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]