Mala MainiDivision of Infection and Immunity

UCL, London

Toronto HBV Cure 2016

Checkpoint inhibitors for HBV cure

Effective T cells control virus Exhausted T cells loose control of virus

CD8 T cells

Infected hepatocytes Infected hepatocytes

INF-γTNF-αIL-2

GranzymePerforin

?Checkpoint blockade

Reversal of T cell exhaustion: the goal of checkpoint inhibitors

T cell activation requires 3 signals

Signal 1

Signal 2

Signal 3

Excessive co-inhibitory signals drive T cell exhaustion

Iwai Y et al, 2003, J.Exp. Med, Dong Immunity 2004, Yu et al, 2004, Hepatol, Mulbauer J Hep 2006Boni et al, J.Virol, 2007, Zhang Gastro 2008, Diehl et al, 2008; Hepatol Kassel Hepatol 2009, Fisicaro et al 2010.Gastroenterology, Schurich et al,2011, Shi et al, IJC, 2011, Hepatology, Tzeng et al, 2012. Plos Pathogens,Maier et al, 2013, JI, Chen J et al, 2013, Inflam Res.

PD-L1

Relevance of PD-1 pathway to HBV-infected patients:a dominant immune checkpoint driving T cell exhaustion in the liver

PD-L1:• expressed by liver parenchymal & non-parenchymal cells• Upregulated during viral hepatitis

PD-1:• Upregulated on HBV-specific T cells

Fisicaro et al, Gastro 2010

Relevance of PD-1 pathway to HBV-infected patients

First clues of in vivo effects will come from trials in HBV-related HCC

PD-1 highly expressed on HBV-specific & intrahepatic T cells

In vitro rescue upon PD-L1 blockade

Lessons from woodchuck hepadnaviral infection:Combining PD-1 blockade with therapeutic vaccination

• Boosting of T and B cell immunity• Sustained viral suppression and sAg seroconversion

Complex layers of co-inhibition drive T cell exhaustion

Blocking CTLA-4 can restore HBV-specific T cell responses

Anna Schurich

Pooja Khanna

Gaia Nebbia

Complementary roles for CTLA-4 and PD-1 in CHB

Schurich, Khanna et al, Hepatology 2011

The co-inhibitory receptor TIM-3 is upregulatedon HBV-specific CD8 T cells

Nebbia et al, PLoSOne 2012

The TIM-3 / Galectin-9 pathway is induced in CHB

Non-redundant role with PD-1

Checkpoint modulation to boost antiviral T cells-need for personalised combinations?

Revived

Co-inhibitory signalsPD-1CTLA-4Tim-3Lag-3

CD8 T cell

Co-stimulatory signalsBoni J Virol 2007Fisicaro Gastro 2010Schurich Hepatol 2011Nebbia PLoS One 2012

Response to HBV-specific T cell blockade• dominated by PD-1 • predicted by intermediate T cell differentiation

Bengsh et al, J Hep 2014

?

Enhancing co-stimulation as an alternative to checkpoint blockade

Revived

Co-inhibitory signalsPD-1CTLA-4Tim-3Lag-3

CD8 T cell

Co-stimulatory signals41BBOX-40ICOSIL-12

,,,,

Fisicaro Gastro 2012Isogawa PLoS Path 2013Schurich PLoS Path 2013

Boni J Virol 2007Fisicaro Gastro 2010Schurich Hepatol 2011Nebbia PLoS One 2012

IL-12 increases IFN-g production by HBV-specific but not CMV-specific CD8 T cells

Schurich et al PLoS Path 2013

PD-L blockade in combination with IL-12 optimisesHBV-specific CD8 T cell recovery in vitro

HBV DNA (IU/ml)

Going deeper than Checkpoint inhibitors

Irreversible epigenetic T cell defects Pauken et al Science 2016

Metabolic and mitochondrial T cell defects Schurich et al Cell Reports 2016

Schurich et al Cell Rep 2016

IL-12 re-programmes defective mitochondrial metabolism

The trade-off between immunity and immunopathology

• Minimize antigen load

• Develop adjunctive approaches to limit collateral damage

• Focus T cell boosting on HBV-specific component

Hepatic flares an inevitable result of effective immune boosting

Potential immunomodulatory approaches for CHB

Checkpoint blockade

• PD-1 is the dominant exhaustion marker in chronic HBV• Nearly 100% of HBV-specfiic T cells in liver are PD-1+

• PD-1, CTLA-4 and Tim-3 play potentially non-redundant roles

• May require personalized approach to optimally restore T cells

Enhancing co-stimulation• Cytokines – Signal 3

• IL-12 enhances T cell expansion and functionality

• Additive/synergistic effect in combination with PD-1

• Restore effective T cell metabolism

AcknowledgementsDivision of Infection and Immunity, UCL

Dimitra PeppaRoss Lopes

Abhishek DasClaire Dunn

Pooja KhannaLorenzo Micco

Gaia NebbiaAntony ChenSimran Singh

Anna SchurichLaura Palletttziar Otano

Kerstin StegmannWei-Chen HuangNicholas Easom

Kasha SinghAlice Burton

Emily Colbeck

All healthy donors, patients and clinic staff

University of DundeeDoreen Cantrell

UCL Clinical CollaboratorsWilliam Rosenberg

Guiseppe FusaiEleni NastouliRichard GilsonBrian Davidson

Francis RobertsonA*Star, Singapore

Muzlifa HaniffaAntonio Bertoletti

UCL collaboratorsNiclas ThomasNathan Davies

Barts and the London HospitalUpkar GillJyoti Hansi

Patrick KennedyKings Liver InstituteAlberto Quaglia