- Email: [email protected]
PHARMACODYNAMIC PARAMETERS FOR THE NOVEL HCV POLYMERASE INHIBITOR A-848837
S234
POSTERS
16181 OPTIMAL PRETREATMENT VIRAL LOAD CUT-OFF TO PREDICT TREATMENT OUTCOME IN PATIENTS WITH CHRONIC HEPATITIS C TREATED WITH PEGINTERFERON a-2b PLUS RlBAVlRlN M. Martinot-Peignoux’, M.P. Ripault2, S . Maylin’, N. Boye?, N. Giuily2, C. Castelnau2, T. Asselah2, M. Marcellin’,2. ’INSERM, 1J-773, Centre de Recherche Biom4dicule Bi(.hat-Beaujon CRB3 Hipital Beaujon, Clichy; ’Seroice d’H&putologie, H6pital Beaujon, Clichy, France E-mail: [email protected] Viral load (VL) is an important predictor for treatment outcome in patients with chronic hepatitis C. A HCV-RNA cut-off of 800,000 IU/ml was used to define high and low pre-treatment VL in standard-interferon based therapy. Recently, Zeuzem et al. (AASLD 2006) proposed 400,000 lUiml (assessed with the COBAS TaQMan HCV assay) as optimal cu t - o f t o best discriminate low and high VL, based on the probability to achieve SVR in patients treated with peginterferon (PEG-IFN) alpha 2a+ribavirin (RBV). Our study aimed to analyze the predictive value of this cut-off in patients treated with PEG-IFN alpha 2b+RBV Patients and Methods: 3 I2 patients ( I 77 naives; I35 non-naives) consecutively treated with PEG-IFN alpha-2b+RBV, were included in this study. Patients with genotypes 1, 4 or 5 or non-responders were treated 48 weeks; naive patients infected with genotypes 2 and 3 were treated 24 weeks. Serum HCVRNA was measured using VERSANT HCV-RNA 3.0 (bDNA) (Bayer diagnostics). Results: In naive patients SVR rate was 54% (G 1: 43%; G 2-3: 72%; G 4: 48%). SVR in patients with VL (lU/ml) <400,000 vs >400,000, <600,000 vs >600,000 and <800,000 vs >800,000,respectively, was: all naive patients: 73% vs 43%; 64% vs 44% and 60% vs 45%; genotype 1: 63% vs 37%; 55% vs 36% and 51% vs 38%; genotype 2-3: 86% vs 63%; 79% vs 66% and 77% vs 66% SVR rates were similar for all the three cut-offs in patients with high VL. In the 135 non-naive patients SVR rate was 38% (G I : 3 I%; G 2-3: 72%). SVR in patients with VL (IU/ml) <400,000 vs >400,000, <600,000 vs >600,000 and <800,000 vs > 800,000, respectively, was: 40% vs 37%; 41% vs 36% and 43% vs 35%. Conclusions: Similarly to PEG-IFN alpha-2a+RBV therapy, the optimal pretreatment VL cut-off(assessed with VERSANT HCV-RNA 3.0 (bDNA) for the best prediction of treatment outcome is 400,000 IU/ml, in naive patients (mainly genotype 1) treated with PEG-IFN alpha-2b+RBV This cut-off is not efficient for non-naive patients.
1200mg/day for 48 weeks. Patients were assessed by HPLC for ribavirin plasma concentration at W4 of combination therapy. Sustained virological response (SVR) was classically defined as undetectable HCV-RNA 6 months after treatment. Results: Among 22 patients, 10 (46%) achieved SVR whereas 12 were non-responders. The median ribavirin plasma concentration at W4 (1.74 mgimL) varied from 1.57mg/mL in non-responders to 2.32 mgimL in sustained responders (p = 0.04). A ROC curve analysis indicated that the threshold of 1.89 mgimL gave the best sensitivityispecificity ratio with a sensitivity of 70% and a specificity of 75% (AUC=0.76; p=0.038). 70% of patients with a ribavirin plasma concentration above 1.89mg/ml at W4 subsequently achieved SVR versus only 25% among patients below 1.89 mg/ml. When the ribavirin threshold was increased to 2 mg/mL, SVR rates were 86% and 27%, respectively (p = 0.02). All patients above 2.70 mgimL subsequently achieved SVR. Conclusions: This study does indicate that ribavirin plasma concentration at week 4 can be predictive oftreatment response with significantly higher levels in sustained virological responders. The SVR rate among patients reaching a concentration higher than 2mgimL at W4 increased by 60% compared with patients below this threshold which confirms the relevance of plasma ribavirin levels for monitoring therapy. A threshold between 2 and 3mgimL could therefore be proposed as target concentration for ribavirin dose adjustment after week 4 in future prospective trials warranted to further confirm this proof concept.
16201 CHARACTERIZATION OF PHARMACOKlNETlCl PHARMACODYNAMIC PARAMETERS FOR THE NOVEL HCV POLYMERASE INHIBITOR A-848837
-
16191 PREDICTION OF SUSTAINED VIROLOGICAL RESPONSE BY RlBAVlRlN PLASMA CONCENTRATION AT WEEK 4 DURING PEGYLATED-INTERFERONlRlBAVlRlN COMBINATION THERAPY IN HCV PATIENTS M. Maynard’, M.C. Gagnieu2, P. Pradat’, C. Souvignet’, C. Trepo’. ‘Department of hepatogustroentrrolog~~, Hfitel-Dieu, Lyon; 2Depurtment of hiochemistry, Hipitul Edouurd-Herriot, Lyon, France E-mail: marianne.maynard-muetejchu-lyon.fr
Background and Aim: Combination therapy with ribavirin and pegylated interferon is currently the standard treatment for chronic hepatitis C virus (HCV) infection. Approved body weight ribavirin adjusted dose (800 to 1200 mgiday) is recommended. However, previous pharmacokinetics studies have shown that there was no relation between ribavirin ingested dose and plasma concentration which is critical for response. Previous personal data suggested that ribavirin plasma concentration at week 4 under therapy could be predictive of early virological clearance at week 12. The aim of this pilot study was therefore to define the target steady state plasma ribavirin concentration at week 4 associated with sustained virological response. Methods: 22 patients with genotype 1 HCV infection were treated with pegylated interferon 1.5 Liglkgiweek and ribavirin at a dose of 800-
A. Molla’, R. Wagner’, L. Lu’, D. He’, C.-M. Chen’, G. Koev’, S. Masse’, Y. Cai’, C. Klein’, D. Beno’, L. Hernandez’, P. Krishnan’, R. Pithawalla’ , T. Pilot-Matias’ , T. Middleton’, R. Lanford2, W. Kati’ , D. Kempf‘ . ‘Antiuirul Research, Glohul Phurmaceuticul Research and Deoelopntent, Abhott Laboratories, Ahbott Park, IL; ’Depurtntent of‘ virology and Intminology, Southwest Foundation ,fbr Biomedical Research (SFBR), Sun Antonio, TX, USA E-mail: [email protected]
Background: A series of potent thiadiazine inhibitors of the HCV NS5B polymerase discovered at Abbott have demonstrated excellent pharmacokinetics and anti-HCV activity in vivo. To understand pharmacokineticipharmacodynamic (PWPD) relationships and the development of resistance for this series, the lead compound A-848837 was studied in an HCV-infected chimpanzee. Methods: Antiviral activity and in vitro selection were performed in HCV replicon cells. A genotype la-infected chimpanzee was dosed orally from 1 mg to 700mg BID in a scheme with dose escalation every 2 days for 10 days. Samples were periodically withdrawn to determine viral load, resistance and drug levels. Viral kinetics was simulated and in vivo EC50s and resulting viral load declines were assessed using the equations of Neumann [l]. Results: A-848837 was a selective inhibitor of HCV genotype 1 polymerases with EC50 values in the presence of 40% human serum were 28 and 62 nM against genotype l b and l a replicons, respectively. Following in vitro selection, replicon colonies were isolated which contained 1-3 mutations in the NS5B gene and were approximately 33- to ~800fold resistant to A-848837. Combination treatment of replicon cells with A-848837 and HCV protease inhibitor SCH 503034 reduced RNA to an undetectable level, “curing” the replicon. In the HCV-infected chimpanzee, plasma HCVRNA remained relatively constant with dosing from I to 20 mg then declined significantly after escalation to 100 mg BID (measured trough concentration 0.28 mM). The liver to plasma drug concentration ratio was approximately 10: 1, PK/PD analysis estimated an in vivo EC50 of 0.13 to 0.38 mM in plasma. Sequence analysis revealed C316Y/F, Y448C/H or G554D mutations in NSSB polymerase gene.
05G. VIRAL HEPATITIS
-
G) HEPATITIS C
-
CLINICAL (THERAPZ NEW COMPOUNDS, RESISTANCE)
Conclusion: Benzothiadiazine polymerase inhibitors are efficacious in the HCV-infected chimpanzee model. An escalating-dose protocol in chimpanzees can be used to estimate in vivo EC50 and may be more predictive of human efficacy than the replicon EC50. The outgrowth of resistant viruses in the HCV 1a-infected chimpanzee suggests that this compound would likely need to be used in combination with a different inhibitor class. References [I] Neumann et al.. Science 282, 103-107, 1998
16211 THE USE OF GROWTH FACTORS (GF) IN THE RE-TREATMENT OF PATIENTS WITH CHRONIC HEPATITIS C (CHC) WHO ARE PREVIOUS NON RESPONDERS (NR) TO COMBINATION THERAPY F. Nader’, C. Bail, K. Terra’, C. Gurung’, M. Srishord’, Y. Fang’. R. Collantes’ , S. Makay’, J.P. Ong’ , R. Sjogren’, Z.M. Younossi’ . Center ,fi,r Liuer Diseuses, lnouu FuirfiuI Hospitul, Annundule, VA; ’Kuiser Perntunente Medical Group, Fulls Church, VA, USA E-mail: [email protected] Treatment of CHC patients, NR to previous therapy, is associated with low sustained virologic response (SVR). One reason may be dose reductions due to cytopenias. Management of cytopenias with GF [Darbepoetin Alfa (DA) and Filgrastim (FL)] can provide hematological support in maintaining the optimal dose. Methods: In a multi-center study, CHC patients were treated with Pegylated Interferon a-2b (1.5 mcgikglwk) and RBV (800-1400 mgid). Patients who developed anemia [Hemoglobin (Hgb)
16221 LACK R1479, A NOVEL HEPATITIS C POLYMERASE INHIBITOR: OF PRE-EXISTING RESISTANCE MUTATION SUPPORTS THE OBSERVED IN VlVO HIGH BARRIER TO RESISTANCE
S. Le Pogam, A. Kosaka, S. Hu, H. Kang, A. Seshaadri, J. Symons, K. Klumpp, N. Cammack, I. Naiera. Roche Pulo Alto LLC, Pulo Alto, CA, 7JSA E-mail: [email protected] Introduction: R1479 (4’-Azido-Cytidine) is the parent compound of prodrug R1626, which has shown a maximum mean (median) HCV RNA
S235
reduction of3.7 (4.1) loglo at 4500mg, bid dose. Given the HCV genetic heterogeneity, in principle selection of drug resistance could be facilitated by the presence of major or minority HCV variants within the viral population, which carry amino acid mutations associated with reduced drug susceptibility. Methods: To understand whether the inhibitory activity of R1479 is affected by HCV genetic heterogeneity, we determined the sensitivity to R1479 of subgenomic HCV replicons encoding the NS5B from 64 treatment naive HCV clinical isolates. Sensitivity to two non nucleoside polymerase inhibitors (a benzothiadiazine derivative and a thiophene2-carboxylic acid derivative) was also determined. To determine the frequency of mutations associated with resistance to R1479 and to non nucleoside inhibitors within the HCV quasispecies from treatment naive patients, clonal sequence analysis was performed on multiple clinical isolates and ~ 8 0 0individual full length HCV NS5B sequences were generated. Results: R1479 was similarly active against all 64 genetically diverse clinical isolates whereas the non nucleoside analogs showed variable inhibitory activity. Consensus sequence determination for the 64 clinical isolates showed the presence of non nucleoside-resistance mutations in several isolates, but not the previously identified R 1479-resistance mutation (S96T). Furthermore, clonal analysis of multiple isolates showed the presence of minority variants bearing resistance mutations to non nucleoside inhibitors, but not to R1479. Conclusions: The higher frequency of non-nucleoside inhibitor resistance mutations as compared to the absence of resistance mutations to the nucleoside analog R I479 in the HCV quasispecies of treatment naive HCV patients suggests a potential for faster development of clinically significant resistance for non nucleoside therapies. These findings are consistent with the lack of resistance observed in HCV infected subjects upon 14 day treatment with R1626.
16231 THE GNB3 C825T POLYMORPHISM AFFECTS RESPONSE TO HCV THERAPY WITH PEGYLATED INTERFERON IN HCV/HIV CO-INFECTED BUT NOT IN HCV MONO-INFECTED PATIENTS
J. Nattermann’, K. Bueren’ , HD. Nischalke’, G. Ahlenstiel’, T. Berg’, M. Biermer’, T. Sauerbruch’, M. Vogel’, JK. Rockstroh’, U. Spengler’ . ‘Department of’ Internal Medicine L Unioersity of Bonn, Bonn; ’Medizinische Klinik mit Schwerpnkt Heptologie und GLEstr-oenterologie, UniurrsitLEetsklinik~imChurit4, Cumpi+ VirchowKlinikum, Uniuer~~itutsmedizin Berlin, Berlin, Germuny E-mail: [email protected] Background: Response to HCV treatment with pegylated interferon-a is variable but might at least in part depend on genetic host factors. The G protein b3 unit (GNB3) C825T polymorphism has been shown to affect treatment response in HCV mono-infection. Here, we analyzed the impact of the GNB3 genotype in the context of HCV/HIV co-infection. Methods: HlViHCV co-infected ( n = 112) and HCV mono-infected patients (n = 150), receiving therapy with pegylated lFN-a/ribavirin were enrolled into this study. Furthermore, we analyzed 220 healthy and 98 HIV mono-infected patients. GNB3 genotype was defined and correlated with respect to treatment response. Results: GNB3 genotype distribution differed significantly between HIV/HCV co-infected patients and HIV-positive/HCV-negative (p=0.0002) or healthy controls (p=0.03). In HCV genotype 1 monoinfected patients ETR and SVR were achieved in 69% and 47%, respectively. In HIViHCV co-infected patients ETR was observed in 76.8% and SVR in 63.8% of the treated patients, with markedly lower response rates in patients with a HCV genotypes 1 or 4 infection as compared to subjects infected with genotypes 2 or 3 (ETR: 72% vs. 90%; SVR: 58% vs. 79%). HIViHCV co-infected patients with a GNB3 CC genotype had significantly lower SVR rates as compared to carriers of a non-CC genotype (52% vs. 77%; p = 0.018). In a logistic regression analysis the GNB3 genotype and
POSTERS
16181 OPTIMAL PRETREATMENT VIRAL LOAD CUT-OFF TO PREDICT TREATMENT OUTCOME IN PATIENTS WITH CHRONIC HEPATITIS C TREATED WITH PEGINTERFERON a-2b PLUS RlBAVlRlN M. Martinot-Peignoux’, M.P. Ripault2, S . Maylin’, N. Boye?, N. Giuily2, C. Castelnau2, T. Asselah2, M. Marcellin’,2. ’INSERM, 1J-773, Centre de Recherche Biom4dicule Bi(.hat-Beaujon CRB3 Hipital Beaujon, Clichy; ’Seroice d’H&putologie, H6pital Beaujon, Clichy, France E-mail: [email protected] Viral load (VL) is an important predictor for treatment outcome in patients with chronic hepatitis C. A HCV-RNA cut-off of 800,000 IU/ml was used to define high and low pre-treatment VL in standard-interferon based therapy. Recently, Zeuzem et al. (AASLD 2006) proposed 400,000 lUiml (assessed with the COBAS TaQMan HCV assay) as optimal cu t - o f t o best discriminate low and high VL, based on the probability to achieve SVR in patients treated with peginterferon (PEG-IFN) alpha 2a+ribavirin (RBV). Our study aimed to analyze the predictive value of this cut-off in patients treated with PEG-IFN alpha 2b+RBV Patients and Methods: 3 I2 patients ( I 77 naives; I35 non-naives) consecutively treated with PEG-IFN alpha-2b+RBV, were included in this study. Patients with genotypes 1, 4 or 5 or non-responders were treated 48 weeks; naive patients infected with genotypes 2 and 3 were treated 24 weeks. Serum HCVRNA was measured using VERSANT HCV-RNA 3.0 (bDNA) (Bayer diagnostics). Results: In naive patients SVR rate was 54% (G 1: 43%; G 2-3: 72%; G 4: 48%). SVR in patients with VL (lU/ml) <400,000 vs >400,000, <600,000 vs >600,000 and <800,000 vs >800,000,respectively, was: all naive patients: 73% vs 43%; 64% vs 44% and 60% vs 45%; genotype 1: 63% vs 37%; 55% vs 36% and 51% vs 38%; genotype 2-3: 86% vs 63%; 79% vs 66% and 77% vs 66% SVR rates were similar for all the three cut-offs in patients with high VL. In the 135 non-naive patients SVR rate was 38% (G I : 3 I%; G 2-3: 72%). SVR in patients with VL (IU/ml) <400,000 vs >400,000, <600,000 vs >600,000 and <800,000 vs > 800,000, respectively, was: 40% vs 37%; 41% vs 36% and 43% vs 35%. Conclusions: Similarly to PEG-IFN alpha-2a+RBV therapy, the optimal pretreatment VL cut-off(assessed with VERSANT HCV-RNA 3.0 (bDNA) for the best prediction of treatment outcome is 400,000 IU/ml, in naive patients (mainly genotype 1) treated with PEG-IFN alpha-2b+RBV This cut-off is not efficient for non-naive patients.
1200mg/day for 48 weeks. Patients were assessed by HPLC for ribavirin plasma concentration at W4 of combination therapy. Sustained virological response (SVR) was classically defined as undetectable HCV-RNA 6 months after treatment. Results: Among 22 patients, 10 (46%) achieved SVR whereas 12 were non-responders. The median ribavirin plasma concentration at W4 (1.74 mgimL) varied from 1.57mg/mL in non-responders to 2.32 mgimL in sustained responders (p = 0.04). A ROC curve analysis indicated that the threshold of 1.89 mgimL gave the best sensitivityispecificity ratio with a sensitivity of 70% and a specificity of 75% (AUC=0.76; p=0.038). 70% of patients with a ribavirin plasma concentration above 1.89mg/ml at W4 subsequently achieved SVR versus only 25% among patients below 1.89 mg/ml. When the ribavirin threshold was increased to 2 mg/mL, SVR rates were 86% and 27%, respectively (p = 0.02). All patients above 2.70 mgimL subsequently achieved SVR. Conclusions: This study does indicate that ribavirin plasma concentration at week 4 can be predictive oftreatment response with significantly higher levels in sustained virological responders. The SVR rate among patients reaching a concentration higher than 2mgimL at W4 increased by 60% compared with patients below this threshold which confirms the relevance of plasma ribavirin levels for monitoring therapy. A threshold between 2 and 3mgimL could therefore be proposed as target concentration for ribavirin dose adjustment after week 4 in future prospective trials warranted to further confirm this proof concept.
16201 CHARACTERIZATION OF PHARMACOKlNETlCl PHARMACODYNAMIC PARAMETERS FOR THE NOVEL HCV POLYMERASE INHIBITOR A-848837
-
16191 PREDICTION OF SUSTAINED VIROLOGICAL RESPONSE BY RlBAVlRlN PLASMA CONCENTRATION AT WEEK 4 DURING PEGYLATED-INTERFERONlRlBAVlRlN COMBINATION THERAPY IN HCV PATIENTS M. Maynard’, M.C. Gagnieu2, P. Pradat’, C. Souvignet’, C. Trepo’. ‘Department of hepatogustroentrrolog~~, Hfitel-Dieu, Lyon; 2Depurtment of hiochemistry, Hipitul Edouurd-Herriot, Lyon, France E-mail: marianne.maynard-muetejchu-lyon.fr
Background and Aim: Combination therapy with ribavirin and pegylated interferon is currently the standard treatment for chronic hepatitis C virus (HCV) infection. Approved body weight ribavirin adjusted dose (800 to 1200 mgiday) is recommended. However, previous pharmacokinetics studies have shown that there was no relation between ribavirin ingested dose and plasma concentration which is critical for response. Previous personal data suggested that ribavirin plasma concentration at week 4 under therapy could be predictive of early virological clearance at week 12. The aim of this pilot study was therefore to define the target steady state plasma ribavirin concentration at week 4 associated with sustained virological response. Methods: 22 patients with genotype 1 HCV infection were treated with pegylated interferon 1.5 Liglkgiweek and ribavirin at a dose of 800-
A. Molla’, R. Wagner’, L. Lu’, D. He’, C.-M. Chen’, G. Koev’, S. Masse’, Y. Cai’, C. Klein’, D. Beno’, L. Hernandez’, P. Krishnan’, R. Pithawalla’ , T. Pilot-Matias’ , T. Middleton’, R. Lanford2, W. Kati’ , D. Kempf‘ . ‘Antiuirul Research, Glohul Phurmaceuticul Research and Deoelopntent, Abhott Laboratories, Ahbott Park, IL; ’Depurtntent of‘ virology and Intminology, Southwest Foundation ,fbr Biomedical Research (SFBR), Sun Antonio, TX, USA E-mail: [email protected]
Background: A series of potent thiadiazine inhibitors of the HCV NS5B polymerase discovered at Abbott have demonstrated excellent pharmacokinetics and anti-HCV activity in vivo. To understand pharmacokineticipharmacodynamic (PWPD) relationships and the development of resistance for this series, the lead compound A-848837 was studied in an HCV-infected chimpanzee. Methods: Antiviral activity and in vitro selection were performed in HCV replicon cells. A genotype la-infected chimpanzee was dosed orally from 1 mg to 700mg BID in a scheme with dose escalation every 2 days for 10 days. Samples were periodically withdrawn to determine viral load, resistance and drug levels. Viral kinetics was simulated and in vivo EC50s and resulting viral load declines were assessed using the equations of Neumann [l]. Results: A-848837 was a selective inhibitor of HCV genotype 1 polymerases with EC50 values in the presence of 40% human serum were 28 and 62 nM against genotype l b and l a replicons, respectively. Following in vitro selection, replicon colonies were isolated which contained 1-3 mutations in the NS5B gene and were approximately 33- to ~800fold resistant to A-848837. Combination treatment of replicon cells with A-848837 and HCV protease inhibitor SCH 503034 reduced RNA to an undetectable level, “curing” the replicon. In the HCV-infected chimpanzee, plasma HCVRNA remained relatively constant with dosing from I to 20 mg then declined significantly after escalation to 100 mg BID (measured trough concentration 0.28 mM). The liver to plasma drug concentration ratio was approximately 10: 1, PK/PD analysis estimated an in vivo EC50 of 0.13 to 0.38 mM in plasma. Sequence analysis revealed C316Y/F, Y448C/H or G554D mutations in NSSB polymerase gene.
05G. VIRAL HEPATITIS
-
G) HEPATITIS C
-
CLINICAL (THERAPZ NEW COMPOUNDS, RESISTANCE)
Conclusion: Benzothiadiazine polymerase inhibitors are efficacious in the HCV-infected chimpanzee model. An escalating-dose protocol in chimpanzees can be used to estimate in vivo EC50 and may be more predictive of human efficacy than the replicon EC50. The outgrowth of resistant viruses in the HCV 1a-infected chimpanzee suggests that this compound would likely need to be used in combination with a different inhibitor class. References [I] Neumann et al.. Science 282, 103-107, 1998
16211 THE USE OF GROWTH FACTORS (GF) IN THE RE-TREATMENT OF PATIENTS WITH CHRONIC HEPATITIS C (CHC) WHO ARE PREVIOUS NON RESPONDERS (NR) TO COMBINATION THERAPY F. Nader’, C. Bail, K. Terra’, C. Gurung’, M. Srishord’, Y. Fang’. R. Collantes’ , S. Makay’, J.P. Ong’ , R. Sjogren’, Z.M. Younossi’ . Center ,fi,r Liuer Diseuses, lnouu FuirfiuI Hospitul, Annundule, VA; ’Kuiser Perntunente Medical Group, Fulls Church, VA, USA E-mail: [email protected] Treatment of CHC patients, NR to previous therapy, is associated with low sustained virologic response (SVR). One reason may be dose reductions due to cytopenias. Management of cytopenias with GF [Darbepoetin Alfa (DA) and Filgrastim (FL)] can provide hematological support in maintaining the optimal dose. Methods: In a multi-center study, CHC patients were treated with Pegylated Interferon a-2b (1.5 mcgikglwk) and RBV (800-1400 mgid). Patients who developed anemia [Hemoglobin (Hgb)
16221 LACK R1479, A NOVEL HEPATITIS C POLYMERASE INHIBITOR: OF PRE-EXISTING RESISTANCE MUTATION SUPPORTS THE OBSERVED IN VlVO HIGH BARRIER TO RESISTANCE
S. Le Pogam, A. Kosaka, S. Hu, H. Kang, A. Seshaadri, J. Symons, K. Klumpp, N. Cammack, I. Naiera. Roche Pulo Alto LLC, Pulo Alto, CA, 7JSA E-mail: [email protected] Introduction: R1479 (4’-Azido-Cytidine) is the parent compound of prodrug R1626, which has shown a maximum mean (median) HCV RNA
S235
reduction of3.7 (4.1) loglo at 4500mg, bid dose. Given the HCV genetic heterogeneity, in principle selection of drug resistance could be facilitated by the presence of major or minority HCV variants within the viral population, which carry amino acid mutations associated with reduced drug susceptibility. Methods: To understand whether the inhibitory activity of R1479 is affected by HCV genetic heterogeneity, we determined the sensitivity to R1479 of subgenomic HCV replicons encoding the NS5B from 64 treatment naive HCV clinical isolates. Sensitivity to two non nucleoside polymerase inhibitors (a benzothiadiazine derivative and a thiophene2-carboxylic acid derivative) was also determined. To determine the frequency of mutations associated with resistance to R1479 and to non nucleoside inhibitors within the HCV quasispecies from treatment naive patients, clonal sequence analysis was performed on multiple clinical isolates and ~ 8 0 0individual full length HCV NS5B sequences were generated. Results: R1479 was similarly active against all 64 genetically diverse clinical isolates whereas the non nucleoside analogs showed variable inhibitory activity. Consensus sequence determination for the 64 clinical isolates showed the presence of non nucleoside-resistance mutations in several isolates, but not the previously identified R 1479-resistance mutation (S96T). Furthermore, clonal analysis of multiple isolates showed the presence of minority variants bearing resistance mutations to non nucleoside inhibitors, but not to R1479. Conclusions: The higher frequency of non-nucleoside inhibitor resistance mutations as compared to the absence of resistance mutations to the nucleoside analog R I479 in the HCV quasispecies of treatment naive HCV patients suggests a potential for faster development of clinically significant resistance for non nucleoside therapies. These findings are consistent with the lack of resistance observed in HCV infected subjects upon 14 day treatment with R1626.
16231 THE GNB3 C825T POLYMORPHISM AFFECTS RESPONSE TO HCV THERAPY WITH PEGYLATED INTERFERON IN HCV/HIV CO-INFECTED BUT NOT IN HCV MONO-INFECTED PATIENTS
J. Nattermann’, K. Bueren’ , HD. Nischalke’, G. Ahlenstiel’, T. Berg’, M. Biermer’, T. Sauerbruch’, M. Vogel’, JK. Rockstroh’, U. Spengler’ . ‘Department of’ Internal Medicine L Unioersity of Bonn, Bonn; ’Medizinische Klinik mit Schwerpnkt Heptologie und GLEstr-oenterologie, UniurrsitLEetsklinik~imChurit4, Cumpi+ VirchowKlinikum, Uniuer~~itutsmedizin Berlin, Berlin, Germuny E-mail: [email protected] Background: Response to HCV treatment with pegylated interferon-a is variable but might at least in part depend on genetic host factors. The G protein b3 unit (GNB3) C825T polymorphism has been shown to affect treatment response in HCV mono-infection. Here, we analyzed the impact of the GNB3 genotype in the context of HCV/HIV co-infection. Methods: HlViHCV co-infected ( n = 112) and HCV mono-infected patients (n = 150), receiving therapy with pegylated lFN-a/ribavirin were enrolled into this study. Furthermore, we analyzed 220 healthy and 98 HIV mono-infected patients. GNB3 genotype was defined and correlated with respect to treatment response. Results: GNB3 genotype distribution differed significantly between HIV/HCV co-infected patients and HIV-positive/HCV-negative (p=0.0002) or healthy controls (p=0.03). In HCV genotype 1 monoinfected patients ETR and SVR were achieved in 69% and 47%, respectively. In HIViHCV co-infected patients ETR was observed in 76.8% and SVR in 63.8% of the treated patients, with markedly lower response rates in patients with a HCV genotypes 1 or 4 infection as compared to subjects infected with genotypes 2 or 3 (ETR: 72% vs. 90%; SVR: 58% vs. 79%). HIViHCV co-infected patients with a GNB3 CC genotype had significantly lower SVR rates as compared to carriers of a non-CC genotype (52% vs. 77%; p = 0.018). In a logistic regression analysis the GNB3 genotype and