The present disclosure relates to compounds, compositions and methods for the treatment of hepatitis C virus (HCV) infection. Also disclosed are pharmaceutical compositions containing such compounds and methods for using these compounds in the treatment of HCV infection.

Hepatitis C virus inhibitors

A genetic interaction occurs when the combination of two mutations leads to an unexpected phenotype. Screens for synthetic genetic interactions have been used extensively to identify genes whose products are functionally related. In particular, synthetic lethal genetic interactions often identify genes that buffer one another or impinge on the same essential pathway. For the yeast Saccharomyces cerevisiae, we developed a method termed synthetic genetic array (SGA) analysis, which offers an efficient approach for the systematic construction of double mutants and enables a global analysis of synthetic genetic interactions. In a typical SGA screen, a query mutation is crossed to an ordered array of ~5000 viable gene deletion mutants (representing ~80% of all yeast genes) such that meiotic progeny harboring both mutations can be scored for fitness defects. This approach can be extended to all ~6000 genes through the use of yeast arrays containing mutants carrying conditional or hypomorphic alleles of essential genes. Estimating the fitness for the two single mutants and their corresponding double mutant enables a quantitative measurement of genetic interactions, distinguishing negative (synthetic lethal) and positive (within pathway and suppression) interactions. The profile of genetic interactions represents a rich phenotypic signature for each gene and clustering genetic interaction profiles group genes into functionally relevant pathways and complexes. This array-based approach automates yeast genetic analysis in general and can be easily adapted for a number of different genetic screens or combined with high-content screening systems to quantify the activity of specific reporters in genome-wide sets of single or more complex multiple mutant backgrounds. Comparison of genetic and chemical-genetic interaction profiles offers the potential to link bioactive compounds to their targets. Finally, we also developed an SGA system for the fission yeast Schizosaccharomyces pombe, providing another model system for comparative analysis of genetic networks and testing the conservation of genetic networks over millions of years of evolution.

Synthetic genetic array (SGA) analysis in Saccharomyces cerevisiae and Schizosaccharomyces pombe.

Proper nucleosides availability is crucial for the proliferation of living entities (eukaryotic cells, parasites, bacteria, and virus). Accordingly, the uses of inhibitors of the de novo nucleosides biosynthetic pathways have been investigated in the past. In the following we have focused on dihydroorotate dehydrogenase (DHODH), the fourth enzyme in the de novo pyrimidine nucleosides biosynthetic pathway. We first described the different types of enzyme in terms of sequence, structure, and biochemistry, including the reported bioassays. In a second part, the series of inhibitors of this enzyme along with a description of their potential or actual uses were reviewed. These inhibitors are indeed used in medicine to treat autoimmune diseases such as rheumatoid arthritis or multiple sclerosis (leflunomide and teriflunomide) and have been investigated in treatments of cancer, virus, and parasite infections (i.e., malaria) as well as in crop science.

On Dihydroorotate Dehydrogenases and Their Inhibitors and Uses

Technological advances have made it feasible to conduct high-throughput small-molecule screens based on visual phenotypes of individual cells, using automated imaging and analysis. These screens are rapidly moving from being small, proof-of-principle tests to robust and widespread screens of hundreds of thousands of compounds. Automated imaging screens maximize the information obtained in an initial screen and improve the ability to select high-quality leads. In this Perspective, I highlight the key steps necessary for conducting a high-throughput image-based chemical compound screen.

Image-based chemical screening.

Provided are certain chemical entities, pharmaceutical compositions, and methods of treatment of a member of the flaviviradae family of viruses such as hepacivirus (Hepatitis C or HCV).

Certain Nitrogen Containing Bicyclic Chemical Entities For Treating Viral Infections

Purpose: The design and development of synthetic small molecules to disrupt microtubule dynamics is an attractive therapeutic strategy for anticancer drug discovery research. Loss of clinical efficacy of many useful drugs due to drug resistance in tumor cells seems to be a major hurdle in this endeavor. Thus, a search for new chemical entities that bind tubulin, but neither are a substrate of efflux pump, P-glycoprotein 170/MDR1, nor cause undesired side effects, would potentially increase the therapeutic index in certain cancer treatments. Experimental Design: A high-content cell-based screen of a compound library led to the identification of a new class of compounds belonging to a thienopyrimidine series, which exhibited significant antitumor activities. On structure-activity relationship analysis, R-253 [ N -cyclopropyl-2-(6-(3,5-dimethylphenyl)thieno[3,2- d ]pyrimidin-4-yl)hydrazine carbothioamide] emerged as a potent antiproliferative agent (average EC 50 , 20 nmol/L) when examined in a spectrum of tumor cell lines. Results: R-253 is structurally unique and destabilizes microtubules both in vivo and in vitro . Standard fluorescence-activated cell sorting and Western analyses revealed that the effect of R-253 on cell growth was associated with cell cycle arrest in mitosis, increased select G 2 -M checkpoint proteins, and apoptosis. On-target activity of R-253 on microtubules was further substantiated by immunofluorescence studies and selected counter assays. R-253 competed with fluorescent-labeled colchicine for binding to tubulin, indicating that its binding site on tubulin could be similar to that of colchicine. R-253 neither is a substrate of P-glycoprotein 170/MDR1 nor is cytotoxic to nondividing human hepatocytes. Conclusion: Both biochemical and cellular mechanistic studies indicate that R-253 could become a promising new tubulin-binding drug candidate for treating various malignancies.

https://clincancerres.aacrjournals.org/content/clincanres/12/12/3831.full.pdf

R-253 disrupts microtubule networks in multiple tumor cell lines

The present invention relates to benzisothiazoles and pharmaceutical compositions thereof that inhibit replication and/or proliferation of HCV virus. The present invention also relates to the use of the benzisothiazoles and pharmaceutical compositions comprising the compounds to treat or prevent HCV infections.

Benzisothiazoles useful for treating or preventing HCV infection

Hepatitis C virus (HCV) infection is one of the major causes of viral hepatitis, with a great propensity to induce chronicity (21). Liver inflammation can persist for decades in chronic HCV infection and eventually leads to cirrhosis, end-stage liver disease, and hepatocellular carcinoma. HCV infection is a significant health care problem: it is estimated that approximately 170 million individuals are chronically infected with HCV worldwide, with ∼30,000 cases of new infection each year in the United States alone (1, 2, 46). No vaccine is currently available to prevent HCV infection. The standard treatment for HCV infection, a combination of pegylated alpha interferon (IFN-α) and ribavirin (RBV), is limited by its suboptimal response rate in a significant patient population, side effects, and affordability (11). Thus, it is critical to discover highly effective, safer therapies to improve the clinical management of HCV infection.

HCV is an enveloped RNA virus belonging to the family Flaviviridae (9). HCV clinical isolates display high heterogeneity in their genomic RNA and amino acid sequences, and they are classified into six genotypes and numerous subtypes (49). It is documented that infections by different genotypes may produce different clinical outcomes and may respond differently to IFN-α-based antiviral treatment (for a review, see reference 11). Significantly, patients infected with genotype 1 viruses, which account for approximately 70% of HCV infections in the United States, exhibit poor rates of response to the IFN-α-based treatment. An ideal antiviral should, therefore, be effective against the majority, if not all, of the HCV genotypes.

Upon entering the host cell, HCV releases its 9.6-kb genomic RNA into the cytoplasm, where it directs the translation of a single polyprotein of about 3,000 amino acids. The giant polyprotein is cotranslationally processed by host and viral proteases into structural proteins (core, E1, and E2) and nonstructural proteins (P7, NS2, NS3, NS4a, NS4b, NS5a, and NS5b). The mature nonstructural proteins (except P7 and NS2) and host factors assemble into membrane-associated RNA replication complexes, where a vast quantity of progeny viral RNA molecules are amplified from the incoming HCV genomic RNA (14, 18, 35). Although all the steps in the HCV life cycle can be targeted for drug discovery against HCV, the viral nonstructural proteins, specifically NS3 and NS5b, which encode well-defined enzymatic activities crucial for viral replication, are the major targets for antiviral discovery (10, 53). However, the replication of HCV viral RNA by the viral replication complex is quickly becoming another focus for drug discovery with the development of the HCV replicon system.

Until the establishment of HCV replicons, the analysis of HCV replication was hampered due to the lack of a robust HCV cell culture system (5, 38). The first-generation HCV replicons are human hepatoma Huh-7 cell lines carrying engineered genotype 1b subgenomic RNA with the following genome organization: HCV 5′ nontranslated region (5′ NTR)-neomycin phosphotransferase (NPT) gene (also referred to as the neomycin resistance [Neor] gene)-encephalomyocarditis virus (EMCV) internal ribosome entry site (IRES)-HCV NS3-4a-4b-5a-5b-HCV 3′ NTR. Subsequent studies have shown that the efficiency of replicon establishment can be enhanced substantially by incorporating cell culture-adaptive mutations, especially those in NS3 and NS5a (5, 26, 37, 38). The HCV replicon system has been an effective tool for studying viral RNA replication and virus-host interactions. It also serves as an important cell-based system with which to evaluate antiviral drugs and to reveal drug resistance mechanisms (for a review, see reference 4). Moreover, the HCV replicon presents a unique drug-screening system, allowing for the screening of compounds inhibiting the viral enzymes as well as other targets of the HCV RNA replication process in a cellular environment. Such screens would perhaps facilitate the discovery of inhibitors that block the functions of NS4b and NS5a or interrupt virus-host interactions, discoveries that cannot be readily achieved with biochemical screens. Several efforts have already been made to screen small-molecule compound libraries against different versions of the HCV replicon system (17, 47, 50, 55). Here we describe the development of an HCV replicon assay for high-throughput screening and the characterization of one of the heterocyclic hits from screens of a 230,000-member chemical library. We show that the lead compound of this hit scaffold is effective at inhibiting HCV replicons of different genotypes and can enhance the inhibitory activity of IFN-α in the replicon model.

Eileen Goldstein

Papers

R-253 disrupts microtubule networks in multiple tumor cell lines

Benzisothiazoles useful for treating or preventing HCV infection

Discovery and Characterization of Substituted Diphenyl Heterocyclic Compounds as Potent and Selective Inhibitors of Hepatitis C Virus Replication