New Treatment Modalities

- Innate Immunity -

Adam J. Gehring, Ph.D.Biology Lead

Toronto Centre for Liver Disease

University Health Network (UHN)

Assistant Professor

Department of Immunology

University of Toronto

Disclosures: Gilead, Janssen, Novartis

Innate Immune Response to HBV

➢ Still have little understanding of its role in early viral response

➢ Studied mainly in context of immunopathogenesis of chronic HBV

➢ Arguably more complex than the T cell response

❖ Parenchymal cell responses • Hepatocytes, Endothelial Cells, Stellate cells

❖ Antigen presentation by professional antigen presenting cells (APCs)• Dendritic cells (DC), monocytes, macrophages

❖ Activation of innate effectors• NK cells, MAIT cells, γδ T cells

• Innate effectors can be negative regulators in chronic HBV patients

• Little data on their role in recognizing/eliminating infected hepatocytes

Pallett. Nat Med 21, 591–600 (2015).

Gehring J Clin Invest. 2013 Sep 3;123(9):3766-76 Boltjes PLoS ONE. 2014;9(5):e97006.

Myeloid cell function in chronic HBVDendritic cell • Ex vivo function largely intact

• In vitro studies: Inhibited, activated by HBV

Monocytes• Contain HBsAg in vivo

• No evidence of altered stimulatory capacity

• Intact cytokine production

TNF-α

Alterations in the Innate Immune Response to HBV

Caveats of myeloid cell analysis• Short-lived compared to T & B cells

• Spend few days in circulation

• Susceptible to environmental changes

Myeloid Derived Suppressor Cells (MDSC)• Produce Arginase and IL-10

• Suppress T cell expansion

Gehring Cell. Mol. Immunol. 2015 May;12(3):283–91

NK cell IFN-γ production suppressed• Related to IL-10

• Especially in hepatitis patients

Peppa, PLoS Pathog. 2010 Dec 16;6(12):e1001227.

Peppa J. Exp Med. 210, 99–114 (2013).

Alterations in the Innate Immune Response to HBV

NK cells kill HBV-specific T cells• TRAIL Mediated killing

Dunn, J. Exp Med. 2007 Feb 20;204(3):667–80.

NK cells kill hepatocytes via TRAIL• Induced by IFN-α

• Not HBV-specific (HepG2 cells)

A) Blocking NK TRAIL-mediated killing of HBV-specific T cells.

B) Inducing presentation of the HBV antigen depot in monocytes

C) TLR-8 activation of intrahepatic monocytes stimulating IL-12 and IL-18

D) TLR-7 mediated IFN-a production from plasmacytoid DC.

E) NKT cell recognition of CD1d on infected hepatocytes.

F) Blocking MDSC-mediated suppression

G) Direct triggering of RIG-I in infected hepatocytes

H) CpG induction of iMATEs

Opportunities for Innate-targeted

Immunotherapy

Maini & Gehring. J. Hepatol. 64, S60–S70 (2016).

Pattern Recognition receptors• TLR-7

• TLR-8

• Rig-I

• STING

• Inactivated viruses (PPOV)

Impact on antigen processing and T cell stimulation is unknown

Current Targets for Immunomodulatory Drug

Development

Indiscriminate

Targeting innate/antiviral cytokine production, • mainly from myeloid cells

• Cytokines: IL-1α, IL-1β, IL-6, IL-10, IL-12, IL-18, TNF-α,IFN-α, IFN-λ

• Chemokines: CXCL-8, -9, -10, Mip1a, Mip1B, MCP-1

Gehring, Best Pract Res Clin Gastroenterol. 2017 Jun;31(3):337-345

Mouse work clearly shows that innate activation can reduce HBV replication• infection with other viruses that stimulate innate immune response

• injection of TLR agonists

Mainly an IFN-α mediated response• Highly effective in mice

• IFN-α therapy in humans not so effective

Rationale for Targeting Pattern

Recognition Receptors

Isogawa J. Virol. 2005 May 12;79(11):7269–72.

Ebert, Gastroenterology. 2011 Aug;141(2):696–706.e3.

Luangsay J. Hepatol. 2015 Nov;63(5):1077–85.

RIG-I activation suppresses HBV replication in mice• Stimulates IFN-α, IFN-β and IFN-λ + other cytokines

Rationale for Targeting Pattern

Recognition Receptors

TNF-α

IFN

-γ

NK bright MAITLiver cells + TLR-8

TLR-8 activation of human liver monocytes

induces IL-12 and IL-18 production• Induces innate effector IFN-γ production

• NK cells, MAIT cells, γδ T cells

IL-12 restores HBV-specific T cell function in vitro• Increases IFN-γ production

• synergizes with anti-PD-L1

• Injected into chronic HBV patients = No success

Th1 promoting cytokines clear HBV from the mouse liver- IL-12/IL-18 injection in mice

- Induced IFN-γ production by NK/NKT cells

IL-12

IL-18

Rigopoulou Hepatology. 2005 Nov 1;42(5):1028–36.Schurich, PLoS Pathog. 2013 Mar 14;9(3):e1003208.

Jo et. al. PLoS Pathog. 2014 Jun;10(6):e1004210.

Kimura. J. Virol. 2002 Nov 1;76(21):10702–7.

Cavanaugh J. Virol. 1997 Apr;71(4):3236–43.

Pattern Recognition receptors• TLR-7

• TLR-8

• Rig-I

• STING

• Inactivated viruses (PPOV)

Current Targets for Immunomodulatory Drug

Development

Indiscriminate

Targeting innate/antiviral cytokine production, • mainly from myeloid cells

• Cytokines: IL-1α, IL-1β, IL-10, IL-6, IL-12, IL-18, TNF-α,IFN-α, IFN-λ

• Chemokines: CXCL-8, -9, -10, Mip1a, Mip1B, MCP-1

Gehring, Best Pract Res Clin Gastroenterol. 2017 Jun;31(3):337-345

TLR-7 IFN-α

TLR-7-mediated IFN-alpha Production and

Antiviral Efficacy

Janssen, H.L.A., AASLD Liver Meeting 2016; Poster ID: 1851

Gilead GS-9620 Phase II study• Data from 2016 AASLD

• 12w treatment with 12 w follow-up

• HBsAg decline < 0.5 Log10

Roche RG7795 (RO6864018)• Phase II, 12 w treatment

• No data available

• Removed from PhII Q3 2016?

Grippo, J., AASLD Liver Meeting 2016; Poster ID: 1869

Direct triggering of RIG-I in infected hepatocytes

Korolowicz. PLoS ONE 11, e0161313 (2016).

Chronic Woodchuck Hepatitis Virus Infection model

SpringBank SB-9200• Phase II

• 12 w daily administration then 12 w tenofovir

• Cohorts: 25, 50, 100, 200 mg

Yuen, presented at International HBV meeting, 2017

25 mg SB9200

TLR-8

IL-12/18

NK & MAIT

IFN-γ

TLR-8 activation of intrahepatic monocytes

stimulating IL-12 and IL-18

Daffis et. al. Presented at EASL 2017; ID: SAT-165

Gilead GS-9688• Phase I for chronic HBV

• WHV Data• 8w treatment window

• Significant reduction in WHV DNA

• Significant reduction in HBsAg

Pattern recognition receptor agonists (TLRs, RIG-I)• Real potential - justification from mice – realistic doses?

• IFN-α – limited efficacy

• IL-12 & IL-18 show good mouse/in vitro data but human data is lacking

• Liver is dominated by innate effectors

• Will they respond as predicted by tests in PBMC?

• Can antiviral immunity be targeted over inflammation?

• How can NK cells, γδ T cells, MAIT clear infected hepatocytes?

Negative Innate regulators of immunity• MDSC, NK-TRAIL

• Unclear if negative regulation can be effectively targeted

• Arginase inhibitors, IL-10 neutralization, TRAIL blocking

• Mechanisms may be cohort-specific

Will Innate Immunotherapy Strategies

Improve HBV Cure?