Characterization of V36C, a Novel Amino Acid Substitution Conferring Hepatitis C Virus (HCV) Resistance to Telaprevir, a Potent Peptidomimetic Inhibitor of HCV Protease

Abstract

We characterized a novel substitution conferring moderate resistance to telaprevir, a peptidomimetic inhibitor of hepatitis C virus protease. V36C conferred a 4.0-fold increase in the telaprevir 50% inhibitory concentration in an enzyme assay and a 9.5-fold increase in the replicon model. The replication capacity of a replicon harboring V36C was close to that of the wild-type protease. This case emphasizes the complexity of hepatitis C virus resistance to protease inhibitors.Advances in virology have led to the development of novel therapeutics specifically targeting hepatitis C virus (HCV) (4). Telaprevir (VX-950; Vertex Pharmaceuticals Incorporated, Cambridge, MA) is a novel, highly selective, potent peptidomimetic inhibitor of the HCV nonstructural protein 3/4A (NS3/4A) protease (1, 3) which has reached phase III clinical development in combination with pegylated alpha interferon (IFN-␣) and ribavirin. Amino acid substitutions conferring telaprevir resistance have been reported at positions Val 36, Thr 54, Arg 155, and Ala 156 of the NS3 protease (2, 5). In patients treated with telaprevir and pegylated IFN-␣ with and without ribavirin, breakthroughs during treatment and relapses after treatment are characterized by the recurrence of telaprevir-resistant HCV variant replication (1).Here, we characterized a novel, so far unknown, telaprevir resistance substitution at position Val 36 in a 38-year-old treatment-naïve woman with chronic hepatitis C due to HCV genotype 1b infection. The patient was enrolled in PROVE2, a phase II randomized clinical trial assessing the efficacy and safety of telaprevir in combination with pegylated IFN-␣2a with or without ribavirin (1). The patient was treated with telaprevir at 750 mg/8 h, pegylated IFN-␣2a at 180 g/week, and ribavirin at 1.0 g/day. HCV RNA became undetectable (Ͻ10 IU/ml) on therapy, but after 43 days of treatment, the patient withdrew consent and stopped therapy. She continued to be followed up after treatment withdrawal. Figure 1 shows the kinetics of HCV RNA levels in the patient during the 43 days of therapy. HCV RNA was detected 8 weeks after treatment withdrawal, and HCV RNA levels returned to nearly baseline levels. Twenty to 24 full-length NS3 protease clones were sequenced at each HCV RNA-positive time point. The patient was infected with a wild-type, telaprevir sensitive viral population at the baseline (Fig. 1). At the time of posttreatment relapse, the HCV variants all bore a Val-to-Cys substitution at position 36 (V36C). The V36C substitution remained dominant throughout posttreatment followup, up to day 512 after the start of therapy (Fig. 1). This substitution was associated with a Leu-to-Phe substitution at position 14 of the protease (L14F). L14F is present in approximately 6% of all HCV sequences and 8.5% of HCV subtype 1b sequences available in the European HCV database (http: //euhcvdb.ibcp.fr/euHCVdb/). Based on molecular modeling, it is predicted to be located at more than 20 Å of the telaprevir binding site and is therefore unlikely to alter...

Utility of Detection of Telaprevir-Resistant Variants for Prediction of Efficacy of Treatment of Hepatitis C Virus Genotype 1 Infection

“…NS3/4A protease inhibitor-resistant variants included V36A/C/ M/L/G, T54A/S, Q80K/R/H/G/L, R155K/T/I/M/G/L/S/Q, A156V/T/S/I/G, D168A/V/E/G/N/T/Y/H/I, and V170A. Telaprevir-resistant variants (at aa 36, aa 54, aa 155, aa 156, and aa 170) and TMC435-resistant variants (at aa 80, aa 155, and aa 168) were evaluated (19,20).…”

Prediction of Treatment Efficacy and Telaprevir-Resistant Variants after Triple Therapy in Patients Infected with Hepatitis C Virus Genotype 1

“…Furthermore, patients who did not achieve an SVR were analyzed by ultradeep sequencing, at baseline and at the time of reelevation of viral loads. Telaprevir-resistant variants included V36A/C/M/L/G, T54A/S, R155K/T/I/M/G/L/S/Q, A156V/T/S/ I/G, and V170A (22,23).…”

Use of Illumina Deep Sequencing Technology To Differentiate Hepatitis C Virus Variants

“…The first-generation NS3/4A inhibitors are telaprevir and boceprevir, and most of the reported clinical data on drug resistance were obtained from patients treated with telaprevir. As an illustration, based on in vitro studies, telaprevir resistance related to amino acid substitutions V36A/M/C, T54A/S, R155K/T/Q, A155V/T, and A156T has been reported (4,22,37). Substitutions that generated boceprevir resistance included those detected in a patient treated with telaprevir, plus V170A/T and V55A substitutions (13,41).…”