Potency and Resistance Analysis of Hepatitis C Virus NS5B Polymerase Inhibitor BMS-791325 on All Major Genotypes

Abstract

BMS-791325 is a hepatitis C virus (HCV) inhibitor binding to the thumb domain of the NS5B RNA-dependent RNA polymerase. BMS-791325 is well characterized in genotype 1 (GT1) and exhibits good inhibitory activity (50% effective concentration [EC 50 ], <10 nM) against hybrid replicons containing patient NS5B sequences from GT3a, -4a, and -5a while potency against GT2 is significantly reduced (J. A. Lemm et al., Antimicrob. Agents Chemother. 58:3485-3495, 2014, doi:http://dx.doi.org/10.1128/AAC.02495-13). BMS-791325 potency against GT6a hybrid replicons is more variable, with two of three hybrid clones having EC 50 s similar to that for GT1 while a third patient clone was ϳ10 times less susceptible to BMS-791325. To characterize the resistance profile of BMS-791325 beyond GT1, curing studies were performed across GT1a and -3a to -6a and demonstrated that GT1a has the highest resistance barrier versus BMS-791325 while GT6a has the lowest. Selection of GT3 to -6 NS5B chimeric replicon cells at different concentrations of BMS-791325 revealed substitutions in the thumb domain of NS5B at residues 494 and 495 that conferred different levels of resistance to BMS-791325 but remained susceptible to NS5A or NS3 protease inhibitors. In addition, we demonstrate that the reduced potency of BMS-791325 against one GT6a patient is due to an A494 polymorphism present in ϳ21% of sequences in the European HCV database. The results from this report suggest that BMS-791325 is a candidate for combination treatment of HCV GT3 to -6 chronic infections, and the resistance profiles identified will provide useful information for future clinical development.

Daclatasvir/asunaprevir/beclabuvir, all‐oral, fixed‐dose combination for patients with chronic hepatitis C virus genotype 1

“…Various factors may have contributed to the virologic relapse observed in the two patients infected with GT‐6g. The potency of daclatasvir, asunaprevir, and beclabuvir against GT‐6 subtypes, in in vitro enzymatic assays and in cell‐based assays using patient‐derived viral sequences, is variable and slightly less than reported against GT‐1; however, these differences are not sufficient to explain the lack of response, particularly since two of the four patients with GT‐6g infection did achieve SVR12. Treatment‐emergent substitutions in GT‐6g NS5A and NS3 were observed in both relapsing patients.…”

“…2). The median time from the first grade 3 or 4 elevation to reversal was 22 (range 6-33) days for ALT and 17 (15)(16)(17)(18)(19)(20)(21)(22) days for AST. All eight patients achieved SVR12.…”

“…However, SVR12 was reduced in those GT-1b-infected patients with baseline NS5A RAS at positions L31 or Y93H (SVR12 37-42%). 16 Daclatasvir/asunaprevir/beclabuvir (DCV-TRIO) is a fixed-dose combination consisting of 30 mg daclatasvir, 200 mg asunaprevir, and 75 mg beclabuvir (an allosteric inhibitor of the HCV NS5B polymerase active in vitro against GTs 1, 3, 4, and 5 and with variable activity against GT-6) 17,18 formulated as a single film-coated twice-daily tablet. The inclusion of beclabuvir with daclatasvir and asunaprevir was anticipated to both reduce treatment duration and overcome the potential impact of baseline NS5A RAS on response.…”

Searching for synergy: Identifying optimal antiviral combination therapy using Hepatitis C virus (HCV) agents in a replicon system

“…There are presently four different classes of DAAs including nonstructural protein (NS) 3/4a protease inhibitors, NS5A inhibitors, NS5B nucleoside polymerase inhibitors, and NS5B non-nucleoside polymerase inhibitors. Each class has shown potent activity against genotype 1 HCV in preclinical and clinical studies (Lawitz et al, 2013; Liu et al, 2014; Wyles et al, 2014). …”

Beclabuvir for the treatment of hepatitis C

“…However, no cross-resistance to NS5A or NS3 protease inhibitors was observed. Regarding subtype 6a, it is noteworthy that A494 polymorphism, which confers reduced potency to BCV, is present in 21% of sequences in the European HCV database [74].…”