γδ T-cell killing of primary follicular lymphoma cells is dramatically potentiated by GA101, a type II glycoengineered anti-CD20 monoclonal antibody

Human Vγ9Vδ2 T cell expansion and their cytotoxic responses against cholangiocarcinoma

Human Vγ9Vδ2 T lymphocytes are regarded as promising effector cells for cancer immunotherapy since they have the ability to eliminate several tumor cells through non-peptide antigen recognition. However, the cytotoxic function and the mechanism of Vγ9Vδ2 T cells leading to specific killing of cholangiocarcinoma cells are yet to be confirmed. In this study, we established a protocol for ex vivo expansion of Vγ9Vδ2 T cells from healthy donors' peripheral blood mononuclear cells by culture with zoledronate and addition of IL-2, and IL-15 or IL-18 or neither. Testing the cytotoxic capacity of cultured Vγ9Vδ2 T cells against cholangiocarcinoma cell lines showed higher reactivity than against control cells. Surface expression of CD107 was detected on the Vγ9Vδ2 T cells, suggesting that these cells limit in vitro growth of cholangiocarcinoma cells via degranulation of the perforin and granzyme pathway. Analysis of molecular signaling was used to demonstrate expression of pro- and anti-survival genes and a panel of cytokine genes in Vγ9Vδ2 T cells. We found that in the presence of either IL-15 or IL-18, levels of caspase 3 were significantly reduced. Also, IL-15 and IL-18 stimulated cells contained cytotoxicity against cholangiocarcinoma cells, suggesting that stimulated Vγ9Vδ2 T cells may provide a feasible therapy for cholangiocarcinoma.

Immunotherapies inducing immunogenic cell death in cancer: insight of the innate immune system

Cancer immunotherapies include monoclonal antibodies, cytokines, oncolytic viruses, cellular therapies, and other biological and synthetic immunomodulators. These are traditionally studied for their effect on the immune system's role in eliminating cancer cells. However, some of these therapies have the unique ability to directly induce cytotoxicity in cancer cells by inducing immunogenic cell death (ICD). Unlike general immune stimulation, ICD triggers specific therapy-induced cell death pathways, based on the release of damage-associated molecular patterns (DAMPs) from dying tumour cells. These activate innate pattern recognition receptors (PRRs) and subsequent adaptive immune responses, offering the promise of sustained anticancer drug efficacy and durable antitumour immune memory. Exploring how onco-immunotherapies can trigger ICD, enhances our understanding of their mechanisms and potential for combination strategies. This review explores the complexities of these immunotherapeutic approaches that induce ICD, highlighting their implications for the innate immune system, addressing challenges in cancer treatment, and emphasising the pivotal role of ICD in contemporary cancer research.

γδ T cells in immunotherapies for B-cell malignancies

Despite the advancements in therapy for B cell malignancies and the increase in long-term survival of patients, almost half of them lead to relapse. Combinations of chemotherapy and monoclonal antibodies such as anti-CD20 leads to mixed outcomes. Recent developments in immune cell-based therapies are showing many encouraging results. γδ T cells, with their potential of functional plasticity and their anti-tumoral properties, emerged as good candidates for cancer immunotherapies. The representation and the diversity of γδ T cells in tissues and in the blood, in physiological conditions or in B-cell malignancies such as B cell lymphoma, chronic lymphoblastic leukemia or multiple myeloma, provides the possibility to manipulate them with immunotherapeutic approaches for these patients. In this review, we summarized several strategies based on the activation and tumor-targeting of γδ T cells, optimization of expansion protocols, and development of gene-modified γδ T cells, using combinations of antibodies and therapeutic drugs and adoptive cell therapy with autologous or allogenic γδ T cells following potential genetic modifications.

Vγ9Vδ2 T-cell immunotherapy in blood cancers: ready for prime time?

In the last years, the tumor microenvironment (TME) has emerged as a promising target for therapeutic interventions in cancer. Cancer cells are highly dependent on the TME to growth and evade the immune system. Three major cell subpopulations are facing each other in the TME: cancer cells, immune suppressor cells, and immune effector cells. These interactions are influenced by the tumor stroma which is composed of extracellular matrix, bystander cells, cytokines, and soluble factors. The TME can be very different depending on the tissue where cancer arises as in solid tumors vs blood cancers. Several studies have shown correlations between the clinical outcome and specific patterns of TME immune cell infiltration. In the recent years, a growing body of evidence suggests that unconventional T cells like natural killer T (NKT) cells, mucosal-associated invariant T (MAIT) cells, and γδ T cells are key players in the protumor or antitumor TME commitment in solid tumors and blood cancers. In this review, we will focus on γδ T cells, especially Vγ9Vδ2 T cells, to discuss their peculiarities, pros, and cons as potential targets of therapeutic interventions in blood cancers.

Role of Fc Core Fucosylation in the Effector Function of IgG1 Antibodies

The presence of fucose on IgG1 Asn-297 N-linked glycan is the modification of the human IgG1 Fc structure with the most significant impact on FcɣRIII affinity. It also significantly enhances the efficacy of antibody dependent cellular cytotoxicity (ADCC) by natural killer (NK) cells in vitro, induced by IgG1 therapeutic monoclonal antibodies (mAbs). The effect of afucosylation on ADCC or antibody dependent phagocytosis (ADCP) mediated by macrophages or polymorphonuclear neutrophils (PMN) is less clear. Evidence for enhanced efficacy of afucosylated therapeutic mAbs in vivo has also been reported. This has led to the development of several therapeutic antibodies with low Fc core fucose to treat cancer and inflammatory diseases, seven of which have already been approved for clinical use. More recently, the regulation of IgG Fc core fucosylation has been shown to take place naturally during the B-cell immune response: A decrease in α-1,6 fucose has been observed in polyclonal, antigen-specific IgG1 antibodies which are generated during alloimmunization of pregnant women by fetal erythrocyte or platelet antigens and following infection by some enveloped viruses and parasites. Low IgG1 Fc core fucose on antigen-specific polyclonal IgG1 has been linked to disease severity in several cases, such as SARS-CoV 2 and Dengue virus infection and during alloimmunization, highlighting the in vivo significance of this phenomenon. This review aims to summarize the current knowledge about human IgG1 Fc core fucosylation and its regulation and function in vivo, in the context of both therapeutic antibodies and the natural immune response. The parallels in these two areas are informative about the mechanisms and in vivo effects of Fc core fucosylation, and may allow to further exploit the desired properties of this modification in different clinical contexts.

Contemplating Dichotomous Nature of Gamma Delta T Cells for Immunotherapy

γδ T cells are unconventional T cells, distinguished from αβ T cells in a number of functional properties. Being small in number compared to αβ T cells, γδ T cells have surprised us with their pleiotropic roles in various diseases. γδ T cells are ambiguous in nature as they can produce a number of cytokines depending on the (micro) environmental cues and engage different immune response mechanisms, mainly due to their epigenetic plasticity. Depending on the disease condition, γδ T cells contribute to beneficial or detrimental response. In this review, we thus discuss the dichotomous nature of γδ T cells in cancer, neuroimmunology and infectious diseases. We shed light on the importance of equal consideration for systems immunology and personalized approaches, as exemplified by changes in metabolic requirements. While providing the status of immunotherapy, we will assess the metabolic (and other) considerations for better outcome of γδ T cell-based treatments.

Engineering-Induced Pluripotent Stem Cells for Cancer Immunotherapy

Simple Summary

Induced pluripotent stem cells (iPSCs) that can be genetically engineered and differentiated into different types of immune cells, providing an unlimited resource for developing off-the-shelf cell therapies. Here, we present a comprehensive review that describes the current stages of iPSC-based cell therapies, including iPSC-derived T, nature killer (NK), invariant natural killer T (iNKT), gamma delta T (γδ T), mucosal-associated invariant T (MAIT) cells, and macrophages (Mφs).

Abstract

Cell-based immunotherapy, such as chimeric antigen receptor (CAR) T cell therapy, has revolutionized the treatment of hematological malignancies, especially in patients who are refractory to other therapies. However, there are critical obstacles that hinder the widespread clinical applications of current autologous therapies, such as high cost, challenging large-scale manufacturing, and inaccessibility to the therapy for lymphopenia patients. Therefore, it is in great demand to generate the universal off-the-shelf cell products with significant scalability. Human induced pluripotent stem cells (iPSCs) provide an “unlimited supply” for cell therapy because of their unique self-renewal properties and the capacity to be genetically engineered. iPSCs can be differentiated into different immune cells, such as T cells, natural killer (NK) cells, invariant natural killer T (iNKT) cells, gamma delta T (γδ T), mucosal-associated invariant T (MAIT) cells, and macrophages (Mφs). In this review, we describe iPSC-based allogeneic cell therapy, the different culture methods of generating iPSC-derived immune cells (e.g., iPSC-T, iPSC-NK, iPSC-iNKT, iPSC-γδT, iPSC-MAIT and iPSC-Mφ), as well as the recent advances in iPSC-T and iPSC-NK cell therapies, particularly in combinations with CAR-engineering. We also discuss the current challenges and the future perspectives in this field towards the foreseeable applications of iPSC-based immune therapy.

Tafasitamab mediates killing of B-cell non-Hodgkin's lymphoma in combination with γδ T cell or allogeneic NK cell therapy

Tafasitamab is an Fc-modified monoclonal antibody that binds to CD19, a cell-surface antigen that is broadly expressed on various types of B-cell non-Hodgkin’s lymphoma (NHL). Antibody-dependent cellular cytotoxicity (ADCC), a key mode of action of tafasitamab, is mediated through the binding of tafasitamab’s Fc region to FcγRIIIa receptors on immune effector cells and results in antitumor activity. Despite the proven clinical activity of tafasitamab in combination with lenalidomide in the treatment of diffuse large B-cell lymphoma (DLBCL), a higher number of immune cells in cancer patients may improve the activity of tafasitamab. Here, we characterized two ex vivo-expanded FcγRIIIa receptor—expressing cell types—γδ T and MG4101 natural killer (NK) cells—as effector cells for tafasitamab in vitro, and found that in the presence of these cells tafasitamab was able to induce ADCC against a range of NHL cell lines and patient-derived cells. We also explored the concept of effector cell supplementation during tafasitamab treatment in vivo by coadministering MG4101 NK cells in Raji and Ramos xenograft models of NHL. Combination treatment of tafasitamab and allogeneic MG4101 NK cells in these models demonstrated a survival benefit compared with tafasitamab or MG4101 monotherapy (Raji: 1.7- to 1.9-fold increase in lifespan; Ramos: 2.0- to 4.1-fold increase in lifespan). In conclusion, adoptive cell transfer of ex vivo-expanded allogeneic NK or autologous γδ T cells in combination with tafasitamab treatment may potentially be a promising novel approach to increase the number of immune effector cells and enhance the antitumor effect of tafasitamab.

Allogeneic gamma delta T cells as adoptive cellular therapy for hematologic malignancies

Cancer immunotherapy, especially T-cell driven targeting, has significantly evolved and improved over the past decade, paving the way to treat previously refractory cancers. Hematologic malignancies, given their direct tumor accessibility and less immunosuppressive microenvironment compared to solid tumors, are better suited to be targeted by cellular immunotherapies. Gamma delta (γδ) T cells, with their unique attributes spanning the entirety of the immune system, make a tantalizing therapeutic platform for cancer immunotherapy. Their inherent anti-tumor properties, ability to act like antigen-presenting cells, and the advantage of having no major histocompatibility complex (MHC) restrictions, allow for greater flexibility in their utility to target tumors, compared to their αβ T cell counterpart. Their MHC-independent anti-tumor activity, coupled with their ability to be easily expanded from peripheral blood, enhance their potential to be used as an allogeneic product. In this review, the potential of utilizing γδ T cells to target hematologic malignancies is described, with a specific focus on their applicability as an allogeneic adoptive cellular therapy product.

The Diverse Roles of γδ T Cells in Cancer: From Rapid Immunity to Aggressive Lymphoma

γδ T cells are unique players in shaping immune responses, lying at the intersection between innate and adaptive immunity. Unlike conventional αβ T cells, γδ T cells largely populate non-lymphoid peripheral tissues, demonstrating tissue specificity, and they respond to ligands in an MHC-independent manner. γδ T cells display rapid activation and effector functions, with a capacity for cytotoxic anti-tumour responses and production of inflammatory cytokines such as IFN-γ or IL-17. Their rapid cytotoxic nature makes them attractive cells for use in anti-cancer immunotherapies. However, upon transformation, γδ T cells can give rise to highly aggressive lymphomas. These rare malignancies often display poor patient survival, and no curative therapies exist. In this review, we discuss the diverse roles of γδ T cells in immune surveillance and response, with a particular focus on cancer immunity. We summarise the intriguing dichotomy between pro- and anti-tumour functions of γδ T cells in solid and haematological cancers, highlighting the key subsets involved. Finally, we discuss potential drivers of γδ T-cell transformation, summarising the main γδ T-cell lymphoma/leukaemia entities, their clinical features, recent advances in mapping their molecular and genomic landscapes, current treatment strategies and potential future targeting options.

Case Report: Clinical Responses to Tislelizumab as a First-Line Therapy for Primary Hepatocellular Carcinoma With B-Cell Indolent Lymphoma

Background

As an emerging therapy with a promising efficacy, immunotherapy has been widely used in the treatment of solid tumors and hematologic malignancies. This clinical study compares the efficacy of tislelizumab, a domestic immune checkpoint inhibitor (ICI), to that of sorafenib when used as a first-line therapeutic option in hepatocellular carcinoma (HCC), and the concurrence of HCC and non-Hodgkin's lymphoma (NHL) is rare, especially in the treatment of ICIs.

Case presentation

A 61-year-old patient presenting with primary HCC and indolent B-cell lymphoma had a partial clinical response to tislelizumab for his primary HCC. Besides, we described a phenomenon of pseudo-progression and delayed diagnosis of his lymphoma during a long course of treatment.

Conclusion

Tislelizumab, an immunotherapeutic option with a favorable efficacy and toxicity, can be used to manage double primary tumors. However, studies should aim to elucidate the probable mechanisms of this therapy. Pseudo-progression and separation remission make the treatment of double primary tumors even more challenging, which calls for additional caution in patients undergoing immunotherapy to avoid misdiagnosis and, therefore, begin early appropriate interventions.

Improving Immunotherapy Against B-Cell Malignancies Using γδ T-Cell-specific Stimulation and Therapeutic Monoclonal Antibodies

Tumor antigen-targeting monoclonal antibodies (mAbs) are an important element of current cancer therapies. Some of these therapeutic mAbs enable antibody-dependent cell mediated cytotoxicity (ADCC) against tumor cells. However, cancer-related functional impairment of immune effector cells may limit the clinical efficacy of antibody treatments. We reckoned that combining mAbs with cell-based immunotherapies would provide a clinically relevant synergism and benefit for cancer patients. Here, we focus on γδ T cells, as earlier studies demonstrated that γδ T-cell-based therapies are safe and promising for several types of malignancies. Similar to natural killer cells, their antitumor effects can be enhanced using antibodies, and they could, therefore, become a versatile effector cell platform for use with a variety of licensed therapeutic mAbs against cancer. In this study, we explore the potential of a combination therapy of activated γδ T cells with rituximab and the more recently developed mAbs (obinutuzumab and daratumumab) in different B-cell malignancies in vitro. Obinutuzumab outperformed the other mAbs with regard to direct target cell lysis and ADCC by γδ T cells in several CD20 cell lines and primary lymphoma specimens. We demonstrate that comparatively few CD16 γδ T cells are sufficient to mediate a strong ADCC. Using Fc-receptor-positive B-cell lymphomas as target cells, ADCC cannot be blocked by high concentrations of immunoglobulins or anti-CD16 antibodies, but both substances can promote cell mediated target cell lysis. This study expands on earlier reports on the therapeutic potential of distinctive tumor antigen-targeting mAbs and facilitates the understanding of the mechanism and potential of ADCC by γδ T-cell subsets.

Identification of prognostic factors for γδT cell immunotherapy in patients with solid tumor

BACKGROUND AIMS

Activated γδT cells have been shown to exhibit cytotoxicity against tumor cells. However, the efficacy of γδT cell immunotherapy for a large number of patients with solid tumors remains unclear. In this study, we examined the efficacy of γδT cell immunotherapy using in vitro-activated γδT lymphocytes in combination with standard therapies in terms of the survival of patients with solid tumors, and determined prognostic factor for γδT cell immunotherapy.

METHODS

131 patients enrolled in this study received γδT cell immunotherapy with or without standard therapies. Their overall survival was analyzed by the Kaplan-Meier with log-rank test and Cox regression methods. Immunological analysis was performed by flow cytometry (FCM) before and after six cycles of γδT cell immunotherapy.

RESULTS

Multivariable analysis revealed that patients who showed stable disease (SD) and partial response (PR) to γδT cell immunotherapy showed better prognosis than those with a progressive disease (PD) (P = 0.0269, hazard ratio [HR], 0.410, 95% confidence interval [CI], 0.190-0.901). Furthermore, when immunological parameters were examined by FCM, the high Vγ9/γδT ratio (i.e., the high purity of the Vγ9 cells within the adoptively transferred γδT cells) before treatment was found to be a good prognostic factor for γδT cell immunotherapy (P = 0.0142, HR, 0.328, 95% CI, 0.125-0.801). No serious adverse events were reported during γδT cell immunotherapy.

CONCLUSION

Thus, γδT cell immunotherapy might extend the survival of patients with solid tumors.

B7-H3 inhibits the IFN-γ-dependent cytotoxicity of Vγ9Vδ2 T cells against colon cancer cells

The immunoregulatory protein B7-H3, a member of the B7 family, has been confirmed to be highly expressed in colon cancer. However, the exact influence of B7-H3 on the features and antitumor ability of γδT cells in colon cancer remains unknown. In the present study, we investigated that the proportions of B7-H3⁺ γδT cells were distinctly increased in the peripheral blood and tumor tissues of colon cancer patients. B7-H3 blockade or knockdown promoted proliferation, inhibited cell apoptosis and induced the expression of activation markers (CD25 and CD69) on Vδ2 T cells. In contrast, treatment with the B7-H3 agonist 4H7 had the opposite effect. Furthermore, B7-H3 suppressed IFN-γ expression by inhibiting T-bet in Vδ2 T cells. Moreover, B7-H3 mediated the inhibition of Vδ2 T cell cytotoxicity via the downregulation of IFN-γ and perforin/granzyme B expression. More importantly, blocking the B7-H3 function significantly enhanced the cytotoxicity of Vδ2 T cells against colon cancer cells in vivo. Therefore, the inhibition or blockade of B7-H3 is a potential immunotherapeutic approach for colon cancer.

Innate Immune Responses in the Outcome of Haploidentical Hematopoietic Stem Cell Transplantation to Cure Hematologic Malignancies

In the context of allogeneic transplant platforms, human leukocyte antigen (HLA)-haploidentical hematopoietic stem cell transplantation (haplo-HSCT) represents one of the latest and most promising curative strategies for patients affected by high-risk hematologic malignancies. Indeed, this platform ensures a suitable stem cell source immediately available for virtually any patents in need. Moreover, the establishment in recipients of a state of immunologic tolerance toward grafted hematopoietic stem cells (HSCs) remarkably improves the clinical outcome of this transplant procedure in terms of overall and disease free survival. However, the HLA-mismatch between donors and recipients has not been yet fully exploited in order to optimize the Graft vs. Leukemia effect. Furthermore, the efficacy of haplo-HSCT is currently hampered by several life-threatening side effects including the onset of Graft vs. Host Disease (GvHD) and the occurrence of opportunistic viral infections. In this context, the quality and the kinetic of the immune cell reconstitution (IR) certainly play a major role and several experimental efforts have been greatly endorsed to better understand and accelerate the post-transplant recovery of a fully competent immune system in haplo-HSCT. In particular, the IR of innate immune system is receiving a growing interest, as it recovers much earlier than T and B cells and it is able to rapidly exert protective effects against both tumor relapses, GvHD and the onset of life-threatening opportunistic infections. Herein, we review our current knowledge in regard to the kinetic and clinical impact of Natural Killer (NK), γδ and Innate lymphoid cells (ILCs) IRs in both allogeneic and haplo-HSCT. The present paper also provides an overview of those new therapeutic strategies currently being implemented to boost the alloreactivity of the above-mentioned innate immune effectors in order to ameliorate the prognosis of patients affected by hematologic malignancies and undergone transplant procedures.

Tim-3 suppresses the killing effect of Vγ9Vδ2 T cells on colon cancer cells by reducing perforin and granzyme B expression

Gamma delta (γδ) T cell-based tumor immunotherapy has been one of the most promising cancer immunotherapeutic strategies. However, the key regulators of the Vγ9Vδ2 T cell-mediated antitumor response remain unclear. Recently, mounting reports have indicated that Tim-3 performs critical roles in the regulation of the activities of immune cells, including Vγ9Vδ2 T cells. However, the roles of Tim-3 in Vγ9Vδ2 T cell-mediated killing of colon cancer cells and the underlying mechanism remain largely unknown. Here, the proportion of Tim-3+ γδ T cells was significantly increased in both the peripheral blood and colon cancer tissue of patients and was significantly associated with TNM staging and tumor volume. Additionally, the activation of Tim-3 signaling significantly inhibited the killing efficiency of Vγ9Vδ2 T cells against colon cancer cells. In addition, Tim-3 signaling reduced the expression of perforin and granzyme B in Vγ9Vδ2 T cells. Blocking the perforin/granzyme B pathway also decreased the cytotoxicity of Vγ9Vδ2 T cells to colon cancer cells. Moreover, Tim-3 signaling reduced the perforin and granzyme B expression of Vγ9Vδ2 T cells in an ERK1/2 signaling pathway-dependent manner. This knowledge reveals that Tim-3 may be a promising therapeutic target to improve Vγ9Vδ2 T cell-based adoptive immunotherapy for colon cancer.

A Tridimensional Model for NK Cell-Mediated ADCC of Follicular Lymphoma

Follicular lymphoma (FL) is the second most frequent subtype of B non-Hodgkin's lymphomas (NHL) for which the treatment is based on the use of anti-CD20 mAbs. NK cells play a crucial role in their mechanism of action and the number of these cells mediating antibody-dependent cell cycotoxicity (ADCC) in the peripheral blood of FL patients predict the outcome. However, their presence in FL biopsies, their activation and their role have been poorly investigated. Moreover, in vitro studies have not deciphered the exact signaling cascades triggered by NK cells in presence of anti-CD20 mAbs on both effector and target cells in a relevant FL model. We performed in silico analyses and ex vivo functional assays to determine the presence and the activation status of NK cells in FL biopsies. We modelized ADCC phenomenon by developing a co-culture model composed by 3D-cultured FL cells and NK cells. Thus, we investigated the biological effect of anti-CD20 mAbs by fluorescent microscopy and the phosphorylation status of survival pathways by cell bar coding phosphoflow in target cells. In parallel, we measured the status of activation of downstream FcγRIIIa signaling pathways in effector cells and their activation (CD69, perforin, granzyme B, IFNγ) by flow cytometry. We determined by in vivo experiments the effects of anti-CD20 mAbs in presence of NK cells in SCID-Beige engrafted FL mice. Here, we show that functional NK cells infiltrate FL biopsies, and that their presence tends to correlate with the survival of FL patients. Using our 3D co-culture model, we show that rituximab and GA101 are able to promote degranulation, CD69 expression, IFNγ production and activate FcγRIIIa signaling cascade in NK cells, and inhibit survival pathways and induce apoptosis in FL cells. The effect of GA101 seems to be more pronounced as observed in vivo in a xenograft FL model. This study strongly supports the role of NK cells in FL and highlights the application of the 3D co-culture model for in vitro validation.

Immune precision medicine for cancer: a novel insight based on the efficiency of immune effector cells

Cancer cell growth is associated with immune surveillance failure. Nowadays, restoring the desired immune response against cancer cells remains a major therapeutic strategy. Due to the recent advances in biological knowledge, efficient therapeutic tools have been developed to support the best bio-clinical approaches for immune precision therapy. One of the most important successes in immune therapy is represented by the applicational use of monoclonal antibodies, particularly the use of rituximab for B-cell lymphoproliferative disorders. More recently, other monoclonal antibodies have been developed, to inhibit immune checkpoints within the tumor microenvironment that limit immune suppression, or to enhance some immune functions with immune adjuvants through different targets such as Toll-receptor agonists. The aim is to inhibit cancer proliferation by the diminishing/elimination of cancer residual cells and clinically improving the response duration with no or few adverse effects. This effect is supported by enhancing the number, functions, and activity of the immune effector cells, including the natural killer (NK) lymphocytes, NKT-lymphocytes, γδ T-lymphocytes, cytotoxic T-lymphocytes, directly or indirectly through vaccines particularly with neoantigens, and by lowering the functions of the immune suppressive cells. Beyond these new therapeutics and their personalized usage, new considerations have to be taken into account, such as epigenetic regulation particularly from microbiota, evaluation of transversal functions, particularly cellular metabolism, and consideration to the clinical consequences at the body level. The aim of this review is to discuss some practical aspects of immune therapy, giving to clinicians the concept of immune effector cells balancing between control and tolerance. Immunological precision medicine is a combination of modern biological knowledge and clinical therapeutic decisions in a global vision of the patient.

IL-21-mediated expansion of Vγ9Vδ2 T cells is limited by the Tim-3 pathway

Vγ9Vδ2 T cells are the main γδ T subset in the peripheral blood and lymphoid organs. Previous studies have shown that Vγ9Vδ2 T cells could expand in the presence of phosphoantigens and IL-2 and exert antitumor functions. However, their potency was limited because sustained proliferation could not be achieved, possibly due to exhaustion caused by prolonged antigenic stimulation. In this study, we examined the proliferative response of Vγ9Vδ2 T cells to IL-21, a cytokine previously shown to promote NK cell and CD8 T cell cytotoxicity. We found that IL-21 could significantly improve the proliferation of phosphoantigen-stimulated Vγ9Vδ2 T cells in a dose-dependent manner. However, in acute myeloid leukemia (AML) patients, the efficacy of IL-21 was significantly reduced. Vγ9Vδ2 T cells from AML patients exhibited lower expression of IL-21R, and required higher levels of IL-21 for expansion. IL-21-treated Vγ9Vδ2 T cells from AML patients presented lower increase in STAT1 phosphorylation than Vγ9Vδ2 T cells from healthy volunteers. Interestingly, AML Vγ9Vδ2 T cells presented significantly higher Tim-3 expression than healthy Vγ9Vδ2 T cells. IL-21 treatment further induced Tim-3 upregulation. Blocking Tim-3 increased the proliferation and the STAT phosphorylation in Vγ9Vδ2 T cells in response to IL-21. Together, these results demonstrated that IL-21 could significantly expand the Vγ9Vδ2 T cells, but its efficacy was limited since it also increased the expression of checkpoint molecule Tim-3.

Expansion and Adoptive Transfer of Human Vδ2+ T Cells to Assess Antitumor Effects In Vivo

Recent clinical trials have yielded promising results suggesting that γδ T cell62-based immunotherapies can be effective against hematological malignancies. Human T cells expressing Vγ9Vδ2⁺ receptors are particularly attractive candidates for this application, since they can be readily expanded in vitro in large quantities for adoptive transfer and do not require HLA-matching of donors and recipients. While it is well established that Vγ9Vδ2⁺ T cells are potently cytolytic against many human cancers and it has been shown that they can control transplanted human tumors in xenogeneic model systems, little is known about the parameters that determine the antitumor efficacy of adoptively transferred Vγ9Vδ2⁺ T cells in physiologically relevant scenarios. In particular, it may be important to separate their immunosurveillance functions from those employed in the context of an established tumor. Moreover, it is critical to understand how the presence of an immunosuppressive environment, such as one where tumor-infiltrating T cells are held in check by inhibitory ligands, affects the functions of Vγ9Vδ2⁺ T cells. This chapter describes how to establish Epstein-Barr virus (EBV) infection of human umbilical cord blood mononuclear cells (CBMCs) within immunodeficient mice, so as to drive the in vivo formation of human B cell lymphomas that contain an immunosuppressive environment. Details are provided on how to expand human Vγ9Vδ2⁺ T cells from peripheral blood mononuclear cells (PBMCs), administer them to the mice, and evaluate tumors and other tissues.

Boosting γδ T cell-mediated antibody-dependent cellular cytotoxicity by PD-1 blockade in follicular lymphoma

Follicular lymphoma (FL) is a common non Hodgkin's lymphoma subtype in which immune escape mechanisms are implicated in resistance to chemo-immunotherapy. Although molecular studies point to qualitative and quantitative deregulation of immune checkpoints, in depth cellular analysis of FL immune escape is lacking. Here, by functional assays and in silico analyses we show that a subset of FL patients displays a 'high' immune escape phenotype. These FL cases are characterized by abundant infiltration of PD1⁺ CD16⁺ TCRVγ9Vδ2 γδ T lymphocytes. In a 3D co-culture assay (MALC), γδ T cells mediate both direct and indirect (ADCC in the presence of anti-CD20 mAbs) cytolytic activity against FL cell aggregates. Importantly, PD-1, which is expressed by most FL-infiltrating γδ T lymphocytes with ADCC capacity, impairs these functions. In conclusion, we identify a PD1-regulated γδ T cell cytolytic immune component in FL. Our data provide a treatment rational by PD-1 blockade aimed at boosting γδ T cell anti-tumor functions in FL.

CD38 Antibodies in Multiple Myeloma: Mechanisms of Action and Modes of Resistance

MM cells express high levels of CD38, while CD38 is expressed at relatively low levels on normal lymphoid and myeloid cells, and in some non-hematopoietic tissues. This expression profile, together with the role of CD38 in adhesion and as ectoenzyme, resulted in the development of CD38 antibodies for the treatment of multiple myeloma (MM). At this moment several CD38 antibodies are at different phases of clinical testing, with daratumumab already approved for various indications both as monotherapy and in combination with standards of care in MM. CD38 antibodies have Fc-dependent immune effector mechanisms, such as complement-dependent cytotoxicity (CDC), antibody-dependent cellular cytotoxicity (ADCC), and antibody-dependent cellular phagocytosis (ADCP). Inhibition of ectoenzymatic function and direct apoptosis induction may also contribute to the efficacy of the antibodies to kill MM cells. The CD38 antibodies also improve host-anti-tumor immunity by the elimination of regulatory T cells, regulatory B cells, and myeloid-derived suppressor cells. Mechanisms of primary and/or acquired resistance include tumor-related factors, such as reduced cell surface expression levels of the target antigen and high levels of complement inhibitors (CD55 and CD59). Differences in frequency or activity of effector cells may also contribute to differences in outcome. Furthermore, the microenvironment protects MM cells to CD38 antibody-induced ADCC by upregulation of anti-apoptotic molecules, such as survivin. Improved understanding of modes of action and mechanisms of resistance has resulted in rationally designed CD38-based combination therapies, which will contribute to further improvement in outcome of MM patients.

Glyco-Engineered Anti-Human Programmed Death-Ligand 1 Antibody Mediates Stronger CD8 T Cell Activation Than Its Normal Glycosylated and Non-Glycosylated Counterparts

The programmed death 1 (PD-1)/programmed death-ligand 1 (PD-L1) axis plays a central role in suppression of anti-tumor immunity. Blocking the axis by targeting PD-L1 with monoclonal antibodies is an effective and already clinically approved approach to treat cancer patients. Glyco-engineering technology can be used to optimize different properties of monoclonal antibodies, for example, binding to FcγRs. We generated two glycosylation variants of the same anti-PD-L1 antibody: one bearing core fucosylated N-glycans in its Fc part (92%) and its de-fucosylated counterpart (4%). The two glycosylation variants were compared to a non-glycosylated commercially available anti-PD-L1 antibody in various assays. No differences were observed regarding binding to PD-L1 and blocking of this interaction with its counter receptors PD-1 or CD80. The de-fucosylated anti-PD-L1 antibody showed increased FcγRIIIa binding resulting in enhanced antibody dependent cellular cytotoxicity (ADCC) activity against PD-L1⁺ cancer cells compared to the "normal"-glycosylated variant. Both glycosylation variants showed no antibody-mediated lysis of B cells and monocytes. The non-glycosylated reference antibody showed no FcγRIIIa engagement and no ADCC activity. Using mixed leukocyte reaction it was observed that the de-fucosylated anti-PD-L1 antibody induced the strongest CD8 T cell activation determined by expression of activation markers, proliferation, and cytotoxicity against cancer cells. The systematic comparison of anti-PD-L1 antibody glycosylation variants with different Fc-mediated potencies demonstrates that our glyco-optimization approach has the potential to enhance CD8 T cell-mediated anti-tumor activity which may improve the therapeutic benefit of anti-PD-L1 antibodies.

Human γδ T-Cells: From Surface Receptors to the Therapy of High-Risk Leukemias

γδ T lymphocytes are potent effector cells, capable of efficiently killing tumor and leukemia cells. Their activation is mediated by γδ T-cell receptor (TCR) and by activating receptors shared with NK cells (e.g., NKG2D and DNAM-1). γδ T-cell triggering occurs upon interaction with specific ligands, including phosphoantigens (for Vγ9Vδ2 TCR), MICA-B and UL16 binding protein (for NKG2D), and PVR and Nectin-2 (for DNAM-1). They also respond to cytokines undergoing proliferation and release of cytokines/chemokines. Although at the genomic level γδ T-cells have the potential of an extraordinary TCR diversification, in tissues they display a restricted repertoire. Recent studies have identified various γδ TCR rearrangements following either hematopoietic stem cell transplantation (HSCT) or cytomegalovirus infection, accounting for their “adaptive” potential. In humans, peripheral blood γδ T-cells are primarily composed of Vγ9Vδ2 chains, while a minor proportion express Vδ1. They do not recognize antigens in the context of MHC molecules, thus bypassing tumor escape based on MHC class I downregulation. In view of their potent antileukemia activity and absence of any relevant graft-versus-host disease-inducing effect, γδ T-cells may play an important role in the successful clinical outcome of patients undergoing HLA-haploidentical HSCT depleted of TCR αβ T/CD19⁺ B lymphocytes to cure high-risk acute leukemias. In this setting, high numbers of both γδ T-cells (Vδ1 and Vδ2) and NK cells are infused together with CD34⁺ HSC and may contribute to rapid control of infections and leukemia relapse. Notably, zoledronic acid potentiates the cytolytic activity of γδ T-cells in vitro and its infusion in patients strongly promotes γδ T-cell differentiation and cytolytic activity; thus, treatment with this agent may contribute to further improve the patient clinical outcome after HLA-haploidentical HSCT depleted of TCR αβ T/CD19⁺ B lymphocytes.

Improving the Efficiency of Vγ9Vδ2 T-Cell Immunotherapy in Cancer

Increasing immunological knowledge and advances in techniques lay the ground for more efficient and broader application of immunotherapies. gamma delta (γδ) T-cells possess multiple favorable anti-tumor characteristics, making them promising candidates to be used in cellular and combination therapies of cancer. They recognize malignant cells, infiltrate tumors, and depict strong cytotoxic and pro-inflammatory activity. Here, we focus on human Vγ9Vδ2 T-cells, the most abundant γδ T-cell subpopulation in the blood, which are able to inhibit cancer progression in various models in vitro and in vivo. For therapeutic use they can be cultured and manipulated ex vivo and in the following adoptively transferred to patients, as well as directly stimulated to propagate in vivo. In clinical studies, Vγ9Vδ2 T-cells repeatedly demonstrated a low toxicity profile but hitherto only the modest therapeutic efficacy. This review provides a comprehensive summary of established and newer strategies for the enhancement of Vγ9Vδ2 T-cell anti-tumor functions. We discuss data of studies exploring methods for the sensitization of malignant cells, the improvement of recognition mechanisms and cytotoxic activity of Vγ9Vδ2 T-cells. Main aspects are the tumor cell metabolism, antibody-dependent cell-mediated cytotoxicity, antibody constructs, as well as activating and inhibitory receptors like NKG2D and immune checkpoint molecules. Several concepts show promising results in vitro, now awaiting translation to in vivo models and clinical studies. Given the array of research and encouraging findings in this area, this review aims at optimizing future investigations, specifically targeting the unanswered questions.

Role of the microenvironment across histological subtypes of NHL

Recent progress in next-generation sequencing strategies has revealed the genetic landscape of B-cell non-Hodgkin lymphoma, but the tumor microenvironment is increasingly recognized as crucial to sustaining malignant B-cell survival and growth, subclonal evolution, and drug resistance. The tumor niche is made up of a dynamic and organized network of strongly heterogeneous immune and stromal cell subsets characterized by specific phenotypic, transcriptomic, and functional features. Nonmalignant cell recruitment and plasticity are dictated by lymphoma B cells, which convert their surrounding microenvironment into a supportive niche. In addition, they are also influenced by the crosstalk between the various components of this niche. In agreement with this, the B-cell lymphoma subtype is a key determinant of the organization of the tumor niche, but genetic alteration patterns, tumor localization, stage of the disease, and treatment strategy may also modulate its composition and activity. Moreover, the complex set of bidirectional interactions between B cells and their microenvironment has been proposed as a promising therapeutic target with the aim of reinforcing antitumor immunity and/or of abbrogating the lymphoma-promoting signals delivered by the tumor niche.

T follicular helper cells: a potential therapeutic target in follicular lymphoma

Follicular lymphoma (FL), the most common indolent B-cell non-Hodgkin lymphoma (B-NHL), is a germinal center (GC)-derived lymphoma. The mechanisms underlying B-cell differentiation/maturation in GCs could be also involved in their malignant transformation. Moreover, the non-malignant cell composition and architecture of the tumor microenvironment can influence FL development and outcome. Here, we review recent research advances on CD4 helper T cells in FL that highlight the pivotal role of T follicular helper (TFH) cells in a complex multicellular system where they interact with B cells during GC dynamics. After describing the mechanism of FL lymphomagenesis, we discuss the emerging evidence about TFH cell enrichment and involvement in FL tumorigenesis and in B-T cell interaction, TFH regulation by T follicular regulatory cells (TFR) and its potential effect on FL. Then, we provide an overview on the flexible interplay between the different CD4 T-cell subtypes and how this may be predicted in normal and pathologic contexts, according to the cell epigenetic state. Finally, we highlight the importance of targeting TFH cells in the clinic, summarize the main outstanding questions about TFH and TFR cells in FL, and describe strategies to potentiate FL therapy by taking into account TFH cells.

Zoledronic acid sensitizes rhabdomyosarcoma cells to cytolysis mediated by human γδ T cells

Rhabdomyosarcoma (RMS) is the most common type of soft-tissue sarcoma in children. Immunotherapy has been proposed as a treatment for this deadly tumor. In the present study, the cytotoxicity of ex vivo expanded γδ T cells on RMS cell lines was evaluated and the molecular interactions involved were investigated. γδ T cells were expanded in vitro using peripheral blood mononuclear cells from 5 healthy donors and were stimulated with zoledronic acid (Zol) and interleukin 2. RMS cell lines RD and A-673 were used as target cells. The cytotoxicity of the γδ T cells against RMS was assessed in vitro and in vivo. γδ T cells were cytotoxic to RMS cells. Importantly, Zol markedly increased their cytotoxic potential. RMS cells treated with Zol-stimulated γδ T cells to produce interferon γ. γδ T cell-mediated cytotoxicity was primarily through the T cell receptor-dependent signaling pathway in blocking studies. Transfer of γδ T cells together with Zol into nude mice induced the regression of RD tumor xenotransplants. The results of the present study provide the rationale for the clinical evaluation of γδ T cells in RMS.

Dual Face of Vγ9Vδ2-T Cells in Tumor Immunology: Anti- versus Pro-Tumoral Activities

Vγ9Vδ2-T cells are considered as potent effector cells for tumor immunotherapy through directly killing tumor cells and indirectly regulating other innate and adaptive immune cells to establish antitumoral immunity. The antitumoral activity of Vγ9Vδ2-T cells is governed by a complicated set of activating and inhibitory cell receptors. In addition, cytokine milieu in tumor microenvironment can also induce the pro-tumoral activities and functional plasticity of Vγ9Vδ2-T cells. Here, we review the anti- versus pro-tumoral activities of Vγ9Vδ2-T cells and discuss the mechanisms underlying the recognition, activation, differentiation and regulation of Vγ9Vδ2-T cells in tumor immunosurveillance. The comprehensive understanding of the dual face of Vγ9Vδ2-T cells in tumor immunology may improve the therapeutic efficacy and clinical outcomes of Vγ9Vδ2-T cell-based tumor immunotherapy.

Key Features of Gamma-Delta T-Cell Subsets in Human Diseases and Their Immunotherapeutic Implications

The unique features of gamma-delta (γδ) T cells, related to their antigen recognition capacity, their tissue tropism, and their cytotoxic function, make these cells ideal candidates that could be targeted to induce durable immunity in the context of different pathologies. In this review, we focus on the main characteristics of human γδ T-cell subsets in diseases and the key mechanisms that could be explored to target these cells.

Nano-technology based carriers for nitrogen-containing bisphosphonates delivery as sensitisers of γδ T cells for anticancer immunotherapy

Nitrogen containing bisphosphonates (N-BPs) including zoledronate (ZOL) and alendronate (ALD) inhibit farnesyl diphosphate synthase, and have been shown to have a cytotoxic affect against cancer cells as a monotherapy and to also sensitise tumour cells to destruction by γδ T cells. γδ T cells are a subset of human T lymphocytes and have a diverse range of roles in the immune system including the recognition and destruction of cancer cells. This property of γδ T cells can be harnessed for use in cancer immunotherapy through in vivo expansion or the adoptive transfer of ex vivo activated γδ T cells. The use of N-BPs with γδ T cells has been shown to have a synergistic effect in in vitro, animal and clinical studies. N-BPs have limited in vivo activity due to rapid clearance from the circulation. By encapsulating N-BPs in liposomes (L) it is possible to increase the levels of N-BPs at non-osseous tumour sites. L-ZOL and L-ALD have been shown to have different toxicological profiles than free ZOL or ALD. Both L-ALD and L-ZOL led to increased spleen weight, leucocytosis, neutrophilia and lymphocytopenia in mice after intravenous injection. L-ALD was shown to be better tolerated than L-ZOL in murine studies. Biodistribution studies have been performed in order to better understand the interaction of N-BPs and γδ T cells in vivo. Additionally, in vivo therapy studies have shown that mice treated with both L-ALD and γδ T cells had a significant reduction in tumour growth compared to mice treated with L-ALD or γδ T cells alone. The use of ligand-targeted liposomes may further increase the efficacy of this combinatory immunotherapy. Liposomes targeting the αvβ6 integrin receptor using the peptide A20FMDV2 had a greater ability than untargeted liposomes in sensitising cancer cells to destruction by γδ T cells in αvβ6 positive cancer cell lines.

Human γδT-cell subsets and their involvement in tumor immunity

γδT cells are a conserved population of innate lymphocytes with diverse structural and functional heterogeneity that participate in various immune responses during tumor progression. γδT cells perform potent immunosurveillance by exerting direct cytotoxicity, strong cytokine production and indirect antitumor immune responses. However, certain γδT-cell subsets also contribute to tumor progression by facilitating cancer-related inflammation and immunosuppression. Here, we review recent observations regarding the antitumor and protumor roles of major structural and functional subsets of human γδT cells, describing how these subsets are activated and polarized, and how these events relate to subsequent function in tumor immunity. These studies provide insights into the manipulation of γδT-cell function to facilitate more targeted approaches for tumor therapy.

In vitro potency, in vitro and in vivo efficacy of liposomal alendronate in combination with γδ T cell immunotherapy in mice

Nitrogen-containing bisphosphonates (N-BP), including zoledronic acid (ZOL) and alendronate (ALD), have been proposed as sensitisers in γδ T cell immunotherapy in pre-clinical and clinical studies. Therapeutic efficacy of N-BPs is hampered by their rapid renal excretion and high affinity for bone. Liposomal formulations of N-BP have been proposed to improve accumulation in solid tumours. Liposomal ALD (L-ALD) has been suggested as a suitable alternative to liposomal ZOL (L-ZOL), due to unexpected mice death experienced in pre-clinical studies with the latter. Only one study so far has proven the therapeutic efficacy of L-ALD, in combination with γδ T cell immunotherapy, after intraperitoneal administration of γδ T cell resulting in delayed growth of ovarian cancer in mice. This study aims to assess the in vitro efficacy of L-ALD, in combination with γδ T cell immunotherapy, in a range of cancerous cell lines, using L-ZOL as a comparator. The therapeutic efficacy was tested in a pseudo-metastatic lung mouse model, following intravenous injection of γδ T cell, L-ALD or the combination. In vivo biocompatibility and organ biodistribution studies of L-N-BPs were undertaken simultaneously. Higher concentrations of L-ALD (40-60μM) than L-ZOL (3-10μM) were required to produce a comparative reduction in cell viability in vitro, when used in combination with γδ T cells. Significant inhibition of tumour growth was observed after treatment with both L-ALD and γδ T cells in pseudo-metastatic lung melanoma tumour-bearing mice after tail vein injection of both treatments, suggesting that therapeutically relevant concentrations of L-ALD and γδ T cell could be achieved in the tumour sites, resulting in significant delay in tumour growth.

Taking up Cancer Immunotherapy Challenges: Bispecific Antibodies, the Path Forward?

As evidenced by the recent approvals of Removab (EU, Trion Pharma) in 2009 and of Blincyto (US, Amgen) in 2014, the high potential of bispecific antibodies in the field of immuno-oncology is eliciting a renewed interest from pharmaceutical companies. Supported by rapid advances in antibody engineering and the development of several technological platforms such as Triomab or bispecific T cell engagers (BiTEs), the “bispecifics” market has increased significantly over the past decade and may occupy a pivotal space in the future. Over 30 bispecific molecules are currently in different stages of clinical trials and more than 70 in preclinical phase. This review focuses on the clinical potential of bispecific antibodies as immune effector cell engagers in the onco-immunotherapy field. We summarize current strategies targeting various immune cells and their clinical interests. Furthermore, perspectives of bispecific antibodies in future clinical developments are addressed.

Targeted Therapies in Adult B-Cell Malignancies

B-lymphocytes are programmed for the production of immunoglobulin (Ig) after antigen presentation, in the context of T-lymphocyte control within lymphoid organs. During this differentiation/activation process, B-lymphocytes exhibit different restricted or common surface markers, activation of cellular pathways that regulate cell cycle, metabolism, proteasome activity, and protein synthesis. All molecules involved in these different cellular mechanisms are potent therapeutic targets. Nowadays, due to the progress of the biology, more and more targeted drugs are identified, a situation that is correlated with an extended field of the targeted therapy. The full knowledge of the cellular machinery and cell-cell communication allows making the best choice to treat patients, in the context of personalized medicine. Also, focus should not be restricted to the immediate effects observed as clinical endpoints, that is, response rate, survival markers with conventional statistical methods, but it should consider the prediction of different clinical consequences due to other collateral drug targets, based on new methodologies. This means that new reflection and new bioclinical follow-up have to be monitored, particularly with the new drugs used with success in B-cell malignancies. This review discussed the principal aspects of such evident bioclinical progress.

The past, present and future of immunotherapy against tumor

Tumor is one of the most common lethal diseases in the world. Current progress of therapy remains insufficient survival benefit. Tumor immunotherapies have been proposed for more than a century. With the improvement in the understanding of the role of the immune system in the tumorigenesis and immune response to tumor, immunotherapy has obtained a rapid development and plays the significant role in tumor therapy nowadays. This review designs to provide a general overview of immunotherapy in tumors. We will introduce the landmark events in the past research of immunotherapy and elaborate a range of strategies using different immune response mechanism, which have been demonstrated successfully and even some of them have been approved by US Food and Drug Administration (FDA) to certain tumor therapy. Finally, we will discuss the future direction of immunotherapy so that we can predict the possible and valuable strategies for future tumor therapy.

Plasticity of γδ T Cells: Impact on the Anti-Tumor Response

The tumor immune microenvironment contributes to tumor initiation, progression, and response to therapy. Among the immune cell subsets that play a role in the tumor microenvironment, innate-like T cells that express T cell receptors composed of γ and δ chains (γδ T cells) are of particular interest. γδ T cells can contribute to the immune response against many tumor types (lymphoma, myeloma, melanoma, breast, colon, lung, ovary, and prostate cancer) directly through their cytotoxic activity and indirectly by stimulating or regulating the biological functions of other cell types required for the initiation and establishment of the anti-tumor immune response, such as dendritic cells and cytotoxic CD8+ T cells. However, the notion that tumor-infiltrating γδ T cells are a good prognostic marker in cancer was recently challenged by studies showing that the presence of these cells in the tumor microenvironment was associated with poor prognosis in both breast and colon cancer. These findings suggest that γδ T cells may also display pro-tumor activities. Indeed, breast tumor-infiltrating γδ T cells could exert an immunosuppressive activity by negatively regulating dendritic cell maturation. Furthermore, recent studies demonstrated that signals from the microenvironment, particularly cytokines, can confer some plasticity to γδ T cells and promote their differentiation into γδ T cells with regulatory functions. This review focuses on the current knowledge on the functional plasticity of γδ T cells and its effect on their anti-tumor activities. It also discusses the putative mechanisms underlying γδ T cell expansion, differentiation, and recruitment in the tumor microenvironment.

Neuroblastoma killing properties of Vδ2 and Vδ2-negative γδT cells following expansion by artificial antigen-presenting cells

PURPOSE

The majority of circulating human γδT lymphocytes are of the Vγ9Vδ2 lineage, and have T-cell receptor (TCR) specificity for nonpeptide phosphoantigens. Previous attempts to stimulate and expand these cells have therefore focused on stimulation using ligands of the Vγ9Vδ2 receptor, whereas relatively little is known about variant blood γδT subsets and their potential role in cancer immunotherapy.

EXPERIMENTAL DESIGN

To expand the full repertoire of γδT without bias toward specific TCRs, we made use of artificial antigen-presenting cells loaded with an anti γδTCR antibody that promoted unbiased expansion of the γδT repertoire. Expanded cells from adult blood donors were sorted into 3 populations expressing respectively Vδ2 TCR chains (Vδ2(+)), Vδ1 chains (Vδ1(+)), and TCR of other δ chain subtypes (Vδ1(neg)Vδ2(neg)).

RESULTS

Both freshly isolated and expanded cells showed heterogeneity of differentiation markers, with a less differentiated phenotype in the Vδ1 and Vδ1(neg)Vδ2(neg) populations. Expanded cells were largely of an effector memory phenotype, although there were higher numbers of less differentiated cells in the Vδ1(+) and Vδ1(neg)Vδ2(neg) populations. Using neuroblastoma tumor cells and the anti-GD2 therapeutic mAb ch14.18 as a model system, all three populations showed clinically relevant cytotoxicity. Although killing by expanded Vδ2 cells was predominantly antibody dependent and proportionate to upregulated CD16, Vδ1 cells killed by antibody-independent mechanisms.

CONCLUSIONS

In conclusion, we have demonstrated that polyclonal-expanded populations of γδT cells are capable of both antibody-dependent and -independent effector functions in neuroblastoma.

Vγ2Vδ2 T cell Costimulation Increases NK cell Killing of Monocyte-derived Dendritic Cells

Interactions between NK and dendritic cells (DC) affect maturation and function of both cell populations, including NK killing of DC (editing) that is important for controlling the quality of immune responses. We also know that antigen-stimulated Vγ2Vδ2 T cells costimulate NK cells via 4-1BB to enhance killing of tumor cell lines but we do not know what regulates 4-1BB expression or whether other NK effector functions including DC killing, might also be influenced by NK:γδ T cell cross talk. Here we show that antigen-stimulated γδ T cells costimulate NK through ICOS:ICOSL and this signal increases NK killing of autologous DC. Effects of NK:γδ T cell co-culture, which could be reproduced with soluble ICOS-Fc fusion protein, included increased CD69 and 4-1BB expression, IFN-γ, TNF-α, MIP-1β, I-309, RANTES and sFasL production, as well as elevated mRNA levels for costimulatory receptors OX40 (TNFRSF4) and GITR (TNFRSF18). Thus, ICOS/ICOSL costimulation of NK by Vγ2Vδ2 T cells had broad effects on NK phenotype and effector functions. The NK γδ T cell cross talk links innate and antigen-specific lymphocyte responses in the control of cytotoxic effector function and dendritic cell killing. This article is protected by copyright. All rights reserved.

The feature of distribution and clonality of TCR γ/δ subfamilies T cells in patients with B-cell non-Hodgkin lymphoma

Restricted T-cell receptor (TCR) Vα/Vβ repertoire expression and clonal expansion of αβ T cells especially for putative tumor-associated antigens were observed in patients with hematological malignancies. To further characterize the γδ T-cell immune status in B-cell non-Hodgkin lymphoma (B-NHL), we investigated the distribution and clonality of TCR Vγ/Vδ repertoire in peripheral blood (PB), bone marrow (BM), and lymph node (LN) from patients with B-NHL. Four newly diagnosed B-NHL cases, including three with diffuse large B-cell lymphoma (DLBCL) and one with small lymphocytic lymphoma (SLL), were enrolled. The restrictive expression of TCR Vγ/Vδ subfamilies with different distribution patterns could be detected in PB, BM, or LN from all of four patients, and partial subfamily T cells showed clonal proliferation. At least one clonally expanded Vδ subfamily member was found in PB from each patient. However, the expression pattern and clonality of TCR Vγ/Vδ changed in different immune organs and showed individual feature in different patients. The clonally expanded Vδ5, Vδ6, and Vδ8 were detected only in PB but neither in BM nor LN while clonally expanded Vδ2 and Vδ3 could be detected in both PB and BM/LN. In conclusion, the results provide a preliminary profile of distribution and clonality of TCR γ/δ subfamilies T cells in PB, BM, and LN from B-NHL; similar clonally expanded Vδ subfamily T cells in PB and BM may be related to the same B-cell lymphoma-associated antigens, while the different reactive clonally expanded Vγ/Vδ T cells may be due to local immune response.

Manipulating immune cells for adoptive immunotherapy of cancer

The immune system can be induced to respond against cancer with some success reported in clinical trials using a range of approaches including vaccines and antibodies. In addition to these approaches, cell based therapies are demonstrating much promise as potential therapies for cancer. In cell therapies autologous patient leukocytes are isolated and manipulated in vitro before transfer back to the patient in adoptive transfer regimens. The majority of approaches utilize conventional T cells or dendritic cells, but a wide variety of other types of leukocytes exist which can possess anti-cancer activity. In this review, we present a brief overview of T cell adoptive cell transfer followed by a review of approaches using alternate lymphocyte subsets and other leukocytes including neutrophils, macrophages and eosinophils.

γδ T cells for cancer immunotherapy: A systematic review of clinical trials

γδ T cells contribute to the front line of lymphoid antitumor surveillance and bridge the gap between innate and adaptive immunity. They can be readily expanded to high numbers in vivo and in vitro, starting from the blood of cancer patients, and a number of Phase I trials have demonstrated that these cells can be employed in cancer immunotherapy. Sufficient patients have received γδ T cell-based immunotherapies in the context of clinical trials to evaluate their utility, and to inform the direction of new trials. A systematic approach was used to identify Phase I, Phase II, and feasibility studies testing γδ T cell-based immunotherapy in cancer patients. Studies were excluded from further analysis if they did not provide patient-specific data. Data were compiled to evaluate efficacy, with stratification by treatment approach. When possible, comparisons were made with the efficacy of second-line conventional therapeutic approaches for the same malignancy. Twelve eligible studies were identified, providing information on 157 patients who had received γδ T cell-based immunotherapy. The comparison of objective response data suggests that γδ T cell-based immunotherapy is superior to current second-line therapies for advanced renal cell carcinoma and prostate cancer, but not for non-small cell lung carcinoma. An evaluation of pooled data from 132 published in vitro experiments shows a consistent improvement in the cytotoxicity of γδ T cells in the presence of antitumor antibodies. Immunotherapy using γδ T cells alone shows promising clinical activity, but there is a strong preclinical rationale for combining this treatment modality with cancer-targeting antibodies to augment its efficacy.

Targeting gamma delta T cells for cancer immunotherapy: bench to bedside

γδ T lymphocytes represent a minor subset of peripheral blood in humans (<10%). γδ T cells expressing Vγ9Vδ2 T cell receptor recognise the endogenous pool of isopentenyl pyrophosphate (IPP) that is overproduced in cancer cells as a result of dysregulated mevalonate pathway. Aminobisphosphonates increase the endogenous pool of IPP in cells by blocking the enzyme farnesyl pyrophosphate synthase (FPPS) of the mevalonate pathway. Activated γδ T cells release copious amounts of interferon (IFN)-γ and tumour necrosis factor (TNF)-α and exhibit potent anti-tumour activity. Combination of γδ T cells with therapeutic monoclonal antibodies can efficiently mediate antibody dependent cellular cytotoxicity against tumours. These features makes γδ T cells attractive mediator of cancer immunotherapy. We review here, the basic properties and importance of γδ T cells in tumour immunity, and highlight the key advances in anti-tumour effector functions of γδ T cells achieved over the last few years and also summarize the results of the clinical trials that have been done till date. Future immunotherapeutic approach utilizing γδ T cells holds considerable promise for treatment of different types of cancer.

At the Bench: Preclinical rationale for exploiting NK cells and γδ T lymphocytes for the treatment of high-risk leukemias

NK cells and γδ T lymphocytes display potent cytolytic activity against leukemias and CMV-infected cells and are thus, promising immune effector cells in the context of allo-HSCT. NK cells express HLA class I-specific inhibitory receptors and preferentially kill HLA class I(low) tumors or virus-infected cells. Killing occurs upon engagement of activating NKRs with ligands that are up-regulated on tumors and infected cells. A similar activating receptor/ligand interaction strategy is used by γδ T cells, which in addition, use their TCRs for recognition of phosphorylated antigens and still largely undefined ligands on tumor cells. In the haploidentical allo-HSCT setting, alloreactive NK cells, derived from donor HSCs, can exert potent antileukemia activity and kill residual patient DCs and T cells, thus preventing GvHD and graft rejection. However, generation of KIR(+) alloreactive NK cells from HSCs requires many weeks, during which leukemia relapses, and life-threatening infections may occur. Importantly, mature NK cells and γδ T cells can control certain infectious agents efficiently, in particular, limit CMV reactivation, and infusion of such donor cells at the time of HSCT has been implemented. Development of novel, cell-based immunotherapies, allowing improved trafficking and better targeting, will endow NK cells and γδ T lymphocytes with enhanced anti-tumor activity, also making them key reagents for therapies against solid tumors. The clinical aspects of using NK cells and γδ T lymphocytes against hematological malignancies, including the allo-HSCT context, are reviewed in the related side-by-side paper by Locatelli and colleagues [1].

The yin and the yang of follicular lymphoma cell niches: role of microenvironment heterogeneity and plasticity

Follicular lymphoma (FL) results from the malignant transformation of germinal center B cells and is characterized by recurrent genetic alterations providing a direct growth advantage or facilitating interaction with tumor microenvironment. In agreement, accumulating evidences suggest a dynamic bidirectional crosstalk between FL B cells and surrounding non-malignant cells within specialized tumor niches in both invaded lymph nodes and bone marrow. Infiltrating stromal cells, macrophages, and T/NK cell subsets either contribute to anti-tumor immune response, or conversely form a tumor supportive network promoting FL B cell survival, growth, and drug resistance. This review depicts the phenotypic heterogeneity and functional plasticity of the most important FL cell partners and describes their complex interplay. We also unravel how malignant B cells recruit and subvert accessory immune and stromal cells to trigger their polarization toward a supportive phenotype. Based on these observations, innovative therapeutic approaches have been recently proposed, in order to benefit from local anti-tumor immunity and/or to selectively target the protective cell niche.