer (NK) cells played an indispensable role in CVB3-induced myocarditis, and female mice exhibited less pathological cardiac interferon gamma (IFN-γ) + NK cell infiltration than did male mice. However, the precise mechanisms were not well elucidated. Methods We investigated the influence of estrogen on cardiac IFN-γ + NK cell enrichment in CVB3-induced myocarditis and explored the underlying molecular mechanism. Results In this study, we found that CVB3 stimulation could clearly induce IFN-γ expression by NK cells; however, this trend could be blunted by estrogen treatment. Consistently, ovariectomized female mice with decreased estrogen levels exhibited substantially increased enrichment of cardiac IFN-γ + NK cells and displayed significantly aggravated myocarditis. Similarly, estrogen-treated male mice showed less cardiac IFN-γ + NK cell infiltration, accompanied by significantly alleviated viral myocarditis. In sharp contrast, sexually immature female and male mice (with similar estrogen levels) showed comparable levels of cardiac IFN-γ + NK cell infiltration and similar levels of myocarditis severity. Upon further exploration of the underlying mechanisms, we found that estrogen could downregulate expression of Th1-specific T box transcription factor (T-bet), the key transcription factor associated with IFN-γ production, in CVB3-stimulated NK cells. Conclusions Overall, this study might help us understand the mechanism of increased cardiac infiltration by IFN-γ + NK cells in CVB3-infected male mice compared with that in female mice and might provide new clues for the sex bias in CVB3-induced myocarditis.

Supplemental Digital Content is Available in the Text., Background: Fostemsavir is a prodrug of temsavir, an attachment inhibitor that binds to HIV-1 gp120, blocking viral attachment to host CD4+ T-cells. The phase 2b trial AI438011 investigated the safety, efficacy, and dose–response of fostemsavir vs ritonavir-boosted atazanavir (ATV/r) in treatment-experienced, HIV-1–infected subjects. Methods: Two hundred fifty-one treatment-experienced subjects with baseline (BL) susceptibility to study drugs [temsavir half-maximal inhibitory concentration (IC50) 3-fold increase). Results: 66/200 fostemsavir and 14/51 ATV/r subjects had resistance testing performed; 44/66 and 9/14 were successfully tested using the PhenoSense GT assay. No subjects had emergent tenofovir disoproxil fumarate or ATV resistance. Six fostemsavir-treated subjects developed emergent raltegravir resistance. 29/66 fostemsavir-treated subjects had an evaluable phenotype using PhenoSense Entry (which tests for viral susceptibility to temsavir) and 13/29 exhibited >3-fold increase in temsavir IC50 from BL. gp120 population sequencing was successful in 11/13 subjects and 7 had emergent substitutions in gp120 associated with reduced temsavir susceptibility (S375, M426, or M434). However, 5/13 fostemsavir-treated subjects achieved subsequent suppression to

Most patients with cholangiocarcinoma (CCA) develop extrahepatic malignant biliary obstructions, which require palliative drainage to normalize bilirubin levels and to improve the patients' overall survival. Here, we report that the infusion of methotrexate-containing plasma-membrane microvesicles derived from apoptotic human tumour cells into the bile-duct lumen of patients with extrahepatic CCA mobilized and activated neutrophils and relieved biliary obstruction in 25% of the patients. Neutrophil recruitment by the microvesicles was associated with an increase in uridine diphosphate glucose and complement C5, and led to the degradation of the stromal barrier of CCA. The microvesicles induced pyroptosis of CCA cells through a gasdermin E-dependent pathway, and their intracellular contents released upon CCA-cell death activated patient-derived macrophages into producing proinflammatory cytokines, which attracted a secondary wave of neutrophils to the tumour site. Our findings suggest a possible treatment for the alleviation of obstructive extrahepatic CCA with few adverse effects, and highlight the potential of tumour-cell-derived microvesicles as drug carriers for antitumour therapies.

HCV genotype 6 (GT-6) is found predominantly in East and Southeast Asia. Clinical studies have focused on patients infected with hepatitis C virus (HCV) GT-6a, where high sustained virologic response (SVR) rates to direct-acting antivirals (DAAs) have been achieved. However, GT-6 is highly diverse, with 29 reported subtypes. We explored the diversity of GT-6 polymorphisms at residues associated with DAA resistance, their impact on DAA in vitro potency when evaluated in a GT-6a consensus replicon, and their association with specific GT-6 subtypes. GT-6 sequences from 25 patient-derived samples and 105 sequences from the U.S. HCV database were compared, and substitutions at resistance-associated residue positions were phenotyped against different DAAs. Preexisting resistance-associated substitutions (RASs) to NS3 protease (A156V and D168E) and NS5B nucleotide (L159F and S282C) inhibitors were rare (5,000 nM) and were detected in evaluated GT-6b and -6f sequences. NS5A-L28A-R30A, observed in GT-6r, did not replicate. In conclusion, HCV GT-6b, GT-6f, and GT-6r sequences harbored highly resistant RASs to all evaluated NS5A drugs. Therefore, monitoring SVR in patients infected with these GT-6 subtypes treated with NS5A drug-containing regimens is suggested to confirm any association between noted NS5A polymorphisms and treatment failure.

OBJECTIVE Daclatasvir (DCV) is a pan-genotypic non-structural protein 5A (NS5A) inhibitor that is approved for treatment of hepatitis C virus (HCV) genotype (GT)1 and GT3 in the USA and GT1, GT3 and GT4 in Europe. We set out to examine the impact of daclatasvir-based regimens on the sustained virologic response (SVR) in patients with GT2 infection with respect to GT2 subtype and NS5A polymorphisms at amino acid positions associated with daclatasvir resistance. METHODS Analyses were performed on 283 GT2 NS5A sequences from five daclatasvir regimen-based clinical trials (ClinicalTrials.gov: NCT-01257204, NCT-01359644, NCT-02032875, NCT-02032888 and NCT-01616524) and 143 NS5A sequences from the Los Alamos HCV database. Susceptibility analyses of substitutions at amino acid positions associated with daclatasvir resistance and patient-derived NS5A sequences were performed using an in vitro HCV replication assay. RESULTS Of 13 GT2 subtypes identified from 426 NS5A sequences, the most prevalent were GT2a (32%), GT2b (48%) and GT2c (10%). The most prevalent NS5A polymorphism was L31M (GT2a = 88%; GT2b = 59%; GT2c = 10%). Substitutions identified in 96% of GT2 NS5A sequences exhibited daclatasvir EC50 values ranging from 0.005 to 20 nM when tested in vitro. A similar range in daclatasvir EC50 values was observed for 16 diverse GT2 patient-derived NS5A sequences (EC50 = 0.005-60 nM). Depending on the daclatasvir-based regimen studied (daclatasvir/interferon-based or daclatasvir/sofosbuvir-based), SVR rates ranged from 90% to 100% in GT2 patients with the most prevalent baseline NS5A-L31M polymorphism, compared with from 96% to 100% without this polymorphism. CONCLUSIONS High SVR rates were achieved in patients infected with GT2 treated with daclatasvir-based regimens irrespective of GT2 subtype or baseline NS5A polymorphisms.

Background. Daclatasvir is an NS5A inhibitor approved for treatment of infection due to hepatitis C virus (HCV) genotypes (GTs) 1–4. To support daclatasvir use in HCV genotype 4 infection, we examined a diverse genotype 4–infected population for HCV genotype 4 subtype prevalence, NS5A polymorphisms at residues associated with daclatasvir resistance (positions 28, 30, 31, or 93), and their effects on daclatasvir activity in vitro and clinically. Methods. We performed phylogenetic analysis of genotype 4 NS5A sequences from 186 clinical trial patients and 43 sequences from the European HCV database, and susceptibility analyses of NS5A polymorphisms and patient-derived NS5A sequences by using genotype 4 NS5A hybrid genotype 2a replicons. Results. The clinical trial patients represented 14 genotype 4 subtypes; most prevalent were genotype 4a (55%) and genotype 4d (27%). Daclatasvir 50% effective concentrations for 10 patient-derived NS5A sequences representing diverse phylogenetic clusters were ≤0.080 nM. Most baseline sequences had ≥1 NS5A polymorphism at residues associated with daclatasvir resistance; however, only 3 patients (1.6%) had polymorphisms conferring ≥1000-fold daclatasvir resistance in vitro. Among 46 patients enrolled in daclatasvir trials, all 20 with baseline resistance polymorphisms achieved a sustained virologic response. Conclusions. Circulating genotype 4 subtypes are genetically diverse. Polymorphisms conferring high-level daclatasvir resistance in vitro are uncommon before therapy, and clinical data suggest that genotype 4 subtype and baseline polymorphisms have minimal impact on responses to daclatasvir-containing regimens.

Background Daclatasvir (DCV) is an approved NS5A inhibitor with potent anti-HCV activity and broad genotype coverage. DCV resistance-associated variants (RAVs) have been described for patients infected with genotype (GT) 1, but increased GT4 prevalence in European countries as a result of immigration has boosted interest in this genotype. Objectives Establishment of NS5A variability in treatment-naive patients with HCV genotype 4 infection and a case study of the dynamics of resistance-associated variants in a virologic failure receiving pIFN/RBV + DCV, as assessed by ultra-deep sequencing. Study design Five treatment-naive GT4 patients (GT4a [n = 1], GT4d [n = 3], GT4o [n = 1]) were evaluated for inclusion in the COMMAND-4 study and treatment with pIFN/RBV ± DCV. Results Patient (Pt) 1 received pIFN/RBV; Pts2–4 received pIFN/RBV + DCV; Pt5 was a screening failure. Pt1 relapsed; Pt2 experienced breakthrough at Wk4; Pts3 and 4 achieved a sustained virologic response. No substitutions associated with DCV-resistance were detected at baseline. In terms of viremic time points for Pts1 and 2, the extent of NS5A diversity pre-treatment was not significantly related to viral load (r = −0568; p = 0.035). In Pt2, multiple substitutions associated with DCV-resistance were observed after breakthrough at NS5A amino acid positions 28, 31 and 93. These substitutions were frequently observed on the same haplotype (L28S + M31I = 55.52, 82.50, and 99.36% at Wk4, 8 and 9; L28S + M31I + Y93H = 11.77, 5.01 and Conclusions This is the first report to describe DCV-resistance in patients infected with GT4d, supporting a possible role for a recently described RAV (L28S), and presenting the dynamics of HCV quasispecies during therapy failure, with indications of changes of diversity and association of mutations.

Background Daclatasvir (DCV; non-structural [NS]5A inhibitor) plus asunaprevir (ASV; NS3 inhibitor) plus beclabuvir (BCV; non-nucleoside NS5B inhibitor) is an approved regimen for hepatitis C virus (HCV) genotype (GT)-1 treatment in Japan. A comprehensive analysis of pre-treatment and treatment-emergent HCV resistance to this regimen ± ribavirin (RBV) was performed. Methods Data were pooled from five Phase 2/3 studies of DCV+ASV+BCV±RBV given for 12 weeks to GT-1a- or GT-1b-infected patients. The prevalence and impact of pre-treatment resistance-associated substitutions (RAS) in NS5A, NS3, and NS5B on sustained virological response (SVR) was assessed, as were emergent RAS and their post-treatment persistence. Results Baseline NS5A RAS (GT-1a: M28T, Q30H/L/R/S, L31M, Y93C/H; GT-1b: L31I/M, Y93C/H) were present in 5% (26/561) of GT-1a and 16% (85/537) of GT-1b sequences. SVR12 for GT-1b without RBV was 100% (82/82) with RAS and >99% (427/428) without RAS. For GT-1a, SVR12 without RAS was 97% (85/88) with RBV and 92% (410/447) without RBV; SVR12 with RAS was 100% (2/2) with RBV and 54% (13/24) without RBV. Baseline NS3 (at R155 or D168) and NS5B (at P495) RAS were rare (≤1%). Treatment-emergent NS5A RAS (mostly Q30E/H/K/R+Y93H/N) in GT-1a persisted 60 weeks post-treatment, while NS3 RAS (mostly R155K) and NS5B-P495L/S were no longer detected after 48 or 24 weeks, respectively. Conclusions DCV+ASV+BCV+RBV was highly efficacious in HCV GT-1 infection, including HCV GT-1b with NS5A RAS. The fitness of treatment-emergent RAS post-treatment was NS5A > NS3 > NS5B; NS3 and NS5B RAS were generally replaced by wild-type sequence within 48 weeks.

Please cite this article as: Hassanein, T., Sims, K.D., Bennett, M., Gitlin, N., Lawitz, E., Nguyen, T., Webster, L., Younossi, Z., Schwartz, H., Thuluvath, P.J., Zhou, H., Rege, B., McPhee, F., Zhou, N., Wind-Rotolo, M., Chung, E., Griffies, A., Grasela, D.M., Gardiner, D.F., A Randomized Trial of Daclatasvir in Combination With Asunaprevir and Beclabuvir in Patients With Chronic Hepatitis C Virus Genotype 4 Infection, Journal of Hepatology (2015), doi: http://dx.doi.org/10.1016/j.jhep.2014.12.025

In a sentinel cohort, hepatitis C virus (HCV) patients (primarily genotype [GT] 1a) were treated with daclatasvir (NS5A inhibitor) and asunaprevir (NS3 protease inhibitor). Preexistence, emergence, and persistence of resistance variants in patients who failed this treatment are described. HCV-infected null responders received daclatasvir (60 mg once daily) and asunaprevir (600 mg twice daily) alone (Group A, 11 patients) or with peginterferon alfa-2a and ribavirin (Group B, 10 patients) for 24 weeks. Resistance testing was performed on baseline samples and samples with HCV RNA ≥1,000 IU/mL at Week 1 through posttreatment Week 48. Resistance substitution susceptibility to inhibition by asunaprevir and daclatasvir was assessed using HCV replicon assays. In Group A, six GT1a patients experiencing viral breakthrough and one GT1a patient who relapsed had detectable NS5A (Q30E/R, L31V/M, Y93C/N) and NS3 (R155K, D168A/E/V/Y) resistance-associated variants at failure. Two of six viral breakthrough patients achieved SVR48 after treatment intensification with peginterferon alfa-2a and ribavirin. For 2/4 viral breakthrough patients not responding to treatment intensification, NS3 resistance variants changed (D168Y to D168T; R155K to V36M-R155K). At posttreatment Week 48, daclatasvir-resistant variants persisted while asunaprevir-resistant variants were generally replaced by wild-type sequences. The NS3 sequence remained unchanged in the one patient with NS3-R155K at baseline, relapse, and posttreatment Week 48. In Group B, no viral breakthrough was observed. Conclusion: The treatment failure of daclatasvir and asunaprevir in HCV GT1a patients was associated with both NS5A and NS3 resistance variants in prior null responders. NS5A resistance variants persisted while NS3 resistance variants generally decayed, suggesting a higher relative fitness of NS5A variants. (Hepatology 2013;53:902–911)

Background Hepatitis C virus (HCV) NS5A replication complex inhibitors (RCIs) have been shown to exhibit picomolar antiviral activity against genotype 1 (GT1) in vitro. This has translated into rapid and robust declines in HCV RNA in GT1 patients. Less is known about the susceptibility of other genotypes such as GT3 to inhibition by NS5A RCIs. Objectives To detect and phenotype naturally occurring HCVGT3 NS5A polymorphisms against two NS5A RCIs (daclatasvir [DCV] and GS-5885) currently in clinical development. Study design The NS5A region from 96 HCV GT3 treatment-naive patients spanning North America, Europe and Australia was determined. Results Phylogenetic analysis revealed a broad distribution with no significant geographic clustering. GT1 DCV resistance-associated variants (RAVs) were observed in GT3 subjects; variants (and their frequencies) included 28M/V (1%), 30A/K/S/T/V (10%), 31L/M (1%), E92A (1%) and Y93H (8.3%). A consensus sequence was used to generate a JFH1/3a-NS5A hybrid replicon and employed to assess susceptibility to NS5A RCIs. Against JFH1/3a-NS5A, DCV was more potent (EC50 = 0.52 nM) than GS-5885 (EC50 = 141 nM). DCV sensitivity was increased against JFH1/3a-NS5A-M28V (EC50 = 0.006 nM), A30V (EC50 = 0.012 nM), and E92A (EC50 = 0.004 nM) while the NS5A-A30K and -Y93H variants exhibited reduced sensitivity to DCV (EC50 values of 23 nM and 1120 nM, respectively) and to GS-5885 (EC50 values of 1770 nM and 4300 nM, respectively). Conclusions Substitutions conferring resistance to NS5A RCIs pre-existed in treatment-naive patients infected with HCV GT3. The effectiveness of these NS5A RCIs to exert efficacy in the clinic may depend on which inhibitor is used in combination with other antivirals.

Introduction Oral daclatasvir (DCV; pangenotypic NS5A inhibitor) plus asunaprevir (ASV; NS3 protease inhibitor) is approved in Japan and Korea for treatment of chronic hepatitis C virus (HCV) genotype 1. Response to DCV + ASV is affected by DCV resistance-associated polymorphisms (RAPs) in HCV NS5A. The prevalence and influence of these RAPs on 12-week sustained virologic response (SVR12) to DCV + ASV was evaluated in Asian and non-Asian patients. Methods Data were pooled from 5 national and international studies of patients with HCV genotype 1b (GT-1b) receiving DCV + ASV at their recommended doses. Baseline NS5A RAPs and their effect on SVR12 were assessed overall, in older (≥65 years) patients, patients with cirrhosis, and in patients stratified by baseline HCV RNA or prior treatment experience with interferon-based therapy. Results Baseline NS5A sequences were available from 988 patients (374 Japanese; 125 Korean/Taiwanese; 489 from non-Asian countries), 979 of whom were assessed for SVR12. Pretreatment NS5A-L31F/I/M/V and/or NS5A-Y93H polymorphisms were present in 18% of Japanese and 12–13% of non-Japanese patients; these RAPs reduced SVR12 by 54.9% overall (93.9% [787/838] SVR12 when absent, 39.0% [55/141] SVR12 when present), with comparable reductions observed in Asians and non-Asians and across all categories of treatment experience, age, and cirrhosis. RAP-associated SVR12 rates declined with increasing baseline HCV RNA (SVR12 with RAPs: 64.7% [11/17] at 5-6 log10 IU/mL, 29.8% [14/47] at 7–8 log10). Without baseline RAPs, very high SVR12 rates (92–100%) were observed in older patients and patients with cirrhosis irrespective of national origin, with similarly high rates observed among treatment-naïve and interferon-experienced patients and those with high baseline HCV RNA. Conclusions Following DCV + ASV treatment, the SVR12 rates in GT-1b patients without baseline NS5A-L31F/I/M/V and/or NS5A-Y93H polymorphisms were very high (approximately 90–100%), irrespective of age, cirrhosis, prior interferon treatment, or baseline HCV RNA. Funding Bristol-Myers Squibb. Electronic supplementary material The online version of this article (doi:10.1007/s12325-015-0221-5) contains supplementary material, which is available to authorized users.

Background Daclatasvir (DCV; BMS-790052) is a picomolar inhibitor of HCV non-structural protein 5A (NS5A) and has demonstrated efficacy in patients chronically infected with HCV. Methods In the double-blind, randomized studies AI444021 and AI444022, 71 Japanese patients chronically infected with HCV genotype 1 (predominantly genotype 1b) received DCV (10 mg or 60 mg) plus peginterferon alfa-2b or alfa-2a and ribavirin. Virological failure occurred in 14% (5/36) of treatment-naive patients and 54% (19/35) of prior alfa/ribavirin non-responders. Resistance testing was performed on baseline samples and samples with HCV RNA≥1,000 IU/ml at week 1 through post-treatment week 24. Results Baseline NS5A resistance-associated polymorphisms had less impact on virological response rates than IL28B genotype. All patients with virological failure had NS5A DCV-resistant variants at the time of failure. The predominant NS5A variants were L31V/M/I plus Y93H; this combination was detected in 100% (5/5) of treatment-naive patients and 74% (14/19) of non-responders with failure. Emergent resistance variants in prior non-responders (four viral breakthroughs, one relapse) were more varied with novel combinations such as L31F-DP32 and L28M-R30Q-A92K detected. Significant loss in DCV antiviral activity was generally only seen with ≥ two resistance-associated NS5A substitutions. All DCV-resistant variants were still detected at end of study. Conclusions Virological failure in HCV genotype 1b treatment-naive Japanese patients receiving DCV plus alfa-2a/ribavirin or alfa-2b/ribavirin was associated with enrichment of NS5A resistance variants L31V/M-Y93H. In prior non-responders, emergent variants associated with failure also included NS5A-A92K or NS5A-DP32. As with L31-Y93 variants, these variants persisted.

Treatment with HIV attachment inhibitors (AIs) can select for escape mutants throughout the viral envelope. We report on three such mutations: F423Y (gp120 CD4 binding pocket) and I595F and K655E (gp41 ectodomain). Each displayed decreased sensitivity to the AI BMS-488043 and earlier generation AIs, along with increased sensitivity to the broadly neutralizing antibodies 2F5 and 4E10, without affecting the rate of viral entry or sensitivity to the entry inhibitors AMD-3100 and Enfuvirtide. We also observed that I595F did not substantially increase envelope sensitivity to HIV-infected patient sera. Based on these observations, we propose that although F423Y, I595F and K655E may all affect the presentation of the 2F5 and 4E10 epitopes, natural immune mimicry is rare only for the I595F effect. Thus, it seems that in addition to restricting AI resistance development, incorporation of I595F into an appropriate vehicle could elicit a novel antiviral response to improve vaccine efficacy.

Introduction Daclatasvir is a non-structural protein 5A (NS5A) inhibitor with activity against hepatitis C virus (HCV) genotypes 1–6 in vitro, and asunaprevir is a non-structural protein 3 (NS3) protease inhibitor with activity against genotypes 1, 4, 5, and 6. This study evaluates potential options for the re-treatment of HCV genotype 1b-infected patients who have failed combination therapy with daclatasvir plus asunaprevir. Methods The antiviral activity of drug combination regimens in HCV subgenomic replicon cell lines representing genotype 1b (Con1 strain) wild-type or a variant with specific NS5A and NS3 amino acid substitutions conferring resistance to daclatasvir and asunaprevir were compared using replicon elimination assays. Drug concentrations representing multiple 50% effective concentrations (EC50) derived in vitro and trough plasma concentrations observed in a clinical setting were utilized. Results At multiple EC50 values of each drug (3×, 10×, and 30× EC50), combinations of daclatasvir plus sofosbuvir, sofosbuvir plus ledipasvir, sofosbuvir plus simeprevir, and sofosbuvir plus either a next-generation NS3 or NS5A inhibitor demonstrated comparable activity in wild-type and daclatasvir/asunaprevir-resistant cell lines. At clinically relevant drug trough concentrations, combination regimens of daclatasvir plus asunaprevir plus beclabuvir (±ribavirin), and daclatasvir plus asunaprevir plus beclabuvir plus sofosbuvir efficiently cleared daclatasvir + asunaprevir-resistant replicons from cells within 5 days of treatment. Conclusion Our in vitro results highlight a number of potential all-oral treatment options for patients who do not achieve a sustained virologic response following therapy with daclatasvir plus asunaprevir. These results require further evaluation in clinical studies. Electronic supplementary material The online version of this article (doi:10.1007/s40121-014-0052-8) contains supplementary material, which is available to authorized users.