ΔΙΗΜΕΡΙΔΑ 2017

Αναδυόμενες Θεραπείεςστη Χρονία Ηπατίτιδα Β

Στέφανος Ι. Χατζηγιάννης

“Emerging Therapies in Chronic Hepatitis B”

Stephanos J. Hadziyannis

Emerging HBV therapies are aiming at a Cureof chronic HBV infection.

Therefore a reminder of the meaning and definitions of HBV Cure is of order

In HBV infection the general term “Cure” is further differentiated into:

A. Functional or Clinical Cure

and

B. Complete HBV Cure*

*Also referred as Radical and VirologicalCure

Definitions of HBV Cure

HBsAg Anti-HBs Viraemia cccDNA

Functional Cure − + − +

Complete Cure − + − −

Functional Cure is also referred as Clinical Cure while Complete

Cure is also referred as Virological or Radical HBV Cure

Reminder of the 2 Definitions of HBV Cure

In this presentation the terms “Functional” and “Virological” (or complete) cure of chronic HBV infection refer to stable off-drug suppression of

HBV viraemia and HBs antigenaemia with

normalization of ALTs and with the suggestion that such cures should be the goal of future

therapies in all patients with CHB

Cure of HBV represents a most challenging issue because chronic HBV infection, despite the existence of a safe and protective HBV vaccine, still remains a major public health problem globally.

And, unfortunately, as stressed in a most recent article * on “Time Trends in Chronic HBV Infection Over Prior Decades” , some countries of Africa and Eastern Europe show stable and even increasing HBsAg prevalence.

*(Jördis J. J Hepatol. Jan 2017:48-54)

But first a note on Current Therapies in CHB and on what they

can achieve

Interferon alfa-2b

Lamivudine

Adefovir

Peginterferon alfa-2a

Telbivudine

Tenofovir

1990 1998 2002 2005 2006 2008

Entecavir

Τhe 2017 Landscape of HBV Therapy is the same as in 2008 except for TDF ALAF*

*Tenofovir Alafenamide (Vemlidi) first approved by FDA in late 2016

• This new nucleotide analogue is a pro-drug of Tenofovir, promising superiority compared to

Tenofovir, particularly regarding renal side effects and BMD .

• It has received FDA approval in November 2016 under the name of Vemlidi, a positive opinion of

MEA in Nov.2016 and approval for Europe on January 13, 2017

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0

2

4

-8

-6

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0

2

4

Seto, AASLD 2016, OP67

Changes in BMD in CHB Patients Treated with TAF or TDF

Study 108 and 110: Phase 3 CHB Studies

TAF treatment resulted in smaller decline in Hip and Spine BMD compared to TDF

-6

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SpineHip

Mea

n (

SD)

% C

han

ge F

rom

B

asel

ine,

g/c

m2

Week 0 24 48

TAF, N 851 822 807

TDF, N 426 405 404

0 24 48

856 830 814

426 410 407

p <0.001p <0.001 p <0.001

TAF TDF

p <0.001p <0.001

p <0.001

‒0.60

‒2.52

−2.43

−0.29

72

753

373

72

757

374

‒0.57

‒2.37−1.86

−0.16

But What Current anti-HBV Therapies Can Achieve?

They suppress the HBV but cannot eradicate the virus (no Virological Cure)

They achieve only low rates of HBsAg loss (Functional Cure) and only partial reversion of liver necro-inflammation and fibrosis

They reduce but do not eliminate the risk for

development of HCC

The Goal of New and Emerging Therapies in Chronic HBV Infection is:

At least to achieve functional cure and

Ideally eradication of HBV infection

The New Anti-HBV Drugs UnderDevelopment :

Are actually evaluated for their anti-HBV efficacy in the areas of 1.Interference with the viral replicative cycle 2.Elimination of covalently closed circular DNA 3.Modulation of host immunity and 4.Regarding several other aspects and targets.

In general, novel compounds have already shown great inhibitory effects on HBV replication in vitro and in animal models and in this context the Chimeric Mouse Model has offered important new information.

Tong S et al : Current Opinions Infect. Dis. 2016 Dec;29:632-38

The Chimeric Mice MUP-uPA/SCID/Bg Engrafted With Human Hepatocytes and Infected with HBV

or HCV

HBVHCV

The Landscape of New and Emerging HBV therapies

from 2014 to the end of 2015 has been reviewed in this

Meeting in 2015 and 2016 and in the following major

Review Articles:

• Durantel D and Joulim F. New antiviral targets and innovative treatment

concepts in HBV and HDV. J. Hepatol. 2016;64:S1-S132.

• Wiegand J et al. Clinical Trial Watch. Reports from the Liver Meeting of

AASLD of Nov. 2015. J. Hepatol. 2016;64:1428-1445.

• Peterson J. et al. Aiming for cure in HBV and HDV infection . J Hepatol

2016;65:836-48.

• Tajiri K. and Shimizu Y. Therapeutic Agents Against HBV Currently in

Development. WJH 2016

• The landscape from Jan. 2016 to Jan 2017 is

summarized in the present lecture.

The Following 3 Slides Summarize

the Landscape in 2015 and 2016

Therapeutic Approaches

Α΄ Targeting the Virus

• 1. Είσοδος του ΗΒV (και του HDV) στα ηπατοκύττταρα δια του

υποδοχέα ΝΤCP: Mircludex-Β

• 2. Συναρμολόγηση/ενκαψιδίωση του ιού:

Eteroaryldihydropyrimidines, phenylpropenamides, AT-130

• 3.΄Εκκριση του HBsAg :Nitazoxanide, tizoxanide, new triazolo-

pyrimidine inhibitors

• 4. Φακελλοποίηση των καψιδίων: Rep 9AC’ εμποδίζει την απέκκριση

HBsAg SVPs χωρίς να επιδρά στην έκκριση λοιμωδών σωματιδίων ιού

• 5. Σε επίπεδο cccDNA : Αδρανοποίηση/αποβολή /διάσπαση/

/επιγενετική σιωποίηση: Zinc-finger nucleases (ZFNs), disubstituted

sulfonamides (DSS), termed CCC-0975 and CCC-0346,

• 6. Σε επίπεδο αγγελιοφόρου mRNA του ιού: RNA-i

Therapeutic Approaches

B΄ Targeting the Host

• TLR agonists: GS-9620, ένας από του στόματος

χορηγούμενος αγωνιστής του TLR-7

• Κυτταροκίνες :IL-7 και IL-21

• Προγραμματισμένος κυτταρικός θάνατος-1:

programmed death ligand-1

• Tregs

• Θεραπευτικοί εμβολιασμοί

And New Compounds Against HBV

Appearing to Emerge in 2015

However similar was the Landscape in 2016 (As Reviewed by Tajiri K. and Shimizu Y. in the WJH)

I have grouped the hitherto relevant research and strategies in the development of new HBV

(and HDV) therapies in 4 MAJOR categories:

A. Direct Acting Antivirals (DAAs) targeting :

1.HB pol* 2.HB core 3.HB surface 4.HBV RNAs

B. Host Targeting Antivirals (HTA) for:

1.NTCP 2.Promotion of Apoptosis 3.Prenylation/Farnesylation (in HDV infection)

C. Immune Stimulations (e.g. IFN-λ, TLR7 agonists)

D. Adaptive Responses (e.g. Therapeutic Vaccines)

*Regarding the first major category i.e. of DDAs

it is important to remember that:

• All current antivirals for CHB are nucleos(t)ide analogues (NAs) inhibiting only the reverse transcriptase (RT) activity of the polymerase enzyme of the virus.

• However, this enzyme executes many functions required for the replication cycle of the virus including viral RNA binding, RNA packaging, protein priming, template switching, DNA synthesis and RNA degradation and for these functions, it must interact with host proteins .

• Thus, new inhibitors of HBV DNA polymerase may inhibit not only the DNA synthesis steps, carried out by the RT domain (as all current antivirals do), but also other domains, functions and interactions which are essential to the HBV replication cycle

Possible Targets of Therapy are shown in green in a Simplified Schema of the Hepatitis B Virus Life Cycle

Figure 1

And in a more detailed figure Potential Targets of Anti-HBV Therapy are numbered from 1 to 9)

New and Emerging HBV Therapies

Target Point * Agent Clinical Development Phase

1 Entry Inhibitors 2

2 cccDNA Inhibitors Preclinical

3 Silencing cccDNA Preclinical

4 Capsid Formation Inhibitors Preclinical and 1/2

5 HBV Polymerase Inhibitors 2 and 3

6 HBV RNA Interference Preclinical and 1-2

7 HBsAg Release Inhibitors 2/3

8 TLR Agonists & anti-PD1 Preclinical and 2

9 Therapeutic Vaccines 1,2 and 3

* Points 1-7 refer to the life cycle of HBV and points 8 and 9 refer to host targets

New compounds for HBV therapy

Target Compound Clinical Phase

1. NTCP Myrcludex 2

2 . HBV pol TDF Alafenamide 3

Besifovir 3

Agenix 3?

3. HB core GLS-4 2

NVR -778 1

4. HBsAg REP-2139 Ca 2

5. HBV RNA siRNA ARC 520 2

ISIS-iHBV Rx 1 or 2

6. Apoptosis Birinapant 1

7. Frenylation/ Lonufarnid 2

Prenylation

8. pDC Stimulation TLR7 Agonist 2

& anti-PD1 (GS-9620)

9. Adaptive Immune ABX-302 2/3 2

Responses GS-4774

(Tamogen)

Regarding HBV cccDNA (Targets 2 and 3)

Genome editing technologies, such as zinc finger nucleases, transcription activator-like effector nucleases, and the clustered regularly interspaced short palindromic repeats/Cas9 (CRISPR/Cas9) system, which are designed to target specific DNA sequences, represent highly promising potential therapeutic tools.

In particular, the CRISPR/Cas9 system is an easily customizable sequence-specific nuclease with high flexibility and may be the most feasible approach to target HBV cccDNA.

Further research to develop easier, safer, and more effective protocols should be pursued.

Ohno M et al: WJG 2015 (23):7084-8

Lin G. et al: Application of CRISPR/Cas9 Technology to HBV. Int. J. Mol. Sci.2015,16,26077-86

And for Targets 8 and 9 it must be noted that New Concepts and Insights concern:

Immune responses in the different phases of chronic

HBV disease.

The HB viral/immune interactions of T and B cells.

Evolution of new HBV therapies combining directly

acting antivirals with immunomodulatory approaches

Mechanisms contributing to the exhaustion of HBV-specific CD8+ T cells. There are several mechanisms involved in T-cell exhaustion during chronic HBV infection, including high viral (or

antigen) load, loss of CD4+ T-cell help, suppressive cytokines IL-10 and TGF-β and DCs, as well as Treg cells, which are the major sources of the immunosuppressive cytokines IL-10 and TGF-β. All

these factors are able to promote the exhaustion of T cells during chronic HBV infections.

B Ye, X Liu, X Li, H Kong, L Tianand Y Chen, Cell Death and Disease (2015) 6, e1694

Few novel therapeutic approaches have already reached with success clinical phase 2 with promising results and are becoming candidates for Phase 3 clinical (Preregistration) trials.

Yet, even when such new therapies become approved for clinical application they have to be applied not alone but in combination with current antivirals, or even as components of a multi-target therapeutic approach of CHB, aiming at functional and hopefully at radical HBV cure .

But up to January 2017 :

This is actually illustrated with the case of inhibitors of HBsAg secretion

Several agents have been found in in-vitro and in-vivo studies, in

animal models, in pre-clinical and clinical trials, to suppress the

secretion of HBsAg with the most promising ones currently

appearing to be the siRNA and NAP based therapies.

It is quite possible that such HBsAg secretion inhibitors

applied in combination with first line NAs will achieve functional

cure of HBV.

Thus in the last AASLD Meeting an RCT was reported on:2 nucleic acid polymers (REP 2139- Mg or its

derivative REP 2165-Mg) used in CHB in combination with TDF and Pegasys:

The new therapy blocks the expression of HBsAg with a nucleic acid polymer and then hits it with 2 commonly applied antivirals (= a two punch hit to HBV) .

The nucleic acid polymers block the assembly and release of the HBsAg subviral particles from hepatocytes and this results in a mechanism that leads to an efficient clearance of HBsAg from the blood.

Other studies on new HBV therapies

presented

at the 2016 Meeting of AASLD

have focused on:

HBV entry inhibitors

HBV capsid or core inhibitors

Inhibitors of HBV gene expression

Inhibitors of HBV cccDNA formation & stability

Immunological approaches:

Non-specific

HBV specific

Therapeutic vaccines

Inhibitors of the Capsid or Core of HBV

A. Of the encapsidation of pgRNA

(by phenylpropenamide derivatives)

B. Of the assembly of the nucleocapsid

(by heteroaryl-dihydropyrimidines)

Compounds shown in White and Pharmas in Green

ΝVR1221/3778 (Novira), Sulfamoylabenzamides (Oncore),

GLS4 (HEC Pharm group-China) , Bay41-4109 (AiCuris), (agents

from Roche, Janssen, Assembly, Biosciences et al)

And the same is true for inhibitors of the expression of other HBV genes

• Inhibition of mRNA:Overlapping reading frames of RNA in the HBV genome are ideal HBV target for RNA interference with

–Antisense oligonucleotides

–Ribozymes

–Short interfering RNA (siRNA or just RNAi)

REP2139-Ca (Replicor), ARC520 (Arrowhead), TKM-

HBV (Tekmira), ALN-HBV (Alnylam), DNA-directed RNAi (Benitec), ISIS HBV (Isis)

On the basis of hitherto published and recently reported data the following considerations and

suggestions can be made on Emerging HBV therapies A.

1. Treatment strategies of lowering serum HBsAg levels as small interfering RNAs (siRNAs) and nucleic acid polymers (NAPs) are most promising in terms of functional HBV cure, may have an impact on immune restoration, are in advanced clinical phases but further clinical evaluation is still needed.

2. It is most likely that for a radical HBV cure a combination of strategies targeting directly or indirectly cccDNA and immune restoration will be needed

B.

3. The efficacy of new antiviral drugs and immune restoration strategies need to be balanced with potential induction of damage of the liver and/or of extra-hepatic sites (a dilemma vs the suboptimal but safe current NAs).

4. Immune restoration or boosting of innate immunity leading to a non-cytolytic purging of cccDNA may be considered as a safe approach.

Το siRNA (ή απλώς RNAi) και το γενετικό σύστημα CRISPR/Cas9

Αποτελούν προοπτικές ευρύτερης θεραπευτικής σημασίας και ειδικότερα η εφαρμογή του siRNA στα νοσήματα του ήπατος, προάγεται με σύνδεσή του με GalNac: Μια χημική ενότητα που αναγνωρίζεται και προσλαμβάνεται από τους υποδοχείς ασιελογλυκοπρωτείνης της επιφάνειας των ηπατοκυττάρων.

Levin A.A. Clinical Implications of Basic Research. Targeting Therapeutic Oligonucleotides. NEJM 2017;17: 86-88

΄Οσον αφορά το εύρυτερης θεραπευτικής

σημασίας σύστημα CRISPR/Cas9 μου δίνεται η

ευκαιρία να αναφερθώ με καμάρι και σε δύο

΄Ελληνες ερευνητές που διέπρεψαν παγκοσμίως

τo 2016:

• Οι Κ.Τζελέπης και Γ.Βασιλείου, από το Ινστιτούτο

Wellcome Trust Sanger ανέπτυξαν μιά εξελιγμένη

μορφή της γενετικής μεθόδου CRISPR/Cas9 gene

editing με στόχο την γονιδιακή θεραπεία της Οξείας

Μυελογενούς Λευχαιμίας.

Hoping that data from successful phase 3 Registration RCTs on the efficacy and safety of the currently most-promising New Therapies become available soon and reviewed critically in this Meeting on Viral Hepatitis of

following years

And a Final Slide to

Thank you for attending this presentation in which I have tried to

cover in an understandable by clinicians approach the large and complex topic of “Emerging Curative HBV Therapies”