IAS 2015 Towards an HIV Cure symposium Vancouver
HBV Cure: Possible Lessons for HIV
Professor Stephen Locarnini WHO Regional Reference Laboratory for Hepatitis B, Victorian Infectious Diseases Reference Laboratory,
Doherty Institute Melbourne, Victoria 3000, AUSTRALIA
Disclosure
Gilead
Sciences Arrowhead Research
Consulting Fees yes yes Fees for Contract Research and/or Clinical
Trials yes yes
Outline of Presentation
1. Introduction 2. Barriers to Curing Chronic
Hepatitis B 3. Overcoming the Barriers
a) Virological b) immunological
4. Challenges and Opportunities Ahead
Hepatitis B: Global Burden • 240 - 350 million people living with CHB globally
– Ott, JJ, et al. 2012. Vaccine;30:2212-2219. Lavanchy, D. 2004. J Viral Hep;11:97-107.
• 786,000 attributable deaths from hepatitis B annually in 2010; 1.3 million from viral hepatitis B & C collectively (GBD 2010)
– Lozano, R et al 2012. Lancet;380:2095-128
• Viral hepatitis was the 9th ranked cause of human death; similar numbers of deaths to HIV, malaria and TB (GBD 2010)
– Lozano, R et al 2012. Lancet;380:2095-128. Cowie, B et al 2013. Antiviral Ther;18:953-954.
• Without appropriate management, 15-25% of people with CHB will develop advanced liver disease &/or HCC
– Lavanchy, D. 2004. J Viral Hep;11:97-107.
• Liver cancer is the 2nd most common cause of cancer death globally
– GBD report 2013
Serology
HBeAg Anti-HBe
ALT level
HBV DNA level
Disease
Minimal
necroinflammatory
activity
Chronic hepatitis Cirrhosis/HCC
Immunotolerance Immunoelimination HBeAg-Negative
0 10 20 30 40 50 60 70 Years
IFN-α LMV/LdT ADV/TVF ETV
THERAPY
Phase
Viral Load (IU/ml) >20,000 >2,000 >20,000
Inac
tive
HBsAg
Occ
ult
<2,000
Natural History
CH-B
Current Treatment Challenges and Why we Need a Cure
• if use low genetic barrier NUCs, drug resistance a serious problem
• in China, > 3 x 106 LAM-resistant cases • long term therapy with NUCs (> 3 years) affects
patient compliance and typically has little effect on HBsAg levels
• Peg-IFN has substantial toxicity, low (<20%) efficacy
• Cost: very few countries in high prevalence regions have reimbursement policies
• HBsAg-positivity poor prognosis
Importance of HBsAg Clearance/Seroconversion
• ↓ Hepatic decompensation • ↓ HCC • ↑ Survival • ↓ Levels of cccDNA • As close to cure as we can
expect to achieve in chronic hepatitis B
Fattovich G, et al. Am J Gastro 1998; 93:896-900. Werle-Lapostolle B, et al. Gastroenterology 2004; 126(7):1750-1758. Perrillo R. Hepatology 2009; 49:1063-1065
Major Barriers to Curing CHB
• Viral cccDNA Both unaffected by NUC therapy HBsAg
• Immunological
– T-cell exhaustion – emerging role of (inadequate) B-cell
responses
Productive HBV Replication: cccDNA Pathway
Uncoating
ER
Mature Nucleocapsid
Immature Nucleocapsid
Nuclear Transport
RC-DNA
Transcription
viralRNA
Core Polymerase
Surface
HBeAg Spherical & Filamentous HBsAg
GOLGI
Translation
Precore
Mature HBV virion
Intracellular Conversion Pathway RC-DNA
Reverse Transcription
RC-DNA
1. RC DNA cccDNA • DNA repair • TDP-2
Koniger, C et al 2014. Proc Natl Acad Sci;111:4244
2. HBeAg (early protein) • synthesised from
precore mRNA
Non-Productive HBV Replication: HBsAg (from Integrated DNA) Pathway
Uncoating
ER
Mature Nucleocapsid
Immature Nucleocapsid
Nuclear Transport
RC-DNA
Transcription
viralRNA
Core Polymerase
Surface
GOLGI
Translation
DSL- DNA
HBsAg Pre-S truncation
Viral Integration
Spherical & Filamentous HBsAg
Mature HBV virion
Viral Integration Pathway DSL- DNA
Reverse Transcription
Bock, T. et al 1994. Virus Genes;8:215
Bock, T. et al 2001. JMB;307:183
Newbold, J and Locarnini, S 1995. J. Virol;69:3350
High Replication Phenotype
Transcriptionally Active High Viraemia
Low Replication Phenotype
Quiescent or active Medium to Low Viraemia
The cccDNA is a Minichromosome
HBV Minichromosomes and Chromatin Modelling
• Relaxed Chromatin : Histone Acetylase (HAT)
– transcription activation complex containing HATs – HATs acetylate lysine residues of the histone tails
• Compacted Chromatin : Histone Deacetylases (HDAT)
– transcription repression complex containing HDAC – HDACs deacetylate histone lysine tails
• Conclusion – acetylation status of HBV minichromosome (cccDNA-bound H3 & H4
histones) regulates HBV transcription/replication and is reflected in viral load
Activation of Gene Expression
Repression of Gene Expression
Pollicino, T. et al 2006. Gastroenterology;130:823
Haematologica. 2009;94(11):1618-22
HBV and Subviral (HBsAg) Particles
• HBsAg secreted in vast excess over virions (3-4 orders of magnitude)
• circulate in blood 100-400 µg/ml • half-life is ? • NUC therapy has minimal effect on HBsAg levels or its
clearance
HBsAg as An Immune Regulator • mounting evidence for HBsAg proteins
playing a key role in HBV persistence • can suppress both innate (TLR-2,
TLR-9 and IFN-α) as well as adaptive (mDC) responses to infection
• “immuno competence” of host can affect HBsAg “set-points”
• co-existence of HBsAg and anti-HBs (include heterologous sub-type specificity) Wang, S et al 2013. J Immunol;190:5142.
Xu, Y et al 2009. Mol Immunol;46:2640. Op den Brouw, ML et al 2009. Immunol;126:280.
Zhang, J-M et al 2007. Clin Infec Dis;44:1161.
HBsAg Major Neutralisation Domain The major anti-HBs neutralisation domain contains major immunogenic epitopes located within Loop1 (aa107-138) and Loop2 ( aa139-147).
The ‘a’ determinant is highly conformational, with a raft of cysteine & proline residues
HBsAg ‘a’ determinant topology and/or epitope availability influence the HBV neutralisation phenotype
HBsAg ‘a’ determinant model
Selective 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
- developed a 19plex panel of anti-HBs mAbs covering HBsAg ‘a’ determinant and C-terminal domain (residues 99-226)
[Cooreman, et al., J Biomed Sci. 2001. 8:237-47]
N-terminal (1) Loop 1 (5,6,10) Loop 2 (7,8,11,12,16,17,19)
Combo loop1/2 (13,14,15)
C-terminal (2,3,4)
Conformational (9, 18)
In a treatment naïve cohort of genotype A chronic hepatitis B (CHB) patients receiving tenofovir disoproxil fumarate (TDF) therapy (TF103 trial):
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)
Conclusion/Findings 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 (2015), submitted
Nucleic Acid-Based Approaches
Name Approach Phase Company
ARC-520 RNAi IIa Arrowhead
TKM-HBV RNAi Preclinical Tekmira/OnCore
ALN-HBV RNAi Preclinical Alnylam
ddRNAi DNA-directed RNA Preclinical Benitec/Biomics
Isis HBV anti-sense Isis/GSK
RNA Therapeutics can Reduce HBV RNAs and Protein Production Differentiation from nucleos(t)ide reverse transcriptase inhibitors
Nucs (NRTI)
X siRNA
X & core
Revival of innate and adaptive immune response and functional cure
HBeAg HBsAg
↓
↓
↓ ↓
Wooddell, CI et al 2013. Molecular Therapy;21(5):976-985
TKM-HBV: Targeting Multiple HBV Transcripts
• Design an anti-HBV RNAi Trigger ‘payload’ that is: ─ Potent - reduces viral protein
production, especially HBsAg ─ Universal - effective against all
genotypes
• All three triggers target the 2.1/2.4 kb sAg encoding mRNAs and also cleave 3.5 kb and 0.7 kb mRNA and pgRNA with potential for additional therapeutic benefit by reducing eAg, HBx, and core Ag
Kindly provided by Dr Mike Sofia & Dr Tom Frohlich
TKM-HBV: Reduction in Multiple HBV Markers • deep reduction in HBsAg
• strong inhibition of HBeAg
• viral DNA and cccDNA are reduced by TKM-HBV Liver HBV DNA
cccDNA Liver Serum
n=5, mean ± SEM
Day 32 Day 42 (terminal analyses)
Serum eAg
0
25
50
75
100
125
% U
n t r e
a t e d
a t D
a y 4
2
0
25
50
75
100
125
% U
n t r e
a t e d
a t D
a y 3
2
20
Arrowhead Research • Achieved similar effects in HBV-infected chimpanzees
Lanford, RE 2013. Hepatology;58(S1):705A-730A
Kindly provided by Dr Mike Sofia & Dr Tom Frohlich (Tekmira/OnCore)
ARC-520 in CHB Patients • Phase 2 multicenter, randomized, double-blind, placebo-
controlled, dose-escalation study in HBsAg+ (>1000 IU/ml), HBeAg-neg CHB patients with viremia controlled on ETV – randomized 1:3 (placebo or ARC520) for up to 24 patients
• Single IV dose at 1, 2 and 3 mg/kg • Safe, well-tolerated, no SAE’s or dose-limiting toxicities • 1mg/kg group:
• mean HBsAg nadir: -39% (-22 to -57) • mean HBsAg change on day 85: -31% (-14 to -39)
• 2mg/kg group: • mean HBsAg nadir: -51% (‘46 to -59) • mean HBsAg change on day 85: -22% (range -7 to -40) • Statistically significant difference vs placebo from days 3 to 43
post-dose • 3mg/kg group: Results not yet available
Yuen, MF et al 2014. Hepatology;60:1267A-1290A
Dynamic Polyconjugate (DPC) Technology for siRNA Delivery in vivo • DPC polymer composition
and physical characteristics – amphipathic peptide – peptide amines reversibly
“masked” with CDM – slightly negatively charged
• cellular uptake of peptide is ligand-driven (N-acetyl galactosamine (NAG)) for hepatocytes)
• siRNA is made liver tropic by attachment of lipophilic ligand (e.g. cholesterol)
• ↓ pH in endosomes drives peptide unmasking
• unmasked peptide disrupts endosomal membrane
• siRNA released to cytoplasm
Rozema, DB et al 2007. Proc Natl Acad Sci(USA);104:12982
Overcoming the Immunological Barriers i. Role of Immune Regulatory Receptors • in CHB, immune regulatory receptors (IRR) have been
shown to be the key drivers of T-cell dysfunction [eg: PD-1] (Fisicaro, P et al 2010. Gasto;138:682-693.,
Fisicaro, P et al 2012. Gastro; 143(6):1576-1585.e4)
• blocking these inhibitory IRRs has the potential to restore T-cell function [eg: anti-PD-1/PD-L1] (Robert, C et al 2013. Euro J Cancer; 49(14):2968-71)
ii. Follicular Helper T-Cells (Tfh) • Tfh (CXCR5+ CD4+) under influence of IL-21 provide
help to B-cells • elevated serum IL-21 levels associated with HBeAg
seroconversion (Ma, S-W et al 2012. J Heapatol;56:775-781)
Immunotherapy: Results Reported at AASLD 2014
Product Description Company ABX-2013 Therapeutic vaccine: HBsAg,
HBcAg Center for Genetic Engineering and Technology, Cuba AbiVax
GS-4774 Therapeutic vaccine: yeast based, express HBV S, X and core proteins
Gilead
GS-9620 Oral agonist of TLR-7 Gilead DV-601 Therapeutic vaccine with
recombinant HBsAg and HBcAg and adjuvant
Dynavax
Why have attempts at therapeutic vaccination failed? • approaches not HBV-specific or target only 1 HBV
epitope • HBV replication and HBsAg production not shut down • inappropriate selection of patients
• TLR-7
− intracellular pathogen sensor
• endolysosomal RNA
− agonism induces anti-viral response via innate immune activation
• GS-9620
− oral
− nanomolar potency
− selective (TLR-7 >>> TLR-8)
− pharmacodynamic effects in mouse, cyno, chimp, human
− efficacy in woodchuck model
N
N N
HN
O
NH2O
N
GS-9620: Oral TLR-7 Agonist
Menne, S et al 2015. J Hepatol;62:1237
0
20
40
60
80
100
1.00E+04
1.00E+05
1.00E+06
1.00E+07
1.00E+08
-30 -15 0 15 30 45 60 75 90 105 120 135
Percent of Pretreatment
day
4x0139Viral Titer HBeAg HBsAg
108
107
106
105
104
IU/m
L
1mg/kg 2mg/kg
Lanford, RE et al. 2013. Gastroenterol;144(7):1508-1517
GS-9620: Reduction in HBV DNA, and Serum HBsAg and HBeAg in Chimpanzee
Reverse T Cell Exhaustion by PD-1/PD-L1 Pathway Blockade
Exhausted Functional
PD-L1 Ab
PD-1 Ab
Proliferation Cytokine secretion
Cytotoxicity
Proliferation IFN-γ, TNF-α, IL-2
Cytotoxicity
In vivo PD-L1 Blockade Synergizes with Therapeutic Vaccination to Control WHV Replication.
DNA WHsAg
Liu, J et al 2014. PLOS Pathogens;10(1):e1003856
Companies Developing the Anti-PD-1/Anti-PD-L1 Therapies BMS, Merck & Co, Novartis, Roche, MedImmune
Stopping Treatment APASL Recommendation to Stop Antiviral Treatment (Liaw, Y-F et al 2008. Hepatol Int;2:263)
In HBeAg-positive patients: when HBeAg seroconversion has developed > 6 months In HBeAg-negative patients: when HBV DNA remaining undetectable for three separate occasions 6 months apart • Outcomes
– 25-50% develop viral relapse with hepatitis – up to 40% remain treatment free (SVR) – half of these lose HBsAg
• Factors – HBV DNA undetectable at stop – HBsAg < 100 IU/ml [low] – duration of AV therapy (4-5 years)
Hadziyannis, S et al 2012. Gastro;143:629. Liang, Y et al 2011. Aliment Pharacol Ther;34:344.
Patwardham, N et al 2014. Aliment Pharmacol Ther;40:804. He, D et al 2013. BMC Infec Dis;13:458. Jeng, W-J et al 2013. Hepatol;58:1888.
International Efforts to Cure CHB • Coalition to Eradicate Viral Hepatitis from Asia-Pacific
(CEVHAP): policy & advocacy • ANRS – Collaborate Workshop (Zeisel, MB et al 2015. GUT;0:1-13)
• ICE-HBV - International Collaboration to Eradicate HBV (being modelled on IAS approach): viral and immunological targets
• Philanthropy – focused on vaccination • Pharmaceutical Companies
– post-HCV era
• Professional Societies (EASL, AASLD, APASL) • Hepatitis B Foundation (USA): community
engagement
• The goalposts are shifting • The medium-term aim for the field is to achieve
“cure” – HBsAg seroconversion
• New agents for CHB are starting to emerge – identification of a HBV-Receptor (NTCP) is paradigm
shifting – improved delivery to the liver for molecular
therapeutics now a reality
Future Perspectives and Developments
PALPABLE OPTIMISM
What Might a HBV Curative Regimen Look Like?
Potent NA
cccDNA Inhibitor
Immune Activator
HBV Antigen Inhibitor
⊕
⊕
⊕
agent to prevent viral spread and cccDNA re-amplification
safe and selective agent to reduce or silence cccDNA
agent(s) to activate specific antiviral immune responses or relieve repression/exhaustion of the system
agent(s) to block/inhibit the HBV life-cycle [entry, cell-spread, capsid assembly, HBx, HBeAg, HBsAg]