CD27(-)CD45(+) γδ T cells can be divided into two populations, CD27(-)CD45(int) and CD27(-)CD45(hi) with little proliferation potential

Dysfunctional tumor-infiltrating Vδ1 + T lymphocytes in microsatellite-stable colorectal cancer

Although γδ T cells are known to participate in immune dysregulation in solid tumors, their relevance to human microsatellite-stable (MSS) colorectal cancer (CRC) is still undefined. Here, using integrated gene expression analysis and T cell receptor sequencing, we characterized γδ T cells in MSS CRC, with a focus on Vδ1 + T cells. We identified Vδ1+ T cells with shared motifs in the third complementarity-determining region of the δ-chain, reflective of antigen recognition. Changes in gene and protein expression levels suggested a dysfunctional effector state of Vδ1+ T cells in MSS CRC, distinct from Vδ1+ T cells in microsatellite-instable (MSI). Interaction analysis highlighted an immunosuppressive role of fibroblasts in the dysregulation of Vδ1+ T cells in MSS CRC via the TIGIT-NECTIN2 axis. Blocking this pathway with a TIGIT antibody partially restored cytotoxicity of the dysfunctional Vδ1 phenotype. These results define an operative pathway in γδ T cells in MSS CRC.

γδ T cells in human colon adenocarcinomas comprise mainly Vδ1, Vδ2, and Vδ3 cells with distinct phenotype and function

Γδ T cell infiltration into tumours usually correlates with improved patient outcome, but both tumour-promoting and tumoricidal effects of γδ T cells have been documented. Human γδ T cells can be divided into functionally distinct subsets based on T cell receptor (TCR) Vδ usage. Still, the contribution of these different subsets to tumour immunity remains elusive. Here, we provide a detailed γδ T cell profiling in colon tumours, using mass and flow cytometry, mRNA quantification, and TCR sequencing. δ chain usage in both the macroscopically unaffected colon mucosa and tumours varied considerably between patients, with substantial fractions of Vδ1, Vδ2, and non-Vδ1 Vδ2 cells. Sequencing of the Vδ complementarity-determining region 3 showed that almost all non-Vδ1 Vδ2 cells used Vδ3 and that tumour-infiltrating γδ clonotypes were unique for every patient. Non-Vδ1Vδ2 cells from colon tumours expressed several activation markers but few NK cell receptors and exhaustion markers. In addition, mRNA analyses showed that non-Vδ1 Vδ2 cells expressed several genes for proteins with tumour-promoting functions, such as neutrophil-recruiting chemokines, Galectin 3, and transforming growth factor-beta induced. In summary, our results show a large variation in γδ T cell subsets between individual tumours, and that Vδ3 cells make up a substantial proportion of γδ T cells in colon tumours. We suggest that individual γδ T cell composition in colon tumours may contribute to the balance between favourable and adverse immune responses, and thereby also patient outcome.

Metabolic heterogeneity in tumor microenvironment - A novel landmark for immunotherapy

The surrounding non-cancer cells and tumor cells that make up the tumor microenvironment (TME) have various metabolic rhythms. TME metabolic heterogeneity is influenced by the intricate network of metabolic control within and between cells. DNA, protein, transport, and microbial levels are important regulators of TME metabolic homeostasis. The effectiveness of immunotherapy is also closely correlated with alterations in TME metabolism. The response of a tumor patient to immunotherapy is influenced by a variety of variables, including intracellular metabolic reprogramming, metabolic interaction between cells, ecological changes within and between tumors, and general dietary preferences. Although immunotherapy and targeted therapy have made great strides, their use in the accurate identification and treatment of tumors still has several limitations. The function of TME metabolic heterogeneity in tumor immunotherapy is summarized in this article. It focuses on how metabolic heterogeneity develops and is regulated as a tumor progresses, the precise molecular mechanisms and potential clinical significance of imbalances in intracellular metabolic homeostasis and intercellular metabolic coupling and interaction, as well as the benefits and drawbacks of targeted metabolism used in conjunction with immunotherapy. This offers insightful knowledge and important implications for individualized tumor patient diagnosis and treatment plans in the future.

Re-generation of cytotoxic γδT cells with distinctive signatures from human γδT-derived iPSCs

For a long time, ex vivo-expanded peripheral-blood-derived γδT cell (PBγδT)-based immunotherapy has been attractive, and clinical trials have been undertaken. However, the difficulty in expanding cytotoxic γδT cells to an adequate number has been a major limitation to the efficacy of treatment in most cases. We successfully re-generated γδT cells from γδT cell-derived human induced pluripotent stem cells (iPSCs). The iPSC-derived γδT cells (iγδTs) killed several cancer types in a major histocompatibility complex (MHC)-unrestricted manner. Single-cell RNA sequencing (scRNA-seq) revealed that the iγδTs were identical to a minor subset of PBγδTs. Compared with a major subset of PBγδTs, the iγδTs showed a distinctive gene expression pattern: lower CD2, CD5, and antigen-presenting genes; higher CD7, KIT, and natural killer (NK) cell markers. The iγδTs expressed granzyme B and perforin but not interferon gamma (IFNγ). Our data provide a new source for γδT cell-based immunotherapy without quantitative limitation.

The tissue-resident marker CD103 on peripheral blood T cells predicts responses to anti-PD-1 therapy in gastric cancer

BACKGROUND

Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment. Since clinical benefits are limited to a subset of patients, we aimed to identify peripheral blood biomarkers that predict the efficacy of the anti-programmed cell death protein 1 (PD-1) antibody (nivolumab) in patients with gastric cancer.

METHODS

We collected peripheral blood samples from gastric cancer patients (n = 29) before and after treatment with nivolumab and investigated the relationship between the frequency of surface or intracellular markers among nivolumab-binding PD-1⁺CD8⁺ T cells and treatment responses using multicolor flow cytometry. The tumors, lymph nodes, and peripheral blood of gastric cancer patients who underwent gastrectomy following nivolumab treatment were collected, and nivolumab-binding PD-1⁺CD8⁺ T cells in these tissue samples were characterized.

RESULTS

Patients with a high frequency of CD103 among PD-1⁺CD8⁺ T cells in peripheral blood 2 weeks after the start of treatment had significantly better progression-free survival than the low group (P = 0.032). This CD103⁺PD-1⁺CD8⁺ T cell population mainly consisted of central memory T cells, showing the high expression of Ki-67 and few cytotoxic granules. In contrast, effector memory T cells were more frequently observed among CD103⁺PD-1⁺CD8⁺ T cells in tumors, which implied a change in the differentiated status of central memory T cells in lymph nodes and peripheral blood to effector memory T cells in tumors during the treatment with ICIs.

CONCLUSIONS

A high frequency of CD103 among PD-1⁺CD8⁺ T cells 2 weeks after nivolumab treatment in patients with advanced gastric cancer may be a useful biomarker for predicting the efficacy of anti-PD-1 therapy.

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.

Tissue-Specific Expression of TIGIT, PD-1, TIM-3, and CD39 by γδ T Cells in Ovarian Cancer

Phenotypic characterization of γδ T cells in the MALs (malignant ascites lymphocytes), TILs (tumor infiltrating lymphocytes), and PBLs (peripheral blood lymphocytes) of ovarian cancer (OvCA) patients is lacking. Therefore, we quantified γδ T cell prevalence in MAL, TIL, and PBL specimens from n = 18 OvCA patients and PBL from age-matched healthy donors (HD, n = 14). Multicolor flow cytometry was performed to evaluate the expression of inhibitory receptors (TIGIT, PD-1 and TIM-3), stimulatory receptors (Ox40), and purinergic ectoenzymes (CD39 and CD73) on γδ T cell subsets. We identified an abundant infiltration of Vδ1 T cells in the MALs and TILs. These cells varied in their differentiation: The majority of Vδ1 TILs displayed an effector memory (EM) phenotype, whereas Vδ1 MALs had a more mature phenotype of terminally differentiated effector memory cells (TEMRA) with high CD45RA expression. TIGIT and TIM-3 were abundantly expressed in both MALs and PBLs, whereas Vδ1 TILs exhibited the highest levels of PD-1, CD39, and Ox40. We also observed specific clusters on mature differentiation stages for the analyzed molecules. Regarding co-expression, Vδ1 TILs showed the highest levels of cells co-expressing TIGIT with PD-1 or CD39 compared to MALs and PBLs. In conclusion, the Vδ1 T cell population showed a high prevalence in the MALs and primary tumors of OvCA patients. Due to their (co-)expression of targetable immune receptors, in particular TIGIT with PD-1 and CD39 in TILs, Vδ1 T cell-based approaches combined with the inhibition of these targets might represent a promising strategy for OvCA.

The Mysterious Actor-γδ T Lymphocytes in Chronic Lymphocytic Leukaemia (CLL)

Chronic lymphocytic leukaemia (CLL) is the most common leukaemia among adults. It is the clonal expansion of B cells expressing CD19 and CD5. Despite significant progress in treatment, CLL is still incurable. γδ T cells comprise an important subset of the cytotoxic T cells. Although γδ T cells in CLL are dysfunctional, they still can possibly be used for immunotherapy. The current paper reviews our understanding of γδ T lymphocytes in CLL.

Expression level of BTN3A1 on the surface of CD14+ monocytes is a potential predictor of γδ T cell expansion efficiency

Human γδ T cells expressing Vγ9Vδ2 T cell receptors exert a robust response to pathogens and malignant cells. These cells are activated by BTN3A1, which is expressed by pathogen-derived phosphoantigens (pAgs) or host-derived pAgs that accumulate in transformed cells or in cells exposed to aminobisphosphonates. Activated Vδ2 (+) T cells exert multiple effector functions; therefore, they are a promising candidate for immunotherapy. However, not all donors have γδ T cells with adequate proliferative activity. Here, we performed ex vivo culture of γδ T cells from 20 healthy donors and explored factors that may affect their expansion efficiency. Consistent with previous studies, we found that amplification of γδ T cells requires CD14⁺ monocytes to act as accessory cells. We also show here that surface expression of BTN3A1 by monocytes correlates positively with γδ T cell expansion. Moreover, treatment with BTN3A1-Fc increased the expansion efficiency of peripheral blood mononuclear cells (PBMCs) from donors harboring γδ T cells with poor expansion capacity. Taken together, the data suggest that the level of BTN3A1 expressed on the surface of monocytes is a useful biomarker for predicting the degree of expansion of γδ T cells.

Bone Marrow-Resident Vδ1 T Cells Co-express TIGIT With PD-1, TIM-3 or CD39 in AML and Myeloma

Background: γδ T cells represent a unique T cell subpopulation due to their ability to recognize cancer cells in a T cell receptor- (TCR) dependent manner, but also in a non-major histocompatibility complex- (MHC) restricted way via natural killer receptors (NKRs). Endowed with these features, they represent attractive effectors for immuno-therapeutic strategies with a better safety profile and a more favorable anti-tumor efficacy in comparison to conventional αβ T cells. Also, remarkable progress has been achieved re-activating exhausted T lymphocytes with inhibitors of co-regulatory receptors e.g., programmed cell death protein 1 (PD-1), T cell immunoreceptor with Ig and ITIM domains (TIGIT) and of the adenosine pathway (CD39, CD73). Regarding γδ T cells, little evidence is available. This study aimed to immunophenotypically characterize γδ T cells from patients with diagnosed acute myeloid leukemia (AML) in comparison to patients with multiple myeloma (MM) and healthy donors (HD).

Methods: The frequency, differentiation, activation, and exhaustion status of bone marrow- (BM) derived γδ T cells from patients with AML (n = 10) and MM (n = 11) were assessed in comparison to corresponding CD4⁺ and CD8⁺ T cells and peripheral blood- (PB) derived γδ T cells from HDs (n = 16) using multiparameter flow cytometry.

Results: BM-infiltrating Vδ1 T cells showed an increased terminally differentiated cell population (TEMRAs) in AML and MM in comparison to HDs with an aberrant subpopulation of CD27⁻CD45RA⁺⁺ cells. TIGIT, PD-1, TIM-3, and CD39 were more frequently expressed by γδ T cells in comparison to the corresponding CD4⁺ T cell population, with expression levels that were similar to that on CD8⁺ effector cells in both hematologic malignancies. In comparison to Vδ2 T cells, the increased frequency of PD-1⁺-, TIGIT⁺-, TIM-3⁺, and CD39⁺ cells was specifically observed on Vδ1 T cells and related to the TEMRA Vδ1 population with a significant co-expression of PD-1 and TIM-3 together with TIGIT.

Conclusion: Our results revealed that BM-resident γδ T cells in AML and MM express TIGIT, PD-1, TIM-3 and CD39. As effector population for autologous and allogeneic strategies, inhibition of co-inhibitory receptors on especially Vδ1 γδ T cells may lead to re-invigoration that could further increase their cytotoxic potential.

Methods for Characterization of Senescent Circulating and Tumor-Infiltrating T-Cells: An Overview from Multicolor Flow Cytometry to Single-Cell RNA Sequencing

Immunosenescence is the general term used to describe the aging-associated decline of immunological function that explains the higher susceptibility to infectious diseases and cancer, increased autoimmunity, or the reduced effectiveness of vaccinations. Senescence of CD8+ T-cells has been described in all these conditions.The most important classical markers of T senescent cells are the cell cycle inhibitors p16ink4a, p21, and p53, together with positivity for SA-βgal expression and the acquirement of a peculiar IFNγ -based secretory phenotype commonly defined SASP (Senescence Associated Secretory Phenotype). Other surface markers are the CD28 and CD27 loss together with gain of expression of CD45RA, CD57, TIGIT, and/or KLRG1. However, this characterization could not be sufficient to distinguish from truly senescent cells and exhausted T-cells. Furthermore, more complexity is added by the wide heterogeneity of T-cells subset in aged individuals or in the tumor microenvironment. A combined analysis by multicolor flow cytometry for surface and intracellular markers integrated with gene-expression arrays and single-cell RNA sequencing is required to develop effective interventions for therapeutic modulation of specific T-cell subsets. The RNASeq offers the great possibility to reveal at single-cell resolution the exact molecular hallmarks of senescent CD8+ T-cells without the limitations of bulk analysis. Furthermore, the comprehensive integration of multidimensional approaches (genomics, epigenomics, proteomics, metabolomics) will increase our global understanding of how immunosenescence of T-cells is interlinked to human aging.

Adoptive γδT-cell transfer alone or combined with chemotherapy for the treatment of advanced esophageal cancer

BACKGROUND AIMS

After therapy with platinum, 5-fluorouracil and taxane, no further recommended therapy is available for recurrent or metastatic esophageal cancer (r/mEC). Here the authors report two phase 1 trials of adoptive γδT-cell therapy, one for treatment-refractory r/mEC (γδT-monotherapy-P1, UMIN000001419) and the other for r/mEC with no prior systemic therapy (DCF-γδT-P1, UMIN000008097).

METHODS

For γδT-monotherapy-P1, patients received four weekly and four biweekly injections of autologous γδT cells. For DCF-γδT-P1, patients received docetaxel, cisplatin and 5-fluorouracil (DCF) chemotherapy consisting of docetaxel (60 mg/m²) and cisplatin (60 mg/m²) on day 1 and continuous injection of 5-fluorouracil (600 mg/m²/day) on days 1-5 of each 28-day cycle; additionally, they received autologous γδT-cell injections on day 15 and day 22 of each cycle.

RESULTS

Twenty-six patients were enrolled for γδT-monotherapy-P1. No severe adverse events were associated with γδT-cell therapy. Median overall survival was 5.7 months (95% confidence interval [CI], 4.3-10.0), and median progression-free survival was 2.4 months (95% CI, 1.7-2.8). Eighteen patients received DCF-γδT-P1. All treatment-related adverse events were associated with DCF chemotherapy, not γδT injection. Median overall survival was 13.4 months (95% CI, 6.7-not reached), and median progression-free survival was 4.0 months (95% CI, 2.5-5.7). The response rate and disease control rate were 39% and 78%, respectively.

CONCLUSIONS

The use of γδT-cell immunotherapy with or without chemotherapy was safe and feasible for r/mEC patients. Although the authors failed to demonstrate any clinical benefit of γδT-monotherapy-P1, survival benefits were observed in the DCF-γδT-P1 trial.

Adoptive transfer of zoledronate-expanded autologous Vγ9Vδ2 T-cells in patients with treatment-refractory non-small-cell lung cancer: a multicenter, open-label, single-arm, phase 2 study

BACKGROUND

Not all non-small cell lung cancer (NSCLC) patients possess drug-targetable driver mutations, and response rates to immune checkpoint blockade therapies also remain unsatisfactory. Therefore, more effective treatments are still needed. Here, we report the results of a phase 2 clinical trial of adoptive cell therapy using zoledronate-expanded autologous Vγ9Vδ2 T-cells for treatment-refractory NSCLC.

METHODS

NSCLC patients who had undergone at least two regimens of standard chemotherapy for unresectable disease or had had at least one treatment including chemotherapy or radiation for recurrent disease after surgery were enrolled in this open-label, single-arm, multicenter, phase 2 study. After preliminary testing of Vγ9Vδ2 T-cell proliferation, autologous peripheral blood mononuclear cells were cultured with zoledronate and IL-2 to expand the Vγ9Vδ2 T-cells. Cultured cells (>1×10⁹) were intravenously administered every 2 weeks for six injections. The primary endpoint of this study was progression-free survival (PFS), and secondary endpoints included overall survival (OS), best objective response rate (ORR), disease control rate (DCR), safety and immunomonitoring. Clinical efficacy was defined as median PFS significantly >4 months.

RESULTS

Twenty-five patients (20 adenocarcinoma, 4 squamous cell carcinoma and 1 large cell carcinoma) were enrolled. Autologous Vγ9Vδ2 T-cell therapy was administered to all 25 patients, of which 16 completed the foreseen course of 6 injections of cultured cells. Median PFS was 95.0 days (95% CI 73.0 to 132.0 days); median OS was 418.0 days (179.0-479.0 days), and best overall responses were 1 partial response, 16 stable disease (SD) and 8 progressive disease. ORR and DCR were 4.0% (0.1%-20.4%) and 68.0% (46.5%-85.1%), respectively. Severe adverse events developed in nine patients, mostly associated with disease progression. In one patient, pneumonitis and inflammatory responses resulted from Vγ9Vδ2 T-cell infusions, together with the disappearance of a massive tumor.

CONCLUSIONS

Although autologous Vγ9Vδ2 T-cell therapy was well tolerated and may have an acceptable DCR, this trial did not meet its primary efficacy endpoint.

TRIAL REGISTRATION NUMBER

UMIN000006128.

Comparison of a Novel Bisphosphonate Prodrug and Zoledronic Acid in the Induction of Cytotoxicity in Human Vγ2Vδ2 T Cells

Increasing attention has been paid to human γδ T cells expressing Vγ2Vδ2 T cell receptor (also termed Vγ9Vδ2) in the field of cancer immunotherapy. We have previously demonstrated that a novel bisphosphonate prodrug, tetrakis-pivaloyloxymethyl 2-(thiazole-2-ylamino)ethylidene-1,1-bisphosphonate (PTA), efficiently expands peripheral blood Vγ2Vδ2 T cells to purities up to 95–99% in 10–11 days. In the present study, we first examined the effect of PTA on farnesyl diphosphate synthase (FDPS) using liquid chromatography mass spectrometry (LC-MS) to analyze the mechanism underlying the PTA-mediated expansion of Vγ2Vδ2 T cells. We find that the prodrug induced the accumulation of both isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), direct upstream metabolites of FDPS. This indicates that not only IPP but also DMAPP plays an important role in PTA-mediated stimulation of Vγ2Vδ2 T cells. We next analyzed TCR-independent cytotoxicity of Vγ2Vδ2 T cells. When human lung cancer cell lines were challenged by Vγ2Vδ2 T cells, no detectable cytotoxicity was observed in 40 min. The lung cancer cell lines were, however, significantly killed by Vγ2Vδ2 T cells after 4–16 h in an effector-to-target ratio-dependent manner, demonstrating that Vγ2Vδ2 T cell-based cell therapy required a large number of cells and longer time when tumor cells were not sensitized. By contrast, pulsing tumor cell lines with 10–30 nM of PTA induced significant lysis of tumor cells by Vγ2Vδ2 T cells even in 40 min. Similar levels of cytotoxicity were elicited by ZOL at concentrations of 100–300 μM, which were much higher than blood levels of ZOL after infusion (1–2 μM), suggesting that standard 4 mg infusion of ZOL was not enough to sensitize lung cancer cells in clinical settings. In addition, Vγ2Vδ2 T cells secreted interferon-γ (IFN-γ) when challenged by lung cancer cell lines pulsed with PTA in a dose-dependent manner. Taken together, PTA could be utilized for both expansion of Vγ2Vδ2 T cells ex vivo and sensitization of tumor cells in vivo in Vγ2Vδ2 T cell-based cancer immunotherapy. For use in patients, further studies on drug delivery are essential because of the hydrophobic nature of the prodrug.

Single-cell RNA sequencing unveils the shared and the distinct cytotoxic hallmarks of human TCRVδ1 and TCRVδ2 γδ T lymphocytes

γδ T lymphocytes represent ∼1% of human peripheral blood mononuclear cells and even more cells in most tissues of vertebrates. Although they have important anticancer functions, most current single-cell RNA sequencing (scRNA-seq) studies do not identify γδ T lymphocytes because their transcriptomes at the single-cell level are unknown. Here we show that high-resolution clustering of large scRNA-seq datasets and a combination of gene signatures allow the specific detection of human γδ T lymphocytes and identification of their T cell receptor (TCR)Vδ1 and TCRVδ2 subsets in large datasets from complex cell mixtures. In t-distributed stochastic neighbor embedding plots from blood and tumor samples, the few γδ T lymphocytes appear collectively embedded between cytotoxic CD8 T and NK cells. Their TCRVδ1 and TCRVδ2 subsets form close yet distinct subclusters, respectively neighboring NK and CD8 T cells because of expression of shared and distinct cytotoxic maturation genes. Similar pseudotime maturation trajectories of TCRVδ1 and TCRVδ2 γδ T lymphocytes were discovered, unveiling in both subsets an unattended pool of terminally differentiated effector memory cells with preserved proliferative capacity, a finding confirmed by in vitro proliferation assays. Overall, the single-cell transcriptomes of thousands of individual γδ T lymphocytes from different CMV+ and CMV- donors reflect cytotoxic maturation stages driven by the immunological history of donors. This landmark study establishes the rationale for identification, subtyping, and deep characterization of human γδ T lymphocytes in further scRNA-seq studies of complex tissues in physiological and disease conditions.

Synergistic effect of IL-12 and IL-18 induces TIM3 regulation of γδ T cell function and decreases the risk of clinical malaria in children living in Papua New Guinea

BACKGROUND

γδ T cells are important for both protective immunity and immunopathogenesis during malaria infection. However, the immunological processes determining beneficial or detrimental effects on disease outcome remain elusive. The aim of this study was to examine expression and regulatory effect of the inhibitory receptor T-cell immunoglobulin domain and mucin domain 3 (TIM3) on γδ T cells. While TIM3 expression and function on conventional αβ T cells have been clearly defined, the equivalent characterization on γδ T cells and associations with disease outcomes is limited. This study investigated the functional capacity of TIM3+ γδ T cells and the underlying mechanisms contributing to TIM3 upregulation and established an association with malaria disease outcomes.

METHODS

We analyzed TIM3 expression on γδ T cells in 132 children aged 5-10 years living in malaria endemic areas of Papua New Guinea. TIM3 upregulation and effector functions of TIM3+ γδ T cells were assessed following in vitro stimulation with parasite-infected erythrocytes, phosphoantigen and/or cytokines. Associations between the proportion of TIM3-expressing cells and the molecular force of infection were tested using negative binomial regression and in a Cox proportional hazards model for time to first clinical episode. Multivariable analyses to determine the association of TIM3 and IL-18 levels were conducted using general linear models. Malaria infection mouse models were utilized to experimentally investigate the relationship between repeated exposure and TIM3 upregulation.

RESULTS

This study demonstrates that even in the absence of an active malaria infection, children of malaria endemic areas have an atypical population of TIM3-expressing γδ T cells (mean frequency TIM3+ of total γδ T cells 15.2% ± 12). Crucial factors required for γδ T cell TIM3 upregulation include IL-12/IL-18, and plasma IL-18 was associated with TIM3 expression (P = 0.002). Additionally, we show a relationship between TIM3 expression and infection with distinct parasite clones during repeated exposure. TIM3+ γδ T cells were functionally impaired and were associated with asymptomatic malaria infection (hazard ratio 0.54, P = 0.032).

CONCLUSIONS

Collectively our data demonstrate a novel role for IL-12/IL-18 in shaping the innate immune response and provide fundamental insight into aspects of γδ T cell immunoregulation. Furthermore, we show that TIM3 represents an important γδ T cell regulatory component involved in minimizing malaria symptoms.

Adjuvant combination therapy with gemcitabine and autologous γδ T-cell transfer in patients with curatively resected pancreatic cancer

BACKGROUND AIMS

The outcome for pancreatic cancer after surgery remains highly unsatisfactory, and development of more effective therapies is urgently needed. Therefore, we conducted a phase I clinical study of a novel combination of gemcitabine (GEM) and autologous γδ T-cell therapy for patients with curatively resected pancreatic cancer (University Hospital Medical Information Clinical Trials Registry identifier 000000931).

METHODS

From July 2008 to December 2012, 56 consenting patients were recruited. After preliminary testing of γδ T-cell proliferative capacity, 28 patients were eligible to receive combined GEM plus γδ T-cell therapy.

RESULTS

During treatment, most of the adverse events observed were due to GEM, including myelosuppression and gastrointestinal disorders. No severe adverse events were obviously related to the γδ T-cell therapy. To evaluate clinical efficacy, patients receiving combined therapy (Group A, n = 28) were compared with those receiving GEM alone (Group B, n = 20). No significant differences were observed between the two groups in recurrence-free survival or overall survival. However, we found that, relative to progressing patients, more γδ T-cells were detectable in the blood of recurrence-free patients after only two injections (P < .0388) and more so five injections (P < .0175). Patients with >15% peripheral γδ T-cells after two injections and >20% after five injections had a chance of a more favorable clinical outcome. Accumulation of γδ T cells was positively related to the quality of the infused products, with those having >80% γδ T cells being optimal.

DISCUSSION

High quality of the γδ T-cell product is crucial to achieve a high percentage of γδ T cells in the blood and to achieve better clinical outcome.