Impact of fludarabine and treosulfan on ovarian tumor cells and mesothelin chimeric antigen receptor T cells.

In addition to their immunosuppressive effect, cytostatics conditioning prior to adoptive therapy such as chimeric antigen receptor (CAR) T cells may play a role in debulking and remodeling the tumor microenvironment. We investigated in vitro the killing efficacy and impact of treosulfan and fludarabine on ovarian cancer cells expressing mesothelin (MSLN) and effect on MSLN-targeting CAR T cells. Treosulfan and fludarabine had a synergetic effect on killing of SKOV3 and OVCAR4 cells. Sensitivity to the combination of treosulfan and fludarabine was increased when SKOV3 cells expressed MSLN and when OVCAR4 cells were tested in hypoxia, while MSLN cells surface expression by SKOV3 and OVCAR4 cells was not altered after treosulfan or fludarabine exposure. Exposure to treosulfan or fludarabine (10 µM) neither impacted MSLN-CAR T cells degranulation, cytokines production upon challenge with MSLN + OVCAR3 cells, nor induced mitochondrial defects. Combination of treosulfan and fludarabine decreased MSLN-CAR T cells anti-tumor killing in normoxia but not hypoxia. In conclusion, treosulfan and fludarabine killed MSLN + ovarian cancer cells without altering MSLN-CAR T cells functions (at low cytostatics concentration) even in hypoxic conditions, and our data support the use of treosulfan and fludarabine as conditioning drugs prior to MSLN-CAR T cell therapy.

Intraoperative radiofrequency ablation for unresectable abdominal paraganglioma: a case report.

For pheochromocytoma and paraganglioma (PPGL), the efficacy of percutaneous ablative therapies in achieving control of metastatic tumors measuring <3 cm had been demonstrated in only few reports, and intraoperative radiofrequency ablation (RFA) of locally invasive primary PPGLs has not been reported. We presented the case of a 31-year-old man who had a 9-cm functioning unresectable PPGL. He was treated with 13 cycles of cytotoxic chemotherapy without objective tumor response, according to the Response Evaluation Criteria in Solid Tumors (RECIST). Subsequently, magnetic resonance imaging revealed a 9.0 × 8.6 × 6.0-cm retroperitoneal mass that extended to the inferior portion of the inferior vena cava, the inferior mesenteric artery, and the infrarenal aorta. Biochemical evaluation demonstrated high level of plasma normetanephrine (20.2 nmol/L, normal range <0.9 nmol/L). Genetic investigation showed the germline pathogenic variant c.1591delC (p. Ser198Alafs*22) in the SDHB gene. I131-metaiodobenzylguanidine scintigraphy was negative and Ga68-dotatate PET-CT scan showed high tumor uptake without distant metastases. On open laparotomy, tumor debulking was not possible. Therefore, intraoperative RFA was performed by a highly experienced team of interventional radiologists. At 12 months after the RFA, the tumor volume decreased from 208 to 45 mL (78%), plasma normetanephrine decreased from 20.2 to 2.6 nmol/L (87%), and the doxazosin dose was reduced from 16 to 8 mg/day. To our best knowledge, this was the first report on intraoperative RFA that markedly reduced the size of a large primary unresectable PPGL, along with clinical and biochemical responses.

CAR T cells and T cells phenotype and function are impacted by glucocorticoid exposure with different magnitude.

BACKGROUND: Chimeric antigen receptor (CAR) T cell therapy is associated with high risk of adverse events. Glucocorticoids (GCs) are cornerstone in the management of high-grade cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). Given the potentially deleterious effects of GCs on CAR T cells anti-tumor activity, increasing our understanding of GCs impact on CAR T cells is crucial. METHODS: Using several CAR T cells i.e., CD19, mesothelin (MSLN)-CD28 and MSLN-41BB CAR T cells (M28z and MBBz), we compared phenotypical, functional, changes and anti-tumor activity between i) transduced CD19 CAR T cells with untransduced T cells, ii) M28z with MBBz CAR T cells induced by Dexamethasone (Dx) or Methylprednisolone (MP) exposures. RESULTS: Higher levels of GC receptor were found in less differentiated CAR T cells. Overall, Dx and MP showed a similar impact on CAR T cells. Compared to untreated condition, GCs exposure increased the expression of PD-1 and TIM-3 and reduced the expression of LAG3 and function of T cells and CAR T cells. GC exposures induced more exhausted (LAG3 + PD1 + TIM3 +) and dysfunctional (CD107a-INFγ-TNF-IL2-) untransduced T cells in comparison to CD19 CAR T cells. GC exposure impaired more CD4 + than CD8 + CD19 CAR T cells. GC exposures increased more PD-1 expression associated with reduced proliferative capacity and function of M28z as compared to MBBz CAR T cells. CAR T cells anti-tumor activity was greatly affected by repeated GC exposure but partly recovered within 48h after GCs withdrawal. CONCLUSIONS: In summary, GCs impacted phenotype and function of untransduced and CAR T cell with different magnitude. The nature of the CAR costimulatory domain influenced the magnitude of CAR T cell response to GCs.

Tuned activation of MSLN-CAR T cells induces superior antitumor responses in ovarian cancer models.

BACKGROUND: Limited persistence of functional CAR T cells in the immunosuppressive solid tumor microenvironment remains a major hurdle in the successful translation of CAR T cell therapy to treat solid tumors. Fine-tuning of CAR T cell activation by mutating CD3ζ chain immunoreceptor tyrosine-based activation motifs (ITAMs) in CD19-CAR T cells (containing the CD28 costimulatory domain) has proven to extend functional CAR T cell persistence in preclinical models of B cell malignancies. METHODS: In this study, two conventional second-generation MSLN-CAR T cell constructs encoding for either a CD28 co-stimulatory (M28z) or 4-1BB costimulatory (MBBz) domain and a novel mesothelin (MSLN)-directed CAR T cell construct encoding for the CD28 costimulatory domain and CD3ζ chain containing a single ITAM (M1xx) were evaluated using in vitro and in vivo preclinical models of ovarian cancer. Two ovarian cancer cell lines and two orthotopic models of ovarian cancer in NSG mice were used: SKOV-3 cells inoculated through microsurgery in the ovary and to mimic a disseminated model of advanced ovarian cancer, OVCAR-4 cells injected intraperitoneally. MSLN-CAR T cell treatment efficacy was evaluated by survival analysis and the characterization and quantification of the different MSLN-CAR T cells were performed by flow cytometry, quantitative PCR and gene expression analysis. RESULTS: M1xx CAR T cells elicited superior antitumor potency and persistence, as compared with the conventional second generation M28z and MBBz CAR T cells. Ex vivo M28z and MBBz CAR T cells displayed a more exhausted phenotype than M1xx CAR T cells as determined by co-expression of PD-1, LAG-3 and TIM-3. Furthermore, M1xx CAR T cells showed superior ex vivo IFNy, TNF and GzB production and were characterized by a self-renewal gene signature. CONCLUSIONS: Altogether, our study demonstrates the enhanced therapeutic potential of MSLN-CAR T cells expressing a mutated CD3ζ chain containing a single ITAM for the treatment of ovarian cancer. CAR T cells armored with calibrated activation potential may improve the clinical responses in solid tumors.

Production system influences color stability and lipid oxidation in gluteus medius muscle.

OBJECTIVE: We aimed to evaluate the color and oxidative stability of beef gluteus medius (GM) from cattle raised in organic and non-organic production systems. METHODS: The GM samples (n = 10) were obtained from organic (ORG; n = 5) or non-organic (NORG; n = 5) beef samples, sliced into 2.54-cm steaks, packaged in aerobic conditions, and stored for nine days at 4°C. ORG and NORG steaks were compared regarding myoglobin concentration, pH, instrumental color, delta E (ΔE), metmyoglobin reducing activity (MRA), and lipid oxidation on days 0, 5, and 9. RESULTS: Feeding system did not influence (p>0.05) the myoglobin concentration. ORG steaks exhibited greater (p<0.05) meat pH, yellowness, and MRA, whereas NORG steaks exhibited greater (p<0.05) redness, chroma, R630/580, delta E, and lipid oxidation. ORG and NORG steaks exhibited similar (p>0.05) lightness and hue angle. During storage, ORG and NORG exhibited an increase in muscle pH, hue angle, and lipid oxidation; and a decrease (p<0.05) in redness, yellowness, chroma, and color stability (R630/580). Both samples exhibited a stable (p>0.05) pattern for lightness and MRA. CONCLUSION: Therefore, the production system can affect beef color and lipid stability during storage.

Trogocytosis and fratricide killing impede MSLN-directed CAR T cell functionality.

Successful translation of chimeric antigen receptor (CAR) T cell therapy for the treatment of solid tumors has proved to be troublesome, mainly due to the complex tumor microenvironment promoting T cell dysfunction and antigen heterogeneity. Mesothelin (MSLN) has emerged as an attractive target for CAR T cell therapy of several solid malignancies, including ovarian cancer. To improve clinical response rates with MSLN-CAR T cells, a better understanding of the mechanisms impacting CAR T cell functionality in vitro is crucial. Here, we demonstrated superior cytolytic capacity of CD28-costimulated MSLN-CAR T cells (M28z) relative to 4-1BB-costimulated MSLN-CAR T cells (MBBz). Furthermore, CD28-costimulated MSLN CAR T cells displayed enhanced cytolytic capacity against tumor spheroids with heterogeneous MSLN expression compared to MBBz CAR T cells. In this study, we identified CAR-mediated trogocytosis as a potential impeding factor for successful MSLN-CAR T cell therapy due to fratricide killing and contributing to tumor antigen heterogeneity. Moreover, we link antigen-dependent upregulation of LAG-3 with reduced CAR T cell functionality. Taken together, our study highlights the therapeutic potential and bottlenecks of MSLN-CAR T cells, providing a rationale for combinatorial treatment strategies.

Targeting of Nrf2 improves antitumoral responses by human NK cells, TIL and CAR T cells during oxidative stress.

BACKGROUND: Adoptive cell therapy using cytotoxic lymphocytes is an efficient immunotherapy against solid and hematological cancers. However, elevated levels of reactive oxygen species (ROS) in the hostile tumor microenvironment can impair NK cell and T cell function. Auranofin, a gold (I)-containing phosphine compound, is a strong activator of the transcription factor Nrf2. Nrf2 controls a wide range of downstream targets important for the cells to obtain increased resistance to ROS. In this study, we present a strategy using auranofin to render human cytotoxic lymphocytes resistant toward oxidative stress. METHODS: Melanoma patient-derived tumor infiltrating lymphocytes (TIL) and healthy donor-derived NK cells and CD19-directed CAR T cells were pretreated with a low dose of auranofin. Their resistance toward oxidative stress was assessed by measuring antitumoral responses (killing-assay, degranulation/CD107a, cytokine production) and intracellular ROS levels (flow cytometry) in conditions of oxidative stress. To confirm that the effects were Nrf2 dependent, the transcription level of Nrf2-driven target genes was analyzed by qPCR. RESULTS: Pretreatment of human TIL and NK cells ex vivo with a low-dose auranofin significantly lowered their accumulation of intracellular ROS and preserved their antitumoral activity despite high H2O2 levels or monocyte-derived ROS. Furthermore, auranofin pretreatment of CD19 CAR-T cells or TIL increased their elimination of CD19 +tumor cells or autologous tumor spheroids, respectively, especially during ROS exposure. Analysis of Nrf2-driven target genes revealed that the increased resistance against ROS was Nrf2 dependent. CONCLUSION: These novel findings suggest that Nrf2 activation in human cytotoxic lymphocytes could be used to enhance the efficacy of adoptive cell therapy.

Molecular, cellular and systemic aspects of epithelial ovarian cancer and its tumor microenvironment.

Ovarian cancer encompasses a heterogeneous group of malignancies that involve the ovaries, fallopian tubes and the peritoneal cavity. Despite major advances made within the field of cancer, the majority of patients with ovarian cancer are still being diagnosed at an advanced stage of the disease due to lack of effective screening tools. The overall survival of these patients has, therefore, not substantially improved over the past decades. Most patients undergo debulking surgery and treatment with chemotherapy, but often micrometastases remain and acquire resistance to the therapy, eventually leading to disease recurrence. Here, we summarize the current knowledge in epithelial ovarian cancer development and metastatic progression. For the most common subtypes, we focus further on the properties and functions of the immunosuppressive tumor microenvironment, including the extracellular matrix. Current and future treatment modalities are discussed and finally we provide an overview of the different experimental models used to develop novel therapies.

Mesothelin-Specific CAR T Cells Target Ovarian Cancer.

New therapeutic options for patients with ovarian cancer are urgently needed. Therefore, we evaluated the efficacy of two second-generation mesothelin (MSLN)-directed CAR T cells in orthotopic mouse models of ovarian cancer. Treatment with CAR T cells expressing an MSLN CAR construct including the CD28 domain (M28z) significantly prolonged survival, but no persistent tumor control was observed. Despite lower response rates, MSLN-4-1BB (MBBz) CAR T cells induced long-term remission in some SKOV3-bearing mice. Tumor-infiltrating M28z and MBBz CAR T cells upregulated PD-1 and LAG3 in an antigen-dependent manner while MSLN+ tumor cells expressed the corresponding ligands (PD-L1 and HLA-DR), demonstrating that coinhibitory pathways impede CAR T-cell persistence in the ovarian tumor microenvironment. Furthermore, profiling plasma soluble factors identified a cluster of M28z- and MBBz-treated mice characterized by elevated T-cell secreted factors that had increased survival, higher CD8+ T-cell tumor infiltration, less exhausted CAR T-cell phenotypes, and increased HLA-DR expression by tumor cells. Altogether, our study demonstrates the therapeutic potential of MSLN-CAR T cells to treat ovarian cancer. SIGNIFICANCE: These findings demonstrate that MSLN-directed CAR T cells can provide antitumor immunity against ovarian cancer.

Mesothelin Expression in Patients with High-Grade Serous Ovarian Cancer Does Not Predict Clinical Outcome But Correlates with CD11c+ Expression in Tumor.

INTRODUCTION: Mesothelin (MSLN) is overexpressed in several tumors including ovarian cancer and is the target of current trials. There is limited and conflicting data on MSLN prognostic impact in ovarian cancer. METHODS: We performed a retrospective study on patients with high-grade serous ovarian cancer, analyzing MSLN expression by immunohistochemistry and examining the correlation of its expression to overall and progression-free survival. Correlations of expression of MSLN, CD8, and macrophage markers in different tumor compartments were also investigated. RESULTS: Positive MSLN expression was detected in 55.1% of primary tumors and 51.5% of the metastases. MSLN expression was not correlated with survival. We observed a significant positive correlation (r = 0.34, p = 0.01) between MSLN expression in the metastatic site and CD11c expression in total tumor area and perivascular area in the primary tumor. CONCLUSION: Our results show that MSLN expression does not correlate with clinical outcome. The impact of the correlation between MSLN and CD11c+ cells on immunotherapy outcome should be further explored.

MAIT Cells in Health and Disease.

Mucosal-associated invariant T (MAIT) cells are a newly described subset of T cells that are found in the blood and are enriched in many tissues, particularly in the liver. MAIT cells express a semi-invariant T cell receptor restricted by the MHC class I-related (MR1) molecule. MAIT cells are activated in a MR1-dependent manner in response to microbial-derived riboflavin metabolites which leads to rapid effector functions, but they can also be activated in a MR1-independent manner by cytokines and viruses. The use of mice models and MR1 tetramers, among other recent methodological advances, have provided more insight into the development, mode of activation, characterization in different diseases and tissues of MAIT cells. In this chapter, we provide an overview of MAIT cells and yet remaining questions about their potential therapeutic role.

The Metabolic Profile of Tumor and Virally Infected Cells Shapes Their Microenvironment Counteracting T Cell Immunity.

Upon activation naïve T cells undergo metabolic changes to support the differentiation into subsets of effector or regulatory cells, and enable subsequent metabolic adaptations to form memory. Interfering with these metabolic alterations leads to abrogation or reprogramming of T cell differentiation, demonstrating the importance of these pathways in T cell development. It has long been appreciated that the conversion of a healthy cell to a cancerous cell is accompanied by metabolic changes, which support uncontrolled proliferation. Especially in solid tumors these metabolic changes significantly influence the tumor microenvironment (TME) and affect tumor infiltrating immune cells. The TME is often hypoxic and nutrient depleted, additionally tumor cells produce co-inhibitory signals, together suppressing the immune response. Interestingly, viruses can stimulate a metabolism akin to that seen in tumor cells in their host cells and even in neighboring cells (e.g., via transfer of virally modified extracellular vesicles). Thus, viruses create their own niche which favors viral persistence and propagation, while again keeping the immune response at bay. In this review we will focus on the mechanisms employed by tumor cells and viruses influencing T cell metabolic regulation and the impact they have on shaping T cell fate.

Recruitment of MAIT Cells to the Intervillous Space of the Placenta by Placenta-Derived Chemokines.

The intervillous space of the placenta is a part of the fetal-maternal interface, where maternal blood enters to provide nutrients and gas exchange. Little is known about the maternal immune cells at this site, which are in direct contact with fetal tissues. We have characterized the T cell composition and chemokine profile in paired intervillous and peripheral blood samples from healthy mothers giving birth following term pregnancies. Mucosal-associated invariant T (MAIT) cells and effector memory (EM) T cells were enriched in the intervillous blood compared to peripheral blood, suggesting that MAIT cells and other EM T cells home to the placenta during pregnancy. Furthermore, pregnant women had lower proportions of peripheral blood MAIT cells compared to non-pregnant women. The levels of several chemokines were significantly higher in intervillous compared to peripheral blood, including macrophage migration inhibitory factor (MIF), CXCL10, and CCL25, whereas CCL21, CCL27 and CXCL12 were lower. Migration assays showed that MAIT cells and EM T cells migrated toward conditioned medium from placental explants. A multivariate factor analysis indicated that high levels of MIF and CCL25 were associated with high proportions of MAIT cells in intervillous blood. Blocking of MIF or a combination of MIF, CCL25, and CCL20 in migration assays inhibited MAIT cell migration toward placenta conditioned medium. Finally, MAIT cells showed migratory capacities toward recombinant MIF. Together, these findings indicate that term placental tissues attract MAIT cells, and that this effect is at least partly mediated by MIF.

Facing the future: challenges and opportunities in adoptive T cell therapy in cancer.

INTRODUCTION: In recent years, immunotherapy for the treatment of solid cancer has emerged as a promising therapeutic alternative. Adoptive cell therapy (ACT), especially T cell-based, has been found to cause tumor regression and even cure in a percentage of treated patients. Checkpoint inhibitors further underscore the potential of the T cell compartment in the treatment of cancer. Not all patients respond to these treatments; however, many challenges remain. AREAS COVERED: This review covers the challenges and progress in tumor antigen target identification and selection, and cell product manufacturing for T cell ACT. Tumor immune escape mechanisms and strategies to overcome those in the context of T cell ACT are also discussed. EXPERT OPINION: The immunotherapy toolbox is rapidly expanding and improving, and the future promises further breakthroughs in the T cell ACT field. The heterogeneity of the tumor microenvironment and the multiplicity of tumor immune escape mechanisms pose formidable challenges to successful T cell immunotherapy in solid tumors, however. Individualized approaches and strategies combining treatments targeting different immunotherapeutic aspects will be needed in order to expand the applicability and improve the response rates in future.

Immune profiling and identification of prognostic immune-related risk factors in human ovarian cancer.

Suppression of immune reactivity by increased expression of co-inhibitory receptors has been discussed as a major reason as to why the immune system fails to control tumor development. Elucidating the co-inhibitory expression pattern of tumor-infiltrating lymphocytes in different cancer types will help to develop future treatment strategies. We characterized markers reflecting and affecting T-cell functionality by flow cytometry on lymphocytes isolated from blood, ascites and tumor from advanced ovarian cancer patients (n = 35). Significantly higher proportions of CD4+ and CD8+ T-cells expressed co-inhibitory receptors LAG-3, PD-1 and TIM-3 in tumor and ascites compared to blood. Co-expression was predominantly observed among intratumoral CD8+ T-cells and the most common combination was PD-1 and TIM-3. Analysis of 26 soluble factors revealed highest concentrations of IP-10 and MCP-1 in both ascites and tumor. Correlating these results with clinical outcome revealed the proportion of CD8+ T-cells without expression of LAG-3, PD-1 and TIM-3 to be beneficial for overall survival. In total we identified eight immune-related risk factors associated with reduced survival. Ex vivo activation showed tumor-derived CD4+ and CD8+ T-cells to be functionally active, assessed by the production of IFN-γ, IL-2, TNF-α, IL-17 and CD107a. Blocking the PD-1 receptor resulted in significantly increased release of IFN-γ suggesting potential reinvigoration. The ovarian tumor environment exhibits an inflammatory milieu with abundant presence of infiltrating immune cells expressing inhibitory checkpoints. Importantly, we found subsets of CD8+ T-cells with double and triple expression of co-inhibitory receptors, supporting the need for multiple checkpoint-targeting agents to overcome T-cell dysfunction in ovarian cancer.

Metabolic regulation of CAR T cell function by the hypoxic microenvironment in solid tumors.

The field of immunometabolism has attracted growing attention as an area at the heart of immune regulation. Upon activation, T cells undergo significant metabolic changes allowing them to mediate effector responses. The advent of chimeric antigen receptor T cell-adoptive therapy has shown some striking clinical efficacy but fails to induce sufficient antitumor response in many patients. Solid tumors put up significant opposition creating a microenvironment deficient of oxygen and glucose, depriving T cells of energy and pushing them to exhaustion. Here, we focus on immune suppressive mechanisms related to hypoxia in the tumor microenvironment and the resulting metabolic changes in T cells. New therapeutic approaches such as generating chimeric antigen receptor T cells able to withstand the challenging solid tumor microenvironment are needed.

Media evaluation for production and expansion of anti-CD19 chimeric antigen receptor T cells.

BACKGROUND: The use of CD19 chimeric antigen receptor (CAR) T cells to treat B-cell malignancies has proven beneficial. Several groups use serum to produce CD19 CAR T cells. Today, ready-to-use serum-free media that require no addition of serum are commercially available. Therefore, it becomes important to evaluate the production of CD19 CAR T cells with and without the addition of serum. METHODS: T cells from buffy coats were cultured in AIM-V and TexMACS (TM) supplemented with 5% human serum (A5% and TM5%, respectively), and in TM without serum. Cells were activated with OKT3 and expanded in interleukin (IL)-2. Viral transduction was performed in RetroNectin-coated plates using the spinoculation method. CD19 CAR T cells were tested for their viability, expansion, transduction efficacy, phenotype and cytotoxicity. RESULTS: CD19 CAR T cells expanded in A5% and TM5% showed significantly better viability and higher fold expansion than cells expanded in TM. TM promoted the expansion of CD8+ T cells and effector phenotype of CD19 CAR T cells. The transduction efficacy and the cytotoxic function were comparable between the different media. Higher CD107a+ cells were detected in TM and TM5%, whereas higher IL-2+ and IL-17+ cells were detected in A5%. CD19 CAR exhibited co-expression of inhibitory receptors such as TIM-3+LAG-3+ and/or TIM-3+PD-1+. CONCLUSION: Our results indicate that serum supplementation promotes better CD19 CAR T-cell expansion and viability in vitro. CD19 CAR T cells produced in TM medium showed lower CD4/CD8 ratio, which warrants further evaluation in clinical settings. Overall, the choice of culture medium impacts CD19 CAR T-cell end product.

CD19 Chimeric Antigen Receptor T Cells From Patients With Chronic Lymphocytic Leukemia Display an Elevated IFN-γ Production Profile.

CD19 chimeric antigen receptor (CAR) T cell immunotherapy has demonstrated dramatic results for the treatment of B cell malignancies such as chronic lymphocytic leukemia (CLL). As T cell defects are common in patients with CLL, we compared the T cells from these patients with healthy donors (HDs), and subsequently the CD19 CAR T cells produced from patients and HDs. Despite initial differences when comparing the phenotype of circulating T cells in patients with CLL and HDs, the CD19 CAR T cells manufactured from patients' or HDs' cells showed a similar phenotype (effector memory or terminally differentiated), both were specifically activated by and killed CD19 target cells, and secreted cytokines (ie, IL-2, TNF, and IFN-γ). The frequency of CD19 CAR T cells producing IFN-γ was significantly higher in cells produced from patients as compared with those produced from HDs. Furthermore, our data showed that the polyfunctional profile of CD19 CAR T cells was differently modulated by CD19 K562 cells and autologous B cells. The increased IFN-γ production by CD19 CAR T cells produced from patients with CLL after in vitro stimulation, may if this is also the case in vivo, contribute to a higher risk of a cytokine release syndrome in patients. The different impact by CD19 target cells on the polyfunctional profile of CD19 CAR T cells in vitro underlines the importance of the choice of CD19 target cells when assessing CD19 CAR T cells functions.

MAIT cells accumulate in placental intervillous space and display a highly cytotoxic phenotype upon bacterial stimulation.

During pregnancy, the maternal immune system must tolerate the developing foetus, and yet retain a potent antimicrobial response to prevent infections. Mucosal associated invariant T (MAIT) cells recognize microbial-derived vitamin B metabolites presented on the MR1 molecule, but their presence and function at the foetal-maternal interface is not known. We here isolated mononuclear cells from paired samples of peripheral blood (PB), intervillous blood (IVB), and decidua parietalis (DP) following uncomplicated term pregnancies. Interestingly, MAIT cells were highly enriched in IVB compared to PB and DP. The activation status of IVB MAIT cells was similar to that of PB MAIT cells, except for a lower expression of PD-1. Both IVB MAIT cells and conventional T cells were more dominated by an effector memory phenotype compared to PB MAIT cells and T cells. IVB MAIT cells also responded more vigorously with expression of IFN-γ, granzyme B, and perforin in response to Escherichia coli stimulation compared to PB. MR1 was not expressed in syncytiotrophoblasts, but in placental villous and decidual macrophages. These data indicate that maternal MAIT cells accumulate in the intervillous space of the placenta and that they are highly armed to quickly respond if bacteria are encountered at the foetal-maternal interface.

No effect of HLA-C mismatch after allogeneic hematopoietic stem cell transplantation with unrelated donors and T-cell depletion in patients with hematological malignancies.

HLA-C mismatch in unrelated donor's hematopoietic stem cell transplantation (HSCT) has been associated with poor patient outcome. However, the impact of HLA-C mismatch in the context of HSCT combined with in vivo T-cell depletion remains unclear. We therefore performed a single-center, retrospective analysis of the clinical outcome on patients with hematological malignancies treated with allo-HSCT, who underwent T-cell depletion. The majority of the patients (n=276) received a HLA-A, HLA-B, HLA-DRB1-matched graft that were either also HLA-C matched (n=260), or patients with the permissive HLA-C*03:03/03:04 mismatch (n=16), while the remaining patients (n=95) received a HLA-C-mismatched graft (excluding HLA-C*03:03/03:04 mismatches). We did not observe any significant differences between the HLA-C-matched patients (including the permissive HLA-C*03:03/03:04 mismatch) and the HLA-C-mismatched patients regarding cumulative proportion surviving, graft failure, relapse-free survival, relapse, or acute graft-versus-host disease. Our data suggest that in the context of high dose T lymphocyte-depleting agents, HLA-C matching is not essential for patients with hematological malignancies.