Treatment of HCV with ABT-450/r-ombitasvir and dasabuvir with ribavirin

BACKGROUND The interferon-free combination of the protease inhibitor ABT-450 with ritonavir (ABT-450/r) and the NS5A inhibitor ombitasvir (also known as ABT-267) plus the nonnucleoside polymerase inhibitor dasabuvir (also known as ABT-333) and ribavirin has shown efficacy against the hepatitis C virus (HCV) in patients with HCV genotype 1 infection. In this phase 3 trial, we evaluated this regimen in previously untreated patients with HCV genotype 1 infection and no cirrhosis

Evolution of Resistant M414T Mutants among Hepatitis C Virus Replicon Cells Treated with Polymerase Inhibitor A-782759▿

Treatment of hepatitis C virus (HCV) replicon cells with any single specific anti-HCV inhibitor in vitro leads to a rapid selection of resistant mutants. However, the source and the kinetic evolution of these resistant mutants during treatment are poorly understood. In this study we developed allele-specific real-time PCR assays for quantitative detection of the M414T mutant that was selected by a number of benzothiadiazine HCV polymerase inhibitors. Low levels of preexisting M414T mutants were detected in both 1b-con1 (0.22%) and 1b-N (0.18%) subgenomic replicon cell lines, as well as in 6 of 15 HCV RNA isolated from the sera of treatment-naive HCV-infected patients ranging from 0.11 to 0.60%. The proportion of M414T mutants in replicons rapidly increased in a dose-dependent manner upon treatment with benzothiadiazine inhibitor A-782759. After 4 days of treatment, 2.5, 26, or 60% of the replicon population contained M414T mutants with the use of A-782759 at 1×, 10×, or 100× its 50% effective concentration, respectively. In addition, the short 4-day treatment resulted in significant changes in inhibitor susceptibility in the replicon cells. Our results indicated that the resistant mutant preexisted as a minor population in replicon cells and that the mutant was selected within days of treatment with the inhibitor. The findings from this study suggested that early application of combination therapy of an HCV-specific inhibitor with interferon-based regimens or other classes of available inhibitors will be necessary to avoid quick viral rebound or treatment failure

Prevalence, Mutation Patterns, and Effects on Protease Inhibitor Susceptibility of the L76V Mutation in HIV-1 Protease▿ †

Patterns of HIV-1 protease inhibitor (PI) resistance-associated mutations (RAMs) and effects on PI susceptibility associated with the L76V mutation were studied in a large database. Of 20,501 sequences with ≥1 PI RAM, 3.2% contained L76V; L76V was alone in 0.04%. Common partner mutations included M46I, I54V, V82A, I84V, and L90M. L76V was associated with a 2- to 6-fold decrease in susceptibility to lopinavir, darunavir, amprenavir, and indinavir and a 7- to 8-fold increase in susceptibility to atazanavir and saquinavir

Mutations Conferring Resistance to a Potent Hepatitis C Virus Serine Protease Inhibitor In Vitro

BILN 2061 is a novel, specific hepatitis C virus (HCV) NS3 serine protease inhibitor discovered by Boehringer Ingelheim that has shown potent activity against HCV replicons in tissue culture and is currently under clinical investigation for the treatment of HCV infection. The poor fidelity of the HCV RNA-dependent RNA polymerase will likely lead to the development of drug-resistant viruses in treated patients. The development of resistance to BILN 2061 was studied by the in vitro passage of HCV genotype 1b replicon cells in the presence of a fixed concentration of the drug. Three weeks posttreatment, four colonies were expanded for genotypic and phenotypic characterization. The 50% inhibitory concentrations of BILN 2061 for these colonies were 72- to 1,228-fold higher than that for the wild-type replicon. Sequencing of the individual colonies identified several mutations in the NS3 serine protease gene. Molecular clones containing the single amino acid substitution A156T, R155Q, or D168V resulted in 357-fold, 24-fold, and 144-fold reductions in susceptibility to BILN 2061, respectively, compared to the level of susceptibility shown by the wild-type replicon. Modeling studies indicate that all three of these residues are located in close proximity to the inhibitor binding site. These findings, in addition to the three-dimensional structure analysis of the NS3/NS4A serine protease inhibitor complex, provide a strategic guide for the development of next-generation inhibitors of HCV NS3/NS4A serine protease

Hepatitis C virus genetic diversity by geographic region within genotype 1-6 subtypes among patients treated with glecaprevir and pibrentasvir.

Hepatitis C virus (HCV) is genetically diverse and includes 7 genotypes and 67 confirmed subtypes, and the global distribution of each HCV genotype (GT) varies by geographic region. In this report, we utilized a large dataset of NS3/4A and NS5A sequences isolated from 2348 HCV GT1-6-infected patients treated with the regimen containing glecaprevir/pibrentasvir (GLE/PIB) to assess genetic diversity within HCV subtypes by geographic region using phylogenetic analyses, and evaluated the prevalence of baseline amino acid polymorphisms in NS3 and NS5A by region/country and phylogenetic cluster. Among 2348 NS3/4A and NS5A sequences, phylogenetic analysis identified 6 genotypes and 44 subtypes, including 3 GT1, 8 GT2, 3 GT3, 13 GT4, 1 GT5, and 16 GT6 subtypes. Phylogenetic analysis of HCV subtype 1a confirmed the presence of two clades, which differed by geographic region distribution and NS3 Q80K prevalence. We detected phylogenetic clustering by country in HCV subtypes 1a, 1b, 2a, 2b, and 5a, suggesting that genetically distinct virus lineages are circulating in different countries. In addition, two clades were detected in HCV GT4a and GT6e, and NS5A amino acid polymorphisms were differentially distributed between the 2 clades in each subtype. The prevalence of NS3 and NS5A baseline polymorphisms varied substantially by genotype and subtype; therefore, we also determined the activity of GLE or PIB against replicons containing NS3/4A or NS5A from HCV GT1-6 clinical samples representing 6 genotypes and 21 subtypes overall. GLE and PIB retained activity against the majority of HCV replicons containing NS3/4A or NS5A from HCV GT1-6 clinical samples, with a median EC50 of 0.29 nM for GLE and 1.1 pM for PIB in a transient replicon assay. The data presented in this report expands the available data on HCV epidemiology, subtype diversity by geographic region, and NS3 and NS5A baseline polymorphism prevalence