Low-dose cyclophosphamide depletes circulating naïve and activated regulatory T cells in malignant pleural mesothelioma patients synergistically treated with dendritic cell-based immunotherapy.

: Regulatory T cells (Treg) play a pivotal role in the immunosuppressive tumor micro-environment in cancer, including mesothelioma. Recently, the combination of autologous tumor lysate-pulsed dendritic cells (DC) and metronomic cyclophosphamide (mCTX) was reported as a feasible and well-tolerated treatment in malignant pleural mesothelioma patients and further as a method to reduce circulating Tregs. : The aim of this study was to establish the immunological effects of mCTX alone and in combination with DC-based immunotherapy on circulating Treg and other T cell subsets in mesothelioma patients.

Autologous Dendritic Cells Pulsed with Allogeneic Tumor Cell Lysate in Mesothelioma: From Mouse to Human.

Mesothelioma has been regarded as a nonimmunogenic tumor, which is also shown by the low response rates to treatments targeting the PD-1/PD-L1 axis. Previously, we demonstrated that autologous tumor lysate-pulsed dendritic cell (DC) immunotherapy increased T-cell response toward malignant mesothelioma. However, the use of autologous tumor material hampers implementation in large clinical trials, which might be overcome by using allogeneic tumor cell lines as tumor antigen source.

Pleural Effusion of Patients with Malignant Mesothelioma Induces Macrophage-Mediated T Cell Suppression.

Introduction: Clinical studies have demonstrated beneficial effects of immunotherapy in malignant pleural mesothelioma. The pleural cavity seems an attractive compartment to administer these types of therapies; however, local immunosuppressive mechanisms could hamper their efficacy. Macrophages are abundantly present within the mesothelioma microenvironment.

Precision immunotherapy; dynamics in the cellular profile of pleural effusions in malignant mesothelioma patients.

Objectives: Clinical studies have proven the potential of immunotherapy in malignancies. To increase efficacy, a prerequisite is that treatment is tailored, so precision immune-oncology is the logical next step. In order to tailor treatment, characterization of the patient's tumor environment is key.

Extended Tumor Control after Dendritic Cell Vaccination with Low-Dose Cyclophosphamide as Adjuvant Treatment in Patients with Malignant Pleural Mesothelioma.

Rationale: We demonstrated previously that autologous tumor lysate-pulsed dendritic cell-based immunotherapy in patients with malignant pleural mesothelioma is feasible, well-tolerated, and capable of inducing immunologic responses against tumor cells. In our murine model, we found that reduction of regulatory T cells with metronomic cyclophosphamide increased the efficacy of immunotherapy.

Objectives: To assess the decrease in number of peripheral blood regulatory T cells during combination therapy of low-dose cyclophosphamide and dendritic cell immunotherapy and determine the induction of immunologic responses with this treatment in patients with mesothelioma.

Intratumoral macrophage phenotype and CD8+ T lymphocytes as potential tools to predict local tumor outgrowth at the intervention site in malignant pleural mesothelioma.

Objectives: In patients with malignant pleural mesothelioma (MPM), local tumor outgrowth (LTO) after invasive procedures is a well-known complication. Currently, no biomarker is available to predict the occurrence of LTO. This study aims to investigate whether the tumor macrophage infiltration and phenotype of and/or the infiltration of CD8+ T-cells predicts LTO.

Immunomodulation in cancer.

We have to strengthen our 'chess-playing skills' when using immunotherapeutic approaches in cancer treatment: know the cancerous opponent, study its evolution and have an eye for its weaknesses. Besides tumor cells, other pieces on the board are stromal cells, endothelial cells and different immune cells. Some of these immune cells, like helper and cytotoxic T cells, natural killer (T) cells and mature dendritic cells are of help, others like regulatory T cells and myeloid-derived suppressor cells belong to the opponent, while macrophages and neutrophils can belong to both.

Tumour-derived exosomes as antigen delivery carriers in dendritic cell-based immunotherapy for malignant mesothelioma.

Background: In 2001, it was postulated that tumour-derived exosomes could be a potent source of tumour-associated antigens (TAA). Since then, much knowledge is gained on their role in tumorigenesis but only very recently tumour-derived exosomes were used in dendritic cell (DC)-based immunotherapy. For this, DCs were cultured ex-vivo and loaded with exosomes derived from immunogenic tumours such as melanoma or glioma and re-administrated to induce anti-tumour responses in primary and metastatic tumour mouse models.

Arginase-1 mRNA expression correlates with myeloid-derived suppressor cell levels in peripheral blood of NSCLC patients.

Myeloid-derived suppressor cells (MDSC) are a heterogeneous population of immature and progenitor myeloid cells with immunosuppressive activity that are increased in cancer patients. Until now, the characterization of MDSC in humans was very challenging. The aim of this study was to determine the characterization and optimal assessment of MDSC and to investigate their presence and function in blood of advanced-stage NSCLC patients.

COX-2 inhibition improves immunotherapy and is associated with decreased numbers of myeloid-derived suppressor cells in mesothelioma. Celecoxib influences MDSC function.

Background: Myeloid-derived suppressor cells (MDSC) are a heterogeneous population of immature cells that accumulates in tumour-bearing hosts. These cells are induced by tumour-derived factors (e.g.

Low-dose cyclophosphamide synergizes with dendritic cell-based immunotherapy in antitumor activity.

Clinical immunotherapy trials like dendritic cell-based vaccinations are hampered by the tumor's offensive repertoire that suppresses the incoming effector cells. Regulatory T cells are instrumental in suppressing the function of cytotoxic T cells. We studied the effect of low-dose cyclophosphamide on the suppressive function of regulatory T cells and investigated if the success rate of dendritic cell immunotherapy could be improved.

Protein profiling of pleural effusions to identify malignant pleural mesothelioma using SELDI-TOF MS.

Diagnosis of malignant pleural mesothelioma (MM) is limited. Novel proteomic techno_logies can be utilized to discover changes in expression of pleural proteins that might have diagnostic value. The objective of this study was to detect protein profiles that could be used to identify malignant pleural mesothelioma with surface enhanced laser desorption/ionization time-of-flight (SELDI-TOF) mass spectrometry (MS).

Exosomes.

Exosomes are small natural membrane vesicles released by a wide variety of cell types into the extracellular compartment by exocytosis. The biological functions of exosomes are only slowly unveiled, but it is clear that they serve to remove unnecessary cellular proteins (e.g.

Gene expression profiling and gene copy-number changes in malignant mesothelioma cell lines.

Malignant mesothelioma (MM) is an asbestos-induced tumor that acquires aneuploid DNA content during the tumorigenic process. We used instable MM cell lines as an in vitro model to study the impact of DNA copy-number changes on gene expression profiling, in the course of their chromosomal redistribution process. Two MM cell lines, PMR-MM2 (early passages of in vitro culture) and PMR-MM7 (both early and late passages of in vitro culture), were cytogenetically characterized.

Immunotherapy of murine malignant mesothelioma using tumor lysate-pulsed dendritic cells.

Rationale: Exploiting the immunostimulatory capacities of dendritic cells holds great promise for cancer immunotherapy. Currently, dendritic cell-based immunotherapy is evaluated clinically in a number of malignancies, including melanoma and urogenital and lung cancer, showing variable but promising results.

Objective: To evaluate if pulsed dendritic cells induce protective immunity against malignant mesothelioma in a mouse model.

Proteomic analysis of exosomes secreted by human mesothelioma cells.

Exosomes are small membrane vesicles secreted into the extracellular compartment by exocytosis. Tumor exosomes may be involved in the sampling of antigens to antigen presenting cells or as decoys allowing the tumor to escape immune-directed destruction. The proteins present in exosomes secreted by tumor cells have been poorly defined.