1. Do we still need an HCV vaccine in the DAA era? How far we are from its clinical application ? Daniel Shouval Liver Unit Hadassah-Hebrew University hospital Jerusalem, Israel Argentina, Hospital Universitario Austral Oct 27,2014

2. Overall prospects for eradication of hepatitis viruses - 2014

3. Global control of HCV Clearance of HCV infection in the individual patient will sooner or later become a SOC in countries which can afford it The future of vaccines for prevention or intervention in persistent HCV infection is still unclear due to a number of technical barriers as well as gaps in understanding the immunologic mechanisms involved in induction of protective immunity

4. HCV Outcome of acute HCV infection is determined by an interplay between host genetics, the virus and the host immune response The majority of patients with acute HCV infection (70-80%) develop persistent infection. However in a minority of patients, a combined cellular and humoral immune response is efficient in clearing the virus Recent data suggest that in contrast to previous assumptions, antibody responses may play an essential role in neutralization and development of an immune memory in those patients who cleared the virus* * Abdel-Hakim M et al. Protective immunity against HCV: Many shades of gray. Frontiers in immunology 2014;5, article 274

5. Some imminent challenges in coping with the recent developments of potent anti-HCV agents Limited access to testing Cost Whom to treat? Priorities in allocation of funds

6. HCV The goal: all oral, pan-genotypic anti- viral agent 2011- >50 companies worked on development of anti-HCV agents 2011 – FDA approves 1 st generation PIs 2013- > 12 phase 2 and phase 3 clinical trials 2013- FDA approves first 2 nd generation PI 2014 –Approval of a combination of 2 or 3 DAAs is pending

7. The revolution in treatment of chronic HCV infection Kwong AD. Acs Med Chem letters 2014;5:214

8. Global control of hepatitis C: where challenge meets opportunity Thomas DL. Nature Medicine 2013;19:850

9. Pros and Cons for development of HCV vaccine(s ) Pros Control of global HCV infection Reduction in rates of cirrhosis and hepatocellular carcinoma Control of HCV infection in specific risk groups Pros Control of global HCV infection Reduction in rates of cirrhosis and hepatocellular carcinoma Control of HCV infection in specific risk groups Cons Priorities and cost Limited knowledge on protective immune response post acute HCV Development of DAAs leading to SVR Anticipated duration of clinical trials Lack of predictive modeling how combined vaccination with DAA will reduce global pool and interrupt transmission in rural and urban populations Scarcity of candidates for controlled clinical trials on protective vaccines as well as ethical considerations

10. Debate In view of the immense progress in development of anti-viral agents against HCV: What is the rational for developing a vaccine against HCV? – Preventive vaccine (i.e. for specific risk groups Vs universal mass vaccination) – Therapeutic vaccine Inability of anti-virals to restore protective immunity may justify induction of HCV T cell mediated responses to maintain an SVR Combination with anti-viral agents with vaccine to prevent relapse after cessation of anti-virals (variable timing in administration of anti-virals) Induction of viral suppression and control of HCV infection without complete viral clearance

11. Impediments for developing an HCV vaccine Complex nature of immune response to HCV Existence of multiple HCV genotypes(differences in ~30% in nucleotide position) HCV exists as a population of related viral quasi-species which enables emergence of HCV variants eluding the immune response Risk of HCV re-infection Limited availability of animal models  Chimpanzees  Immuno-deficient mice  Cell culture systems

12. HCV genome (~9.6 kb pairs, 7 genotypes, 67 subtypes*) Reproduced from Abdel-Hakim M et al. Frontiers in immunology 2014;5, article 274 * *

13. Natural course of HCV infection and types of protective immunity Liang TJ. Nature Medicine 2013;19:869

14. Immunity during and after resolution of primary HCV infection Persistent HCV infection and uncertain influence of DAA on immunity and second. HCV infection A. B. Honegger JR et al. Semin Liv Dis 2014;34:79

15. Hypothetical model for protective immunity upon HCV infection Development of long-lasting CD4/CD8 viral specific immune memory post acute infection maintained by homeostatic cytokines Abdel-Hakim M et al. Frontiers in immunology 2014;5, article 274

16. Hypothetical model for non-protective immunity upon HCV infectio n Abdel-Hakim M et al. Frontiers in immunology 2014;5, article 274 Unprotected individuals: Re-infection associated with a weak late recall response and incomplete T cell control of viremia

17. Correlates of protective HCV immunity and the mechanisms of viral evasion of immune responses Torresi J et al. J Hepatol 2011;54:1273 Clearance of HCV infection requires early and multi-specific class 1 restricted CD8 + T cell and class 2 restricted CD4 + cell responses to both structural and non-structural proteins

18. Targets for an HCV vaccine Base line concepts:  Clearance of HCV requires early and multi-specific class 1 restricted CD8 + T cells and class 2 restricted CD4 + T cells  Potential targets include HLA class 1 restricted HCV core, E1, NS3, NS4 and NS5 epitopes  Importance of induction of cross protective HCV specific neutralizing antibodies to E1 and E2 epitopes  Targeting of viral entry into hepatocytes (capture of several cell surface proteins (including LDL receptor, tetraspanin CD81,SR-B1,tight junction proteins Claudin 1 and Occlodin)

19. Barriers to development of HCV vaccine(s) Questionable role of sterilizing immunity and role of neutralizing antibodies in HCV clearance HCV is capable of evasion of the host immune response through: – Inhibition of intracellular interferon pass ways – Impairs activation of dendritic cells, CD 4 and CD 8 T- cell responses – Induces a state of T-cell exhaustion – Selects escape variants with mutations of CD 8 T-cell epitopes – Viral polymerase activity is error prone (NS5b) – HDL lipoprotein and glycoprotein interference in binding neutralizing antibodies – Genetically pre-determined polymorphism (IL28)

20. Candidate HCV vaccines Recombinant E1 and E2 proteins(i.e.E1E2/MF59; yeast derived core poly protein with ISCOMATRIX) Synthetic peptides (IC41) Virosomes based vaccines Tarmogens (GI-5005-1 yeast derived core-NS3 fusion protein +/- IFN) Modified recombinant DNA vaccines:( i.e. vaccinia Ankara based vaccine TG4040 encoding NS3,NS4,NS5B proteins; adeno virus NS3-NS5B proteins, used to deliver HCV antigens to prime a T cell response) HCV virus like particles based vaccine Torresi J et al. J Hepatol 2011;54;1273 Liang TJ. NatureMedicine 2013;19:869 Swadling L et al. Expert Opin Biol Ther 2013;13:1109 Honeger JR et al.Seminars Liv Dis 2014;34:79

21. Some reasons for limited success in developing an HCV vaccine Limited number of protective epitopes Inclusion of incorrectly folded recombinant proteins Limited humoral and cellular mediated responses associated with recombinant DNA vaccines Suboptimal potency of adjuvants

22. Primate and human studies describing candidate prophylactic HVC vaccines Swadling L et al. Exp Opinion Biol Ther 2013;13:1109

23. Liang TJ. Nature Medicine 2013;19:869 Prophylactic HCV vaccines studies in chimpanzees and in humans 2013

24. Candidate HCV vaccines and clinical trials in 2011 Torresi J et al. J Hepatology 2011;54:1273

25. Ongoing and completed trials for therapeutic HCV vaccines - 2014 Xue J et al. Infection,Genetics & Evolution 2014;22:140

26. Major sites of action of different HCV preventive and therapeutic vaccines Torresi J et al. J Hepatology 2011;54:1273

27. Liang TJ. Nature Medicine 2013;19:869 Steps for vaccine trial design and follow-up

28. Summary During the past 2 years, there is a a general misconception that we are facing the control and the end of HCV infection. Yet, despite the exiting recent development of efficient DAAs, control of the global burden of HCV infection remains an elusive goal. Efforts continue to develop an HCV vaccine generating a broad and long-lasting cellular and humoral immune responses which is capable of coping with the viral evading properties However, the development of DAAs may paradoxically slow down future efforts for further development of HCV vaccines and especially of therapeutic vaccines There still is a justification for further development of a preventive vaccine suitable for specific risk groups (i.e. HCWs. IVDA, countries with exceedingly high endemicity) ) while the future of a therapeutic HCV vaccine is undetermined

29. Candidates for an HCV vaccine Preventive vaccine – Healthcare workers – IVDA patients – General population in highly endemic regions (i.e. Egypt) Therapeutic vaccine – Direct Anti-viral Agents (DAA) treated HCV patients in SVR who cleared HCV and potentially at risk for HCV re-infection – HCV carries not responding to DAA (incl. relapsers – HIV/HCV co-infection)

30. The Hadassah Medical Center in Jerusalem Thank You

31. Backup

32. Liang TJ. Nature Medicine 2013;19:869 Targets and mechanisms of vaccine induced immunity in prevention of HCV infection

33. Innate and adaptive immunity during primary HCV infection Abdel-Hakim M et al. Frontiers in immunology 2014;5, article 274

34. Summary of neutralizing domains in hypervariable regions \ of both the E1 and E2 proteins Torresi J et al. J Hepatol 2011;54:1273 AR 3

35. Primate and human studies describing candidate prophylactic HCV vaccines Swadling L et al. Exp Opinion Biol Ther 2013; 13:1109