In Vitro Resistance Profile of the Hepatitis C Virus NS3 Protease Inhibitor BI 201335

Abstract

The in vitro resistance profile of BI 201335 was evaluated through selection and characterization of variants in genotype 1a (GT 1a) and genotype 1b (GT 1b) replicons. NS3 R155K and D168V were the most frequently observed resistant variants. Phenotypic characterization of the mutants revealed shifts in sensitivity specific to BI 201335 that did not alter susceptibility to alpha interferon. In contrast to macrocyclic and covalent protease inhibitors, changes at V36, T54, F43, and Q80 did not confer resistance to BI 201335.T he hepatitis C virus (HCV)-encoded NS3 protease is essential for viral replication and has long been considered an attractive target in drug design efforts (3, 5). NS3 protease inhibitors (PIs) can induce substantial reductions in HCV RNA plasma levels, and several candidates have progressed through clinical development to offer improved treatment options (for a review, see reference 27). Two PIs, boceprevir and telaprevir, were recently approved for use in combination with pegylated interferon (Peg-IFN) and ribavirin (1,6,7,19). The selection of drug-resistant variants is commonly observed in patients experiencing virologic rebound during treatment with PIs (16,[20][21][22]24).BI 201335 is a potent HCV NS3/4A PI (15, 28) currently in phase 3 clinical trials in combination with Peg-IFN and ribavirin as well as phase 2 assessment with other HCV direct acting antivirals in IFN-sparing regimens. BI 201335 exhibited a profound reduction in viral load when administered for 14 days as monotherapy in treatment-naïve patients or for 28 days in combination with Peg-IFN and ribavirin in treatment-experienced patients (16). In these studies, viral breakthrough was observed in most patients on monotherapy, whereas breakthrough was less frequent in patients undergoing combination treatment. Distinct resistant NS3 variants R155K and D168V predominated for genotype 1a and 1b (GT 1a and GT 1b), respectively (8,16).This study was designed to evaluate the genotypic and phenotypic profiles of the resistant variants that emerged during in vitro selection in the presence of BI 201335 in the replicon system and to relate these results to clinical observations. Replicons resistant to BI 201335 were selected in GT 1a H77 and GT 1b CON-1 replicon cell lines in the presence of 2 concentrations (100ϫ and 1,000ϫ drug concentration required to reduce HCV RNA or the luciferase reporter levels by 50% [EC 50 ]) of drug for 3 weeks and G-418 as previously described (9). With the lower concentration of BI 201335, resistant variants encoding NS3 changes at residues 155, 156, and 168 were selected with the GT 1b replicon, with D168G as the predominant variant (55%). R155K was the predominant variant (68%) selected with the GT 1a replicon (Table 1) and is consistent with the predominant variant selected in GT 1a HCV-infected patients (16). At the higher concentration of BI 201335, essentially only D168 variants were selected with D168 A and V as the predominant variants in both genotypes.In order to confirm that the mutations ob...

Antiviral Effect, Safety, and Pharmacokinetics of Five-Day Oral Administration of Deleobuvir (BI 207127), an Investigational Hepatitis C Virus RNA Polymerase Inhibitor, in Patients with Chronic Hepatitis C

“…This finding, coupled with the low fold changes in sensitivity associated with several substitutions that confer resistance to other NS5B polymerase inhibitors, suggests that deleobuvir may have an enhanced barrier to resistance compared with other members of this class. Importantly, RAVs that emerged in this trial were different from those reported with NS3/4A PIs (30,31), reflecting their nonoverlapping resistance profiles. PK assessments demonstrated supraproportional plasma exposure and progressive reductions in clearance with increasing dose of deleobuvir.…”

“…The most common types of event (mild to moderate GI, nervous system, and skin/subcutaneous reactions) have also been reported with PIs (7,10,12,20,30,32,33) and with other NS5B polymerase inhibitors under development (alone or in combination regimens) (34)(35)(36)(37). Baseline and follow-up electrocardiographs revealed no clinically relevant findings.…”

Development of a high-throughput pyrosequencing assay for monitoring temporal evolution and resistance associated variant emergence in the Hepatitis C virus protease coding-region

“…In patient B, the Q80L mutation is detectable via pyrosequencing at low levels pre-Faldeprevir therapy and becomes dominant post-therapy. Interestingly, Q80L mutations do not render replicons resistant to a range of PIs (Lenz et al, 2010) and are not implicated in Faldeprevir resistance in vitro (Lagace et al, 2012) or in vivo (Berger et al, 2013). Our data demonstrate the Q80L mutation is selectively neutral with respect to viral replication and does not confer cross-resistance to Boceprevir or Teleprevir.…”

Baseline Hepatitis C Virus (HCV) NS3 Polymorphisms and Their Impact on Treatment Response in Clinical Studies of the HCV NS3 Protease Inhibitor Faldaprevir

“…Drug sensitivity assays showed that Q80K resulted in mean reductions in simeprevir susceptibility of 9.5-fold and 14.0-fold in genotype 1a and 1b replicon assays, respectively ( Fig. 2) (29). It should be noted that since this variant occurs almost exclusively in HCV genotype 1a clinical isolates, it is more relevant to also assess its impact on in vitro drug susceptibility in a genotype 1a background.…”