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Purpose: An increased risk to develop cancer is one of the most challenging negative side effects of long-term immunosuppression in organ transplant recipients and impaired cancer immunosur-veillance is assumed as underlying mechanism. This study aims to elucidate transplant-related changes in the tumor immune micro-environment (TME) of cancer. Experimental Design: Data from 123 organ transplant recipients (kidney, heart, lung, and liver) were compared with historic data from non-immunosuppressed patients. Digital image analysis of whole-section slides was used to assess abundance and spatial distribution of T cells and tertiary lymphoid structures (TLS) in the TME of 117 tumor samples. Expression of programmed cell death 1 ligand 1 (PD-L1) and human-leucocyte-antigen class I (HLA-I) was assessed on tissue microarrays. Results: We found a remarkably reduced immune infiltrate in the center tumor (CT) regions as well as the invasive margins (IM) of post-transplant cancers. These differences were more pronounced in the IM than in the CT and larger for CD8 thorn T cells than for CD3 thorn T cells. The Immune-score integrating results from CT and IM was also lower in transplant recipients. Density of TLS was lower in cancer samples of transplant recipients. The fraction of samples with PD-L1 expression was higher in controls whereas decreased expression of HLA-I was more common in transplant recipients. Conclusions: Our study demonstrates the impact of immunosup-pression on the TME and supports impaired cancer immunosurveil-lance as important cause of post-transplant cancer. Modern immu-nosuppressive protocols and cancer therapies should consider the distinct immune microenvironment of post-transplant malignancies.

Objective: Recent data imply that strengthening host immunity by checkpoint inhibition improves outcome in invasive fungal infections (IFI), particularly in candidiasis. Methods: To assess T-cell exhaustion in this context, we compared peripheral blood mononuclear cells (PBMCs) and serum samples of patients with invasive Candida albicans infection (IC, n = 21) to PBMCs or tumor-infiltrating lymphocytes (TILs) from cancer patients (n = 14) and PBMCs of healthy controls (n = 20). Type and differentiation of lymphocytes and expression of 29 immune-regulatory molecules were analyzed by flow cytometry. C. albicans specific responses were assessed by FluoroSpot (n = 8) and antibody measurement (n = 14). Results: Fractions and phenotypes of lymphocyte subsets in PBMCs of IC patients were similar compared to PBMCs of controls, while they were different in TILs. PBMCs of patients with IC showed increased expression of immune-checkpoint molecules. The pattern of upregulated molecules was similar to TILs, but not present in PBMCs of control cancer patients. Fractions of T-cells expressing PD-1 and TIGIT were higher in IC patients that died. FluoroSpot analysis showed a Candida-specific IFN-y or IL-2 response in 5/8 patients, enhanced by addition of nivolumab in vitro. Conclusions: Together with preclinical data and preliminary evidence of clinical efficacy in mucormycosis, our results support clinical evaluation of immune-checkpoint inhibition in IFI treatment. (C) 2021 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

BackgroundSpecific immune response is a hallmark of cancer immunotherapy and shared tumor-associated antigens (TAAs) are important targets. Recent advances using combined cellular therapy against multiple TAAs renewed the interest in this class of antigens. Our study aims to determine the role of TAAs in esophago-gastric adenocarcinoma (EGA).MethodsRNA expression was assessed by NanoString in tumor samples of 41 treatment-nai''ve EGA patients. Endogenous T cell and antibody responses against the 10 most relevant TAAs were determined by FluoroSpot and protein-bound bead assays. Digital image analysis was used to evaluate the correlation of TAAs and T-cell abundance. T-cell receptor sequencing, in vitro expansion with autologous CD40-activated B cells (CD40Bs) and in vitro cytotoxicity assays were applied to determine specific expansion, clonality and cytotoxic activity of expanded T cells.Results68.3% of patients expressed >= 5 TAAs simultaneously with coregulated clusters, which were similar to data from The Cancer Genome Atlas (n=505). Endogenous cellular or humoral responses against >= 1 TAA were detectable in 75.0% and 53.7% of patients, respectively. We found a correlation of T-cell abundance and the expression of TAAs and genes related to antigen presentation. TAA-specific T-cell responses were polyclonal, could be induced or enhanced using autologous CD40Bs and were cytotoxic in vitro. Despite the frequent expression of TAAs co-occurrence with immune responses was rare.ConclusionsWe identified the most relevant TAAs in EGA for monitoring of clinical trials and as therapeutic targets. Antigen-escape rather than missing immune response should be considered as mechanism underlying immunotherapy resistance of EGA.

The role of B cells in antitumor immunity and their impact on emerging immunotherapies is increasingly gaining attention. B-cell effector functions include not only secretion of antibodies, but also presentation of antigens to T cells. A physiologic B-cell subset with immunostimulatory properties was described in humans, defined by a high expression of CD86 and down regulation of CD21. We used multicolor flow cytometry and IHC to elucidate abundance and spatial distribution of these antigen-presenting B cells (BAPC) in blood (peripheral blood mononuclear cells, PBMC) and tumor samples of 237 patients with cancer. Antigen-specific T-cell responses to cancer testis antigens were determined using tetramer staining and sorted BAPCs in FluoroSpot assays for selected patients. We found that BAPCs were increased in the tumor microenvironment of 9 of 10 analyzed cancer types with site-specific variation. BAPCs were not increased in renal cell carcinoma, whereas we found a systemic increase with elevated fractions in tumor-infiltrating lymphocytes (TIL) and PBMCs of patients with colorectal cancer and gastroesophageal adenocarcinoma. BA PCs were localized in lymphoid follicles of tertiary lymphoid structures (TLS) and were enriched in tumors with increased numbers of TLSs. BAPCs isolated from tumor-draining lymph nodes of patients with cancer showed increased percentages of tumor antigen-specific B cells and induced responses of autologous T cells in vitro. Our results highlight the relevance of BAPCs as professional antigen-presenting cells in tumor immunity and provide a mechanistic rationale for the observed correlation of B-cell abundance and response to immune checkpoint inhibition.

Recognition of folate and biotin surface receptors by dual-functionalized nanoparticles (NPs) is key for site-selective receptor-mediated transport of anticancer drugs to cancer cells. We present here dopamine-capped iron oxide nanoprobes (Fe3O4, 10 +/- 2 nm) containing two surface-grafted biologically relevant ligands, namely, folic acid (FA) and biotin (BT). The covalent attachment of both FA and BT on Fe3O4 nanoparticles was achieved by following carbodiimide coupling and click-chemistry protocols. The dual-function Fe 3 0 4 probes were delivered into E-G7 and human HeLa cancer cell lines and tested toward their cellular uptake by immunofluorescence and flow cytometry analysis. Owing to receptor-mediated endocytosis, enhanced accumulation of nanoprobes in cancer cells was successfully monitored by confocal laser microscopy. When compared to dual-function probes, single-functionalized nanoparticles possessing either FA or BT ligands showed significantly reduced uptake in the tested cell lines, underlining the superior interaction potential of dual-purpose probes. A time-dependent receptor-mediated endocytosis of FA-Fe3O4-BT nanovectors was demonstrated by flow cytometry analysis, whereas the unfunctionalized NPs did not show any specificity in terms of uptake. Besides their specific uptake, the surface-functionalized nanoparticles exhibited promising cytotoxicity profiles by demonstrating good viability of more than 95% with analogous cancer cell lines. Our results demonstrate that dual and/or multivariate conjugation of receptor-specific ligands on NPs is highly effective in molecular recognition of surface biomarkers that enhances their potential in anticancer treatment for pretargeting-radio strategies based on biotin/avidin interactions.

Efficient therapies for breast cancer remain elusive because of the lack of strategies for targeted transport and receptor-mediated uptake of synthetic drug molecules by cancer cells. Conjugation of nanoparticles (NPs) with active targeting ligands enabling selective molecular recognition of antigens expressed on the surface of cancer cells is promising for localization and treatment of malignant cells. In this study, covalent attachment of synthetic estrogen 17 alpha-ethynylestradiol on the silica (SiO2) shell of silica-gold NPs (SiO2@Au) was undertaken to improve the cancer-targeting ability of the nano-biotags. Chemical and structural analysis of the bioconjugates examined in solution (UV-vis and xi-potential) and solid state (Fourier transform infrared spectroscopy, X-ray diffractometry, and transmission electron microscopy) confirmed the identity of the carrier particles and surface-bound ligands. The mesoporous silica shell served as a reservoir for anticancer drugs (doxorubicin and quercetin) and to facilitate covalent attachment of receptor molecules by click chemistry protocols. The chemoselective recognition between the nanoconjugates and cell membranes was successfully demonstrated by the accumulation of nanoprobes in the tumor tissue of mice with subcutaneous breast cancer, whereas healthy cells were unaffected. The drug release studies showed sustained release kinetics over several weeks. These findings elaborate the exceptional selectivity and potential of estrogen-coated nano-biolabels in efficient diagnosis and detection of breast cancer cells.

B cells are not only producers of antibodies, but also contribute to immune regulation or act as potent antigen-presenting cells. The potential of B cells for cellular therapy is still largely underestimated, despite their multiple diverse effector functions. The CD40L/CD40 signaling pathway is the most potent activator of antigen presentation capacity in B lymphocytes. CD40-activated B cells are potent antigen-presenting cells that induce specific T-cell responses in vitro and in vivo. In preclinical cancer models in mice and dogs, CD40-activated B cell-based cancer immunotherapy was able to induce effective antitumor immunity. So far, there have been only few early-stage clinical studies involving B cell-based cancer vaccines. These trials indicate that B cell-based immunotherapy is generally safe and associated with little toxicity. Furthermore, these studies suggest that B-cell immunotherapy can elicit antitumor T-cell responses. Alongside the recent advances in cellular therapies in general, major obstacles for generation of good manufacturing practice-manufactured B-cell immunotherapies have been overcome. Thus, a first clinical trial involving CD40-activated B cells might be in reach. (C) 2019 S. Karger AG, Basel

B lymphocytes are important players in immune responses to cancer. However, their composition and function in head and neck squamous cell carcinoma (HNSCC) has not been well described. Here, we analyzed B cell subsets in HNSCC (n = 38), non-cancerous mucosa (n = 14) and peripheral blood from HNSCC patients (n = 38) and healthy controls (n = 20) by flow cytometry. Intratumoral B cells contained high percentages of activated (CD86(+)), antigen-presenting (CD86(+)/CD21(-)) and memory B cells (IgD(-)/CD27(+)). T follicular helper cells (CD4(+)/CXCR5(+)/CD45RA(-)/CCR7(-)) as key components of tertiary lymphoid structures and plasma cells made up high percentages of the lymphocyte infiltrate. Percentages of regulatory B cell varied depending on the regulatory phenotype. Analysis of humoral immune responses against 23 tumor-associated antigens (TAA) showed reactivity against at least one antigen in 56% of HNSCC patients. Reactivity was less frequent in human papillomavirus associated (HPV+) patients and healthy controls compared to HPV negative (HPV-) HNSCC. Likewise, patients with early stage HNSCC or MHC-I loss on tumor cells had low TAA responses. Patients with TAA responses showed CD4(+) dominated T cell infiltration compared to mainly CD8(+) T cells in tumors without detected TAA response. To summarize, our data demonstrates different immune infiltration patterns in relation to serological TAA response detection and the presence of B cell subpopulations in HNSCC that can engage in tumor promoting and antitumor activity. In view of increasing use of immunotherapeutic approaches, it will be important to include B cells into comprehensive phenotypic and functional analyses of tumor-associated lymphocytes.

Tumor-infiltrating lymphocytes (TILs) are correlated to prognosis of several kinds of cancer. Most studies focused on T cells, while the role of tumor-associated B cells (TABs) has only recently gained more attention. TABs contain subpopulations with distinct functions, potentially promoting or inhibiting immune responses. This study provides a detailed analysis of TABs in gastro-esophageal adenocarcinoma (EAC). Flow cytometric analyses of single cell suspensions of tumor samples, mucosa, lymph nodes and peripheral blood mononuclear cells (PBMC) of EAC patients and healthy controls revealed a distinct B cell compartment in cancer patients. B cells were increased in tumor samples and subset-analyses of TILs showed increased proportions of differentiated and activated B cells and an enrichment for follicular T helper cells. Confocal microscopy demonstrated that TABs were mainly organized in tertiary lymphoid structures (TLS), which resemble lymphoid follicles in secondary lymphoid organs. A panel of 34 tumor-associated antigens (TAAs) expressed in EAC was identified based on public databases and TCGA data to analyze tumor-specific B cell responses using a LUMINEX (TM) bead assay and flow cytometry. Structural analyses of TLS and the detection of tumor-specific antibodies against one or more TAAs in 48.1% of analyzed serum samples underline presence of anti-tumor B cell responses in EAC. Interestingly, B cells were decreased in tumors with expression of Programmed Death Ligand 1 or impaired HLA-I expression. These data demonstrate that anti-tumor B cell responses are an additional and underestimated aspect of EAC. Our results are of immediate translational relevance to emerging immunotherapies.

Small cell lung cancer (SCLC) represents the most aggressive pulmonary neoplasm and is often diagnosed at late stage with limited survival, despite combined chemotherapies. We show in an autochthonous mouse model of SCLC that combined anti-VEGF/anti-PD-L1-targeted therapy synergistically improves treatment outcome compared with anti-PD-L1 and anti-VEGF monotherapy. Mice treated with anti-PD-L1 alone relapsed after 3 weeks and were associated with a tumor-associated PD-1/TIM-3 double-positive exhausted T-cell phenotype. This exhausted T-cell phenotype upon PD-L1 blockade was abrogated by the addition of anti-VEGF-targeted treatment. We confirmed a similar TIM-3-positive T-cell phenotype in peripheral blood mononuclear cells of patients with SCLC with adaptive resistance to anti-PD-1 treatment. Mechanistically, we show that VEGFA enhances coexpression of the inhibitory receptor TIM-3 on T cells, indicating an immunosuppressive function of VEGF in patients with SCLC during anti-PD-1-targeted treatment. Our data strongly suggest that a combination of anti-VEGF and anti-PD-L1 therapies can be an effective treatment strategy in patients with SCLC. Significance: Combining VEGF and PD-L1 blockade could be of therapeutic benefit to patients with small cell lung cancer. (C) 2018 AACR.

Traditionally, B cells have been best known for their role as producers of antibodies. However, in recent years, a growing body of evidence has accumulated showing that B cells fulfill a range of other immunologic functions. One of the functions that has attracted increasing attention is the capacity of B cells to induce antigen-specific activation of T cells through presentation of antigens. However, the analysis of this B cell function has been hampered by the lack of a phenotypically well-defined antigen-presenting B cell subset. Here, we report the identification of a human antigen-presenting B cell subset with strong immunostimulatory properties. This B cell subset is characterized by low expression of CD21 and high expression of the activation marker CD86 and exhibits strong T cell-stimulatory activity, as demonstrated by means of an autologous mixed-lymphocyte reaction. Phenotypically, CD21(low)CD86(pos) immunostimulatory B cells (B-APC) represented CD27(+) class-switched IgM(neg)IgD(neg) B lymphocytes and displayed a higher expression of cell surface receptors, which mediate the migration from peripheral blood to sites of inflammation. Flow cytometric analysis of peripheral blood obtained from individuals with inflammatory conditions revealed that the B-APC subset was expanded following vaccination and in patients with rheumatoid arthritis. Taken together, our work shows that B-APC represents a strongly immunostimulatory B cell subset, which could be a promising target for immunotherapeutic intervention in inflammatory diseases.

The introduction of checkpoint inhibitors represents a major advance in cancer immunotherapy. Some studies on checkpoint inhibition demonstrate that combinatorial immunotherapies with secondary drivers of anti-tumor immunity provide beneficial effects for patients that do not show a strong endogenous immune response. CD40-activated B cells ( CD40B cells) are potent antigen presenting cells by activating and expanding naive and memory CD4(+) and CD8(+) and homing to the secondary lymphoid organs. In contrast to dendritic cells, the generation of highly pure CD40B cells is simple and time efficient and they can be expanded almost limitlessly from small blood samples of cancer patients. Here, we show that the vaccination with antigen-loaded CD40B cells induces a specific T-cell response in vivo comparable to that of dendritic cells. Moreover, we identify vaccination parameters, including injection route, cell dose and vaccination repetitions to optimize immunization and demonstrate that application of CD40B cells is safe in terms of toxicity in the recipient. We furthermore show that preventive immunization of tumor-bearing mice with tumor antigen-pulsed CD40B cells induces a protective anti-tumor immunity against B16. F10 melanomas and E.G7 lymphomas leading to reduced tumor growth. These results and our straightforward method of CD40B-cell generation underline the potential of CD40B cells for cancer immunotherapy.

The composition of tumor-infiltrating lymphocytes (TIL) reflects biology and immunogenicity of cancer. Here, we characterize T-cell subsets and expression of immune checkpoint molecules in head and neck squamous cell carcinoma (HNSCC). We analyzed TIL subsets in primary tumors (n = 34), blood (peripheral blood mononuclear cells (PBMC); n = 34) and non-cancerous mucosa (n = 7) of 34 treatment-naive HNSCC patients and PBMC of 15 healthy controls. Flow cytometry analyses revealed a highly variable T-cell infiltration mainly of an effector memory phenotype (CD45RA(-)/CCR7(-)). Naive T cells (CD45RA(+)/CCR7(+)) were decreased in the microenvironment compared to PBMC of patients, while regulatory T cells (CD4(+)/CD25(+)/CD127(low) and CD4(+)/CD39(+)) were elevated. Furthermore, we performed digital image analyses of entire cross sections of HNSCC to define the 'Immunoscore' (CD3(+) and CD8(+) cell infiltration in tumor core and invasive margin) and quantified MHC class I expression on tumor cells by immunohistochemistry. Immune checkpoint molecules cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), programmed cell death 1 (PD-1) and programmed cell death 1 ligand 1 (PD-L1) were increased in TILs compared to peripheral T cells in flow-cytometric analysis. Human papillomavirus (HPV) positive tumors showed higher numbers of TILs, but a similar composition of T-cell subsets and checkpoint molecule expression compared to HPV negative tumors. Taken together, the tumor microenvironment of HNSCC is characterized by a strong infiltration of regulatory T cells and high checkpoint molecule expression on T-cell subsets. In view of increasingly used immunotherapies, a detailed knowledge of TILs and checkpoint molecule expression on TILs is of high translational relevance.