Defective T-cell immunity in hepatitis B virus infection: why therapeutic vaccination needs a helping hand

Hepatitis B virus (HBV) remains a major cause of morbidity and mortality worldwide. Treatments that can induce functional cure in patients chronically infected with this hepatotropic, non-cytopathic virus are desperately needed. Attempts to use therapeutic vaccines to expand the weak antiviral T-cell response and induce sustained immunity have been unsuccessful. However, exciting progress has been made in defining the molecular defects that must be overcome to harness T-cell immunity. A large arsenal of immunotherapeutic agents and direct-acting antivirals targeting multiple steps of the viral lifecycle is emerging. In this Review, we discuss how to translate the new insights into T-cell manipulation, combined with better understanding of patient heterogeneity, into optimisation of therapeutic vaccines against HBV. We review the opportunities and risks involved in boosting endogenous T-cell responses using combinations of next generation therapeutic vaccines and immunotherapy agents

A glutamine 'tug-of-war': targets to manipulate glutamine metabolism for cancer immunotherapy

Within the tumour microenvironment (TME), there is a cellular ‘tug-of-war’ for glutamine, the most abundant amino acid in the body. This competition is most evident when considering the balance between a successful anti-tumour immune response and the uncontrolled growth of tumour cells that are addicted to glutamine. The differential effects of manipulating glutamine abundance in individual cell types is an area of intense research and debate. Here, we discuss some of the current strategies in development altering local glutamine availability focusing on inhibition of enzymes involved in the utilisation of glutamine and its uptake by cells in the TME. Further studies are urgently needed to complete our understanding of glutamine metabolism, to provide critical insights into the pathways that represent promising targets and for the development of novel therapeutic strategies for the treatment of advanced or drug resistant cancers

Irreversible Electroporation (IRE) in Locally Advanced Pancreatic Cancer: A Review of Current Clinical Outcomes, Mechanism of Action and Opportunities for Synergistic Therapy

Locally advanced pancreatic cancer (LAPC) accounts for 30% of patients with pancreatic cancer. Irreversible electroporation (IRE) is a novel cancer treatment that may improve survival and quality of life in LAPC. This narrative review will provide a perspective on the clinical experience of pancreas IRE therapy, explore the evidence for the mode of action, assess treatment complications, and propose strategies for augmenting IRE response. A systematic search was performed using PubMed regarding the clinical use and safety profile of IRE on pancreatic cancer, post-IRE sequential histological changes, associated immune response, and synergistic therapies. Animal data demonstrate that IRE induces both apoptosis and necrosis followed by fibrosis. Major complications may result from IRE; procedure related mortality is up to 2%, with an average morbidity as high as 36%. Nevertheless, prospective and retrospective studies suggest that IRE treatment may increase median overall survival of LAPC to as much as 30 months and provide preliminary data justifying the well-designed trials currently underway, comparing IRE to the standard of care treatment. The mechanism of action of IRE remains unknown, and there is a lack of data on treatment variables and efficiency in humans. There is emerging data suggesting that IRE can be augmented with synergistic therapies such as immunotherapy

Eomeshi NK Cells in Human Liver Are Long-Lived and Do Not Recirculate but Can Be Replenished from the Circulation.

Human liver contains an Eomes(hi) population of NK cells that is not present in the blood. In this study, we show that these cells are characterized by a molecular signature that mediates their retention in the liver. By examining liver transplants where donors and recipients are HLA mismatched, we distinguish between donor liver-derived and recipient-derived leukocytes to show that Eomes(lo) NK cells circulate freely whereas Eomes(hi) NK cells are unable to leave the liver. Furthermore, Eomes(hi) NK cells are retained in the liver for up to 13 y. Therefore, Eomes(hi) NK cells are long-lived liver-resident cells. We go on to show that Eomes(hi) NK cells can be recruited from the circulation during adult life and that circulating Eomes(lo) NK cells are able to upregulate Eomes and molecules mediating liver retention under cytokine conditions similar to those in the liver. This suggests that circulating NK cells are a precursor of their liver-resident counterparts

Characterisation and induction of tissue-resident gamma delta T-cells to target hepatocellular carcinoma

Immunotherapy is now the standard of care for advanced hepatocellular carcinoma (HCC), yet many patients fail to respond. A major unmet goal is the boosting of T-cells with both strong HCC reactivity and the protective advantages of tissue-resident memory T-cells (TRM). Here, we show that higher intratumoural frequencies of γδ T-cells, which have potential for HLA-unrestricted tumour reactivity, associate with enhanced HCC patient survival. We demonstrate that γδ T-cells exhibit bona fide tissue-residency in human liver and HCC, with γδTRM showing no egress from hepatic vasculature, persistence for >10 years and superior anti-tumour cytokine production. The Vγ9Vδ2 T-cell subset is selectively depleted in HCC but can efficiently target HCC cell lines sensitised to accumulate isopentenyl-pyrophosphate by the aminobisphosphonate Zoledronic acid. Aminobisphosphonate-based expansion of peripheral Vγ9Vδ2 T-cells recapitulates a TRM phenotype and boosts cytotoxic potential. Thus, our data suggest more universally effective HCC immunotherapy may be achieved by combining aminobisphosphonates to induce Vγ9Vδ2TRM capable of replenishing the depleted pool, with additional intratumoural delivery to sensitise HCC to Vγ9Vδ2TRM-based targeting

Fine needle aspirates comprehensively sample intrahepatic immunity.

OBJECTIVE: In order to refine new therapeutic strategies in the pipeline for HBV cure, evaluation of virological and immunological changes compartmentalised at the site of infection will be required. We therefore investigated if liver fine needle aspirates (FNAs) could comprehensively sample the local immune landscape in parallel with viable hepatocytes. DESIGN: Matched blood, liver biopsy and FNAs from 28 patients with HBV and 15 without viral infection were analysed using 16-colour multiparameter flow cytometry. RESULTS: The proportion of CD4 T, CD8 T, Mucosal Associated Invariant T cell (MAIT), Natural Killer (NK) and B cells identified by FNA correlated with that in liver biopsies from the same donors. Populations of Programmed Death-1 (PD-1)hiCD39hi tissue-resident memory CD8 T cells (CD69+CD103+) and liver-resident NK cells (CXCR6+T-betloEomeshi), were identified by both FNA and liver biopsy, and not seen in the blood. Crucially, HBV-specific T cells could be identified by FNAs at similar frequencies to biopsies and enriched compared with blood. FNAs could simultaneously identify populations of myeloid cells and live hepatocytes expressing albumin, Scavenger Receptor class B type 1 (SR-B1), Programmed Death-Ligand 1 (PD-L1), whereas hepatocytes were poorly viable after the processing required for liver biopsies. CONCLUSION: We demonstrate for the first time that FNAs identify a range of intrahepatic immune cells including locally resident sentinel HBV-specific T cells and NK cells, together with PD-L1-expressing hepatocytes. In addition, we provide a scoring tool to estimate the extent to which an individual FNA has reliably sampled intrahepatic populations rather than contaminating blood. The broad profiling achieved by this less invasive, rapid technique makes it suitable for longitudinal monitoring of the liver to optimise new therapies for HBV.Wellcome Trust Clinical Research Training Fellowship (107389/Z/15/Z)Barts and The London Charity Project Grant (723/1795)NIHR Research for patient benefit award (PBPG-0614-34087)Medical Research Council grant (G0801213)Wellcome Trust Senior Investigator Award and Enhancement (101849/Z/13/A) to MKM

Therapeutic potential of TLR8 agonist GS-9688 (selgantolimod) in chronic hepatitis B: re-modelling of antiviral and regulatory mediators

Background & Aims: GS‐9688 (selgantolimod) is a toll‐like receptor 8 (TLR8) agonist in clinical development for the treatment of chronic hepatitis B (CHB). Antiviral activity of GS‐9688 has previously been evaluated in vitro in hepatitis B virus (HBV)‐infected hepatocytes and in vivo in the woodchuck model of CHB. Here we evaluated the potential of GS‐9688 to boost responses contributing to viral control and to modulate regulatory mediators. Approach & Results: We characterised the effect of GS‐9688 on immune cell subsets in vitro in PBMC of healthy controls and CHB patients. GS‐9688 activated dendritic cells and mononuclear phagocytes to produce IL‐12 and other immunomodulatory mediators, inducing a comparable cytokine profile in healthy controls and CHB patients. GS‐9688 increased the frequency of activated natural killer (NK) cells, mucosal‐associated invariant T‐cells (MAITs), CD4+ follicular helper T‐cells (TFH) and, in ~50% of patients, HBV‐specific CD8+T‐cells expressing interferon‐γ (IFNγ). Moreover, in vitro stimulation with GS‐9688 induced NK cell expression of IFNγ and TNFα and promoted hepatocyte lysis. We also assessed whether GS‐9688 inhibited immunosuppressive cell subsets that might enhance antiviral efficacy. Stimulation with GS‐9688 reduced the frequency of CD4+ regulatory T‐cells and monocytic myeloid‐derived suppressor cells (MDSC). Residual MDSC expressed higher levels of negative immune regulators, galectin‐9 and PD‐L1. Conversely, GS‐9688 induced an expansion of immunoregulatory TNF‐related apoptosis‐inducing ligand+ (TRAIL) regulatory NK cells and degranulation of arginase‐I+ polymorphonuclear‐MDSC (PMN‐MDSC). Conclusions: GS‐9688 induces cytokines in human PBMC that are able to activate antiviral effector function by multiple immune mediators (HBV‐specific CD8+T‐cells, TFH, NK cells and MAITs). Whilst reducing the frequency of some immunoregulatory subsets, it enhances the immunosuppressive potential of others, highlighting potential biomarkers and immunotherapeutic targets to optimise the antiviral efficacy of GS‐9688