- Email: [email protected]
88 PARTICULAR IN VITRO ANTI-HCV ACTIVITIES AND RESISTANCE PROFILE OF THE CYCLOPHILIN INHIBITOR DEBIO 025
S36
Friday, April 24
Conclusions: SCH 900518 administered alone or in combination with PegIntron was safe and well tolerated. Robust reductions in plasma HCV RNA levels were achieved in both treatment-experienced and naive HCV genotype 1-infected patients. 87 MOLECULAR CHARACTERIZATION OF HCV RESISTANCE TO TELAPREVIR, A NOVEL, POTENT HCV PROTEASE INHIBITOR S. Chevaliez1 , A. Ahmed-Belkacem1 , L. Barbotte1 , A. Soulier1 , D. Bartels2 , Y. Zhou2 , A. Ardzinski2 , N. Mani2 , G. Rao2 , C. Hezode1 , S. George2 , A. Kwong2 , J.-M. Pawlotsky1 . 1 French National Reference Center for Viral Hepatitis B, C and Delta, INSERM U841, Hˆopital Henri Mondor, Universit´e Paris 12, Cr´eteil, France; 2 Vertex Pharmaceuticals, Cambridge, Massachusetts, USA E-mail: [email protected] Telaprevir (VX-950, Vertex Pharmaceuticals) is a potent inhibitor of HCV NS3 serine protease. Resistance to telaprevir monotherapy occurs early as a result of the selection of amino acid substitutions at 4 positions (V36, T54, R155 and/or A156). Objective: To characterize HCV resistance to telaprevir at the molecular level in patients also receiving peginterferon alpha with or without ribavirin. Results: Among 20 patients with HCV genotype 1 infection included in the Phase II PROVE 2 trial, a breakthrough on therapy or post-treatment relapse occurred in 6 patients receiving telaprevir, 750 mg q8 h, and peginterferon alpha-2a, 180 microg qw, without ribavirin, for 12 weeks (3 breakthroughs, all subtype 1a; 3 relapses, 1 subtype 1a) and 2 patients receiving the triple combination of telaprevir, peginterferon alpha-2a and ribavirin for 12 weeks. In all instances, the wild-type virus was replaced by complex mixtures of viral quasispecies variants bearing known telaprevir resistance substitutions at the time of breakthrough/relapse that subsequently deeply fluctuated in their composition. Most of the selected variants bore additional amino acid changes together with the known telaprevir resistanceassociated substitutions. 3D-modeling suggested that none of them affected telaprevir binding to NS3 protease, except maybe T42S and A40T. In a replicon-based phenotypic assay, these additional amino acid changes did not confer a significant change in baseline sensitivity to telaprevir, suggesting that their selection was related to an improvement in fitness for telaprevir-resistant variants. A novel resistance mutation at a known resistance position (V36C) was observed in one patient receiving the triple combination who stopped therapy early. This substitution increased the IC50 by 8.6 fold, while the relative in vitro replication capacity and kinetic parameters were not different from the wild-type V36 variant. Conclusion: Breakthroughs during and relapses after telaprevir administration in combination with peginterferon alpha with or without ribavirin are associated with the selection of complex mixtures of viral variants bearing amino acid substitutions that confer resistance to telaprevir plus additional changes likely conferring improved fitness to the telaprevirresistant variants. 88 PARTICULAR IN VITRO ANTI-HCV ACTIVITIES AND RESISTANCE PROFILE OF THE CYCLOPHILIN INHIBITOR DEBIO 025 L. Coelmont1 , P. Gallay2 , M. Bobardt2 , S. Kaptein1 , J. Paeshuyse1 , I. Vliegen1 , G. Vuagniaux3 , J. Neyts1 . 1 Rega Institute, Leuven, Belgium; 2 The Scripps Research Institute, La Jolla, USA; 3 Debiopharm, Lausanne, Switzerland E-mail: [email protected] Background: Debio 025 (D25) is a potent inhibitor of HCV replication in vitro and in patients [Hepatology 43:761−70; Hepatology 47:817−26]. This study was aimed at better characterising the in vitro anti-HCV properties and resistance profile of the molecule. Methods: Combination with interferon-a (IFN-a), ribavirin or specifically targeted antiviral therapy for HCV (STAT-C) inhibitors, clearance and
rebound, and resistance selection experiments were performed using Huh7 cells containing subgenomic HCV replicons. Results: Combinations of D25 with either IFN-a, ribavirin or STAT-C inhibitors resulted in an additive to slightly synergistic antiviral activity. D25 showed the unique ability to rapidly clear hepatoma cells from their HCV replicon when used alone or at low concentration in combination with IFN-a and STAT-C inhibitors. Development of escape variants against STAT-C inhibitors in colony formation assays was delayed by D25 and the drug proved equipotent against wild-type HCV, as against HCV replicons that are resistant to STAT-C inhibitors. Replicons were selected that are resistant to D25 (3 independent selections) with mutations clustered in the nonstructural 5A gene following long term culture. Re-engineering of these mutations in a WT background only partially recovered resistance. D25 resistant replicons remained fully susceptible to IFN-a and STAT-C inhibitors. Huh Lunet cells were stably transfected with D25res replicon RNA, which resulted in a partial transfer of the resistance indicating that also host cell factors may be involved in the observed resistance in vitro. Such potential candidate host factors were further studied. Conclusions: The particular in vitro anti-HCV activities and unique resistance profile of D25 indicate that the drug forms an attractive drug candidate for the treatment of HCV infections in combination with standard of care and/or STAT-C.
89 SAFETY, PLASMA PHARMACOKINETICS, AND ANTI-VIRAL ACTIVITY OF SCY-635 IN ADULT PATIENTS WITH CHRONIC HEPATITIS C VIRUS INFECTION S. Hopkins1 , D. Heuman2 , E. Gavis2 , J. Lalezari3 , E. Glutzer3 , B. DiMassimo1 , P. Rusnak1 , S. Wring1 , C. Smitley1 , Y. Ribeill1 . 1 Research, Scynexis Inc, Durham, North Carolina, 2 Hepatology, McGuire VA Medical Center, Richmond, Virginia, 3 Clinical Development, Quest Clinical Research, San Francisco, California, USA E-mail: [email protected] Background and Aims: SCY-635 is a non-immunosuppressive analog of cyclosporine A that exhibits potent suppression of HCV RNA replication in vitro. SCY-635 binds to human cyclophilin A at nanomolar concentrations. Exposure of replicon cells to SCY-635 upregulates efflux of cyclophilin A. This phase 1b clinical study was conducted to determine if treatment with SCY-635 monotherapy could suppress HCV-associated plasma RNA. Methods: Enrollment was open to adults with genotype 1 infection and plasma RNA exceeding 100,000 IU/mL. Subjects with evidence of co-infection with HIV-1, HBV, decompensated liver function, or ALT values 2.5 times above the ULN were excluded. Patients were sequentially enrolled into one of three ascending cohorts. Within cohorts patients were randomized to receive SCY-635 or placebo in a 6:1 ratio. Total daily doses were 300, 600 and 900 milligrams. Study medications were given orally in divided doses three times per day for 15 days. Intensive sampling for pharmacokinetic assessments and viral load monitoring was performed throughout the treatment period. Results: Cohorts exhibited similar baseline characteristics. All subjects were male (n = 20); 75% were African American. Average age was 53.0 years. Average HCV RNA at baseline was 5.6×106 IU/mL. 55% of patients were treatment naive. There were no deaths, no Serious Adverse Events and no discontinuations. Adverse events were similar across cohorts. There were no trends in Adverse Events indicative of a Dose Limiting Toxicity. Greater than proportional increases in plasma exposure to SCY-635 were observed with dose. Steady state was achieved on Day 3. In the 900 milligram cohort mean trough plasma concentrations remained above the replicon derived EC90 value from Days 3 through 15. Consistent decreases in plasma RNA were observed only in the 900 milligram cohort. Maximum responses were observed on Days 11 and 15. Group mean and median nadir values were 2.20 and 1.82 log10 below baseline. One subject achieved undetectable RNA levels at Day 15. Conclusions: The demonstration of clinically relevant suppression of plasma RNA in the absence of dose-limiting toxicity establishes Proof of Concept for SCY-635 as a new anti-viral agent for treating individuals with chronic hepatitis C infection.
Friday, April 24
Conclusions: SCH 900518 administered alone or in combination with PegIntron was safe and well tolerated. Robust reductions in plasma HCV RNA levels were achieved in both treatment-experienced and naive HCV genotype 1-infected patients. 87 MOLECULAR CHARACTERIZATION OF HCV RESISTANCE TO TELAPREVIR, A NOVEL, POTENT HCV PROTEASE INHIBITOR S. Chevaliez1 , A. Ahmed-Belkacem1 , L. Barbotte1 , A. Soulier1 , D. Bartels2 , Y. Zhou2 , A. Ardzinski2 , N. Mani2 , G. Rao2 , C. Hezode1 , S. George2 , A. Kwong2 , J.-M. Pawlotsky1 . 1 French National Reference Center for Viral Hepatitis B, C and Delta, INSERM U841, Hˆopital Henri Mondor, Universit´e Paris 12, Cr´eteil, France; 2 Vertex Pharmaceuticals, Cambridge, Massachusetts, USA E-mail: [email protected] Telaprevir (VX-950, Vertex Pharmaceuticals) is a potent inhibitor of HCV NS3 serine protease. Resistance to telaprevir monotherapy occurs early as a result of the selection of amino acid substitutions at 4 positions (V36, T54, R155 and/or A156). Objective: To characterize HCV resistance to telaprevir at the molecular level in patients also receiving peginterferon alpha with or without ribavirin. Results: Among 20 patients with HCV genotype 1 infection included in the Phase II PROVE 2 trial, a breakthrough on therapy or post-treatment relapse occurred in 6 patients receiving telaprevir, 750 mg q8 h, and peginterferon alpha-2a, 180 microg qw, without ribavirin, for 12 weeks (3 breakthroughs, all subtype 1a; 3 relapses, 1 subtype 1a) and 2 patients receiving the triple combination of telaprevir, peginterferon alpha-2a and ribavirin for 12 weeks. In all instances, the wild-type virus was replaced by complex mixtures of viral quasispecies variants bearing known telaprevir resistance substitutions at the time of breakthrough/relapse that subsequently deeply fluctuated in their composition. Most of the selected variants bore additional amino acid changes together with the known telaprevir resistanceassociated substitutions. 3D-modeling suggested that none of them affected telaprevir binding to NS3 protease, except maybe T42S and A40T. In a replicon-based phenotypic assay, these additional amino acid changes did not confer a significant change in baseline sensitivity to telaprevir, suggesting that their selection was related to an improvement in fitness for telaprevir-resistant variants. A novel resistance mutation at a known resistance position (V36C) was observed in one patient receiving the triple combination who stopped therapy early. This substitution increased the IC50 by 8.6 fold, while the relative in vitro replication capacity and kinetic parameters were not different from the wild-type V36 variant. Conclusion: Breakthroughs during and relapses after telaprevir administration in combination with peginterferon alpha with or without ribavirin are associated with the selection of complex mixtures of viral variants bearing amino acid substitutions that confer resistance to telaprevir plus additional changes likely conferring improved fitness to the telaprevirresistant variants. 88 PARTICULAR IN VITRO ANTI-HCV ACTIVITIES AND RESISTANCE PROFILE OF THE CYCLOPHILIN INHIBITOR DEBIO 025 L. Coelmont1 , P. Gallay2 , M. Bobardt2 , S. Kaptein1 , J. Paeshuyse1 , I. Vliegen1 , G. Vuagniaux3 , J. Neyts1 . 1 Rega Institute, Leuven, Belgium; 2 The Scripps Research Institute, La Jolla, USA; 3 Debiopharm, Lausanne, Switzerland E-mail: [email protected] Background: Debio 025 (D25) is a potent inhibitor of HCV replication in vitro and in patients [Hepatology 43:761−70; Hepatology 47:817−26]. This study was aimed at better characterising the in vitro anti-HCV properties and resistance profile of the molecule. Methods: Combination with interferon-a (IFN-a), ribavirin or specifically targeted antiviral therapy for HCV (STAT-C) inhibitors, clearance and
rebound, and resistance selection experiments were performed using Huh7 cells containing subgenomic HCV replicons. Results: Combinations of D25 with either IFN-a, ribavirin or STAT-C inhibitors resulted in an additive to slightly synergistic antiviral activity. D25 showed the unique ability to rapidly clear hepatoma cells from their HCV replicon when used alone or at low concentration in combination with IFN-a and STAT-C inhibitors. Development of escape variants against STAT-C inhibitors in colony formation assays was delayed by D25 and the drug proved equipotent against wild-type HCV, as against HCV replicons that are resistant to STAT-C inhibitors. Replicons were selected that are resistant to D25 (3 independent selections) with mutations clustered in the nonstructural 5A gene following long term culture. Re-engineering of these mutations in a WT background only partially recovered resistance. D25 resistant replicons remained fully susceptible to IFN-a and STAT-C inhibitors. Huh Lunet cells were stably transfected with D25res replicon RNA, which resulted in a partial transfer of the resistance indicating that also host cell factors may be involved in the observed resistance in vitro. Such potential candidate host factors were further studied. Conclusions: The particular in vitro anti-HCV activities and unique resistance profile of D25 indicate that the drug forms an attractive drug candidate for the treatment of HCV infections in combination with standard of care and/or STAT-C.
89 SAFETY, PLASMA PHARMACOKINETICS, AND ANTI-VIRAL ACTIVITY OF SCY-635 IN ADULT PATIENTS WITH CHRONIC HEPATITIS C VIRUS INFECTION S. Hopkins1 , D. Heuman2 , E. Gavis2 , J. Lalezari3 , E. Glutzer3 , B. DiMassimo1 , P. Rusnak1 , S. Wring1 , C. Smitley1 , Y. Ribeill1 . 1 Research, Scynexis Inc, Durham, North Carolina, 2 Hepatology, McGuire VA Medical Center, Richmond, Virginia, 3 Clinical Development, Quest Clinical Research, San Francisco, California, USA E-mail: [email protected] Background and Aims: SCY-635 is a non-immunosuppressive analog of cyclosporine A that exhibits potent suppression of HCV RNA replication in vitro. SCY-635 binds to human cyclophilin A at nanomolar concentrations. Exposure of replicon cells to SCY-635 upregulates efflux of cyclophilin A. This phase 1b clinical study was conducted to determine if treatment with SCY-635 monotherapy could suppress HCV-associated plasma RNA. Methods: Enrollment was open to adults with genotype 1 infection and plasma RNA exceeding 100,000 IU/mL. Subjects with evidence of co-infection with HIV-1, HBV, decompensated liver function, or ALT values 2.5 times above the ULN were excluded. Patients were sequentially enrolled into one of three ascending cohorts. Within cohorts patients were randomized to receive SCY-635 or placebo in a 6:1 ratio. Total daily doses were 300, 600 and 900 milligrams. Study medications were given orally in divided doses three times per day for 15 days. Intensive sampling for pharmacokinetic assessments and viral load monitoring was performed throughout the treatment period. Results: Cohorts exhibited similar baseline characteristics. All subjects were male (n = 20); 75% were African American. Average age was 53.0 years. Average HCV RNA at baseline was 5.6×106 IU/mL. 55% of patients were treatment naive. There were no deaths, no Serious Adverse Events and no discontinuations. Adverse events were similar across cohorts. There were no trends in Adverse Events indicative of a Dose Limiting Toxicity. Greater than proportional increases in plasma exposure to SCY-635 were observed with dose. Steady state was achieved on Day 3. In the 900 milligram cohort mean trough plasma concentrations remained above the replicon derived EC90 value from Days 3 through 15. Consistent decreases in plasma RNA were observed only in the 900 milligram cohort. Maximum responses were observed on Days 11 and 15. Group mean and median nadir values were 2.20 and 1.82 log10 below baseline. One subject achieved undetectable RNA levels at Day 15. Conclusions: The demonstration of clinically relevant suppression of plasma RNA in the absence of dose-limiting toxicity establishes Proof of Concept for SCY-635 as a new anti-viral agent for treating individuals with chronic hepatitis C infection.