Resistance Studies of a Dithiazol Analogue, DBPR110, as a Potential Hepatitis C Virus NS5A Inhibitor in Replicon Systems

Abstract

bHepatitis C virus (HCV), a member of the Flaviviridae family, affects approximately 3% of the world's population and is becoming the leading cause of liver disease in the world. Therefore, the development of novel or more effective treatment strategies to treat chronic HCV infection is urgently needed. In our previous study, we identified a potential HCV NS5A inhibitor, BP008. After further systemic optimization, we discovered a more potent HCV inhibitor, DBPR110. DBPR110 reduced the reporter expression of the HCV1b replicon with a 50% effective concentration (EC 50 ) and a selective index value of 3.9 ؎ 0.9 pM and >12,800,000, respectively. DBPR110 reduced HCV2a replicon activity with an EC 50 and a selective index value of 228.8 ؎ 98.4 pM and >173,130, respectively. Sequencing analyses of several individual clones derived from the DBPR110-resistant RNAs purified from cells harboring genotype 1b and 2a HCV replicons revealed that amino acid substitutions mainly within the N-terminal region (domain I) of NS5A were associated with decreased inhibitor susceptibility. P58L/T and Y93H/N in genotype 1b and T24A, P58L, and Y93H in the genotype 2a replicon were the key substitutions for resistance selection. In the 1b replicon, V153M, M202L, and M265V play a compensatory role in replication and drug resistance. Moreover, DBPR110 displayed synergistic effects with alpha interferon (IFN-␣), an NS3 protease inhibitor, and an NS5B polymerase inhibitor. In summary, our results present an effective small-molecule inhibitor, DBPR110, that potentially targets HCV NS5A. DBPR110 could be part of a more effective therapeutic strategy for HCV in the future. Hepatitis C virus (HCV) is a small enveloped RNA virus that affects nearly 170 million individuals worldwide, making it a leading cause of hepatitis C and liver disease (1). HCV infection is responsible for the development of severe chronic liver disease and cirrhosis and associated complications, including liver failure, portal hypertension, and hepatocellular carcinoma (2). The main goals of chronic HCV therapy are to eradicate the virus and prevent these potentially life-threatening complications. The mainstays of chronic HCV therapy are PEGylated alpha interferon (IFN-␣) and ribavirin, but these compounds are poorly tolerated and may eventually lead to a suboptimal response rate and a high incidence of adverse effects, including flu-like symptoms, depression, and anemia (3, 4). The chances of sustained viral clearance are only 40 to 50% for genotype 1 infection, which is the predominant genotype in worldwide populations. Therefore, the development of specific antiviral therapies for hepatitis C with improved efficacy and better tolerance is a major public health objective that is urgently important.HCV is a positive-strand RNA virus that has been classified as the sole member of the Hepacivirus genus within the Flaviviridae family. The HCV genome consists of a single strand of RNA that is approximately 9.6 kb long, with a large open reading frame encoding a polyprotein of ...

The discovery and characterization of a novel scaffold as a potent hepatitis C virus inhibitor

“…Indeed, L31V and Y93H mutations have been reported in NS5A inhibitor BMS-790052 induced drug resistance. 13 Mutation in Pro58 has also been reported in DBPR110, another NS5A inhibitor induced resistant mutations, 14 although we observed a P58S as opposed to P58L mutation. Notably, within our sequences of resistance clones, these mutations did not show co-occurrence.…”

“…For example, resistance may be developed as early as four days after the initiation of monotherapy. 13,14 Third, physicochemical properties and pharmacokinetic profiles of current HCV inhibitors remain to be further improved. Marketed DAA drugs generally have complex chemical structures and large molecular weight (Fig.…”

Betulinic acid exerts anti‐hepatitis C virus activity via the suppression of NF‐κB‐ and MAPK‐ERK1/2‐mediated COX‐2 expression

“…Resistance to clinical antiviral therapy has become a major problem in the cure or management of chronic viral infection (Lin et al ., ). Cocktail therapy is a promising strategy to achieve a sustained viral response, such as a combination of inhibitors with IFN‐α and/or the ribavirin, which have a synergistic effect on chronic genotype 1 HCV infection (Saxena and Terrault, ).…”

In Vitro Activity and Resistance Profile of Samatasvir, a Novel NS5A Replication Inhibitor of Hepatitis C Virus

“…NS5A Y93H is an amino acid substitution that has been shown to confer significant resistance to NS5A inhibitors (10,(37)(38)(39)(40), and when introduced into the genotype 1a replicon, this substitution conferred a 4,400-fold shift in activity against samatasvir (Table 10). The emergence of Y93H was examined from RNA samples collected at each cell passage.…”