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Malignant mesothelioma is an aggressive, treatment-resistant tumour, which is increasing in frequency throughout the world. Although the main risk factor is asbestos exposure, a virus, simian virus 40 (SV40), could have a role. Mesothelioma has an unusual molecular pathology with loss of tumour suppressor genes being the predominant pattern of lesions, especially the P16INK4A, and P14ARF, and NF2 genes, rather than the more common p53 and Rb tumour suppressor genes. Cytopathology of mesothelioma effusions or fine-needle aspirations are often sufficient to establish a diagnosis, but histopathology is also often required. Patients typically present with breathlessness and chest pain with pleural effusions. Median survival is now 12 months from diagnosis. Palliative chemotherapy is beneficial for mesothelioma patients with high performance status. The role of aggressive surgery remains controversial and growth factor receptor blockade is still unproven. Gene therapy and immunotherapy are used on an experimental basis only. Patterns identified from microarray studies could be useful for diagnosis as well as prognostication. [ABSTRACT FROM AUTHOR]

Background Mesothelioma is a highly aggressive tumour for which there are no reliable serum tumour markers. Identification of such a marker would be useful in diagnosis of mesothelioma and for monitoring responses to treatment and screening at-risk individuals. Methods We assayed serum concentrations of soluble mesothelin-related proteins (SMR) using a double determinant (sandwich) ELISA in a blinded study of serum samples from 44 patients with histologically proven mesothelioma; 68 matched healthy controls, 40 of whom had been exposed to asbestos; and 160 patients with other inflammatory or malignant lung and pleural diseases. Findings 37 (84%) of 44 patients with mesothelioma had raised concentrations of SMR at a serum dilution of 1/80, compared with three (2%) of 160 patients with other cancers or other inflammatory lung or pleural diseases, and with none of 28 controls who had not been exposed to asbestos. SMR concentrations correlated with tumour size and increased during tumour progression. Seven of the 40 asbestosexposed individuals had increased serum concentrations of SMR; three of those seven developed mesothelioma and one developed lung carcinoma within 1--5 years. None of the 33 asbestos-exposed participants whose serum samples had normal concentrations of SMR and who were followed up over 8 years developed mesothelioma. Interpretation Determination of SMR in serum could be a useful marker for diagnosis of mesothelioma and to monitor disease progression. It might also prove helpful for screening asbestos-exposed individuals for early evidence of mesothelioma. [ABSTRACT FROM AUTHOR]

Background: CD40 signalling can synergise with chemotherapy in preclinical cancer models, and early clinical studies are promising. We set out to define the immunological changes associated with this therapeutic combination to identify biomarkers for a response to the therapy. Here, we present serial immunomonitoring examining dendritic cell and T cell subpopulations over sequential courses of chemoimmunotherapy.Methods: Fifteen patients with mesothelioma received up to six 21-day cycles of pemetrexed plus cisplatin chemotherapy and anti-CD40 (CP-870,893). Peripheral blood was collected weekly, and analysed by flow cytometry. Longitudinal immunophenotyping data was analysed by linear mixed modelling, allowing for variation between patients. Exploratory analyses testing for any correlation between overall survival and immunophenotyping data were undertaken up to the third cycle of treatment.Results: Large statistically significant cyclical variations in the proportions of BDCA-1+, BDCA-2+ and BDCA-3+ dendritic cells were observed, although all subsets returned to baseline levels after each cycle and no significant changes were observed between start and end of treatment. Expression levels of CD40 and HLA-DR on dendritic cells were also cyclically modulated, again without significant change between start and end of treatment. CD8 and CD4 T cell populations, along with regulatory T cells, effector T cells, and markers of proliferation and activation, showed similar patterns of statistically significant cyclical modulation in response to therapy without changes between start and end of treatment. Exploratory analysis of endpoints revealed that patients with a higher than average proportion of BDCA-2+ dendritic cells (p = 0.010) or a higher than average proportion of activated (ICOS+) CD8 T cells (0.022) in pretreatment blood samples had better overall survival. A higher than average proportion of BDCA-3+ dendritic cells was associated with poorer overall survival at both the second (p = 0.008) and third (p = 0.014) dose of anti-CD40.Conclusions: Substantial cyclical variations in DC and T cell populations during sequential cycles of chemoimmunotherapy highlight the critical importance of timing of immunological biomarker assessments in interpretation of results and the value of linear mixed modelling in interpretation of longitudinal change over a full treatment course.Trial Registration: Australia New Zealand Clinical Trials Registry number ACTRN12609000294257 (18th May 2009). [ABSTRACT FROM AUTHOR]

Immune checkpoint blockade (ICPB) is a powerfully effective cancer therapy in some patients. Tumor neo-antigens are likely main targets for attack but it is not clear which and how many tumor mutations in individual cancers are actually antigenic, with or without ICPB therapy and their role as neo-antigen vaccines or as predictors of ICPB responses. To examine this, we interrogated the immune response to tumor neo-antigens in a murine model in which the tumor is induced by a natural human carcinogen (i.e. asbestos) and mimics its human counterpart (i.e. mesothelioma). We identified and screened 33 candidate neo-antigens, and found T cell responses against one candidate in tumor-bearing animals, mutant UQCRC2. Interestingly, we found a high degree of inter-animal variation in the magnitude of neo-antigen responses in otherwise identical mice. ICPB therapy with Cytotoxic T-lymphocyte-associated protein (CTLA-4) and α-glucocorticoid-induced TNFR family related gene (GITR) in doses that induced tumor regression, increased the magnitude of responses and unmasked functional T cell responses against another neo-antigen, UNC45a. Importantly, the magnitude of the pre-treatment draining lymph node (dLN) response to UNC45a closely corresponded to ICPB therapy outcomes. Surprisingly however, boosting pre-treatment UNC45a-specific T cell numbers did not improve response rates to ICPB. These observations suggest a novel biomarker approach to the clinical prediction of ICPB response and have important implications for the development of neo-antigen vaccines. [ABSTRACT FROM AUTHOR]

Neoantigens present unique and specific targets for personalized cancer immunotherapy strategies. Given the low mutational burden yet immunotherapy responsiveness of malignant mesothelioma (MM) when compared to other carcinogen-induced malignancies, identifying candidate neoantigens and T cells that recognize them has been a challenge. We used pleural effusions to gain access to MM tumor cells as well as immune cells in order to characterize the tumor-immune interface in MM. We characterized the landscape of potential neoantigens from SNVs identified in 27 MM patients and performed whole transcriptome sequencing of cell populations from 18 patient-matched pleural effusions. IFNγ ELISpot was performed to detect a CD8+ T cell responses to predicted neoantigens in one patient. We detected a median of 68 (range 7–258) predicted neoantigens across the samples. Wild-type non-binding to mutant binding predicted neoantigens increased risk of death in a model adjusting for age, sex, smoking status, histology and treatment (HR: 33.22, CI: 2.55–433.02, p =.007). Gene expression analysis indicated a dynamic immune environment within the pleural effusions. TCR clonotypes increased with predicted neoantigen burden. A strong activated CD8+ T-cell response was identified for a predicted neoantigen produced by a spontaneous mutation in the ROBO3 gene. Despite the challenges associated with the identification of bonafide neoantigens, there is growing evidence that these molecular changes can provide an actionable target for personalized therapeutics in difficult to treat cancers. Our findings support the existence of candidate neoantigens in MM despite the low mutation burden of the tumor, and may present improved treatment opportunities for patients. [ABSTRACT FROM AUTHOR]

Background: Malignant mesothelioma (MM) is an aggressive cancer of the pleural and peritoneal cavities caused by exposure to asbestos. Asbestos-induced mesotheliomas in wild-type mice have been used extensively as a preclinical model because they are phenotypically identical to their human counterpart. However, it is not known if the genetic lesions in these mice tumours are similar to in the human disease, a prerequisite for any new preclinical studies that target genetic abnormalities.Methods: We performed whole exome sequencing of fifteen asbestos-induced murine MM tumour cell lines from BALB/c, CBA and C57BL/6 mouse strains and compared the somatic mutations and copy number variations with those recurrently reported in human MM. We then catalogued and characterised the mutational landscape of the wild-type murine MM tumours. Quantitative RT-PCR was used to interrogate the expression of key MM genes of interest in the mRNA.Results: Consistent with human MM tumours, we identified homozygous loss of the tumour suppressor Cdkn2a in 14/15 tumours. One tumour retained the first exon of both of the p16INK4a and p19ARF isoforms though this tumour also contained genetic amplification of Myc resulting in increased expression of the c-Myc proto-oncogene in the mRNA. There were no chromosomal losses in either the Bap1 or Nf2 regions. One tumour harbored homozygous loss of Trp53 in the DNA. Mutation rates were similar in tumours generated in the CBA and C57BL/6 strains when compared to human MM. Interestingly, all BALB/c tumour lines displayed high mutational loads, consistent with the known mutator phenotype of the host strain. The Wnt, MAPK and Jak-STAT signaling pathways were found to be the most commonly affected biological pathways. Mutations and copy number deletions also occurred in the Hedgehog and Hippo pathways.Conclusions: These data suggest that in the wild-type murine model asbestos causes mesotheliomas in a similar way to in human MM. This further supports the notion that the murine model of MM represents a genuine homologue of the human disease, something uncommon in cancer, and is thus a valuable tool to provide insight into MM tumour development and to aide the search for novel therapeutic strategies. [ABSTRACT FROM AUTHOR]

Background: Malignant mesothelioma (MM) is a deadly cancer mainly caused by previous exposure to asbestos. With a latency period up to 50 years the incidence of MM is still increasing, even in countries that banned asbestos. Secondary prevention has been established to provide persons at risk regular health examinations. An earlier detection with tumor markers might improve therapeutic options. Previously, we have developed a new blood-based assay for the protein marker calretinin. Aim of this study was the verification of the assay in an independent study population and comparison with the established marker mesothelin.Methods: For a case-control study in men, a total of 163 cases of pleural MM and 163 controls were available from Australia, another 36 cases and 72 controls were recruited in Germany. All controls had asbestosis and/or plaques. Calretinin and mesothelin were determined by ELISA (enzyme-linked immunosorbent assay) in serum or plasma collected prior to therapy. We estimated the performance of both markers and tested factors potentially influencing marker concentrations like age, sample storage time, and MM subtype.Results: Calretinin was able to detect all major subtypes except for sarcomatoid MM. Calretinin showed a similar performance in Australian and German men. At a pre-defined specificity of 95% the sensitivity of calretinin reached 71% and that of mesothelin 69%, when excluding sarcomatoid MM. At 97% specificity, the combination with calretinin increased the sensitivity of mesothelin from 66% to 75%. Sample storage time did not influence the results. In controls the concentrations of calretinin increased 1.87-fold (95% CI 1.10-3.20) per 10 years of age and slightly more for mesothelin (2.28, 95% CI 1.30-4.00).Conclusions: Calretinin could be verified as a blood-based marker for MM. The assay is robust and shows a performance that is comparable to that of mesothelin. Retrospective analyses would not be limited by storage time. The high specificity supports a combination of calretinin with other markers. Calretinin is specific for epithelioid and biphasic MM but not the rarer sarcomatoid form. Molecular markers like calretinin and mesothelin are promising tools to improve and supplement the diagnosis of MM and warrant further validation in a prospective study. [ABSTRACT FROM AUTHOR]

The asbestos induced cancer malignant mesothelioma (MM) is difficult to diagnose and has a poor prognosis. MM is an immunological cancer, therefore autoantibodies may be suitable biomarkers and associated with prognosis. We used Protoarray®microarrays to determine immune responses to 8798 antigens in 10 MM and 10 asbestos exposed controls and developed diagnostic panels using 17 antigens from this. The AUC of these panels were independently tested in these 10 MM patients and controls and in a validation group of 36 controls and 35 MM patients using luminex assays; none of the antigens identified were validated. Immune responses to RAB38 were associated with a better prognosis. [ABSTRACT FROM PUBLISHER]

Background: Malignant mesothelioma is an aggressive, almost uniformly fatal tumor, caused primarily by exposure to asbestos. In this study, serum presence of mesothelioma-specific protein transcript variants of ecto-nicotinamide adenine dinucleotide oxidase disulfide-thiol exchanger 2 (ENOX2), a recently identified marker of malignancy, were investigated using the ONCOblot tissue of origin cancer detection test. Methods: Sequential serum samples collected from asbestos-exposed individuals prior to the development of frank mesothelioma were assayed for ENOX2 presence by 2-D gel immunoblot analysis to determine how long in advance of clinical symptoms mesothelioma-specific ENOX2 transcript variants could be detected. Results: Two mesothelioma-specific ENOX2 protein transcript variants were detected in the serum of asbestosexposed individuals 4-10 years prior to clinical diagnosis of malignant mesothelioma (average 6.2 years). Either one or both ENOX2 protein transcript variants indicative of malignant mesothelioma were absent in 14 of 15 subjects diagnosed with benign pleural plaques either with or without accompanying asbestosis. Conclusions: In a population of asbestos-exposed subjects who eventually developed malignant mesothelioma, ENOX2 protein transcript variants characteristic of malignant mesothelioma were present in serum 4-10 years in advance of clinical symptoms. As with all biomarker studies, these observations require validation in a larger, independent cohort of patients and should include prospective as well as retrospective sampling. [ABSTRACT FROM AUTHOR]

Background: The MexTAg transgenic mouse model of mesothelioma replicates many aspects of human mesothelioma, including induction by asbestos, pathogenicity and response to cytotoxic chemotherapy, despite high levels of the SV40 large T Antigen (TAg) in the mesothelial compartment. This model enables analysis of the molecular events associated with asbestos induced mesothelioma and is utilised here to investigate the molecular dynamics of tumours induced in these mice, using gene expression patterns as a read out.Methods: Gene expression of MexTAg mesothelioma cell lines bearing a high or low number of copies of the TAg transgene were compared to wild type mouse mesotheliomas and normal mouse mesothelial cells using Affymetrix microarray. These data were then compared to a similar published human microarray study using the same platform.Results: The main expression differences between transgenic mouse and wild type mouse mesotheliomas occurred for genes involved in cell cycle regulation and DNA replication, as would be expected from overexpression of the TAg oncogene. Quantitative PCR confirmed that E2F and E2F regulated genes were significantly more upregulated in MexTAg mesotheliomas and MexTAg mesothelial cells compared to wild type mesotheliomas. Like human mesothelioma, both MexTAg and wild type mesotheliomas had more genes underexpressed than overexpressed compared to normal mouse mesothelial cells. Most notably, the cdkn2 locus was deleted in the wild type mouse mesotheliomas, consistent with 80 % human mesotheliomas, however, this region was not deleted in MexTAg mesotheliomas. Regardless of the presence of TAg, all mouse mesotheliomas had a highly concordant set of deregulated genes compared to normal mesothelial cells that overlapped with the deregulated genes between human mesotheliomas and mesothelial cells.Conclusions: This investigation demonstrates that the MexTAg mesotheliomas are comparable with wild type mouse mesotheliomas in their representation of human mesothelioma at the molecular level, with some key gene expression differences that are attributable to the TAg transgene expression. Of particular note, MexTAg mesothelioma development was not dependent on cdkn2 deletion. [ABSTRACT FROM AUTHOR]

Background Pleural malignant mesothelioma (MM) is a deadly tumour predominantly associated with asbestos exposure. A reliable diagnostic and prognostic marker for MM will significantly enhance clinical care and is an area of intense research. Soluble mesothelin is the most studied and an FDA-approved biomarker for MM. A recent report showed promising results using fibulin-3 as a new diagnostic marker. The aim of this study was to compare the utility of fibulin-3 versus mesothelin, singly or in combination. Methods Fibulin-3 and soluble mesothelin were determined by ELISA in the plasma and pleural fluid of 153 patients presenting with a pleural effusion including 82 with MM, 36 with non-MM malignant effusions and 35 with benign effusions. Biomarker concentrations were determined in the plasma of an additional 49 cases with benign asbestos-related disease. Results Mesothelin provides better diagnostic accuracy than fibulin-3 for MM whether measured in plasma or pleural effusion: area under the curve (AUC) for plasma was 0.822 (95% CI 0.76 to 0.87) compared with 0.671 (0.61 to 0.73), respectively, and for pleural fluid AUC was 0.815 (0.74 to 0.87) compared with 0.588 (0.51 to 0.67), respectively. Effusion fibulin-3 was an independent significant prognostic factor for survival in MM patients; HR 2.08 (1.14 to 3.82), p=0.017. MM patients with effusion fibulin-3 levels below the median survived significantly longer than those with levels above the median (14.1 vs 7.9 months, p=0.012). Mesothelin and neutrophil to lymphocyte ratio were not significant prognostic markers. Conclusions Soluble mesothelin is a superior diagnostic biomarker for MM compared with fibulin-3, whereas fibulin-3 provides superior prognostic information compared with mesothelin. [ABSTRACT FROM AUTHOR]

Background This study was conducted to determine if anti-tumor vaccination administered prior to partial debulking surgery could improve survival using a murine solid tumour model. Methods Tumor incidence and survival rates were compared in mice bearing subcutaneous AB1-HA mesothelioma tumors that received either sham surgery, debulking surgery or vaccination prior to debulking surgery. Additionally, mice were depleted of CD4 and/or CD8 T lymphocytes during vaccination to assess their involvement in vaccine induced anti-tumor immunity. Flow cytometry was performed to characterise changes in the proportion and activation status of immune cells associated with anti-tumor immunity. Results Neoadjuvant vaccination combined with debulking surgery resulted in decreased tumor burden, increased survival and generation of tumor-specific immunity compared to surgery alone. Depletion of CD8 T cells completely abrogated any vaccine induced anti-tumor immune response. Conversely, CD4 depletion enhanced CD8 T cell activation resulting in complete tumor regression in 70% of mice treated with combined surgery and vaccination therapy. Tumor free survival was associated with established immunological memory as defined by the induction of effector memory T cells and resistance to rechallenge with parental AB1 mesothelioma cells. Conclusions Neoadjuvant anti-cancer vaccination combined with partial debulking surgery induced CD8-dependent anti-tumor immunity that significantly delayed tumor outgrowth relative to surgery alone. Complete tumor eradication was observed when vaccination and surgery were performed in CD4 T cell depleted animals. This demonstrates that adjuvant immunotherapy can improve post-surgical survival following cancer debulking surgery and provides a scientific rational for clinical trials of such an approach. [ABSTRACT FROM AUTHOR]

Mesothelioma is principally caused by asbestos and may be preventable because there is a long latent period between exposure and disease development. The most at-risk are a relatively well-defined population who were exposed as a consequence of their occupations. Although preventative agents investigated so far have not been promising, discovery of such an agent would have a significant benefit world-wide on healthcare costs and personal suffering. Statins are widely used for management of hypercholesterolemia and cardiovascular risk; they can induce apoptosis in mesothelioma cells and epidemiological data has linked their use to a lower incidence of cancer. We hypothesised that statins would inhibit the development of asbestos-induced mesothelioma in mice and humans. An autochthonous murine model of asbestos-induced mesothelioma was used to test this by providing atorvastatin daily in the feed at 100 mg/kg, 200 mg/kg and 400 mg/kg. Continuous administration of atorvastatin did not alter the rate of disease development nor increase the length of time that mice survived. Latency to first symptoms of disease and disease progression were also unaffected. In a parallel study, the relationship between the use of statins and development of mesothelioma was investigated in asbestos-exposed humans. In a cohort of 1,738 asbestos exposed people living or working at a crocidolite mine site in Wittenoom, Western Australia, individuals who reported use of statins did not have a lower incidence of mesothelioma (HR = 1.01; 95% CI = 0.44–2.29, p = 0.99). Some individuals reported use of both statins and non-steroidal anti-inflammatory drugs or COX-2 inhibitors, and these people also did not have an altered risk of mesothelioma development (HR = 1.01; 95% CI = 0.61–1.67, p = 0.97). We conclude that statins do not moderate the rate of development of mesothelioma in either a mouse model or a human cohort exposed to asbestos. [ABSTRACT FROM AUTHOR]

The MSLN gene products, soluble mesothelin and megakaryocyte potentiating factor (MPF), are being investigated as biomarkers for the asbestos-related cancer malignant mesothelioma (MM). Pleural fluid biomarkers of MM can be elevated when serum levels remain normal. The aim of this study was to determine if this was true for MPF and to compare levels of mesothelin. Biomarker concentrations were compared in 66 MM patients, 39 patients with other malignancies, 37 with benign disease, 18 asbestos-exposed healthy individuals, and 53 patients with chronic kidney disease. In pleural effusions, MPF and soluble mesothelin concentrations were both significantly elevated in MM patients relative to controls. No significant difference between the area under the receiver operator curve (AUC) for MPF (0.945 ± 0.02) and mesothelin (0.928 ± 0.03) when distinguishing MM from all other causes of effusion was observed. MPF and mesothelin serum concentrations were highly correlated and of equivalent diagnostic accuracy with AUCs of 0.813 ± 0.04 and 0.829 ± 0.03, respectively. Serum levels of both markers increased with decreasing kidney function. In conclusion, MPF is elevated in the pleural effusions of MM patients similar to that of mesothelin. Mesothelin and MPF convey equivalent diagnostic information for distinguishing MM from other diseases in pleural effusions as well as serum. [ABSTRACT FROM AUTHOR]

Murine and human mesothelioma tumors are susceptible to immunotherapy, particularly when immune adjuvants are delivered locally. We have shown that direct injection of IL-2 plus agonist anti-CD40 antibody induces regression of large mesothelioma tumors. These studies aimed to determine if NK cells contribute to IL-2/CD40 antibody-driven tumor eradication. We show that NK cells infiltrate developing mesothelioma tumors; however, their absence (in beige mice or in asialo GM1 antibody-depleted C57BL/6J mice) does not alter tumor growth rates suggesting that they cannot function as effector cells in this microenvironment. Anti-CD40 antibody treatment did not alter the percent of NK cells in treated tumors or in draining lymph nodes (dLNs), and tumor resolution occurred in the absence of NK cells. However, a two-tumor model showed that NK cells contributed to CD40-driven systemic immunity leading to resolution of untreated distal tumors. IL-2 treatment led to increased proportions of NK cells in tumors and dLNs, and in the absence of NK cells, IL-2 lost its therapeutic effect. In contrast, the absence of NK cells did not reduce the anti-tumor activity of the IL-2/anti-CD40 antibody combination yet tumors recurred in NK-deficient mice and > 37% of tumor cell re-challenged mice were unable to provide protection, implying insufficient memory. Furthermore, untreated distal tumors in NK-depleted mice were less readily cured than in immunologically intact mice. These data show that NK cells infiltrate mesothelioma tumors, which, after local IL-2 and/or anti-CD40 antibody treatment, provide help for the acquisition and/or maintenance of systemic immunity and long-term effector/memory responses. [ABSTRACT FROM PUBLISHER]

Patients with Malignant Mesothelioma (MM) develop unidentified auto-antibodies to MM tumour antigens. This study was conducted to identify the targets of MM patient auto-antibodies in order to try to understand more of the anti-tumour response and to determine if these antibodies might be helpful for diagnosis or prognostication. Using MM patient sera in a Western immunoblott screening strategy, no common immunoreactive proteins were identified. The sera from one longterm survivor recognised a protein band of 50-60 kDa present in cell lysates from four of five MM cell lines tested. The immunoreactive proteins in this band were identified by 2D electrophoretic separation of a MM cell line protein lysate, followed by analysis of excised immunoreactive proteins on a MALDI TOF mass spectrometer and peptide mass fingerprinting. The immunoreactive proteins identified were vimentin (accession gi55977767) and the ATP synthase (F1- ATPase) beta chain (accession gi114549 and gi47606749). ELISA assays were developed for antibodies to these proteins. Neither vimentin (median and 95% CI 0.346; 0.32-0.468 for MM patients, 0.327; 0.308-0.428 for controls) nor ß-F1-ATPase (0.257; 0.221-0.453 for MM patients, 0.263; 0.22-0.35 for controls) showed significant differences in autoantibody levels between a group of MM patients and controls. Using a dichotomized antibody level (high, low) for these targets we demonstrated that vimentin antibody levels were not associated with survival. In contrast, high ß-F1-ATPase antibody levels were significantly associated with increased median survival (18 months) compared to low ß F1 ATPase antibody levels (9 months; p = 0.049). Immunohistochemical analysis on a MM tissue microarray showed cytoplasmic staining in 28 of 33 samples for vimentin and strong cytoplasmic staining in14 and weak in 16 samples for ß-F1-ATPase. Therefore antibodies to neither vimentin nor ß-F1-ATPase are useful for differential diagnosis of MM, however high antibody levels to ß-F1-ATPase may be associated with increased survival and this warrants further investigation. [ABSTRACT FROM AUTHOR]

Background: Anti-cancer chemotherapy can be simultaneously lymphodepleting and immunostimulatory. Pre-clinical models clearly demonstrate that chemotherapy can synergize with immunotherapy, raising the question how the immune system can be mobilized to generate anti-tumor immune responses in the context of chemotherapy. Methods and Findings: We used a mouse model of malignant mesothelioma, AB1-HA, to investigate T cell-dependent tumor resolution after chemotherapy. Established AB1-HA tumors were cured by a single dose of cyclophosphamide in a CD8 T cell- and NK cell-dependent manner. This treatment was associated with an IFN-α/β response and a profound negative impact on the anti-tumor and total CD8 T cell responses. Despite this negative effect, CD8 T cells were essential for curative responses. The important effector molecules used by the anti-tumor immune response included IFN-c and TRAIL. The importance of TRAIL was supported by experiments in nude mice where the lack of functional T cells could be compensated by agonistic anti-TRAIL-receptor (DR5) antibodies. Conclusion: The data support a model in which chemotherapy sensitizes tumor cells for T cell-, and possibly NK cell-, mediated apoptosis. A key role of tumor cell sensitization to immune attack is supported by the role of TRAIL in tumor resolution and explains the paradox of successful CD8 T cell-dependent anti-tumor responses in the absence of CD8 T cell expansion. [ABSTRACT FROM AUTHOR]

Tumor cell death potentially engages with the immune system. However, the efficacy of anti-tumor chemotherapy may be limited by tumor-driven immunosuppression, e.g., through CD25+ regulatory T cells. We addressed this question in a mouse model of mesothelioma by depleting or reconstituting CD25+ regulatory T cells in combination with two different chemotherapeutic drugs. We found that the efficacy of cyclophosphamide to eradicate established tumors, which has been linked to regulatory T cell depletion, was negated by adoptive transfer of CD25+ regulatory T cells. Analysis of post-chemotherapy regulatory T cell populations revealed that cyclophosphamide depleted cycling (Ki-67hi) T cells, including foxp3+ regulatory CD4+ T cells. Ki-67hi CD4+ T cells expressed increased levels of two markers, TNFR2 and ICOS, that have been associated with a maximally suppressive phenotype according to recently published studies. This suggest that cyclophosphamide depletes a population of maximally suppressive regulatory T cells, which may explain its superior anti-tumor efficacy in our model. Our data suggest that regulatory T cell depletion could be used to improve the efficacy of anti-cancer chemotherapy regimens. Indeed, we observed that the drug gemcitabine, which does not deplete cycling regulatory T cells, eradicates established tumors in mice only when CD25+ CD4+ T cells are concurrently depleted. Cyclophosphamide could be used to achieve regulatory T cell depletion in combination with chemotherapy. [ABSTRACT FROM AUTHOR]

The article discusses the study which aims to determine the CA125 which improves the sensitivity of mesothelin in diagnosing mesothelioma. The study shows that combining CA125 and mesothelin serum levels does not improve the accuracy of diagnosis of malignant mesothelioma over the mesothelin marker. Moreover, the use of mesothelin and CA125 biomakers increases the number of patients who can be monitored.

Background: The diagnosis of malignant mesothelioma is frequently difficult, the most common differential diagnosis being reactive pleural conditions and metastatic adenocarcinoma. Soluble mesothelin levels in serum have recently been shown to be highly specific and moderately sensitive for mesothelioma. As most patients with mesothelioma present with exudative effusions of either the pleura or the peritoneum, a study was undertaken to determine if levels of mesothelin were raised in these fluids and if the increased levels could help to distinguish mesothelioma from other causes of exudative effusion. Methods: Pleural fluid was collected from 192 patients who presented to respiratory clinics (52 with malignant mesothelioma, 56 with non-mesotheliomatous malignancies and 84 with effusions of non-neoplastic origin). Peritoneal fluid was collected from 42 patients (7 with mesothelioma, 14 with non-mesotheliomatous malignancies and 21 with benign effusions). Mesothelin levels were determined in effusion and serum samples by ELISA. Results: Significantly higher levels of mesothelin were found in effusions of patients with mesothelioma; with a specificity of 98%, the assay had a sensitivity of 67% comparing patients with mesothelioma and those with effusions of non-neoplastic origin. In 7 out of 10 cases mesothelin levels were raised in the effusion collected 3 weeks to 10 months before the diagnosis of mesothelioma was made; in 4 out of 8 of these, mesothelin levels were increased in the effusion but not in the serum. Conclusions: Measurement of mesothelin concentrations in the pleural and/or peritoneal effusion of patients may aid in the differential diagnosis of mesothelioma in patients presenting with effusions. [ABSTRACT FROM AUTHOR]