Hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) is a serious health problem in Asia, since the efficacy of current systemic therapies for advanced HCC is still suboptimal with a median overall survival often less than 2 years [
1]. New therapy modalities are needed and in this issue of
Clinical and Molecular Hepatology, Wan et al. [
2] described the experimental efforts to develop and test both in animal model and then in a patient with advanced HBV-related HCC (HBV-HCC), a cellular therapy based on adoptive transfer of autologous T cells engineered to be specific for an HBV epitope (the protein fragment presented by human leukocyte antigen [HLA]-class I and recognized by a specific T cell receptor) presented on the surface of HBVHCC. The rationale to target HBV antigen as a tumor-specific antigen in HBV-HCC is due to the ability of HBV to integrate into the DNA of hepatocytes and therefore be present in the great majority of transformed HCC cells [
3].
Wan et al. [
2] utilized a lentiviral vector to introduce the genetic information of V alpha and V beta regions of a T cell receptor specific for the complex of HLA-A2 molecule and S domain region 20–28 into T cells and elegantly demonstrated in vitro that this lentiviral transduction of T cells generated T cells stably expressing the selected T cell receptor (TCR) (specific for the HLA-A2/S
20-28 region). The engineered HBV-specific TCR T cells were first demonstrated to recognize HBV+ hepatoma cells both in vitro and in an animal model prior to their use in treating a patient with HBV-HCC. Using the developed technology, a large quantity of HBV-specific TCR T cells was produced under Good Manufacturing Practice conditions. The expression of the HBV-TCR on the engineered T cells was tested in vitro and then the autologous HBV-specific TCR-expressing T cells were infused into a lymphodepleted (fludarabine/cyclophosphamide) patient with multifocal HBV-HCC and chronic HBV infection in a single dose of 7.9x10
7xkg (total 5.9x109 T cells).
Even if the critics might point out that this cellular treatment didn’t achieve a complete eradication of the HCC lesion and negativity of hepatitis B surface antigen (HBsAg), the work confirms the potential of this immunotherapeutic strategy for HBV-HCC and chronic HBV treatment. In the treated patient, engineered HBV-TCR T cells efficiently reached the liver, were functional in vivo and targeted both HBV-infected and HBV-expressing HCC cells, showing a shrinkage of the HCC lesion (70% reduction of the initial volume), a reduction of the quantity of HBsAg (a reduction of almost 4 log) and persistence of the HBV-TCR T cells after infusion. Importantly, though the infusion of a single large quantity of engineered TCR T cells immediately caused the triggering of a cytokine release syndrome (with high values of IL-6 detected in serum, onset of fever and hypotension) followed by alanine aminotransferase (ALT) elevation (up to 1,440 IU/L at day 3 after infusion), all symptoms were reversible.
In order to fully appreciate the significance of this new data in terms of safety and of clinical effectiveness against HBV-HCC and HBV infection, we need to consider these findings in the context of the various efforts by different laboratories (mainly from the Protzer lab and our laboratory) to develop T cell therapy for HBV infection and its complications that started more than 15 years ago (
Table 1).
The possibility of modifying the specificity of T cells through expression of a chimeric antigen receptor (CAR) or a classical TCR started back in 2008. Ulrike Protzer's group was the first to engineer HBV-specific T cells utilizing a chimeric antigen receptor specific for HBsAg [
4]. The work was a logical extension, in the HBV field, of the progressive development of molecular methods that utilize viral vectors to introduce CAR or TCR into T cells that endow them with novel specificity [
5]. For the readers not familiar with the difference between a CAR and a TCR, we would direct them to the many specific and detailed reviews on the arguments that have been written in the last 15 years (see for example [
6]). Nevertheless, to briefly summarize, a CAR consists of an extracellular antibody recognition site coupled with a constant region of a TCR (in its cognate form or modified with the insertion of intracellular co-stimulatory domains) that delivers the activation signal. The main difference is that the CAR does not recognize the HLA-class I/viral or tumor epitope complex like a conventional TCR; it instead recognizes the whole conformation of an antigen expressed on the surface of the target cells.
The CAR-T cell strategy has practical advantages in terms of translation to clinic. A single CAR can be used to engineer the T cells of different patients, while a TCR can only be used in patients who possess the HLA-class I molecules that present the correct targeted epitope [
6]. This means that developing a TCR-based strategy is more complex; you need to have a large TCR library, and the number of patients that you can treat with TCR-redirected T cells is limited by their HLA-class I profile.
However, despite the practical advantages of HBV-specific CAR-T cells, their clinical utilization in HBV chronic patients or in HBV-HCC has not been expanded for two fundamental reasons. The first one is that HBsAg is present in high concentrations in the serum of the patients with CHB infection and also in some of the patients with HBV-HCC. Such circulating HBsAg can directly bind to the HBsAgspecific CAR present on the surface of the engineered T cells and potentially interfere with their activation and target recognition [
7]. The second and perhaps even more important reason, particularly in patients with HBV-HCC, is that most of the HBV-HCC do present HBV-DNA integration, but such integration is not complete and thus rarely codes for the whole HBsAg [
8]. Instead, HBV-HCC tumors with partial HBV-DNA integration can still present fragments of HBV proteins associated with their HLA-class I molecules derived from the processing of chimeric/fragmented HBV proteins (often translated from HBV envelope or X regions integrated into the host genome) and thus can be recognized by HBV-specific TCR T cells [
8] but not by HBV-specific CAR-T cells.
Indeed, after the development of HBsAg-specific CAR T cells [
4,
9], our group [
10,
11] and then Protzer’s group [
12] isolated different HBV-specific TCRs with different specificities and HLA-restrictions that recognize both HBV-HCC and HBVinfected hepatocytes in vitro and in animal models [
13,
14].
The demonstration that T cells modified with an HBVspecific TCR can efficiently recognize HBV-HCC did not resolve all the problems of this therapy approach, particularly those related to safety. Utilizing HBV antigen as a tumor antigen for HBV-HCC was not only driven by the frequent HBV-DNA integration found in 80–90% of all HBVHCC, but also because it was relatively easy to isolate and clone HBV-specific TCRs from patients who have resolved acute HBV infection. While HBV-HCC can express other classical tumor antigens (i.e., alpha-fetoprotein, NY-Eso-1, Glypican-3, Mage-3) and T cells specific for these classical tumor-associated antigens are present in HBV-HCC patients [
15], TCRs specific for tumor associated antigens are often of low affinity and require modifications in order to efficiently recognize tumor cells. In contrast, T cells recognizing HBV antigens present in patients that resolved acute HBV infection express high-affinity TCR and recognize with high efficiency the low quantity of HBV epitope present on the surface of the target cells that can be HBV-infected hepatocytes and/or HCC cells with HBV-DNA integration [
10,
12]. However, this inability to distinguish between normal HBVinfected hepatocytes and HCC cells that are expressing HBV antigens from DNA integration is a drawback; the risk of inducing severe liver damage after HBV-TCR T cell treatment in patients with chronic HBV infection who developed HCC cannot be ignored. This is why initial tests of HBVTCR engineered T cell therapy in patients were done in individuals with HBV metastasis after liver transplantations [
8,
16] (after showing that the transplanted liver was not HBV-infected or mismatched in relation to the HLA restriction of the adoptively transferred HBV-specific TCR-T cells) or by using T cells that express the HBV-TCR transiently through mRNA electroporation [
17,
18].
It is therefore important to see in a patient with advanced HBV-HCC and HBV chronic infection that the infusion of a large number of T cells that stably express an HBV-specific TCR causes a marked elevation of ALT at day 3 that was, however, reversible and associated with a significant drop of HBsAg [
2]. Even though the quantity of HBV-infected hepatocytes can be highly variable in patients with chronic HBV infection [
19] and HBV-HCC, it is reassuring to see how a liver chronically infected with HBV can tolerate and recover after the induction of robust inflammation.
We would argue that the observation of a marked expansion of the adoptively transferred HBV-TCR T cells in vivo shown by these new data might also indicate that the number of infused HBV-TCR T cells could be substantially reduced and perhaps this could also avoid or lessen the cytokine-release syndrome (high level of IL-6 and hypotension controlled with Tocilizumab, corticosteroids and noradrenaline) that was observed in the patient immediately after infusion (2 hours). Infusion of lower quantities of HBV-TCR T cells (1x10
5 to 5 x10
6xkg) [
17,
18] produced with mRNA technology in HBV-HCC patients has not been associated with rapid cytokine-release syndrome symptoms, even though in some patients ALT elevation (with increased bilirubin level) was observed.
Furthermore, in addition to dosage and safety, other questions regarding the effectiveness of the treatment arise from the data. For instance, it's uncertain whether HBV-specific TCR T cells that expanded in vivo maintain their functionality over time. The initial expansion and subsequent persistence of the adoptively transferred HBV-TCR T cells in this patient are important observations. They show that the HBV-TCR T cells, after recognizing their "hepatic" target, were not immediately tolerized, but instead proliferated and caused a clear reduction of HBsAg. This reduction serves as indirect evidence of their in vivo functionality. However, after the initial HCC shrinkage, the patient did not completely eliminate the tumor and also did not completely suppress HBsAg. This might indicate that after the initial recognition, the HBV-TCR T cells have gradually lost their effector function.
There may be other reasons for the persistence of HBVHCC lesions and HBV infection, such as the inability of HBV-TCR T cells to reach their targets or low expression or mutation of the HBV epitope targeted by the HBV-TCR T cells. Whatever is the cause, it will be important to understand whether stably engineered HBV-TCR T cells not only proliferate in vivo but also maintain their functionality.
This understanding is vital to better design adoptive T cell therapy strategies in HBV-HCC patients, which at the moment are split between the use of T cells that stably express their TCR (like the one of Wan et al.) [
2] or the use of T cells that express their TCRs transiently [
20] (a strategy used mainly by us).
Wan and colleagues argue in their discussion that the persistence of the adoptively transferred TCR-T cells in treated patients is an indispensable requirement for clinical efficacy. We would argue here that it is certainly correct to note that the persistence of CAR-T cells in patients with liquid tumors is associated with therapeutic success [
21]. Nevertheless, the clinical success of adoptive T cell therapy against solid tumors has been extremely poor so far, and thus, potential biomarkers of clinical success may not depend on T cell persistence.
Unlike the group of Protzer, we favour a strategy of HBVTCR T cell treatment utilizing T cells that are not genetically modified but express the HBV-TCR transiently through mRNA electroporation. This strategy was selected not only for safety (it allows infusion of escalating doses of HBVTCR T cells in patients and a controlled analysis of the side effects) but also because the repetitive infusion of newly engineered HBV-TCR T cells might escape functional exhaustion induced by the immunosuppressive environment of HBV-HCC [
22]. In addition, the repetitive infusions of highly activated HBV-TCR T cells can, despite their transient persistence alter this immunosuppressive environment. As Wan et al. also argue in their discussion, the clinical efficacy of HBV-TCR T cell therapy against HBV-HCC might not be only associated with the direct HBV-HCC cell lysis by the adoptive transferred T cells. It might be also dependent on their ability to modify the HCC microenvironment that can facilitate the induction of novel endogenous tumorspecific T cells. This hypothesis was indeed suggested by initial observations from a clinical trial using mRNA-based HBV-TCR T cells where the response to therapy (fully and partially observed in 1 and 3 out of 8 primary HBV-HCC patients treated, respectively) was not directly proportional to the number of infused TCR-T cells, but was instead associated with the induction of inflammatory liver events [
18]. Demonstrating that the clinical effectiveness of TCR-T cell therapy against a solid tumor is linked to its capacity to boost an endogenous immune response, rather than to the quantity and persistence of adoptively transferred T cells, might change the approach to adoptive T cell therapy against solid tumors.
Therefore, we need to understand whether the success of T cell therapy against HBV-related HCC is associated with the preservation of the function of adoptively transferred T cells or whether a hit-and-run strategy using T cells with limited functional lifespan can be less or more efficacious.
What is certain is that an answer to these questions can only be derived from high-quality data obtained from the detailed study of treated patients, like the study published in this issue of Clinical and Molecular Hepatology. Only by analysing the mechanisms of action of the adoptively transferred T cells, whether they can proliferate and maintain functionality or modify the HCC microenvironment, will we be able to use this therapy more effectively and improve the clinical needs of patients with HBV related HCC. Such studies might also clarify whether we need to use different T cell populations for adoptive T cell therapy. In the future, we might use Mucosal Associated Invariant T cells (MAIT cells) [
23] that are known to have a tropism for the liver, instead of normal T cells, or utilize mixtures of T cells engineered with HLA-class I and HLA-class II TCRs that have also been recently cloned [
24]. The indication of successful HBV-TCR T cell therapy could then be extended to other HBV-related pathologies and, for example, be used to achieve functional HBV cure7 or as a preventive therapy for HBV-HCC relapses after liver transplantations [
25].
The work ahead of us might be long and arduous, but the reward for patients and science will be substantial.
FOOTNOTES
-
Authors’ contribution
Both the authors contributed equally.
-
Conflicts of Interest
A.B. is a cofounder of and A.T.T. consults for Lion TCR, a biotech company developing T cell receptors for treatment of virus-related diseases and cancers.
Table 1.The Road Map of adoptive T cell therapy against HBV-HCC
Table 1.
|
Year |
Reference |
Milestones |
|
2008 |
Bohne F, Chmielewski M, Ebert G, Wiegmann K, Kürschner T, Schulze A, et al. T cells redirected against hepatitis B virus surface proteins eliminate infected hepatocytes. Gastroenterology 2008;134:239-247 |
The first HBV-specific T cells engineered with a CAR specific for HBsAg. |
|
2011 |
Gehring AJ, Xue SA, Ho ZZ, Teoh D, Ruedl C, Chia A, et al. Engineering virus-specific T cells that target HBV infected hepatocytes and hepatocellular carcinoma cell lines. J Hepatol 2011;55:103-110 |
The first HBV-specific T cells engineered with a TCR specific for HBV epitopes. |
|
2013 |
Koh S, Shimasaki N, Suwanarusk R, Ho ZZ, Chia A, Banu N, et al. A practical approach to immunotherapy of hepatocellular carcinoma using T cells redirected against hepatitis B virus. Mol Ther Nucleic Acids 2013;2:e114 |
Pre-clinical development of mRNA electroporated HBV-TCR T cells. Despite transient functionality mRNA HBV-TCR T cells (CD8 and CD4) prevent HCC seeding and suppress growth in a xenograft model. |
|
2013 |
Krebs K, Böttinger N, Huang LR, Chmielewski M, Arzberger S, Gasteiger G, et al. T cells expressing a chimeric antigen receptor that binds hepatitis B virus envelope proteins control virus replication in mice. Gastroenterology 2013;145:456-465 |
Pre-clinical development of engineered HBV-CAR T cells. |
|
2014 |
Banu N, Chia A, Ho ZZ, Garcia AT, Paravasivam K, Grotenbreg GM, et al. Building and optimizing a virus-specific T cell receptor library for targeted immunotherapy in viral infections. Sci Rep 2014;4:4166 |
Development of a library containing HBV-TCRs specific for HBV epitopes restricted by HLA-I molecules commonly found in the Asia region. |
|
2015 |
Qasim W, Brunetto M, Gehring AJ, Xue SA, Schurich A, Khakpoor A, et al. Immunotherapy of HCC metastases with autologous T cell receptor redirected T cells, targeting HBsAg in a liver transplant patient. J Hepatol 2015;62:486-491 |
First-in-man proof-of-concept demonstration of using HBV-TCR T cells to target HBV-HCC relapse in a liver transplant patient. |
|
2017 |
Wisskirchen K, Metzger K, Schreiber S, Asen T, Weigand L, Dargel C, et al. Isolation and functional characterization of hepatitis B virus-specific T-cell receptors as new tools for experimental and clinical use. PLoS One 2017;12:e0182936 |
Characterisation of high affinity HBV-TCRs specific for HLA-A02 restricted HBV epitopes. |
|
2017 |
Kah J, Koh S, Volz T, Ceccarello E, Allweiss L, Lütgehetmann M, et al. Lymphocytes transiently expressing virus-specific T cell receptors reduce hepatitis B virus infection. J Clin Invest 2017;127:3177-3188 |
Pre-clinical evaluation (humanized HBV-infected mice) of the antiviral function of HBV-TCR T cells engineered through mRNA electroporation (transient TCR expression). |
|
2019 |
Wisskirchen K, Kah J, Malo A, Asen T, Volz T, Allweiss L, et al. T cell receptor grafting allows virological control of Hepatitis B virus infection. J Clin Invest 2019;129:2932-2945 |
Pre-clinical evaluation (humanized HBV-infected mice) of the antiviral function of HBV-TCR T cells engineered through viral vector transduction (stable TCR expression). |
|
2019 |
Tan AT, Yang N, Lee Krishnamoorthy T, Oei V, Chua A, Zhao X, et al. Use of expression profiles of HBV-DNA integrated into genomes of hepatocellular carcinoma cells to select T cells for immunotherapy. Gastroenterology 2019;156:1862-1876.e9 |
Proof-of-concept of how integrated HBV DNA can generate T cell epitopes targetable by HBV-TCR T cells in the absence of whole HBV antigen detection. First time mRNA electroporated HBV-TCR T cells were infused in liver transplanted patients with HCC relapses. |
|
2021 |
Meng F, Zhao J, Tan AT, Hu W, Wang SY, Jin J, et al. Immunotherapy of HBV-related advanced hepatocellular carcinoma with short-term HBV-specific TCR expressed T cells: results of dose escalation, phase I trial. Hepatol Int 2021;15:1402-1412 |
Phase 1 dose-escalation trial of mRNA electroporated HBV-TCR T cells in patients with primary HBV-HCC. |
|
2021 |
Tan AT, Meng F, Jin J, Zhang JY, Wang SY, Shi L, et al. Immunological alterations after immunotherapy with short lived HBV-TCR T cells associates with long-term treatment response in HBV-HCC. Hepatol Commun 2022;6:841-854 |
Extended analysis of the Phase 1 trial (Meng et al.17 2021) to show the association of immunological alterations with treatment response in primary HBV-HCC patients. |
|
2021 |
Hafezi M, Lin M, Chia A, Chua A, Ho ZZ, Fam R, et al. Immunosuppressive drug-resistant armored T-Cell receptor T cells for immune therapy of HCC in liver transplant patients. Hepatology 2021;74:200-213. |
Development of HBV-TCR T cells resistant to immunosuppressive drugs used in liver transplanted patients. |
|
2021 |
Healy K, Pavesi A, Parrot T, Sobkowiak MJ, Reinsbach SE, Davanian H, et al. Human MAIT cells endowed with HBV specificity are cytotoxic and migrate towards HBV-HCC while retaining antimicrobial functions. JHEP Rep 2021;3:100318 |
Development and characterisation of engineered HBV-specific MAIT cells. |
|
2021 |
Schreiber S, Honz M, Mamozai W, Kurktschiev P, Schiemann M, Witter K, et al. Characterization of a library of 20 HBV-specific MHC class II-restricted T cell receptors. Mol Ther Methods Clin Dev 2021;23:476-489 |
Development and characterisation of HLA-II restricted HBV-TCRs. |
|
2021 |
Klopp A, Schreiber S, Kosinska AD, Pulé M, Protzer U, Wisskirchen K. Depletion of T cells via Inducible Caspase 9 Increases Safety of Adoptive T-Cell Therapy Against Chronic Hepatitis B. Front Immunol 2021;12:734246. |
Development of HBV-specific CAR/TCR T cells with an inducible suicide switch. |
|
2023 |
Lin M, Bhakdi SC, Tan D, Lee JJX, Tai DWM, Pavesi A, et al. Lytic efficiency of immunosuppressive drug-resistant armoured T cells against circulating HBV-related HCC in whole blood. Immunother Adv 2023;3:ltad015 |
Pre-clinical evaluation (whole blood of transplanted patients) of the lytic ability of immunosuppressive drug resistant HBV-TCR T cells. |
|
2024 |
Wan X, Wisskirchen K, Jin T, Yang L, Wang X, Wu X, et al. Genetically-modified, redirected T cells target hepatitis B surface antigen-positive hepatocytes and hepatocellular carcinoma lesions in a clinical setting. Clin Mol Hepatol 2024;30:735-755 |
Safety and efficacy of genetically redirected HBV-TCR T cells (stable TCR expression) in preclinical model and in a HBV-HCC patient. |
Abbreviations
hepatitis B surface antigen
chimeric antigen receptor
REFERENCES
- 1. Ntellas P, Chau I. Updates on systemic therapy for hepatocellular carcinoma. Am Soc Clin Oncol Educ Book 2024;44:e430028.
- 2. Wan X, Wisskirchen K, Jin T, Yang L, Wang X, Wu X, et al. Genetically-modified, redirected T cells target hepatitis B surface antigen-positive hepatocytes and hepatocellular carcinoma lesions in a clinical setting. Clin Mol Hepatol 2024;30:735-755.
- 3. Bertoletti A, Brunetto M, Maini MK, Bonino F, Qasim W, Stauss H. T cell receptor-therapy in HBV-related hepatocellularcarcinoma. Oncoimmunology 2015;4:e1008354.
- 4. Bohne F, Chmielewski M, Ebert G, Wiegmann K, Kürschner T, Schulze A, et al. T cells redirected against hepatitis B virus surface proteins eliminate infected hepatocytes. Gastroenterology 2008;134:239-247.
- 5. June CH. Principles of adoptive T cell cancer therapy. J Clin Invest 2007;117:1204-1212.
- 6. June CH, Blazar BR, Riley JL. Engineering lymphocyte subsets: tools, trials and tribulations. Nat Rev Immunol 2009;9:704-716.
- 7. Bertoletti A, Tan AT. Challenges of CAR- and TCR-T cell-based therapy for chronic infections. J Exp Med 2020;217:e20191663.
- 8. Tan AT, Yang N, Lee Krishnamoorthy T, Oei V, Chua A, Zhao X, et al. Use of expression profiles of HBV-DNA integrated into genomes of hepatocellular carcinoma cells to select T cells for immunotherapy. Gastroenterology 2019;156:1862-1876.e9.
- 9. Krebs K, Böttinger N, Huang LR, Chmielewski M, Arzberger S, Gasteiger G, et al. T cells expressing a chimeric antigen receptor that binds hepatitis B virus envelope proteins control virus replication in mice. Gastroenterology 2013;145:456-465.
- 10. Gehring AJ, Xue SA, Ho ZZ, Teoh D, Ruedl C, Chia A, et al. Engineering virus-specific T cells that target HBV infected hepatocytes and hepatocellular carcinoma cell lines. J Hepatol 2011;55:103-110.
- 11. Banu N, Chia A, Ho ZZ, Garcia AT, Paravasivam K, Grotenbreg GM, et al. Building and optimizing a virus-specific T cell receptor library for targeted immunotherapy in viral infections. Sci Rep 2014;4:4166.
- 12. Wisskirchen K, Metzger K, Schreiber S, Asen T, Weigand L, Dargel C, et al. Isolation and functional characterization of hepatitis B virus-specific T-cell receptors as new tools for experimental and clinical use. PLoS One 2017;12:e0182936.
- 13. Kah J, Koh S, Volz T, Ceccarello E, Allweiss L, Lütgehetmann M, et al. Lymphocytes transiently expressing virus-specific T cell receptors reduce hepatitis B virus infection. J Clin Invest 2017;127:3177-3188.
- 14. Wisskirchen K, Kah J, Malo A, Asen T, Volz T, Allweiss L, et al. T cell receptor grafting allows virological control of Hepatitis B virus infection. J Clin Invest 2019;129:2932-2945.
- 15. Gehring AJ, Ho ZZ, Tan AT, Aung MO, Lee KH, Tan KC, et al. Profile of tumor antigen-specific CD8 T cells in patients with hepatitis B virus-related hepatocellular carcinoma. Gastroenterology 2009;137:682-690.
- 16. Qasim W, Brunetto M, Gehring AJ, Xue SA, Schurich A, Khakpoor A, et al. Immunotherapy of HCC metastases with autologous T cell receptor redirected T cells, targeting HBsAg in a liver transplant patient. J Hepatol 2015;62:486-491.
- 17. Meng F, Zhao J, Tan AT, Hu W, Wang SY, Jin J, et al. Immunotherapy of HBV-related advanced hepatocellular carcinoma with short-term HBV-specific TCR expressed T cells: results of dose escalation, phase I trial. Hepatol Int 2021;15:1402-1412.
- 18. Tan AT, Meng F, Jin J, Zhang JY, Wang SY, Shi L, et al. Immunological alterations after immunotherapy with short lived HBVTCR T cells associates with long-term treatment response in HBV-HCC. Hepatol Commun 2022;6:841-854.
- 19. Aggarwal A, Odorizzi PM, Brodbeck J, van Buuren N, Moon C, Chang S, et al. Intrahepatic quantification of HBV antigens in chronic hepatitis B reveals heterogeneity and treatmentmediated reductions in HBV core-positive cells. JHEP Rep 2022;5:100664.
- 20. Koh S, Shimasaki N, Suwanarusk R, Ho ZZ, Chia A, Banu N, et al. A practical approach to immunotherapy of hepatocellular carcinoma using T cells redirected against hepatitis B virus. Mol Ther Nucleic Acids 2013;2:e114.
- 21. Porter DL, Levine BL, Kalos M, Bagg A, June CH. Chimeric antigen receptor-modified T cells in chronic lymphoid leukemia. N Engl J Med 2011;365:725-733.
- 22. Suthen S, Lim CJ, Nguyen PHD, Dutertre CA, Lai HLH, Wasser M, et al. Hypoxia-driven immunosuppression by Treg and type-2 conventional dendritic cells in HCC. Hepatology 2022;76:1329-1344.
- 23. Healy K, Pavesi A, Parrot T, Sobkowiak MJ, Reinsbach SE, Davanian H, et al. Human MAIT cells endowed with HBV specificity are cytotoxic and migrate towards HBV-HCC while retaining antimicrobial functions. JHEP Rep 2021;3:100318.
- 24. Schreiber S, Honz M, Mamozai W, Kurktschiev P, Schiemann M, Witter K, et al. Characterization of a library of 20 HBVspecific MHC class II-restricted T cell receptors. Mol Ther Methods Clin Dev 2021;23:476-489.
- 25. Lin M, Bhakdi SC, Tan D, Lee JJX, Tai DWM, Pavesi A, et al. Lytic efficiency of immunosuppressive drug-resistant armoured T cells against circulating HBV-related HCC in whole blood. Immunother Adv 2023;3:ltad015.
