Clinical evaluation of autologous gamma delta T cell-based immunotherapy for metastatic solid tumours

γδ T cells as critical anti-tumor immune effectors

While the effector cells that mediate anti-tumor immunity have historically been attributed to αβ T cells and natural killer cells, γδ T cells are now being recognized as a complementary mechanism mediating tumor rejection. γδ T cells possess a host of functions ranging from antigen presentation to regulatory function and, importantly, have critical roles in eliciting anti-tumor responses where other immune effectors may be rendered ineffective. Recent discoveries have elucidated how these differing functions are mediated by γδ T cells with specific T cell receptors and spatial distribution. Their relative resistance to mechanisms of dysfunction like T cell exhaustion has spurred the development of therapeutic approaches exploiting γδ T cells, and an improved understanding of these cells should enable more effective immunotherapies.

From immunomodulation to therapeutic prospects: Unveiling the biology of butyrophilins in cancer

Butyrophilin (BTN) proteins are a type of membrane protein that belongs to the Ig superfamily. They exhibit a high degree of structural similarity to molecules in the B7 family. They fulfill a complex function in regulating immune responses, including immunomodulatory roles, as they influence γδ T cells. The biology of BTN molecules indicates that they are capable of inhibiting the immune system's ability to detect antigens within tumors. A dynamic association between BTN molecules and cellular surfaces is also recognized in specific contexts, influencing their biology. Notably, the dynamism of BTN3A1 is associated with the immunosuppression of T cells or the activation of Vγ9Vδ2 T cells. Cancer immunotherapy relies heavily on T cells to modulate immune function within the intricate interaction of the tumor microenvironment (TME). A significant interaction between the TME and antitumor immunity involves the presence of BTN, which should be taken into account when developing immunotherapy. This review explores potential therapeutic applications of BTN molecules, based on the current understanding of their biology.

Exercise-induced β2-adrenergic Receptor Activation Enhances the Antileukemic Activity of Expanded γδ T-Cells via DNAM-1 Upregulation and PVR/Nectin-2 Recognition

Exercise mobilizes cytotoxic lymphocytes to blood which may allow superior cell products to be harvested and manufactured for cancer therapy. Gamma-Delta (γδ) T-cells have shown promise for treating solid tumors, but there is a need to increase their potency against hematologic malignancies. Here, we show that human γδ T-cells mobilized to blood in response to just 20 minutes of graded exercise have surface phenotypes and transcriptomic profiles associated with cytotoxicity, adhesion, migration, and cytokine signaling. Following 14 days ex vivo expansion with zoledronic acid and IL2, exercise mobilized γδ T-cells had surface phenotypes and transcriptomic profiles associated with enhanced effector functions and demonstrated superior cytotoxic activity against multiple hematologic tumors in vitro and in vivo in leukemia-bearing xenogeneic mice. Infusing humans with the β1+β2-agonist isoproterenol and administering β1 or β1+β2 antagonists prior to exercise revealed these effects to be β2-adrenergic receptor (AR) dependent. Antibody blocking of DNAM-1 on expanded γδ T-cells, as well as the DNAM-1 ligands PVR and Nectin-2 on leukemic targets, abolished the enhanced antileukemic effects of exercise. These findings provide a mechanistic link between exercise, β2-AR activation, and the manufacture of superior γδ T-cell products for adoptive cell therapy against hematologic malignancies.

SIGNIFICANCE

Exercise mobilizes effector γδ T-cells to blood via β2-adrenergic signaling which allows for generation of a potent expanded γδ T-cell product that is highly cytotoxic against hematologic malignancies.

Controversial role of γδ T cells in colorectal cancer

Colorectal cancer (CRC) is the third most frequent type of cancer, and the second leading cause of cancer-related deaths worldwide. Current treatments for patients with CRC do not substantially improve the survival and quality of life of patients with advanced CRC, thus necessitating the development of new treatment strategies. The emergence of immunotherapy has revitalized the field, showing great potential in advanced CRC treatment. Owing to the ability of tumor cells to evade the immune system through major histocompatibility complex shedding and heterogeneous and low antigen spreading, only a few patients respond to immunotherapy. γδ T cells have heterogeneous structures and functions, and their key roles in immune regulation, tumor immunosurveillance, and specific primary immune responses have increasingly been recognized. γδ T cells recognize and kill CRC cells efficiently, thus inhibiting tumor progress through various mechanisms. However, γδ T cells can potentially promote tumor development and metastasis. Thus, given this dual role in prognosis, these cells can act as either a "friend" or "foe" of CRC. In this review, we explore the characteristics of γδ T cells and their functions in CRC, highlighting their application in immunotherapy.

Directing the migration of serum-free, ex vivo-expanded Vγ9Vδ2 T cells

Vγ9Vδ2 T cells represent a promising cancer therapy platform because the implementation of allogenic, off-the-shelf product candidates is possible. However, intravenous administration of human Vγ9Vδ2 T cells manufactured under good manufacturing practice (GMP)-compliant, serum-free conditions are not tested easily in most mouse models, mainly because they lack the ability to migrate from the blood to tissues or tumors. We demonstrate that these T cells do not migrate from the circulation to the mouse bone marrow (BM), the site of many malignancies. Thus, there is a need to better characterize human γδ T-cell migration in vivo and develop strategies to direct these cells to in vivo sites of therapeutic interest. To better understand the migration of these cells and possibly influence their migration, NSG mice were conditioned with agents to clear BM cellular compartments, i.e., busulfan or total body irradiation (TBI), or promote T-cell migration to inflamed BM, i.e., incomplete Freund's adjuvant (IFA), prior to administering γδ T cells. Conditioning with TBI, unlike busulfan or IFA, increases the percentage and number of γδ T cells accumulating in the mouse BM, and cells in the peripheral blood (PB) and BM display identical surface protein profiles. To better understand the mechanism by which cells migrate to the BM, mice were conditioned with TBI and administered γδ T cells or tracker-stained red blood cells. The mechanism by which γδ T cells enter the BM after radiation is passive migration from the circulation, not homing. We tested if these ex vivo-expanded cells can migrate based on chemokine expression patterns and showed that it is possible to initiate homing by utilizing highly expressed chemokine receptors on the expanded γδ T cells. γδ T cells highly express CCR2, which provides chemokine attraction to C-C motif chemokine ligand 2 (CCL2)-expressing cells. IFNγ-primed mesenchymal stromal cells (MSCs) (γMSCs) express CCL2, and we developed in vitro and in vivo models to test γδ T-cell homing to CCL2-expressing cells. Using an established neuroblastoma NSG mouse model, we show that intratumorally-injected γMSCs increase the homing of γδ T cells to this tumor. These studies provide insight into the migration of serum-free, ex vivo-expanded Vγ9Vδ2 T cells in NSG mice, which is critical to understanding the fundamental properties of these cells.

Effective γδ T-cell clinical therapies: current limitations and future perspectives for cancer immunotherapy

γδ T cells are a unique subset of T lymphocytes, exhibiting features of both innate and adaptive immune cells and are involved with cancer immunosurveillance. They present an attractive alternative to conventional T cell-based immunotherapy due, in large part, to their lack of major histocompatibility (MHC) restriction and ability to secrete high levels of cytokines with well-known anti-tumour functions. To date, clinical trials using γδ T cell-based immunotherapy for a range of haematological and solid cancers have yielded limited success compared with in vitro studies. This inability to translate the efficacy of γδ T-cell therapies from preclinical to clinical trials is attributed to a combination of several factors, e.g. γδ T-cell agonists that are commonly used to stimulate populations of these cells have limited cellular uptake yet rely on intracellular mechanisms; administered γδ T cells display low levels of tumour-infiltration; and there is a gap in the understanding of γδ T-cell inhibitory receptors. This review explores the discrepancy between γδ T-cell clinical and preclinical performance and offers viable avenues to overcome these obstacles. Using more direct γδ T-cell agonists, encapsulating these agonists into lipid nanocarriers to improve their pharmacokinetic and pharmacodynamic profiles and the use of combination therapies to overcome checkpoint inhibition and T-cell exhaustion are ways to bridge the gap between preclinical and clinical success. Given the ability to overcome these limitations, the development of a more targeted γδ T-cell agonist-checkpoint blockade combination therapy has the potential for success in clinical trials which has to date remained elusive.

Isolation and expansion of pure and functional γδ T cells

γδ T cells are important components of the immune system due to their ability to elicit a fast and strong response against infected and transformed cells. Because they can specifically and effectively kill target cells in an MHC independent fashion, there is great interest to utilize these cells in anti-tumor therapies where antigen presentation may be hampered. Since only a small fraction of T cells in the blood or tumor tissue are γδ T cells, they require extensive expansion to allow for fundamental, preclinical and ex vivo research. Although expansion protocols can be successful, most are based on depletion of other cell types rather than γδ T cell specific isolation, resulting in unpredictable purity of the isolated fraction. Moreover, the primary focus only lies with expansion of Vδ2+ T cells, while Vδ1+ T cells likewise have anti-tumor potential. Here, we investigated whether γδ T cells directly isolated from blood could be efficiently expanded while maintaining function. γδ T cell subsets were isolated using MACS separation, followed by FACS sorting, yielding >99% pure γδ T cells. Isolated Vδ1+ and Vδ2+ T cells could effectively expand immediately after isolation or upon freeze/thawing and reached expansion ratios between 200 to 2000-fold starting from varying numbers using cytokine supported feeder stimulations. MACS/FACS isolated and PHA stimulated γδ T cells expanded as good as immobilized antibody mediated stimulated cells in PBMCs, but delivered purer cells. After expansion, potential effector functions of γδ T cells were demonstrated by IFN-γ, TNF-α and granzyme B production upon PMA/ionomycin stimulation and effective killing capacity of multiple tumor cell lines was confirmed in killing assays. In conclusion, pure γδ T cells can productively be expanded while maintaining their anti-tumor effector functions against tumor cells. Moreover, γδ T cells could be expanded from low starting numbers suggesting that this protocol may even allow for expansion of cells extracted from tumor biopsies.

Divergent immune microenvironments in two tumor nodules from a patient with mismatch repair-deficient prostate cancer

Patients with prostate cancer (PC) generally do not respond favorably to immune checkpoint inhibitors, which may be due to a low abundance of tumor-infiltrating lymphocytes even when mutational load is high. Here, we identified a patient who presented with high-grade primary prostate cancer with two adjacent tumor nodules. While both nodules were mismatch repair-deficient (MMRd), exhibited pathogenic MSH2 and MSH6 alterations, had a high tumor mutational burden (TMB), and demonstrated high microsatellite instability (MSI), they had markedly distinct immune phenotypes. The first displayed a dense infiltrate of lymphocytes ("hot nodule"), while the second displayed significantly fewer infiltrating lymphocytes ("cold nodule"). Whole-exome DNA analysis found that both nodules shared many identical mutations, indicating that they were derived from a single clone. However, the cold nodule appeared to be sub-clonal relative to the hot nodule, suggesting divergent evolution of the cold nodule from the hot nodule. Whole-transcriptome RNA analysis found that the cold nodule demonstrated lower expression of genes related to antigen presentation (HLA) and, paradoxically, classical tumor immune tolerance markers such as PD-L1 (CD274) and CTLA-4. Immune cell deconvolution suggested that the hot nodule was enriched not only in CD8+ and CD4 + T lymphocytes, but also in M1 macrophages, activated NK cells, and γδ T cells compared to the cold nodule. This case highlights that MMRd/TMB-high PC can evolve to minimize an anti-tumor immune response, and nominates downregulation of antigen presentation machinery (HLA loss) as a potential mechanism of adaptive immune evasion in PC.

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.

Gamma/delta T cells as cellular vehicles for anti-tumor immunity

Adoptive cellular immunotherapy as a new paradigm to treat cancers is exemplified by the FDA approval of six chimeric antigen receptor-T cell therapies targeting hematological malignancies in recent years. Conventional αβ T cells applied in these therapies have proven efficacy but are confined almost exclusively to autologous use. When infused into patients with mismatched human leukocyte antigen, αβ T cells recognize tissues of such patients as foreign and elicit devastating graft-versus-host disease. Therefore, one way to overcome this challenge is to use naturally allogeneic immune cell types, such as γδ T cells. γδ T cells occupy the interface between innate and adaptive immunity and possess the capacity to detect a wide variety of ligands on transformed host cells. In this article, we review the fundamental biology of γδ T cells, including their subtypes, expression of ligands, contrasting roles in and association with cancer prognosis or survival, as well as discuss the gaps in knowledge pertaining to this cell type which we currently endeavor to elucidate. In addition, we propose how to harness the unique properties of γδ T cells for cellular immunotherapy based on lessons gleaned from past clinical trials and provide an update on ongoing trials involving these cells. Lastly, we elaborate strategies that have been tested or can be explored to improve the anti-tumor activity and durability of γδ T cells in vivo.

The Role of γδ T-Lymphocytes in Glioblastoma: Current Trends and Future Directions

Cell-based immunotherapy for glioblastoma (GBM) encounters major challenges due to the infiltration-resistant and immunosuppressive tumor microenvironment (TME). γδ T cells, unconventional T cells expressing the characteristic γδ T cell receptor, have demonstrated promise in overcoming these challenges, suggesting great immunotherapeutic potential. This review presents the role of γδ T cells in GBM and proposes several research avenues for future studies. Using the PubMed, ScienceDirect, and JSTOR databases, we performed a review of the literature studying the biology of γδ T cells and their role in GBM treatment. We identified 15 studies focused on γδ T cells in human GBM. Infiltrative γδ T cells can incite antitumor immune responses in certain TMEs, though rapid tumor progression and TME hypoxia may impact the extent of tumor suppression. In the studies, available findings have shown both the potential for robust antitumor activity and the risk of protumor activity. While γδ T cells have potential as a therapeutic agent against GBM, the technical challenges of extracting, isolating, and expanding γδ T cells, and the activation of antitumoral versus protumoral cascades, remain barriers to their application. Overcoming these limitations may transform γδ T cells into a promising immunotherapy in GBM.

The capability of heterogeneous γδ T cells in cancer treatment

γδ T cells, a specialized subset of T lymphocytes, have garnered significant attention within the realm of cancer immunotherapy. Operating at the nexus between adaptive and innate immunological paradigms, these cells showcase a profound tumor discernment repertoire, hinting at novel immunotherapeutic strategies. Significantly, these cells possess the capability to directly identify and eliminate tumor cells without reliance on HLA-antigen presentation. Furthermore, γδ T cells have the faculty to present tumor antigens to αβ T cells, amplifying their anti-tumoral efficacy.Within the diverse and heterogeneous subpopulations of γδ T cells, distinct immune functionalities emerge, manifesting either anti-tumor or pro-tumor roles within the tumor microenvironment. Grasping and strategically harnessing these heterogeneous γδ T cell cohorts is pivotal to their integration in tumor-specific immunotherapeutic modalities. The aim of this review is to describe the heterogeneity of the γδ T cell lineage and the functional plasticity it generates in the treatment of malignant tumors. This review endeavors to elucidate the intricate heterogeneity inherent to the γδ T cell lineage, the consequential functional dynamics in combating malignancies, the latest advancements from clinical trials, and the evolving landscape of γδ T cell-based oncological interventions, while addressing the challenges impeding the field.

γδ T cells: origin and fate, subsets, diseases and immunotherapy

The intricacy of diseases, shaped by intrinsic processes like immune system exhaustion and hyperactivation, highlights the potential of immune renormalization as a promising strategy in disease treatment. In recent years, our primary focus has centered on γδ T cell-based immunotherapy, particularly pioneering the use of allogeneic Vδ2+ γδ T cells for treating late-stage solid tumors and tuberculosis patients. However, we recognize untapped potential and optimization opportunities to fully harness γδ T cell effector functions in immunotherapy. This review aims to thoroughly examine γδ T cell immunology and its role in diseases. Initially, we elucidate functional differences between γδ T cells and their αβ T cell counterparts. We also provide an overview of major milestones in γδ T cell research since their discovery in 1984. Furthermore, we delve into the intricate biological processes governing their origin, development, fate decisions, and T cell receptor (TCR) rearrangement within the thymus. By examining the mechanisms underlying the anti-tumor functions of distinct γδ T cell subtypes based on γδTCR structure or cytokine release, we emphasize the importance of accurate subtyping in understanding γδ T cell function. We also explore the microenvironment-dependent functions of γδ T cell subsets, particularly in infectious diseases, autoimmune conditions, hematological malignancies, and solid tumors. Finally, we propose future strategies for utilizing allogeneic γδ T cells in tumor immunotherapy. Through this comprehensive review, we aim to provide readers with a holistic understanding of the molecular fundamentals and translational research frontiers of γδ T cells, ultimately contributing to further advancements in harnessing the therapeutic potential of γδ T cells.

A Bispecific γδ T-cell Engager Targeting EGFR Activates a Potent Vγ9Vδ2 T cell-Mediated Immune Response against EGFR-Expressing Tumors

Vγ9Vδ2 T cells are effector cells with proven antitumor efficacy against a broad range of cancers. This study aimed to assess the antitumor activity and safety of a bispecific antibody directing Vγ9Vδ2 T cells to EGFR-expressing tumors. An EGFR-Vδ2 bispecific T-cell engager (bsTCE) was generated, and its capacity to activate Vγ9Vδ2 T cells and trigger antitumor activity was tested in multiple in vitro, in vivo, and ex vivo models. Studies to explore safety were conducted using cross-reactive surrogate engagers in nonhuman primates (NHP). We found that Vγ9Vδ2 T cells from peripheral blood and tumor specimens of patients with EGFR+ cancers had a distinct immune checkpoint expression profile characterized by low levels of PD-1, LAG-3, and TIM-3. Vγ9Vδ2 T cells could be activated by EGFR-Vδ2 bsTCEs to mediate lysis of various EGFR+ patient-derived tumor samples, and substantial tumor growth inhibition and improved survival were observed in in vivo xenograft mouse models using peripheral blood mononuclear cells (PBMC) as effector cells. EGFR-Vδ2 bsTCEs exerted preferential activity toward EGFR+ tumor cells and induced downstream activation of CD4+ and CD8+ T cells and natural killer (NK) cells without concomitant activation of suppressive regulatory T cells observed with EGFR-CD3 bsTCEs. Administration of fully cross-reactive and half-life extended surrogate engagers to NHPs did not trigger signals in the safety parameters that were assessed. Considering the effector and immune-activating properties of Vγ9Vδ2 T cells, the preclinical efficacy data and acceptable safety profile reported here provide a solid basis for testing EGFR-Vδ2 bsTCEs in patients with EGFR+ malignancies.

Human gamma-delta (γδ) T cell therapy for glioblastoma: A novel alternative to overcome challenges of adoptive immune cell therapy

Glioblastoma is the most common brain malignancy with devastating prognosis. Numerous clinical trials using various target therapeutic agents have failed and recent clinical trials using check point inhibitors also failed to provide survival benefits for glioblastoma patients. Adoptive T cell transfer is suggested as a novel therapeutic approach that has exhibited promise in preliminary clinical studies. However, the clinical outcomes are inconsistent, and there are several limitations of current adoptive T cell transfer strategies for glioblastoma treatment. As an alternative cell therapy, gamma-delta (γδ) T cells have been recently introduced for several cancers including glioblastoma. Since the leading role of γδ T cells is immune surveillance by recognizing a broad range of ligands including stress molecules, phosphoantigens, or lipid antigens, recent studies have suggested the potential benefits of γδ T cell transfer against glioblastomas. However, γδ T cells, as a small subset (1-5%) of T cells in human peripheral blood, are relatively unknown compared to conventional alpha-beta (αβ) T cells. In this context, our study introduced γδ T cells as an alternative and novel option to overcome several challenges regarding immune cell therapy in glioblastoma treatment. We described the unique characteristics and advantages of γδ T cells compared to conventional αβ T cells and summarize several recent preclinical studies using human gamma-delta T cell therapy for glioblastomas. Finally, we suggested future direction of human γδ T cell therapy for glioblastomas.

Local γδ T cells: translating promise to practice in cancer immunotherapy

Rapid bench-to-bedside translation of basic immunology to cancer immunotherapy has revolutionised the clinical practice of oncology over the last decade. Immune checkpoint inhibitors targeting αβ T cells now offer durable remissions and even cures for some patients with hitherto treatment-refractory metastatic cancers. Unfortunately, these treatments only benefit a minority of patients and efforts to improve efficacy through combination therapies utilising αβ T cells have seen diminishing returns. Alongside αβ T cells and B cells, γδ T cells are a third lineage of adaptive lymphocytes. Less is known about these cells, and they remain relatively untested in cancer immunotherapy. Whilst preclinical evidence supports their utility, the few early-phase trials involving γδ T cells have failed to demonstrate convincing efficacy in solid cancers. Here we review recent progress in our understanding of how these cells are regulated, especially locally within tissues, and the potential for translation. In particular, we focus on the latest advances in the field of butyrophilin (BTN) and BTN-like (BTNL) regulation of γδ T cells and speculate on how these advances may address the limitations of historical approaches in utilising these cells, as well as how they may inform novel approaches in deploying these cells for cancer immunotherapy.

Innate lymphoid cells and innate-like T cells in cancer - at the crossroads of innate and adaptive immunity

Immunotherapies targeting conventional T cells have revolutionized systemic treatment for many cancers, yet only a subset of patients benefit from these approaches. A better understanding of the complex immune microenvironment of tumours is needed to design the next generation of immunotherapeutics. Innate lymphoid cells (ILCs) and innate-like T cells (ILTCs) are abundant, tissue-resident lymphocytes that have recently been shown to have critical roles in many types of cancers. ILCs and ILTCs rapidly respond to changes in their surrounding environment and act as the first responders to bridge innate and adaptive immunity. This places ILCs and ILTCs as pivotal orchestrators of the final antitumour immune response. In this Review, we outline hallmarks of ILCs and ILTCs and discuss their emerging role in antitumour immunity, as well as the pathophysiological adaptations leading to their pro-tumorigenic function. We explore the pleiotropic, in parts redundant and sometimes opposing, mechanisms that underlie the delicate interplay between the different subsets of ILCs and ILTCs. Finally, we highlight their role in amplifying and complementing conventional T cell functions and summarize immunotherapeutic strategies for targeting ILCs and ILTCs in cancer.

A close look at current γδ T-cell immunotherapy

Owing to their antitumor and major histocompatibility complex (MHC)-independent capacities, γδ T cells have gained popularity in adoptive T-cell immunotherapy in recent years. However, many unknowns still exist regarding γδ T cells, and few clinical data have been collected. Therefore, this review aims to describe all the main features of the applications of γδ T cells and provide a systematic view of current γδ T-cell immunotherapy. Specifically, this review will focus on how γδ T cells performed in treating cancers in clinics, on the γδ T-cell clinical trials that have been conducted to date, and the role of γδ T cells in the pharmaceutical industry.

NKG2A Immune Checkpoint in Vδ2 T Cells: Emerging Application in Cancer Immunotherapy

Immune regulation has revolutionized cancer treatment with the introduction of T-cell-targeted immune checkpoint inhibitors (ICIs). This successful immunotherapy has led to a more complete view of cancer that now considers not only the cancer cells to be targeted and destroyed but also the immune environment of the cancer cells. Current challenges associated with the enhancement of ICI effects are increasing the fraction of responding patients through personalized combinations of multiple ICIs and overcoming acquired resistance. This requires a complete overview of the anti-tumor immune response, which depends on a complex interplay between innate and adaptive immune cells with the tumor microenvironment. The NKG2A was revealed to be a key immune checkpoint for both Natural Killer (NK) cells and T cells. Monalizumab, a humanized anti-NKG2A antibody, enhances NK cell activity against various tumor cells and rescues CD8 αβ T cell function in combination with PD-1/PD-L1 blockade. In this review, we discuss the potential for targeting NKG2A expressed on tumor-sensing human γδ T cells, mostly on the specific Vδ2 T cell subset, in order to emphasize its importance and potential in the development of new ICI-based therapeutic approaches.

The way of interaction between Vγ9Vδ2 T cells and tumor cells

Immunotherapy has been a promising, emerging treatment for various cancers. Gamma delta (γδ) T cells own a T cell receptor composed of γ- and δ- chain and act as crucial players in the anti-tumor immune effect. Currently, Vγ9Vδ2 T cells, the predominate γδ T cell subset in human peripheral blood, has been shown to exert multiple biological functions. In addition, a growing body of evidence notes that Vγ9Vδ2 T cells interact with tumor cells in many ways, such as TCR-mediated nonpeptidic-phosphorylated phosphoantigens (pAgs) recognization, NKG2D/NKG2D ligand (NKG2DL) pathway, Fas-FasL axis and antibody-dependent cellular cytotoxicity (ADCC) as well as exosome. More importantly, clinical studies with Vγ9Vδ2 T cells in cancers have propelled several clinical applications to investigate their safety and efficacy. Herein, this review summarized the underlying ways and mechanisms of interplay cancer cells and Vγ9Vδ2 T cells, which may help us to generate new strategies for tumor immunotherapy in the future.

Releasing the restraints of Vγ9Vδ2 T-cells in cancer immunotherapy

Objectives

Vγ9Vδ2 T-cells are a subset of T-cells with a crucial role in immunosurveillance which can be activated and expanded by multiple means to stimulate effector responses. Little is known about the expression of checkpoint molecules on this cell population and whether the ligation of these molecules can regulate their activity. The aim of this study was to assess the expression of both activatory and inhibitory receptors on Vγ9Vδ2 T-cells to assess potential avenues of regulation to target with immunotherapy.

Methods

Expression of various activatory and inhibitory receptors was assessed on Vγ9Vδ2 T-cells by flow cytometry following activation and expansion using zoledronic acid (ZA) and Bacillus Calmette-Guérin (BCG). Expression of these markers and production of effector molecules was also examined following co-culture with various tumour cell targets. The effect of immune checkpoint blockade on Vγ9Vδ2 T-cells was also explored.

Results

Vγ9Vδ2 T-cells expressed high levels of activatory markers both at baseline and following stimulation. Vγ9Vδ2 T-cells expressed variable levels of inhibitory checkpoint receptors with many being upregulated following stimulation. Expression of these markers is further modulated upon co-culture with tumour cells with changes reflecting activation and effector functions. Despite their high expression of inhibitory receptors when cultured with tumour cells expressing cognate ligands there was no effect on Vδ2+ T-cell cytotoxic capacity or cytokine production with immune checkpoint blockade.

Conclusions

Our work suggests the expression of checkpoint receptors present on Vγ9Vδ2 T-cells which may provide a mechanism with the potential to be utilised by tumour cells to subvert Vγ9Vδ2 T-cell cytotoxicity. This work suggests important candidates for blockade by ICI therapy in order to increase the successful use of Vγ9Vδ2 T-cells in immunotherapy.

Case Report: Partial response to single-agent pembrolizumab in a chemotherapy-resistant metastatic pancreatic cancer patient with a high tumor mutation burden

Single-agent immune checkpoint blockade has shown no clinical benefits in pancreatic cancer. Recently, the programmed cell death protein 1 (PD-1) antibody pembrolizumab has been recommended as a treatment option for high tumor mutational burden (TMB) solid tumors based on the data from a basket trial. However, no pancreatic cancer patients were enrolled in that trial. Whether pancreatic cancer patients with high TMB respond to PD-1 blockade as well remains unclear. Here, we report a case with a partial response to single-agent immunotherapy with pembrolizumab in pancreatic cancer with high TMB after the failure of several lines of chemotherapy. This result indicates that single-agent immunotherapy may be effective in pancreatic cancer patients with high TMB. In addition, in order to understand the basic immune state of our patients, we also analyzed the changes in immune cells in peripheral blood with cytometry by time-of-flight mass spectrometry (CyTOF) before and after pembrolizumab treatment.

γδ T cells and their clinical application in colon cancer

In recent years, research has focused on colorectal cancer to implement modern treatment approaches to improve patient survival. In this new era, γδ T cells constitute a new and promising candidate to treat many types of cancer because of their potent killing activity and their ability to recognize tumor antigens independently of HLA molecules. Here, we focus on the roles that γδ T cells play in antitumor immunity, especially in colorectal cancer. Furthermore, we provide an overview of small-scale clinical trials in patients with colorectal cancer employing either in vivo activation or adoptive transfer of ex vivo expanded γδ T cells and suggest possible combinatorial approaches to treat colon cancer.

Reviving human γδT cells from apoptosis induced by IL-12/18 via p-JNK inhibition

γδT cells recognize and exert cytotoxicity against tumor cells independently of MHC restriction and have antigen presentation and regulatory functions to promote adaptive immune responses. They are considered as potential immune cells for cellular immunotherapy in cancer patients. However, it is challenging to ex vivo expand human γδT cells that have superb effector functions and long-term survival for adoptive cancer therapy. We found that IL-12/18 combination could drastically promote IFN-γ secretion and cytotoxicity in human γδT cells. However, the enhanced activation of human γδT cells is accompanied by increased apoptosis and elevated expressions of co-inhibitory receptors under the stimulation of IL-12/18. We further demonstrated that IL-12/18 induced apoptosis of human γδT cells was in a phosphoantigen or IFN-γ-independent manner. Transcriptomic analysis suggested that IL-12/18-induced apoptosis of human γδT cells was mediated by the activation of JNK pathway. p-JNK inhibitor (SP-600125) treatment effectively revived human γδT cells from the apoptosis induced by IL-12/18 and maintained their enhanced IFN-γ production and cytotoxicity against tumor cells. Our results provide a novel and feasible strategy for ex vivo expansion of cytokine-activated human γδT cells, which could promote the efficacy of γδT cell adoptive immunotherapy in cancer patients.

Human Vδ2 T Cells and Their Versatility for Immunotherapeutic Approaches

Gamma/delta (γδ) T cells are innate-like immune effectors that are a critical component linking innate and adaptive immune responses. They are recognized for their contribution to tumor surveillance and fight against infectious diseases. γδ T cells are excellent candidates for cellular immunotherapy due to their unique properties to recognize and destroy tumors or infected cells. They do not depend on the recognition of a single antigen but rather a broad-spectrum of diverse ligands through expression of various cytotoxic receptors. In this manuscript, we review major characteristics of the most abundant circulating γδ subpopulation, Vδ2 T cells, their immunotherapeutic potential, recent advances in expansion protocols, their preclinical and clinical applications for several infectious diseases and malignancies, and how additional modulation could enhance their therapeutic potential.

Low expression of INHB co-receptor TGFBR3 in connection with metastasis and immune infiltration in lung adenocarcinoma

OBJECTIVE

Inhibin B (INHB) is one of the TGF-β superfamily member, consisting of α (INHA) and βB (INHBB) subunits. Studies have found that TGF-β receptor 3 (TGFBR3) binds to a convex α subunit on the surface of INHB, and enhances the binding affinity of activin receptor type-2 (ACVR2A/B) to INHβ subunit. This study tried to evaluate the roles of INHB subunits and its receptors (INHA, ACVR2A, ACVR2B, INHBB, TGFBR3) as prognostic biomarkers and therapeutic targets for the effective treatment of lung adenocarcinoma (LUAD).

METHODS

We analyzed INHB subunits and its receptors' expression and the influence of LUAD from Oncomine, GEPIA, HCMDB, CancerSEA, TIMER databases and so on. Then, 41 cases of cancer tissue and 41 cases of adjacent epithelium were detected in LUAD patients by immunohistochemistry.

RESULTS

INHA, ACVR2A, ACVR2B, INHBB were up-regulated while TGFBR3 was down-regulated in LUAD. INHA, ACVR2A and TGFBR3 were found to be strongly associated with high-grade malignancies and advanced TNM, only TGFBR3 expression was negatively correlated with LUAD metastasis probably mainly through cell adhesion molecules and the PI3K-Akt signaling pathway, univariate and multivariate analysis suggested that overall survival was lower in LUAD cases with low TGFBR3 levels. Further analysis revealed that low TGFBR3 expression was related to reduced infiltration of immune cells into the LUAD, promoting metastasis of LUAD cells. TGFBR3 expression negatively correlates with lymphatic metastasis and clinical stage in patients with LUAD.

CONCLUSION

TGFBR3 could be a potential new metastatic biomarker for LUAD, with potential application as a prognostic marker and for immunotherapy of LUAD.

Controversial role of γδ T cells in pancreatic cancer

γδ T cells are rare lymphocytes with cogent impact on immune responses. These cells are one of the earliest cells to be recruited in the sites of infection or tumors and play a critical role in coordinating innate and adaptive immune responses. The anti-tumor activity of γδ T cells have been numerously reported; nonetheless, there is controversy among published studies regarding their anti-tumor vs pro-tumor effect- especially in pancreatic cancer. A myriad of studies has confirmed that activated γδ T cells can potently lyse a broad variety of solid tumors and leukemia/lymphoma cells and produce an array of cytokines; however, early γδ T cell-based clinical trials did not lead to optimal efficacy, despite acceptable safety. Depending on the local micromilieu, γδ T cells can differentiate into tumor promoting or suppressing cells such as Th1-, Th2-, or Th17-like cells and produce prototypical cytokines such as interferon-γ (IFNγ) and interleukin (IL)-4/-10, IL-9, or IL-17. In an abstruse tumor such as pancreatic cancer- also known as immunologically cold tumor- γδ T cells are more likely to switch to their immunosuppressive phenotype. In this review we will adduce the accumulated knowledge on these two controversial aspects of γδ T cells in cancers- with a focus on solid tumors and pancreatic cancer. In addition, we propose strategies for enhancing the anti-tumor function of γδ T cells in cancers and discuss the potential future directions.

Bacillus Calmette-Guerin (BCG) induces superior anti-tumour responses by Vδ2+ T cells compared with the aminobisphosphonate drug zoledronic acid

Vδ2⁺ T cells can recognize malignantly transformed cells as well as those infected with mycobacteria. This cross-reactivity supports the idea of using mycobacteria to manipulate Vδ2⁺ T cells in cancer immunotherapy. To date, therapeutic interventions using Vδ2⁺ T cells in cancer have involved expanding these cells in or ex vivo using zoledronic acid (ZA). Here, we show that the mycobacterium Bacillus Calmette–Guérin (BCG) also causes Vδ2⁺ T-cell expansion in vitro and that resulting Vδ2⁺ cell populations are cytotoxic toward tumour cell lines. We show that both ZA and BCG-expanded Vδ2+ cells effectively killed both Daudi and THP-1 cells. THP-1 cell killing by both ZA and BCG-expanded Vδ2+ cells was enhanced by treatment of targets cells with ZA. Although no difference in cytotoxic activity between ZA- and BCG-expanded Vδ2+ cells was observed, BCG-expanded cells degranulated more and produced a more diverse range of cytokines upon tumour cell recognition compared to ZA-expanded cells. ZA-expanded Vδ2+ cells were shown to upregulate exhaustion marker CD57 to a greater extent than BCG-expanded Vδ2+ cells. Furthermore, ZA expansion was associated with upregulation of inhibitory markers PD-1 and TIM3 in a dose-dependent manner whereas PD-1 expression was not increased following expansion using BCG. Intradermal BCG vaccination of rhesus macaques caused in vivo expansion of Vδ2⁺ cells. In combination with the aforementioned in vitro data, this finding suggests that BCG treatment could induce expansion of Vδ2⁺ T cells with enhanced anti-tumour potential compared to ZA treatment and that either ZA or BCG could be used intratumourally as a means to potentiate stronger anti-tumour Vδ2⁺ T-cell responses.

Bone Metastasis and Immune Checkpoint Inhibitors in Non-Small Cell Lung Cancer (NSCLC): Microenvironment and Possible Clinical Implications

Patients with non-small cell lung cancer (NSCLC) develop bone metastasis (BoM) in more than 50% of cases during the course of the disease. This metastatic site can lead to the development of skeletal related events (SREs), such as severe pain, pathological fractures, spinal compression, and hypercalcemia, which reduce the patient’s quality of life. Recently, the treatment of advanced NSCLC has radically changed due to the advent of immunotherapy. Immune checkpoint inhibitors (ICI) alone or in combination with chemotherapy have become the main therapeutic strategy for advanced or metastatic NSCLC without driver gene mutations. Since survival has increased, it has become even more important to treat bone metastasis to prevent SRE. We know that the presence of bone metastasis is a negative prognostic factor. The lower efficacy of immunotherapy treatments in BoM+ patients could be induced by the presence of a particular immunosuppressive tumor and bone microenvironment. This article reviews the most important pre-clinical and clinical scientific evidence on the reasons for this lower sensitivity to immunotherapy and the need to combine bone target therapies (BTT) with immunotherapy to improve patient outcome.

Human γδ T Cell Subsets and Their Clinical Applications for Cancer Immunotherapy

Simple Summary

Research into the immunotherapeutic potential of T cells has predominantly focused on conventional alpha beta (αβ) T cells, which recognize peptide antigens presented by polymorphic major histocompatibility complex (MHC) class I and class II molecules. However, innate-like T cells, such as gamma delta (γδ) T cells, also play important roles in antitumor immunity. Here, we review the current understanding of γδ T cells in antitumor immunity and discuss strategies that could potentially maximize their potential in cancer immunotherapy.

Abstract

Gamma delta (γδ) T cells are a minor population of T cells that share adaptive and innate immune properties. In contrast to MHC-restricted alpha beta (αβ) T cells, γδ T cells are activated in an MHC-independent manner, making them ideal candidates for developing allogeneic, off-the-shelf cell-based immunotherapies. As the field of cancer immunotherapy progresses rapidly, different subsets of γδ T cells have been explored. In addition, γδ T cells can be engineered using different gene editing technologies that augment their tumor recognition abilities and antitumor functions. In this review, we outline the unique features of different subsets of human γδ T cells and their antitumor properties. We also summarize the past and the ongoing pre-clinical studies and clinical trials utilizing γδ T cell-based cancer immunotherapy.

Gamma Delta T-Cell Based Cancer Immunotherapy: Past-Present-Future

γδ T-cells directly recognize and kill transformed cells independently of HLA-antigen presentation, which makes them a highly promising effector cell compartment for cancer immunotherapy. Novel γδ T-cell-based immunotherapies, primarily focusing on the two major γδ T-cell subtypes that infiltrate tumors (i.e. Vδ1 and Vδ2), are being developed. The Vδ1 T-cell subset is enriched in tissues and contains both effector T-cells as well as regulatory T-cells with tumor-promoting potential. Vδ2 T-cells, in contrast, are enriched in circulation and consist of a large, relatively homogeneous, pro-inflammatory effector T-cell subset. Healthy individuals typically harbor in the order of 50-500 million Vγ9Vδ2 T-cells in the peripheral blood alone (1-10% of the total CD3⁺ T-cell population), which can rapidly expand upon stimulation. The Vγ9Vδ2 T-cell receptor senses intracellular phosphorylated metabolites, which accumulate in cancer cells as a result of mevalonate pathway dysregulation or upon pharmaceutical intervention. Early clinical studies investigating the therapeutic potential of Vγ9Vδ2 T-cells were based on either ex vivo expansion and adoptive transfer or their systemic activation with aminobisphosphonates or synthetic phosphoantigens, either alone or combined with low dose IL-2. Immune-related adverse events (irAE) were generally \mild, but the clinical efficacy of these approaches provided overall limited benefit. In recent years, critical advances have renewed the excitement for the potential of Vγ9Vδ2 T-cells in cancer immunotherapy. Here, we review γδ T-cell-based therapeutic strategies and discuss the prospects of those currently evaluated in clinical studies in cancer patients as well as future therapies that might arise from current promising pre-clinical results.

Direct Cell Radiolabeling for in Vivo Cell Tracking with PET and SPECT Imaging

The arrival of cell-based therapies is a revolution in medicine. However, its safe clinical application in a rational manner depends on reliable, clinically applicable methods for determining the fate and trafficking of therapeutic cells in vivo using medical imaging techniques─known as in vivo cell tracking. Radionuclide imaging using single photon emission computed tomography (SPECT) or positron emission tomography (PET) has several advantages over other imaging modalities for cell tracking because of its high sensitivity (requiring low amounts of probe per cell for imaging) and whole-body quantitative imaging capability using clinically available scanners. For cell tracking with radionuclides, ex vivo direct cell radiolabeling, that is, radiolabeling cells before their administration, is the simplest and most robust method, allowing labeling of any cell type without the need for genetic modification. This Review covers the development and application of direct cell radiolabeling probes utilizing a variety of chemical approaches: organic and inorganic/coordination (radio)chemistry, nanomaterials, and biochemistry. We describe the key early developments and the most recent advances in the field, identifying advantages and disadvantages of the different approaches and informing future development and choice of methods for clinical and preclinical application.

Prodrugs of pyrophosphates and bisphosphonates: disguising phosphorus oxyanions

Pyrophosphates have important functions in living systems and thus pyrophosphate-containing molecules and their more stable bisphosphonate analogues have the potential to be used as drugs for treating many diseases including cancer and viral infections. Both pyrophosphates and bisphosphonates are polyanionic at physiological pH and, whilst this is essential for their biological activity, it also limits their use as therapeutic agents. In particular, the high negative charge density of these compounds prohibits cell entry other than by endocytosis, prevents transcellular oral absorption and causes sequestration to bone. Therefore, prodrug strategies have been developed to temporarily disguise the charges of these compounds. This review examines the various systems that have been used to mask the phosphorus-containing moieties of pyrophosphates and bisphosphonates and also illustrates the utility of such prodrugs.

When Onco-Immunotherapy Meets Cold Atmospheric Plasma: Implications on CAR-T Therapies

T cells engineered with chimeric antigen receptors (CAR) have demonstrated its widespread efficacy as a targeted immunotherapeutic modality. Yet, concerns on its specificity, efficacy and generalization prevented it from being established into a first-line approach against cancers. By reviewing challenges limiting its clinical application, ongoing efforts trying to resolve them, and opportunities that emerging oncotherapeutic modalities may bring to temper these challenges, we conclude that careful CAR design should be done to avoid the off-tumor effect, enhance the efficacy of solid tumor treatment, improve product comparability, and resolve problems such as differential efficacies of co-stimulatory molecules, cytokine storm, tumor lysis syndrome, myelosuppression and severe hepatotoxicity. As a promising solution, we propose potential synergies between CAR-T therapies and cold atmospheric plasma, an emerging onco-therapeutic strategy relying on reactive species, towards improved therapeutic efficacies and enhanced safety that deserve extensive investigations.

Emerging role of γδ T cells in protozoan infection and their potential clinical application

γδ T cells are thymus derived heterogeneous and unconventional T- lymphocyte expressing TCR γ (V γ9) and TCRδ (Vδ2) chain and play an important role in connecting innate and adaptive armaments of immune response. These cells can recognize wide ranges of antigens even without involvement of major histocompatibility complex and exert their biological functions by cytotoxicity or activating various types of immune cells. In recent past, γδ T cells have emerged as an important player during protozoa infection and rapidly expand after exposure with them. They have also been widely studied in vaccine induced immune response against many bacterial and protozoan infections with improved clinical outcome. In this review, we will discuss the various roles of γδ T cells in immunity against malaria and leishmaniasis, the two important protozoan diseases causing significant mortality and morbidity throughout the world.

Regulation of bone mass in inflammatory diseases

Inflammation is among the major determinants of bone loss in chronic disease and aging. Bone metabolism is radically affected by inflammation with consequent bone loss and increased fracture risk. Various cytokines and mediators are involved in the pathogenesis of bone loss in inflammatory conditions. The present review has the aim of discussing the main pathways involved in the pathogenesis of bone loss in inflammatory diseases, focusing in particular on the Wnt system and its regulators. Literature review of studies published between inception to 2021 on osteoporosis and inflammation was conducted. I will discuss the epidemiology of osteoporosis and fractures in common inflammatory diseases. The molecular basis of bone loss related to inflammation will be discussed as well. Finally, the effects of various anti-inflammatory medications on bone metabolism will be reviewed.

T-cell subsets in the skin and their role in inflammatory skin disorders

T lymphocytes (T cells) are major players of the adaptive immune response. Naive T cells are primed in the presence of cytokines, leading to polarization into distinct T-cell subsets with specific functions. These subsets are classified based on their T-cell receptor profile, expression of transcription factors, surface cytokine and chemokine receptors, and their cytokine production, which together determine their specific function. This review provides an overview of the various T-cell subsets and their function in several inflammatory skin disorders ranging from allergic inflammation to skin tumors. Moreover, we highlight similarities of T-cell responses across different skin disorders, demonstrating the presence of similar and opposing functions for the different T-cell subsets. Finally, we discuss the effects of currently available and promising therapeutic approaches to harness T cells in inflammatory skin diseases for which efficacy next to unwanted side effects provide new insights into the pathophysiology of skin disorders.

Adoptive T-Cell Therapy in Advanced Colorectal Cancer: A Systematic Review

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths in the US. For the vast majority of patients with advanced CRC (ie, for those in whom metastatic tumors are unresectable), treatment is palliative and typically involves chemotherapy, biologic therapy, and/or immune checkpoint inhibition. In recent years, the use of adoptive T-cell therapy (ACT), leveraging the body’s own immune system to recognize and target cancer, has become increasingly popular. Unfortunately, while ACT has been successful in the treatment of hematological malignancies, it is less efficacious in advanced CRC due in part to a lack of productive immune infiltrate. This systematic review was conducted to summarize the current data for the efficacy and safety of ACT in advanced CRC. We report that ACT is well tolerated in patients with advanced CRC. Favorable survival estimates among patients with advanced CRC receiving ACT demonstrate promise for this novel treatment paradigm. However, additional stage I/II clinical trials are needed to establish the efficacy and safety of ACT in patients with CRC.

Gastric cancer-derived exosomal miR-135b-5p impairs the function of Vγ9Vδ2 T cells by targeting specificity protein 1

Recent studies have shown that tumor-derived exosomes participate in the communication between tumor cells and their microenvironment and mediate malignant biological behaviors including immune escape. In this study, we found that gastric cancer (GC) cell-derived exosomes could be effectively uptaken by Vγ9Vδ2 T cells, decrease the cell viability of Vγ9Vδ2 T cells, induce apoptosis, and reduce the production of cytotoxic cytokines IFN-γ and TNF-α. Furthermore, we demonstrated that exosomal miR-135b-5p was delivered into Vγ9Vδ2 T cells. Exosomal miR-135b-5p impaired the function of Vγ9Vδ2 T cells by targeting specificity protein 1 (SP1). More importantly, blocking the SP1 function by Plicamycin, an SP1 inhibitor, abolished the effect of stable miR-135b-5p knockdown GC cell-derived exosomes on Vγ9Vδ2 T cell function. Collectively, our results suggest that GC cell-derived exosomes impair the function of Vγ9Vδ2 T cells via miR-135b-5p/SP1 pathway, and targeting exosomal miR-135b-5p/SP1 axis may improve the efficiency of GC immunotherapy based on Vγ9Vδ2 T cells.

γδ T Cell-Based Adoptive Cell Therapies Against Solid Epithelial Tumors

ABSTRACT

Conventionally, adoptive cell therapies have been developed and optimized using αβ T cells. However, the understudied and less abundant γδ T cells offer unique advantages to the immunotherapy field especially for therapies against solid tumors. Recently, γδ T-cell potential against a broad spectrum of malignant cells has been demonstrated in the preclinical setting. In the clinic, γδ T-cell-based immunotherapies have proven to be safe; however, their efficacy needs improvement. Considering the growing body of literature reflecting the increasing interest in γδ T cells, we sought to capture the current topics of discussion in the field, pertaining to their use in adoptive immunotherapy. We aimed to compile information about γδ T-cell enhancement in terms of expansion, phenotype, and inhibitory receptors, in addition to the latest advances in preclinical and clinical research using γδ T cells specifically against solid epithelial tumors.

Human intestinal and circulating invariant natural killer T cells are cytotoxic against colorectal cancer cells via the perforin-granzyme pathway

Invariant natural killer T (iNKT) cells are lipid-specific T lymphocytes endowed with cytotoxic activities and are thus considered important in antitumor immunity. While several studies have demonstrated iNKT cell cytotoxicity against different tumors, very little is known about their cell-killing activities in human colorectal cancer (CRC). Our aim was to assess whether human iNKT cells are cytotoxic against colon cancer cells and the mechanisms underlying this activity. For this purpose, we generated stable iNKT cell lines from peripheral blood and colon specimens and used NK-92 and peripheral blood natural killer cells as cell-mediated cytotoxicity controls. In vitro cytotoxicity was assessed using a panel of well-characterized human CRC cell lines, and the cellular requirements for iNKT cell cytotoxic functions were evaluated. We demonstrated that both intestinal and circulating iNKT cells were cytotoxic against the entire panel of CRC lines, as well as against freshly isolated patient-derived colonic epithelial cancer cells. Perforin and/or granzyme inhibition impaired iNKT cell cytotoxicity, whereas T-cell receptor (TCR) signaling was a less stringent requirement for efficient killing. This study is the first evidence of tissue-derived iNKT cell cytotoxic activity in humans, as it shows that iNKT cells depend on the perforin-granzyme pathway and both adaptive and innate signal recognition for proper elimination of colon cancer cells.

The Use of Oral Amino-Bisphosphonates and Coronavirus Disease 2019 (COVID-19) Outcomes

The determinants of the susceptibility to severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection and severe coronavirus disease 2019 (COVID-19) manifestations are yet not fully understood. Amino-bisphosphonates (N-BPs) have anti-inflammatory properties and have been shown to reduce the incidence of lower respiratory infections, cardiovascular events, and cancer. We conducted a population-based retrospective observational cohort study with the primary objective of determining if oral N-BPs treatment can play a role in the susceptibility to development of severe COVID-19. Administrative International Classification of Diseases, Ninth Revision, Clinical ModificationI (ICD-9-CM) and anatomical-therapeutic chemical (ATC) code data, representative of Italian population (9% sample of the overall population), were analyzed. Oral N-BPs (mainly alendronate and risedronate) were included in the analysis, zoledronic acid was excluded because of the low number of patients at risk. Incidence of COVID-19 hospitalization was 12.32 (95% confidence interval [CI], 9.61-15.04) and 11.55 (95% CI, 8.91-14.20), of intensive care unit (ICU) utilization because of COVID-19 was 1.25 (95% CI, 0.38-2.11) and 1.42 (95% CI, 0.49-2.36), and of all-cause death was 4.06 (95% CI, 2.50-5.61) and 3.96 (95% CI, 2.41-5.51) for oral N-BPs users and nonusers, respectively. Sensitivity analyses that excluded patients with prevalent vertebral or hip fragility fractures and without concomitant glucocorticoid treatment yielded similar results. In conclusion, we found that the incidence of COVID-19 hospitalization, intensive care unit (ICU) utilization, and COVID-19 potentially related mortality were similar in N-BPs-treated and nontreated subjects. Similar results were found in N-BPs versus other anti-osteoporotic drugs. We provide real-life data on the safety of oral N-BPs in terms of severe COVID-19 risk on a population-based cohort. Our results do not support the hypothesis that oral N-BPs can prevent COVID-19 infection and/or severe COVID-19; however, they do not seem to increase the risk. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

PD-1 checkpoint blockade enhances adoptive immunotherapy by human Vγ2Vδ2 T cells against human prostate cancer

Human Vγ2Vδ2 (also termed Vγ9Vδ2) T cells play important roles in microbial and tumor immunity by monitoring foreign- and self-prenyl pyrophosphate metabolites in isoprenoid biosynthesis. Accumulation of isoprenoid metabolites after bisphosphonate treatment allows Vγ2Vδ2 T cells to recognize and kill tumors independently of their MHC expression or burden of non-synonymous mutations. Clinical trials with more than 400 patients show that adoptive immunotherapy with Vγ2Vδ2 T cells has few side effects but has resulted in only a few partial and complete remissions. Here, we have tested Vγ2Vδ2 T cells for expression of inhibitory receptors and determined whether adding PD-1 checkpoint blockade to adoptively transferred Vγ2Vδ2 T cells enhances immunity to human PC-3 prostate tumors in an NSG mouse model. We find that Vγ2Vδ2 T cells express PD-1, CTLA-4, LAG-3, and TIM-3 inhibitory receptors during the 14-day ex vivo expansion period, and PD-1, LAG-3, and TIM-3 upon subsequent stimulation by pamidronate-treated tumor cells. Expression of PD-L1 on PC-3 prostate cancer cells was increased by co-culture with activated Vγ2Vδ2 T cells. Importantly, anti-PD-1 mAb treatment enhanced Vγ2Vδ2 T cell immunity to PC-3 tumors in immunodeficient NSG mice, reducing tumor volume nearly to zero after 5 weeks. These results demonstrate that PD-1 checkpoint blockade can enhance the effectiveness of adoptive immunotherapy with human γδ T cells in treating prostate tumors in a preclinical model.

A combined treatment regimen of MGMT-modified γδ T cells and temozolomide chemotherapy is effective against primary high grade gliomas

Chemotherapeutic drugs such as the alkylating agent Temozolomide (TMZ), in addition to reducing tumor mass, can also sensitize tumors to immune recognition by transient upregulation of multiple stress induced NKG2D ligands (NKG2DL). However, the potential for an effective response by innate lymphocyte effectors such as NK and γδ T cells that recognize NKG2DL is limited by the drug's concomitant lymphodepleting effects. We have previously shown that modification of γδ T cells with a methylguanine DNA methyltransferase (MGMT) transgene confers TMZ resistance via production of O6-alkylguanine DNA alkyltransferase (AGT) thereby enabling γδ T cell function in therapeutic concentrations of TMZ. In this study, we tested this strategy which we have termed Drug Resistant Immunotherapy (DRI) to examine whether combination therapy of TMZ and MGMT-modified γδ T cells could improve survival outcomes in four human/mouse xenograft models of primary and refractory GBM. Our results confirm that DRI leverages the innate response of γδ T cells to chemotherapy-induced stress associated antigen expression and achieves synergies that are significantly greater than either individual approach.

Development of ICT01, a first-in-class, anti-BTN3A antibody for activating Vγ9Vδ2 T cell-mediated antitumor immune response

[Figure: see text].

Molecular imaging of cellular immunotherapies in experimental and therapeutic settings

Cell-based cancer immunotherapies are becoming a routine part of the armamentarium against cancer. While remarkable successes have been seen, including durable remissions, not all patients will benefit from these therapies and many can suffer from life-threatening side effects. These differences in efficacy and safety across patients and across tumor types (e.g., blood vs. solid), are thought to be due to differences in how well the immune cells traffic to their target tissue (e.g., tumor, lymph nodes, etc.) whilst avoiding non-target tissues. Across patient variability can also stem from whether the cells interact with (i.e., communicate with) their intended target cells (e.g., cancer cells), as well as if they proliferate and survive long enough to yield potent and long-lasting therapeutic effects. However, many cell-based therapies are monitored by relatively simple blood tests that lack any spatial information and do not reflect how many immune cells have ended up at particular tissues. The ex vivo labeling and imaging of infused therapeutic immune cells can provide a more precise and dynamic understanding of whole-body immune cell biodistribution, expansion, viability, and activation status in individual patients. In recent years numerous cellular imaging technologies have been developed that may provide this much-needed information on immune cell fate. For this review, we summarize various ex vivo labeling and imaging approaches that allow for tracking of cellular immunotherapies for cancer. Our focus is on clinical imaging modalities and summarize the progression from experimental to therapeutic settings. The imaging information provided by these technologies can potentially be used for many purposes including improved real-time understanding of therapeutic efficacy and potential side effects in individual patients after cell infusion; the ability to more readily compare new therapeutic cell designs to current designs for various parameters such as improved trafficking to target tissues and avoidance of non-target tissues; and the long-term ability to identify patient populations that are likely to be positive responders and at low-risk of side effects.

Clinical Safety and Efficacy of Locoregional Therapy Combined with Adoptive Transfer of Allogeneic γδ T Cells for Advanced Hepatocellular Carcinoma and Intrahepatic Cholangiocarcinoma

PURPOSE

To investigate the safety and efficacy of locoregional therapy plus adoptive transfer of allogeneic gamma delta (γδ) T cells for patients with hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC).

METHODS

Thirty patients with HCC and 29 patients with ICC were randomly assigned to receive locoregional therapy (HCC, Group A, n = 15; ICC, Group C, n = 15) or locoregional therapy plus γδ T cell therapy (HCC, Group B, n = 15; ICC, Group D, n = 14). Groups A and C only received locoregional ablation (cryoablation or irreversible electroporation), whereas Groups B and D received locoregional therapy followed by adoptive transfer of allogeneic γδ T cells. The primary endpoints were safety, distant progression-free survival (PFS), local PFS, and overall survival (OS).

RESULTS

The median distant PFS was significantly longer in the combined treatment groups than the locoregional treatment groups (HCC: 8 vs 4 months, P = .04; ICC: 8 vs 4 months, P = .021). There was no significant difference in local PFS between the 2 treatment modalities. HCC patients in the combined treatment group had a longer OS (median OS: 13 vs 8 months, P = .029). However, there was no significant difference in OS in ICC patients between the 2 treatment modalities (median OS: 9.5 vs 8 months, P = .546). All adverse events were manageable with no significant difference in incidence between groups.

CONCLUSIONS

The novel combination of locoregional ablation with adoptive transfer of allogeneic γδ cells was safe, with encouraging clinical efficacy against HCC and ICC.