Viral dynamics and Resistance Implications for HCV drug development

Transcription

1 Viral dynamics and Resistance Implications for HCV drug development Robert T. Schooley, M.D. University of California, San Diego June 23, 2011

2 SVR Rate Priorities in HCV Therapeutics Treatment Modality

3 RNA copies/ml Days

4 4 x x virions/day

5 Two Compartment Model of HIV-1 Replication Productively infected CD4 lymphocytes viral particles/day 2.6 days per generation >99% of replication T 1/2 ~6 hours <1% of replication Uninfected CD4 lymphocytes <1% Uninfected, activated CD4 lymphocytes Long-lived cell populations (macrophages) CD4 lymphocytes infected with defective virus

6 Conclusions From our study and previous reports, it is now clear that raging fire of viral replication (left side of slide, Fig 2) could be put out by potent antiretroviral agents in 2 3 weeks. However the dynamics of other viral compartments must also be understood.

7 Implications of HIV Dynamics and Replicative Fidelity for Mutational Barrier HIV= 4 x x virions/day Ribeiro et.al. AIDS, 1998.

8 RNA Change (Log 10 Copies/mL) Protocol 035 (Indinavir + ZDV + 3TC) Change in Viral RNA from Baseline 0 Double-Blind Only Double-Blind and Open Label Open Label Only EFV+ZDV+3TC IDV ZDV+3TC Weeks in Study N= N= N= Median Baseline HIV RNA = 4.64 Log 10 copies/ml (43,190 copies/ml)

9 Modeling of HCV Kinetics with Interferon Therapy HCV: 4 x x virions/day HIV= 4 x x virions/day 100 to 3000 fold more HCV produced/day than HIV Zeuzem, Clinics in Liver Disease, 2001

10 Viral RNA The HCV Polymerase has Two Shots at Goal Integrated DNA Viral RNA + Strand - Strand + Strand Reverse Transcriptase Transcription HIV Life Cycle RNA Polymerase RNA Polymerase HCV Life Cycle

11 Slide #11 Genetic Diversity of HIV and HCV HIV G 92NG083 A U455 E 93TH253 H 90CF056 C C2220 B RF F 93BR020 D NDK Distance 0.1 J8 2b ED43 4a VN004 9a VN405 8a VN235 7a JK046 11a BEBE1 2c J6 2a Th580 6b HCV A 1b HCV J 1b G9 1c HCV 1 1a H77 H90 Tr 3b NZL1 3a HK2 6a HCV H1480 5a JK049 10a Source: S Ray

12 Viral characteristics relating to Slide #12 resistance potential HCV virions/day Error prone viral polymerase (x2) Viral quasi-species No overlapping reading frames Moderate infected cell turnover Eradication possible (no known latency) HIV virions/day Error prone viral polymerase Viral quasi-species Overlapping reading frames Rapid infected cell turnover Eradication not possible? (Integrated pro-viral DNA)

13 Based Strictly on Viral Dynamics and Replicative Fidelity, HCV should Pose a Greater Challenge than HIV in Terms of Drug Resistance

14 Evolution of Drug Resistant HCV under Telaprevir Therapy

15 Log 10 Viral Load (IU/mL) Variant Frequency, % Individual Viral Load Plots from Patients infected with Genotype 1a Virus P/R + BOC Follow-up Longitudinal Analysis Wk 28 Quantification of Variants 100 Week 28 Week Total Viral Load V36M R155K Week 25 0 Courtesy of Richard Bernhard, Ph.D.

16 Background OMe MeO 2 CHN N O N N H H N BMS (`052) N O N NHCO 2 Me Cl O O NH O N O N O H N O N H O O S BMS (`032) BMS is a first-in-class, highly selective HCV NS5A inhibitor with picomolar in vitro potency and broad genotypic coverage 1 BMS is a potent and selective HCV NS3 protease inhibitor 2 Combination of BMS and BMS yielded additive to synergistic activity in the replicon system No clinically important pharmacokinetic interaction 3 1 Gao M. Nature 2010;465: McPhee F. J Hepatol 2010;52(Suppl1):S Bifano M. Hepatology 2010;52(Suppl1):719A. 16

17 Study Design Study AI (Phase IIA, open label, randomized trial) Sentinel Cohort Group A BMS BMS (n = 11) follow-up x 48 weeks Group B BMS BMS pegifnα/rbv (n = 10) follow-up x 48 weeks 24-week treatment Post-treatment Week 12: SVR 12 BMS (NS5A inhibitor) 60 mg PO QD BMS (NS3 protease inhibitor) 600 mg PO BID pegifnα-2a 180 µg SC once weekly RBV mg daily according to body weight 17

18 Undetectable HCV RNA (Percent of patients) Virologic Response During and After Treatment * * Group A BMS BMS Group B BMS BMS pegifnα/rbv n = RVR ervr cevr EOTR SVR 12 SVR 24 Four (2/9 GT 1a and 2/2 GT 1b) patients in Group A achieved SVR 12 and SVR 24 10/10 subjects in Group B achieved SVR 12 and 9/10 subjects undetectable at SVR 24 *Group B: 1 patient at week 12 on therapy and another at week 24 post treatment with HCV RNA < LLOQ, both undetectable on retesting 35 days later 18

19 HCV RNA (log 10 IU/mL) HCV RNA by Patient: Group A BMS BMS follow-up Week 24 PT4 PT12 PT24 LLOQ LLOD Six patients (all genotype 1a) experienced viral breakthrough on therapy One patient with EOTR experienced viral relapse at 4 weeks post-treatment PT, post-treatment. 19

20 Why Might HCV More Responsive to Therapy than it Should Be Based on Viral Dynamics and Fidelity Modeling? 1. HCV is cleared ~30% of the time during acute infection During this phase, the virus is exquisitely sensitive to interferon 2. Acceleration of second phase kinetics with increasing regimen potency 3. Antiviral therapy and the equipoise between HCV and innate/adaptive immunity

21 Slide #21 HCV Is Cleared in Acute Infection in a Subset of Patients Acute Hepatitis C Resolved 15-30% Stable <80% Chronic Hepatitis 70-85% Cirrhosis 20%-50% 20 to 30 Years Stable 75% Decompensation 25% HCC 1%-4%/yr

22 Spontaneous Clearance of HCV in Symptomatic Patients Slide #22 Gerlach, Gastroenterology, 2003

23 Slide #23 IL28B Allele also Drives HCV Clearance in Acute Infection Thomas, Nature, 2009

24 Slide #24 Clearance of HCV During Acute Infection With Interferon Therapy Average time from infection ->therapy: 89 days Interferon alpha 5 mu qd x 4 weeks, then 5 mu three times weekly for 24 weeks Jaekel, NEJM, 2001

25 Why is HCV More Responsive to Therapy than it Should Be Based on Viral Dynamics and Fidelity Modeling? 1. HCV is cleared ~30% of the time during acute infection During this phase, the virus is exquisitely sensitive to interferon 2. Acceleration of second phase kinetics with increasing regimen potency 3. Antiviral therapy and the equipoise between HCV and innate/adaptive immunity

26 Decay Kinetics of HCV with Interferon-Based Therapy Rong and Perelson, Crit Rev Immunol 2010

27 Guedj and Perelson, Hepatology 2011

28 Open symbols: Telaprevir Closed Triangles: Telaprevir + Ifn Telaprevir Interferon 10 mu/day Interferon 10 mu/day + Ribavirin Guedj and Perelson, Hepatology 2011

29 Guedj and Perelson, Hepatology 2011

30 Potential Biological Explanations With increasing potency, infected cells are eliminated more quickly but no increase in hepatocellular enzymes With increasing potency, infected cells are being cleared of their HCV replication complexes With more effective suppression of viral replication, the ability of the virus to abrogate innate immunity that is stimulated by HCV through RLR and TLR pathways is compromised

31 Infection of Hepatocytes by HCV Activates Innate Immunity via the RIG-I Pathway RIG-I IPS-1 MAPK NF-κB IRF3 IRF7 Ifn-β Ifn-α

32 Liu and Gale, Gastroenterology Res and Practice, 2011

33 Infection of Hepatocytes by HCV Activates Innate Immunity via the RIG-I Pathway HCV NS3/4a RIG-I IPS-1 MAPK NF-κB IRF3 IRF7 Ifn-β Ifn-α

34 Liang, et. al. Gastroenterology, 2008

35 IL-8 Horner and Gale, J. Interferon and Cytokine Res, 2009

36 HCV and the Innate Immune Response HCV Innate Immune Response

37 HCV and the Innate Immune Response HCV Innate Immune Response Acute Infection -> Chronic Infection

38 HCV and the Innate Immune Response HCV Innate Immune Response Resetting the Balance with Potent and Sustained Antiviral Therapy

39 EASL, 2011

40 Fold Change Drug Susceptibility (log) Change in Drug Susceptibility Over Time Subject 16 Week 2 Subject 2 Week 7 Subject 5 Week 11 ZDV 3TC ABC NVP SQV RTV NFV Time (weeks)

41 Log 10 Viral Load (IU/mL) Log 10 Viral Load (IU/mL) Individual Viral Load Plots from Patients infected with Genotype 1b Virus Genotype 1b Patient 1 T54A/S & V170A WT WT WT WT T54S T54S & V55A WT T54A V158I/M Genotype 1b Patient 1 T54A WT T54A BL Time (Weeks) P/R Lead-In P/R + BOC 0-16 BL Time (Weeks) Courtesy of Richard Bernhard, Ph.D. Follow-up WT Wild Type at specific RAV loci BL Baseline

42 Linkage of Resistance Mutations WT HIV-1 WT HCV

43 Interim Conclusions Remarkable improvements have been seen with first generation HCV PI s when added to SOC Evidence may be emerging that with increasingly potent and sustained antiviral pressure the sum is greater than its parts. It is possible that this is attributable in part to abrogation of the innate immune evasion tactics of HCV

44 Many Questions Remain Is it especially beneficial (or even essential) to include an NS3/4a HCV protease inhibitor as a component of a potent regimen? How important is continuous and sustained antiviral pressure? Is it especially important to take resistance to resistance into account? Are we correct about the resistance linkage issue? What are the implications for retreatment after treatment failure?

45 Interim Recommendations We must continue with pilot sized test of principal studies as the traditional pathway to approval studies continue. We should take full advantage of all available molecular virological tools to quantify and characterize the HCV quasispecies in therapeutic interventions. As in the case of HIV-1, it is essential that we take advantage of therapeutic interventions to better understand fundamental virus-host interactions.

46 Integration of Clinical and Fundamental Biological Research is Essential Clinical and Translational Investigation Fundamental Biological Insights

47 HCV Therapy at a Crossroads: Where is Reality in the Optimism/Pessimism Spectrum?

48 Thank You Acknowledgements Richard Bernhard, MSD Steve Schnittman, BMS