What Would Hepatitis B Cure Look Like?

Transcription

1 Epitope Mapping the HBsAg to Identify Biomarkers Associated with HBsAg Loss in a Treatment Naïve Cohort of Genotype A Chronic Hepatitis B (CHB) Patients Receiving Nucleotide Analogue (NA) Therapy: Implications for Functional Cure Prof Stephen Locarnini, Dr Hans Netter & Dr Renae Walsh WHO Regional Reference Centre for Hepatitis B Victorian Infectious Diseases Reference Laboratory, Doherty Institute Melbourne, Victoria 3000, AUSTRALIA

2 What Would Hepatitis B Cure Look Like? Off Treatment: In the blood: In the liver: HBV DNA/HBsAg negative anti-hbs positive no HBV cccdna no HBV RC/DSL DNA HBcAg staining negative ± HBsAg (occasional) [reflecting integrated HBV DNA] Functional Cure: HBsAg loss/seroconversion Absolute or Complete Cure: Maintenance of undetectable serum HBV DNA off-treatment No cccdna anywhere

3 Outline of Presentation: Steps to Functional Cure 1. Background: HBsAg and Anti-HBs 2. HBsAg Epitope Changes During Functional Cure 3. Broadly Neutralizing Antibodies and CHB 4. Modified HBsAg VLPs 5. Next Steps.

4 HBsAg Clearance & Functional Cure Background HBsAg clearance improves survival rates and reduces risk of HCC Retrospective study of 309 cirrhotics, mean follow-up of 5.7 years Fattovich et al. Am J Gastroenterol 1998 Cumulative risk of HCC Need to achieve clearance < age 50 to reduce HCC risk Yuen M-F, et al. Gastroenterology 2008; 135:1192 There is no biomarker to predict HBsAg loss/seroconversion

5 HBsAg Clearance & Functional Cure Background Rate of spontaneous HBsAg loss/seroconversion ~2% Rate of HBsAg loss/seroconversion on NA therapy (HBeAg+) at 1 year: telbivudine 0% adefovir 0% lamivudine 1% entecarvir 2% tenofovir 3% EASL Clinical Practice Guidelines Panel. J Hepatol. 2009;50: Rate of HBsAg loss/seroconversion on NA therapy (HBeAg+) at 2 years: Lok ASF & McMahon BJ. Hepatology 2007;45: Lau GKK et al. N Engl J Med 2005;352: Chang T-T et al. J Gastroenterol Hepatol 2004;19: Marcellin P et al. Hepatology 2008;48: Gish RG et al. Gastroenterology 2007;133: Gane E et al. Presented at: 59th Annual Meeting of the American Association for the Study of Liver Diseases, San Francisco, USA, 31 October 4 November 2008; Poster 942. Heathcote E et al. Presented at: 59th Annual Meeting of the American Association for the Study of Liver Diseases, San Francisco, USA, 31 October 4 November 2008; Abstract 158. Median number of years to clear HBsAg on NA therapy 52.2 years Chevaliez, et al. J Hepatol (2013) 58:

6 HBsAg Burden HBsAg secreted in vast excess over virions (>10 3 fold) circulate in blood µg/ml (1% of total serum protein) half-life 1-38 days (multiple studies) unique conformational structure (8 cysteines and 8 prolines ) associated with increased risk of HCC (Yuen, MF. et al Gastro;135: ) plays a key role in HBV persistence suppress both innate (TLR-2, TLR-9 and IFN-α) as well as adaptive (mdc) responses to infection Wang, S et al J Immunol;190:5142.; Xu, Y et al Mol Immunol;46:2640.; Op den Brouw, ML et al Immunol;126:280.

7 Detection of Free v s Complexed Anti-HBs Free anti-hbs: Free anti-hbs (concurrent HBsAg and anti-hbs) is more commonly described in HBeAg-positive CHB patients with a high viral load [Shiels M, et al (1987) Gastro 93:675; Zhang J, et al (2007) Clin Infect Dis 44:1161] Reduced detection rates of free anti-hbs (co-existing with HBsAg) probably reflects recent updates of diagnostic kits as required by the FDA (i.e. to recombinant Ag & mabs). In comparison, more sensitive noncommercial assays developed report the detection co-existing anti-hbs (with HBsAg) in ~50% of CHB patients [Maruyama T, et al (1993) J Clin Invest 91:2586] Complexed anti-hbs: Concurrent or complexed HBsAg and anti-hbs has been reported in most CHB patients [de Niet, et al (2014) AVT 19:259] Did not cause or result in significant changes to infection status Possibly represents a heterologous sub-type driven anti-hbs response; i.e. HBsAg serotype ad subtype which is accompanied by an ay anti-hbs response, & vice versa [Fouteh P, et al (1983) Ann Int Med 99:460; Sheils M, et al (1987) Gastro 93:675]

8 Clinical Significance of Concurrent Anti-HBs & HBsAg No apparent significant protective or pathogenic effect Usually associated with high replicative activity (HBeAg-positive CHB) Conclusion: - production of anti-hbs is NOT completely blocked in CHB B-cells encoding high affinity antibodies to the persons own HBsAg are somehow ineffective or not measurable Whereas: - B-cell clones encoding anti-hbs with low affinity to the homologous HBsAg could expand and express their antibody these anti-hbs do not bind person s own HBsAg but to HBsAg with slightly different antigenicity unlikely due to super-infection with a second HBV strain of different serotype/genotype Partly explained by sg145r-type VEM 9.5% in anti-hbs positive CHB versus 2.4% in anti-hbs negative CHB (European patients) (Lada, O et al J Virol;80: ) not seen in Asian patients (HBeAg-pos CHB) (Zhang, JM et al Clin Infect Dis;44:1161-9) position st/i126 most affected (? possible Polymorphic site) [st/i126, N, A, I, L, S]

9 Rituximab a chimeric monoclonal antibody against CD20 CD20 cell surface marker for B-cells selectively destroys B-cells by antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) also induces apoptosis of CD20+ cells binding to amino acids and on CD20

10 Rituximab: Risk of HBV Reactivation Background Non-Rituximab regimen vs. Rituximab regimen Evens AM, et al Non-Rituximab regimen Rituximab regimen Frequency of HBV reactivation 0.6% (3/453) 8.2% (20/244) *14-fold* Non-R R Hazard ratio 5.64 ( ) in the results of a meta-analysis, rituximab containing regimen has been demonstrated to be at a higher risk for HBV reactivation than non-rituximab regimen. a chimeric monoclonal antibody against CD20 (B-cells)

11 Hepatitis B Functional Cure: Hypothesis Role of B Cells & Anti-HBs A functional B cell response is essential to achieve a functional HBV cure = HBsAg loss/seroconversion Challenges and Opportunities: There are a range of B cell / anti-hbs responses, not all responses are equal in driving HBsAg clearance How do we identify and categorise the anti-hbs effectiveness (assays etc)? How can we apply this to drive B cell recovery in CHB & promote HBsAg clearance? How do we favour clearance versus non-clearance anti-hbs / B cell responses?

12 Major HBV Neutralisation Domain the a determinant (aa ) is highly conformational, with a raft of cysteine & proline residues forming discrete loops [loop1:aa ; loop2:aa ] containing the major immunogenic epitopes [Cooreman, et al., J Biomed Sci :237-47] alterations HBsAg a determinant topology directly influence the HBV neutralisation phenotype genotype/serotype variations clinical Vaccine Escape (VEM) sg145r selective therapeutic or immune (anti-hbs) pressures can influence epitope availability and HBsAg profile (loss or gain of binding) potentially a predictive biomarker for HBsAg response on-treatment measured as shape shifting or epitope availability (loss or gain) [Adapted from Torresi et al., Virology : ]

13 BioPlex Multiplex HBsAg Mapping Assay HBsAg Profile Assay Design Multiplex assay to identify/predict HBs variants & VEM s, and anti-hbs epitope profile by mapping the HBsAg fingerprint Developed a 19plex panel of anti-hbs mabs covering HBsAg a determinant and C-terminal domain (residues ) mab 13, 14, 15 mab 10 mab 5, 6 mab LOOP 1 13, 14 mab 15 mab 1 LOOP 2 mab 3 mab 4 mab 7, 8, 11, 12, 16, 17, 19 [Adapted from Bio-Rad; Conformational: mabs 9, 18 mab Anti-HBs mabs sourced from industry & academic collaborators N-terminal (1) Loop 1 (5,6,10) Loop 2 (7,8,11,12,16,17,19) Combo loop1/2 (13,14,15) Conformational (9, 18) C-terminal (2,3,4)

14 VEM Fingerprint: sg145r in vitro HBsAg Variants Phenotype Analysis 95% CI N-term Loop2 (mab17) C-term In vitro sn A2-adw2 baseline gain loss Loop1 Loop2 k/o Conformational Aberrant sg145r VEM phenotype detected across 9/19 mabs VEM predictive mab = 17 (loop2), increased epitope binding for sg145r VEM VEM k/o phenotype across 3 domains: loop1 (6), loop2 (8,12,16), Conformational (9) Loop 2 sg145r VEM alters HBsAg to confer an aberrant phenotype across multiple epitopes or a determinant domains

15 HBsAg Profile: Detection of HBsAg Response Leading to Anti-HBs Seroconversion on Therapy Hypothesis HBsAg epitope profiles are sensitive to therapeutic and immune (i.e. recovery of the B cell / Ab & innate immune responses on-treatment) pressure, and this can be predictive of HBsAg response (loss or seroconversion) on-treatment HBsAg clearance profile (CP) HBsAg epitope pressure (reduced recognition) at both loop 1 AND loop 2 epitopes - associated with HBsAg response/decline (>1log) and potentially HBsAg loss/seroconversion HBsAg non-clearance (or escape) profile (NCP) No change in HBsAg epitope profile, OR reduced epitope binding at only one loop - associated with no HBsAg response/decline (<1log) mab 1 mab 13, 14, 15 Conformational: mabs 9, 18 mab 5, 6 LOOP 1 LOOP 2 mab 10 mab 7, 8, 11, 12, 16, 17, 19 mab 13, 14 mab 15 mab 3 mab 4 mab 2 226

16 Mapping HBsAg epitope profiles to predict HBsAg loss/seroconversion in a treatment naïve cohort of genotype A chronic hepatitis B (CHB) patients receiving tenofovir disoproxil fumarate (TDF) therapy Renae Walsh, Rachel Hammond, Lilly Yuen, Peter Revill, Anuj Gaggar, Mani Subramanian, Kathryn Kitrinos, Alexander Thompson, Stephen Locarnini GS-US (G103) study cohort: HBsAg epitope profile analysis of HBeAg+ patients on NA therapy: Treatment naive CHB patients in the immune clearance phase (HBeAg positive) Treated with tenofovir (TDF) for 48weeks, & continued/followed out to > 4 years 96% achieved viral suppression & 15% HBsAg loss (22/142) at 4 years We studied a subset of 25 HBV genotype A patients: 14 achieved HBsAg loss/seroconversion 11 had no change in HBsAg (<1log decline to 4 years) HBsAg clearance profile (CP) v s non-clearance profile (NCP) conclusions: Significant association (p <0.02) between the development of a HBsAg CP and HBsAg Loss/Seroconversion [PPV 83%] by 48 weeks of treatment Walsh, R et al AASLD. Hepatology

17 Pre-TDF HBsAg NCP in HBsAg Loss Patient Typical pre-treatment NCP for HBsAg loss/seroconversion (Pt ID 3058) [normalised to HBV genotype/serotype backbone] On-treatment HBsAg Profile Analysis A2 adw2 baseline HBsAg loss/seroconversion patient with HBsAg NCP pre-tdf (switched to CP on-treatment)

18 On-TDF HBsAg CP in HBsAg Loss Patient Typical on-treatment CP for HBsAg loss/seroconversion (Pt ID 3058) [normalised to patient s baseline profile] On-treatment HBsAg Profile Analysis Pre-TDF baseline HBsAg loss/serconversion patient with HBsAg CP on-tdf: Switched to CP from pre-treatment NCP CP by wk12 [blue] &maintained at wk48 [orange] HBsAg loss by wk180

19 Pre-TDF HBsAg CP in HBsAg Loss Patient Typical pre-treatment CP for HBsAg loss/seroconversion (Pt ID 7002) [normalised to HBV genotype/serotype backbone] On-treatment HBsAg Profile Analysis A2 adw2 baseline HBsAg loss/seroconversion patient with HBsAg CP pre-tdf (CP maintained on-treatment)

20 On-treatment HBsAg Profile Analysis On-TDF HBsAg CP in HBsAg Loss Patient Typical on-treatment CP for HBsAg loss/seroconversion (Pt ID 7002) [normalised to patient s baseline profile] Pre-TDF baseline HBsAg loss/serconversion patient with HBsAg CP on-tdf: CP maintained from pre-treatment at wk12 [blue] & wk48 [red] HBsAg loss by wk168

21 Pre-TDF HBsAg NCP in HBsAg Non-Responder Typical pre-treatment NCP for HBsAg non-responder (Pt ID 7905) backbone] [normalised to HBV genotype/serotype On-treatment HBsAg Profile Analysis A2 adw2 baseline HBsAg non-responder patient with HBsAg NCP pre-tdf (NCP maintained on-treatment)

22 On-TDF HBsAg NCP in HBsAg Non-Responder Typical on-treatment NCP for HBsAg non-responder (Pt ID 7905) [normalised to patient s baseline profile] On-treatment HBsAg Profile Analysis Pre-TDF baseline HBsAg non-responder patient with HBsAg NCP on-tdf: NCP maintained from pre-treatment at wk24 [purple] & wk48 [blue]

23 Summary: G103 HBsAg CP There is a significant association between the development, maintenance or enhancement of a HBsAg CP and an outcome of HBsAg loss/seroconversion p-value 0.02 PPV: 83% NPV: 69%

24 HBV Biology and ARC-520 MOA Untreated ARC-520

25 Synopsis: ARC-520 Effect on HBsAg CP Identification of an HBsAg CP during the ARC-520 treatment cohorts trials 1-5: Cohort HBeAg BL (pre-treat) W1 W2 W3 W4 W6 W8 W12 1 (ARC, n=6) neg nt 0 1 (placebo, n=2) neg nt 0 2 (ARC, n=6) neg (placebo, n=2) neg (ARC, n=6) neg (placebo, n=2) neg (ARC, n=6) neg (placebo, n=2) neg (ARC, n=6) pos (placebo, n=2) pos Cohorts 1-5 BL (pre-treat) W1 W2 W3 W4 W6 W8 W12 ARC (n=30) (of 24) 5 placebo (n=10) (of 8) 1 p-value There is a significant association between development of a HBsAg CP and ARC-520 RNAi treatment at multiple timepoints

26 HBsAg Profiling ARC-520 Assumption: At pre-treatment / study baseline (day1) HBsAg & anti-hbs co-exist in equilibrium Treatment: ARC-520: RNAi Therapy Primarily induces HBsAg response / drop Secondarily facilitates partial recovery of the B cell (Ab) & innate immune responses Expected Outcomes: To observe a temporal relationship between treatment and an observed effect on the epitope profile. Thus a two phase profile: 1) initial reduction in HBsAg (approx. weeks 2-3) 2) followed by a shift in epitope profile (approx. weeks 3-8+)

27 Complexed Anti-HBs: Hypothesis Aim: To characterise the anti-hbs recovery response during and following ARC-520 Effect ARC-520 Treatment: Induces HBsAg response (reduction), potentially facilitating partial recovery of the B cell (Ab) & innate immune responses Predicted On-treatment Outcomes: Recovery of the anti-hbs response (complexed anti-hbs/hbsag) observed as: 1) Initial reduction in HBsAg & a shift in HBsAg epitope profile (possibly linked to host anti-hbs response) 2) Followed by detection of complexed anti-hbs (with HBsAg) due to antibody response recovery and/or improved ratio of complexed anti-hbs/hbsag compared to free HBsAg

28 Analysis qhbsag: HBsAg epitope profile: Free anti-hbs: Complexed anti-hbs: Conclusions: Walsh, R et al J Hepatol Strong HBsAg response to week2, relapse from week3 to EOS Early weak clearance profile at loop1&2 epitopes at week1, not maintained No free anti-hbs detected at any sample timepoint Complexed anti-hbs detected early at week1, & weak at week4, not maintained 1x1mg induced early HBsAg response & Clearance profile, and early anti-hbs recovery, not maintained

29 Therapy Associated HBsAg & Anti-HBs Responses Mechanisms of HBsAg reduction direct HBsAg load reduction effected by ARC-520 therapy, and/or free HBsAg reduced as complexed HBsAg/anti-HBs increases HBsAg Clearance Profile (loss of recognition at loop 1 & 2 epitopes) structural or folding change less likely with virus replication controlled to limit variant HBsAg anti-hbs specific for loop1 AND 2 HBsAg epitopes (either freed up or newly synthesised) drive a Clearance Profile, via: Complexed anti-hbs 1) increased anti-hbs complexing with HBsAg, or 2) treatment-targeted load reduction of free HBsAg to increase the ratio of complexed HBsAg/anti-HBs to result in HBsAg clearance profile direct anti-hbs recovery to increase complexed anti-hbs, and/or Reduction of free HBsAg increases the ratio of complexed HBsAg/anti-HBs to detectable levels ARC-520 treatment drives down HBsAg load & causes epitope profile changes as a consequence of direct antiviral activity AND enhanced anti-hbs recovery Walsh, R et al J Hepatol. EASL submitted

30 Are Broadly Neutralising Anti-HBs Responses Needed to Develop Functional Cures in CHB?

31 Study Design

32 Median HBV-DNA Over Time Distribution of the Occurrences of HBeAg Seroconversion over the Study Period Anti-HBs Responses All patients remained HBsAg positive Vandepapeliere, P et al Vaccine;25: In Vaccinated Arm: 83% seroconverted to anti-hbs Anti-HBs typically IU/L Several patients > 1,000 IU/L

33 HBV in vitro Neutralisation Assay Serially diluted sera/antibody PEG HepG2-NTCP AD-38 virus MOI 500 Cells supplied from Prof Stefan Urban Soppe, S. 2015

34 HBV XTL Antibodies

35 Prof M Mondelli HBV S MAbs PLOS ONE DOI: /journal.pone April 29, Pages 1-10

36 Hepatitis B Vaccinees: High Responders [anti-hbs: >1000 IU/L]

37 HBV Entry into Hepatocytes Urban, S et al Gastroenterology;147:48-64

38 Inhibitors of HBV Attachment and Entry Sodium taurocholate cotransporting polypeptide (NTCP) identified as HBV and HDV receptor in 2012 Myrcludex in phase 2 trials in chronic HBV and chronic HDV decrease in HBV DNA and HDV RNA Yan H, Elife 2012; 1:e00049 Lempp RA, Urban S. Intervirol 2014 ; 57: 151

39 A Synthetic Peptide Derived from the Large Envelope Protein of HBV Blocks HBV Infection in Susceptible Cells. Infection of HepaRG cells or PHH Incubation o/n at 37 C Collection of supernatant of days 8-12p.i. Gripon et al., PNAS, 99 (24) 2002 Urban et al., J. Virol, 79 (3), 2005 Glebe et al., Gastroenterology, 129, 2005 Engelke et al., Hepatology, 43, 2006 Schulze et al., Hepatology, 46, 2007 Measurement of secreted HBsAg/HBeAg etc.

40 Modified HBsAg VLPs (Bio-Nano-Particles [BNP]), Anti-HBs Immunogenicity, Broadly Neutralising Antibody and Functional Cure

41 VLPs : WT : sn146q : st116n : sg130n Journal of Virology 2015;89(22);

42 Schematic Diagram of HBsAg Hyakumura, M et al J Virol;89:

43 Secreted BNPs: WT, sn146q, st116n, sg130n N = non-glycosylated (24 kd) M = mono-glycosylated (27 kd) D = di-glycosylated (30-31 kd) Hyakumura, M et al J Virol;89:

44 Electron Micrograph of BNP WT sn146q st116n sg130n Hyakumura, M et al J Virol;89:

45 Immunogenicity in BALB/c Mice of BNPs Week 4 Week 6 Week 14 Week 20 Hyakumura, M et al J Virol;89: ? Neutralisability the Same as Immunogenicity?

46 Summary: Predicting HBsAg Loss On- Treatment: Summary Mapping the change in epitope recognition on TDF therapy revealed selection pressures directed against the HBsAg The HBsAg CP is a viral biomarker for HBsAg loss/response on-treatment, possibly reflecting emerging anti-hbs selection pressure Confirmed with the ARC-520 RNAi inhibitor studies Role in: Facilitating individualised patient therapy Predicting HBsAg loss / anti-hbs seroconversion Therapeutic applications (e.g. identification of novel B cell epitopes) Future Studies: Understand the mechanism of immune pressure on HBsAg Analysis of the anti-hbs response (quant anti-hbs, complex HBs/anti-HBs, serotype specific anti-hbs, anti-hbs isotype, broadly neutralising versus non-neutralising responses) Novel MOA : 1.Block Entry; 2.Accelerate Clearance; 3.Block HBV/HBsAg Release; 4.Fc-Dependent Processes (Opsono-phagocytosis;virolysis;ADCC) Therapeutic BNPs/peptide vaccine to mimic and effect an anti-hbs clearance profile (CP) response?