Chemical genetics strategy identifies an HCV NS5A inhibitor with a potent clinical effect

Abstract

The worldwide prevalence of chronic hepatitis C virus (HCV) infection is estimated to be approaching 200 million people. Current therapy relies upon a combination of pegylated interferon-alpha and ribavirin, a poorly tolerated regimen typically associated with less than 50% sustained virological response rate in those infected with genotype 1 virus. The development of direct-acting antiviral agents to treat HCV has focused predominantly on inhibitors of the viral enzymes NS3 protease and the RNA-dependent RNA polymerase NS5B. Here we describe the profile of BMS-790052, a small molecule inhibitor of the HCV NS5A protein that exhibits picomolar half-maximum effective concentrations (EC(50)) towards replicons expressing a broad range of HCV genotypes and the JFH-1 genotype 2a infectious virus in cell culture. In a phase I clinical trial in patients chronically infected with HCV, administration of a single 100-mg dose of BMS-790052 was associated with a 3.3 log(10) reduction in mean viral load measured 24 h post-dose that was sustained for an additional 120 h in two patients infected with genotype 1b virus. Genotypic analysis of samples taken at baseline, 24 and 144 h post-dose revealed that the major HCV variants observed had substitutions at amino-acid positions identified using the in vitro replicon system. These results provide the first clinical validation of an inhibitor of HCV NS5A, a protein with no known enzymatic function, as an approach to the suppression of virus replication that offers potential as part of a therapeutic regimen based on combinations of HCV inhibitors.

The emergence of NS5B resistance associated substitution S282T after sofosbuvir‐based treatment

“…This suggests that S282T has a poor fitness in the absence of drug pressure, and S282T is therefore unlikely to be detected at measurable frequency in untreated patients. In comparison, baseline NS3, NS5A, and NS5B non‐nucleoside inhibitor (NNI) RASs has been detected in 10%‐90% of DAA‐naïve patients depending on genotype and subtype27, 28, 29, 30, 31; for example, NS5A L31M has been detected in >50% of GT2a patients 32. Due to the high error rate of HCV polymerase, substitutions at all sites in the HCV genome can exist within the viral quasispecies33, 34; however, the lack of S282T compared with other RASs suggests that not all positions in the HCV genome has the same allowance for genetic variability.…”

Genotypic and phenotypic analysis of variants resistant to hepatitis C virus nonstructural protein 5A replication complex inhibitor BMS-790052 in Humans: In Vitro and In Vivo Correlations

“…3 BMS-790052 is a potent HCV NS5A replication complex inhibitor, with 50% effective concentration (EC 50 ) values of 9 and 50 pM against genotype 1b and 1a replicons, respectively. 4,5 It is also potent against live virus (genotype 2a, JFH-1), with an EC 50 of $28 pM. 4 BMS-790052 has broad genotype coverage, with EC 50 values ranging from pM to low nM for replicons with NS5A sequences derived from genotype 2a, 3a, 4a, and 5a.…”

“…4,5 It is also potent against live virus (genotype 2a, JFH-1), with an EC 50 of $28 pM. 4 BMS-790052 has broad genotype coverage, with EC 50 values ranging from pM to low nM for replicons with NS5A sequences derived from genotype 2a, 3a, 4a, and 5a. 4 Proof of concept for BMS-790052 has been achieved clinically, where its exceptional in vitro potency translated to an in vivo effect in a single-ascending dose study.…”

“…4 BMS-790052 has broad genotype coverage, with EC 50 values ranging from pM to low nM for replicons with NS5A sequences derived from genotype 2a, 3a, 4a, and 5a. 4 Proof of concept for BMS-790052 has been achieved clinically, where its exceptional in vitro potency translated to an in vivo effect in a single-ascending dose study. 4 In this study, marked HCV RNA decline ($2.9 log 10 ) was needed for detection of resistant variants, suggesting that the variants were likely present as preexisting minor quasi species and were uncovered by the efficient suppression of wild-type virus.…”

Ribavirin suppresses hepatic lipogenesis through inosine monophosphate dehydrogenase inhibition: Involvement of adenosine monophosphate‐activated protein kinase‐related kinases and retinoid X receptor α

“…To exclude the possibility that inhibitors for HCV RNA replication generally induce the suppression of lipogenic genes, we tested the effects of DCV and SOF, DAAs targeting HCV NS5A and NS5B functions, respectively 23, 24. We examined the effects of two types of each DAA concentration, which have been reported to be equivalent to 50% and 90% inhibition of HCV RNA replication, in full‐length HCV RNA‐replicating OR6‐ADK cells.…”