MULTIPLE MUTATIONS IN DOMAIN II OF NS5A IDENTIFIED IN GENOTYPE 2/3 VITAL-1 STUDY BREAKTHROUGH PATIENTS ARE REQUIRED TO REDUCE SUSCEPTIBILITY TO ALISPORIVIR IN VITRO
MULTILEARNING Academy. Pawlotsky J. 04/25/13; 91424
Already Registered? Request your Direct Access here
REGULAR CONTENT
REGULAR CONTENT
This content is available to all registered users. To register, complete Activity Registration form.
Abstract
Discussion Forum (0)
Rate & Comment (0)
Background: VITAL-1 study assessed safety, tolerability and antiviral activity of cyclophilin inhibitor alisporivir (ALV) as monotherapy or combination with ribavirin (RBV) compared to IFN/RBV and ALV/IFN in treatment-naïve genotype (G)2/3 HCV patients. We describe genotypic and phenotypic changes in patients from this study who experienced a viral breakthrough (VB).
Methods: VITAL-1 study patients on IFN-free regimens that did not achieve RVR (< 25 IU/ml) at week 4 were administered IFN/RBV/600 mg QD ALV starting at week 6 (IFN-add-on). VB was defined as an increase of HCV RNA >1 log10 above nadir. The HCV NS5A gene was analyzed by population sequencing. The entire NS5A region isolated at baseline and at VB was cloned into a JFH1- subgenomic shuttle vector for phenotypic analyses. Selected mutations were engineered into a wild type replicon and their impact on replication fitness and susceptibility to ALV and direct acting antiviral drugs were determined.
Results: The VB rate with IFN-free or IFN-add-on regimens was 2.7% (7/260). Low ALV drug level (Cmin< 20% of group mean; < 100 ng/mL) was observed in 5/7 VB patients. Genotypic analysis of the NS5A gene revealed amino acid changes in these patients at the time of VB compared to baseline. Replicons bearing NS5A from patients at breakthrough conferred 1.2-16.9-fold shift over baseline EC50 values; 5/7 had impaired replication fitness. No cross-resistance to other classes of HCV inhibitors was observed. Most frequently identified mutations were D320E (D316E in G2), R347W and A349V in Domain II of NS5A, which by themselves decreased ALV susceptibility by 5-, 4-, and 8-fold, respectively, in vitro when engineered into wild-type replicon. Combination of multiple mutations decreased susceptibility further, but generally at the cost of replication fitness.
Conclusion: In treatment-naïve G2/3 patients with viral breakthrough, mutations in NS5A domain II were selected, which individually conferred ≤8-fold reduced susceptibility to ALV in vitro. The combination of multiple mutations was required to further reduce susceptibility, which is consistent with the high barrier to resistance for host-targeting ALV. Observed genotypic changes did not confer cross-resistance to other classes of HCV inhibitors, supporting the use of ALV in future drug combination therapies.
Keywords: Alisporivir, resistance, interferon-free
Methods: VITAL-1 study patients on IFN-free regimens that did not achieve RVR (< 25 IU/ml) at week 4 were administered IFN/RBV/600 mg QD ALV starting at week 6 (IFN-add-on). VB was defined as an increase of HCV RNA >1 log10 above nadir. The HCV NS5A gene was analyzed by population sequencing. The entire NS5A region isolated at baseline and at VB was cloned into a JFH1- subgenomic shuttle vector for phenotypic analyses. Selected mutations were engineered into a wild type replicon and their impact on replication fitness and susceptibility to ALV and direct acting antiviral drugs were determined.
Results: The VB rate with IFN-free or IFN-add-on regimens was 2.7% (7/260). Low ALV drug level (Cmin< 20% of group mean; < 100 ng/mL) was observed in 5/7 VB patients. Genotypic analysis of the NS5A gene revealed amino acid changes in these patients at the time of VB compared to baseline. Replicons bearing NS5A from patients at breakthrough conferred 1.2-16.9-fold shift over baseline EC50 values; 5/7 had impaired replication fitness. No cross-resistance to other classes of HCV inhibitors was observed. Most frequently identified mutations were D320E (D316E in G2), R347W and A349V in Domain II of NS5A, which by themselves decreased ALV susceptibility by 5-, 4-, and 8-fold, respectively, in vitro when engineered into wild-type replicon. Combination of multiple mutations decreased susceptibility further, but generally at the cost of replication fitness.
Conclusion: In treatment-naïve G2/3 patients with viral breakthrough, mutations in NS5A domain II were selected, which individually conferred ≤8-fold reduced susceptibility to ALV in vitro. The combination of multiple mutations was required to further reduce susceptibility, which is consistent with the high barrier to resistance for host-targeting ALV. Observed genotypic changes did not confer cross-resistance to other classes of HCV inhibitors, supporting the use of ALV in future drug combination therapies.
Keywords: Alisporivir, resistance, interferon-free
Background: VITAL-1 study assessed safety, tolerability and antiviral activity of cyclophilin inhibitor alisporivir (ALV) as monotherapy or combination with ribavirin (RBV) compared to IFN/RBV and ALV/IFN in treatment-naïve genotype (G)2/3 HCV patients. We describe genotypic and phenotypic changes in patients from this study who experienced a viral breakthrough (VB).
Methods: VITAL-1 study patients on IFN-free regimens that did not achieve RVR (< 25 IU/ml) at week 4 were administered IFN/RBV/600 mg QD ALV starting at week 6 (IFN-add-on). VB was defined as an increase of HCV RNA >1 log10 above nadir. The HCV NS5A gene was analyzed by population sequencing. The entire NS5A region isolated at baseline and at VB was cloned into a JFH1- subgenomic shuttle vector for phenotypic analyses. Selected mutations were engineered into a wild type replicon and their impact on replication fitness and susceptibility to ALV and direct acting antiviral drugs were determined.
Results: The VB rate with IFN-free or IFN-add-on regimens was 2.7% (7/260). Low ALV drug level (Cmin< 20% of group mean; < 100 ng/mL) was observed in 5/7 VB patients. Genotypic analysis of the NS5A gene revealed amino acid changes in these patients at the time of VB compared to baseline. Replicons bearing NS5A from patients at breakthrough conferred 1.2-16.9-fold shift over baseline EC50 values; 5/7 had impaired replication fitness. No cross-resistance to other classes of HCV inhibitors was observed. Most frequently identified mutations were D320E (D316E in G2), R347W and A349V in Domain II of NS5A, which by themselves decreased ALV susceptibility by 5-, 4-, and 8-fold, respectively, in vitro when engineered into wild-type replicon. Combination of multiple mutations decreased susceptibility further, but generally at the cost of replication fitness.
Conclusion: In treatment-naïve G2/3 patients with viral breakthrough, mutations in NS5A domain II were selected, which individually conferred ≤8-fold reduced susceptibility to ALV in vitro. The combination of multiple mutations was required to further reduce susceptibility, which is consistent with the high barrier to resistance for host-targeting ALV. Observed genotypic changes did not confer cross-resistance to other classes of HCV inhibitors, supporting the use of ALV in future drug combination therapies.
Keywords: Alisporivir, resistance, interferon-free
Methods: VITAL-1 study patients on IFN-free regimens that did not achieve RVR (< 25 IU/ml) at week 4 were administered IFN/RBV/600 mg QD ALV starting at week 6 (IFN-add-on). VB was defined as an increase of HCV RNA >1 log10 above nadir. The HCV NS5A gene was analyzed by population sequencing. The entire NS5A region isolated at baseline and at VB was cloned into a JFH1- subgenomic shuttle vector for phenotypic analyses. Selected mutations were engineered into a wild type replicon and their impact on replication fitness and susceptibility to ALV and direct acting antiviral drugs were determined.
Results: The VB rate with IFN-free or IFN-add-on regimens was 2.7% (7/260). Low ALV drug level (Cmin< 20% of group mean; < 100 ng/mL) was observed in 5/7 VB patients. Genotypic analysis of the NS5A gene revealed amino acid changes in these patients at the time of VB compared to baseline. Replicons bearing NS5A from patients at breakthrough conferred 1.2-16.9-fold shift over baseline EC50 values; 5/7 had impaired replication fitness. No cross-resistance to other classes of HCV inhibitors was observed. Most frequently identified mutations were D320E (D316E in G2), R347W and A349V in Domain II of NS5A, which by themselves decreased ALV susceptibility by 5-, 4-, and 8-fold, respectively, in vitro when engineered into wild-type replicon. Combination of multiple mutations decreased susceptibility further, but generally at the cost of replication fitness.
Conclusion: In treatment-naïve G2/3 patients with viral breakthrough, mutations in NS5A domain II were selected, which individually conferred ≤8-fold reduced susceptibility to ALV in vitro. The combination of multiple mutations was required to further reduce susceptibility, which is consistent with the high barrier to resistance for host-targeting ALV. Observed genotypic changes did not confer cross-resistance to other classes of HCV inhibitors, supporting the use of ALV in future drug combination therapies.
Keywords: Alisporivir, resistance, interferon-free
Code of conduct/disclaimer available in General Terms & Conditions
{{ help_message }}
{{filter}}