Vaccination for Celiac Disease: utopia or concrete hope for Celiac Disease recovery

Transcription

1 Vaccination for Celiac Disease: utopia or concrete hope for Celiac Disease recovery January 31, 2012 ImmusanT, Inc One Broadway, 14th Floor Cambridge, MA 02142

2 Key Points Objective: Treatment of celiac disease without gluten free diet Design and development of a tolerizing peptide immunotherapy Composition: Validity of peptide selection Proof of concept: Tolerizing T cells in transgenic mice Clinical trial Phase 1 2

3 The future of celiac disease beyond gluten-free diet A large proportion of patients with coeliac disease are dissatisfied with a gluten free diet. Coeliac patients are not taking complimentary and alternative medicine any more than controls, suggesting they do not view complimentary and alternative medicine as an alternative to a gluten free diet. However, all the patients in this survey were keen to consider novel therapies, with a vaccine being the most preferred option. Aziz I, Evans KE, Papageorgiou V, Sanders DS. Are patients with coeliac disease seeking alternative therapies to a gluten-free diet?. J Gastrointestin Liver Dis. 2011;20:

4 Peptide-based Immunotherapy for Celiac Disease: Nexvax2 Replaces GFD Immuno-dominant peptides, T cells and tolerogenic dendritic cells Tolerized E Immature DC T cell Tolerance Peptide-based therapeutic vaccine Nexvax2 Human Data Phase I AUS

5 Use presentation of gluten peptides to delete gluten specific T cells or render them tolerogenic Wheat Barley Rye Gluten partially digested Active disease: TG2 induced with damage. Gluten peptides more Immunogenic with deamidation by TG2 Activated dendritic cell promotes TH1 proinflammatory T cell IFNγ Active disease Inflamed Gluten C D 4 Peptide immunotherapy: Gluten peptides are presented by HLA DQ2 by tolerogenic dendritic cells to gluten specific T cells PQPELPYPQ Treg Foxp3 PQPEQPFPW PFPQPEQPF PFPQPELPY PIPEQPQPY TGF Healed Gluten-free Gluten free diet, healed mucosa. Dendritic cell not activated, promote tolerized T cells IL 10 TCR CD4 Anergy Cell death PFPQPEQPF Tolerance induction with Nexvax2 Healthy Gluten PQPEQPFPW PFPQPELPY TCR IL 10 CD4 CD4 Tolerance maintained with Nexvax2 5

6 Peptide-based Immunotherapy Box 1: Desirable Vaccine Charateristics Soluble in aqueous solution Short linear sequences (avoiding tertiary structure) Native protein sequence (APL may behave unpredictably) Systemic or mucosal administration Failure to trigger innate immune mechanisms (i.e., TLRs) Appropriate MHC-binding characteristics - Promiscuous MHC binding may be advantageous in allergic diseases where strong HLA-disease associations are lacking. - The peptide must mimic the naturally processed epitope in order to induce tolerance among relevant cells. Larché M, Wraith DC. Peptide-based therapeutic vaccines for allergic and autoimmune diseases. Nat Med. 2005;11(4 Suppl):S

7 HLA DQ2.5+ celiac disease is targeted by Nexvax2 Potential for 90% of population HLA DQ gene status determines the peptides that are recognized by gluten-specific T cells Design based on mapping T-cell stimulatory gluten peptides in HLA DQ donors >80% patients with celiac disease are in HLA DQ Karell K, Louka AS, Moodie SJ, et al. HLA types in celiac disease patients not carrying the DQA1*05-DQB1*02 (DQ2) heterodimer: results from the European Genetics Cluster on Celiac Disease. Hum Immunol. 2003;64: Koskinen L, Romanos J, Kaukinen K, et al. Cost-effective HLA typing with tagging SNPs predicts celiac disease risk haplotypes in the Finnish, Hungarian, and Italian populations. Immunogenetics. 2009;61:

8 COMPOSITION Resolving gluten toxicity 8

9 Traditional T-cell Epitope Discovery intestinal T-cell lines Disaggregate Gluten Growth factors Growth factors + Gluten Biopsy T cell Naïve + memory Proliferation Line Clone Vaccination I don t think will ever work. There are too many peptides. EU key opinion leader I m not sure this would really work. To vaccinate against immunodominant epitopes, there are at least 50 different epitopes. You don t really know what the results would be, but it would be worth watching out for it. US key opinion leader DataMonitor April 2009 Lundin KE, Scott H, Hansen T,et al. J Exp Med. 1993;178: van de Wal Y, Kooy YM, van Veelen PA, et al. Proc Natl Acad Sci U S A. 1998;95: Arentz-Hansen H, Körner R, Molberg O, et al. J Exp Med ;191: Vader W, Kooy Y, Van Veelen P, et al. Gastroenterology. 2002;122: Camarca A, Anderson RP, Mamone G, et al. J Immunol. 2009;182:

10 Tracking the T-cell response to gluten challenge in blood Gluten free diet Pools of overlapping A-gliadin 15mers Eat bread 3-days T-cells in blood day 6 Overnight assay -Interferon ELISpot PBMC High throughput, quantitative Gluten peptide screening Anderson RP, Degano P, Godkin AJ, et al. In vivo antigen challenge in celiac disease identifies a single transglutaminase-modified peptide as the dominant A-gliadin T-cell epitope. Nat Med. 2000;6:

11 Tye-Din JA, Stewart JA, Dromey JA, et al. Comprehensive, quantitative mapping of T cell epitopes in gluten in celiac disease. Sci Transl Med ;2:41ra51. 11

12 Oral gluten challenge and T cells in blood: Dominant stimulatory gluten peptides are consistent Focus on wheat and overlooked barley and rye peptides - α-gliadin 33mer epitopes not important after barley or rye challenge gliadin PFPQPELPYPQ Wheat Barley Rye gliadin PFPQPEQPFPW B/C Hordein PIPEQPQPY secalin PFPEQPEQI Tye-Din JA, Stewart JA, Dromey JA, et al. Comprehensive, quantitative mapping of T cell epitopes in gluten in celiac disease. Sci Transl Med ;2:41ra51. 12

13 Nexvax2 consists of three synthetic 15/16mer peptides including 5 T cell eptiopes: DQ2.5 glia α1, α2 DQ2.5 glia ω1, ω2 DQ2.5 hor3 Recognized by the majority of gluten-reactive T cells in blood after combined wheat/barley/rye challenge Standard peptide synthesis Consistent pharmaco-kinetics (rat) t 1/ min and Vd Soluble and stable in saline mg/ml 13

14 PROOF OF CONCEPT Transgenic mouse 14

15 Proof of Concept: HLA DQ2 transgenic mice A B HLA DQ2 TCR+DQ2 1. KO Murine MHC Class II 2. tg HLA DR3-DQ2 3. tg Human CD4 When immunized with peptide + Freund s, mounts TH1 DQ2 restricted T-cell response to dominant wheat gluten epitope. No disease on gluten-diet 1. KO Murine MHC Class II 2. tg HLA DR3-DQ2 3. tg Human CD4 4. TCR specific for one of thedq2-glia-αii in Nexvax2 90% CD4 T cells are clonal: TH1 cytokine profile HLA DQ2-restricted T cells activated in vivo by gavage with wheat gluten peptide, but no disease on gluten-diet 15

16 Proof of Concept: induction of tolerance in DQ2 TCR tg mouse Induction Maintenance TCR-Tg Daily, 3x/weekly Dose escalation or linear Achieve maintenance dose Weekly Maintenance dose ~ED20 dose Collect spleen and analyse T cell response to peptide Anergy Treg induction cell markers and function Suppression interferon-γ, IL-2 Induction IL-10 16

17 PHASE 1: NEXVAX2 IN HLA DQ2.5 CELIAC DISEASE

18 Study design N=34 healthy HLA DQ2+(DQ8-) adults with celiac disease on gluten free diet (GFD) Sequentially randomized to receive 9μg (n=6), 30μg (n=6), 60μg (n=6) or 90μg (n=7) of Nexvax2 or placebo (n=9) i.d. weekly for 3 weeks. Double blind design In two dedicated GCP Phase I clinical trial centres. Serial interferon-gamma (IFN-γ) ELISpot assays were used to enumerate peripheral blood T-cells specific for Nexvax2 in independent lab. 18

19 Results: Safety/Tolerability Well tolerated and safe. Gastrointestinal adverse events more common with 60μg and 90μg of Nexvax2 7/19 subjects administered 30μg, 60μg or 90μg of Nexvax2 vs 0/9 on placebo reported nausea, vomiting or diarrhoea 2 subjects were administered anti-emetics and two vomited (at approximately 2h or 5.5h after the initial dose). One subject in the 90μg cohort withdrew due to gastrointestinal symptoms graded severe. 19

20 Timing and character of AEs resemble those following gluten exposure in a celiac patients on gluten free diet Number of subjects reporting TEAE (number of events) Moderate intensity TEAE Treatment: 9 μg n = 6 30 μg n = 6 60 μg n = 6 90 μg n = 7 Placebo n = 9 Abdominal distension 1 (1) Diarrhoea 1 (1) 1 (1) Nausea 1 (1) 1 (2) 1 (1) Vomiting 1 (2) 1 (1) Headache 2 (2) 2 (3) 2 (6) 3 (5) Hypoaesthesia 1 (1) Lethargy 1 (1) Memory T-cell activation by gluten or by Nexvax2 in the gut causes symptoms? 20

21 Nexvax2-specific T cells induced Nexvax2-specific IFN-y ELISpot Positive Responders Memory T-cell activation and proliferation in lymph nodes by gluten or by Nexvax2 responsible for Nexvax2-specific T cells in blood. 21

22 Development status of Nexvax2 and next steps Nexvax2 therapy HLA DQ2 variant (>80%) of celiac disease Discovery/IP Preclinical Phase 1 Phase 2 Phase 3 Approval Extended dosing, and dose ranging safety, tolerability and bioactivity studies in HLA DQ subjects on GFD Nexvax2 diagnostic Ex vivo cytokine release assay using blood after gluten challenge Companion and monitoring for Nexvax2, and stand-alone diagnostic Development of a tool kit for monitoring induction of tolerance to gluten in patients 22

23 Conclusions Personalized epitope mapping defines Nexvax2 composition Companion diagnostic defines suitable patient group Proof of concept in HLA DQ2 TCR double-transgenic mouse model Nexvax2 Phase 1 study in HLA DQ2.5 celiac disease Safe, well tolerated, clinical effects similar to gluten Activates predicted T cell subpopulation Clinical effects similar to gluten A model for new class of highly specific tolerogenic immunotherapies. 23