Novel T cell antigen discovery technology providing new momentum on a malaria vaccine

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1 Novel T cell antigen discovery technology providing new momentum on a malaria vaccine World Vaccine Congress 2012 Best Vaccine Startup 2008 Jessica Baker Flechtner, PhD Vice President, Research Genocea Biosciences, Inc. Cambridge, MA

2 Genocea Overview 2 Unique platform to target the most challenging pathogens Rapidly discovering T cell antigens that drive novel vaccines Entering clinic in 2012 with therapeutic HSV-2 vaccine Unique conserved protein T cell antigens that prevent Pneumococcus colonization Unique approach to malaria T cell antigen discovery

3 Genocea Value Proposition: Unlocking Vaccine Development for the Most Challenging Pathogens

4 Vaccines Attempt to Mimic Natural Immunity: Humoral and Cellular Responses to Infection 4 For many pathogens, both arms are active

5 Why a Malaria Vaccine? The Burden of Malaria Disease 5 The 2011 WHO World Malaria Report estimates 655,000 malaria deaths and 216 million clinical cases in 2010 In spite of the use of bed nets, anti-malarial drugs, and insecticides, it remains a global problem Prevention is a top priority of the National Institutes of Health, the White House, the military, and the Bill and Melinda Gates Foundation The generation of a vaccine that ameliorates or eradicates infection or effects of the disease is critical to global health.

6 The Complexities of a Malaria Vaccine: The Unique Life Cycle of the Plasmodium Parasite 6

7 Subunit Vaccines That Stimulate Antibody May Not Be Sufficient 7 The RTS,S/AS01 candidate malaria vaccine reduced clinical episodes of malaria and severe malaria by approximately half during the 12 months after vaccination in children 5 to 17 months of age

8 Whole Organism Vaccines Are Promising But Difficult to Manufacture 8 In studies utilizing live mosquitoes as the vaccine delivery mechanism, there was complete protection against malaria in 93% of volunteers (13/14) and 94% of challenges (33/35) 1 1 Luke and Hoffman, J Exp Biol 2003; 206:

9 The Importance of T cells in Immunity to P. falciparum: Sterilizing Immunity Elicited Only to Sporozoite Vaccination 1 9 Irradiated sporozoites arrest in liver stage Once in the liver, inaccessible to antibody Blood stage parasites do not develop, no antibody induced to merozoites Sterilizing immunity from attenuated sporozoite immunization in animals is attributable to: IFNg-secretion from CD8 + T cells Help from CD4 + T cells 2,3 No correlate of protection yet in humans, however sporozoite surface protein-specific CD8 + T cell epitopes are generated after vaccination 4 1 Vaughan et al., Human vaccines 2010; 6: Carvalho et al., Nat Med 2002; 8: Weiss et al., Proc Natl Acad Sci USA 1988; 85: Wizel et al., J Exp Med 1995; 182:

10 If T cell Immunity is important to the control of disease, what part of the parasite will be targeted by an effective vaccine?

11 Genocea Targets Liver Stage of Malaria 11 Progression of Malaria Genocea vaccine (T cell mediated) 60% of subunit vaccines for malaria in clinical development (antibody mediated)

12 AnTigen Lead Acquisition System (ATLAS TM ) Platform 12 1) 2) 3) Human immune response profiling High throughput screening in silico validation 4) in vivo validation Thousands Dozens Leads Vaccine NUMBER OF ANTIGENS

13 1) Human Immune Response Profiling 13 Define disease cohorts Recruit subjects, Collect PBMCs Output Effective Immune Response Key Considerations Ineffective Immune Response Deleterious or Negative Sequellae HLA diversity Age Gender Cohort size needed for statistical power Clinical basis for identifying immune response differences

14 What Cohorts Are Available to Study? 14 Participants in a radiation-attenuated sporozoite vaccination and challenge trial Some protected and some unprotected Collaboration with the Naval Medical Research Center Individuals who were born and raised in areas endemic for malaria Compare those that developed disease and those that did not Individuals who visited malaria-endemic areas for extended periods of time and who took suppressive prophylactic drugs

15 2) High-Throughput Screening: Library Creation 15 Process Genome Library Generation Clone Validation Results to Date PCR amplify each ORF with gene-specific primers Clone ORFs into vector that inserts a surrogate epitope tag at the c-terminus Transfect E. coli (or others) and induce protein expression Cloned libraries for pathogens up to >2,200 proteins Both AT- and GC-rich proteomes Multiple pathogen types

16 Percent of Positive Control Malaria Program Library Generation 16 Attempted expression library for ~1000 genes associated with the preerythrocytic stage of P. falciparum Transcriptome analysis 1,2 Data from NMRC collaborators P. yoelii/p. berghei screens PEXEL (plasmodium export element) motif genes successfully cloned, 84% expressed in E. coli 55% 45% Library Expression in E. coli 35% 25% 15% 5% -5% Clone Number 1 Kaiser et al., 2004; 51: Tarun et al., 2008; 105: Marti et al., 2004; 306:1930-3

17 2) High-Throughput Screening: T Cell Antigen Identification 17 Screen each protein through each patient s APC Separately screen for CD4 + and CD8 + T cell responses E. coli expressing carrier protein and target antigen Phagosome Phagolysosome Presentation on MHC Class I CD8 + CTL E. coli expressing target antigen alone Phagosome Phagolysosome CD4 + Helper T Cell Presentation on MHC Class II CD4 + & CD8 + T cell response from each subject to each antigen Phagocyte (APC) Phagocyte (APC)

18 pg/ml IFNg Library Screening Exemplary Data 18 Library screen readout is IFNg secretion from T cells Compare Frequency of responses across cohorts Magnitude of IFNg secretion to specific clones

19 3) in silico and 4) in vivo Validation 19 Evaluate Protective versus Non-Protective Antigens Filter Antigens for Vaccine Utility Validate Lead Antigens in vivo Frequency Magnitude Phenotype Low homology to self & commensal organisms High homology across strains/species of pathogen Ability to produce recombinantly Established animal models Proof of mechanism Proof of concept Final Vaccine

20 Genocea is Enabling the Next Generation Malaria Subunit Vaccine 20 Pre-erythrocytic stage expression library cloned and banked Sequence verified 84% expression in E. coli 100 identical copies stored at -80 C Screening underway Protected and unprotected RAS-immunized donors from NMRC Immune donors from endemic areas Next steps Protein antigens will be prioritized by comparing protected versus unprotected cohorts Specificity Magnitude CD4 vs. CD8

21 Genocea Biosciences: Leading Pipeline for T Cell-Enabled Vaccines 21 Discovery Animal PoC Manufacturing, Toxicology Clinical Trials HSV-2 Tx Pneumococcus HSV-2 Px Chlamydia Malaria Final vaccine formulation IND

22 Acknowledgements 22 CAPT Thomas Richie Joao Aguiar Noelle Patterson Jessica Bolton LeeAnn Blalock Zheng Yan Alec Sutherland Anastasia Kazimirova Todd Gierahn Seth Hetherington John Carney Dustin Showe Danielle Nolitt

23 Disclosure 23 The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense, nor the U.S. Government. Source of Support The work of authors was supported by TATRC grant W81XWH Human Research Protection/IRB statement The study protocol for the clinical trial presented in this manuscript was approved by the Naval Medical Research Center Institutional Review Board, in compliance with all applicable Federal regulations governing protection of human subjects. All study subjects gave written informed consent Copyright Statement TR is a military service member. This work was prepared as part of official duties. Title 17 U.S.C. 105 provides that Copyright protection under this title is not available for any work of the United States Government. Title 17 U.S.C 101 defines a U.S. Government work as a work prepared by a military service member or employee of the U.S. Government as part of that person s official duties.

24 Genocea: Speeding the Invention of New Vaccines World s Most Intriguing Startups Best Vaccine Startup