Cytotoxic T Cell Responses against Mesothelioma by Apoptotic Cell-pulsed Dendritic Cells

Multiple Classes of Antigen Contribute to the Antigenic Landscape of Mesothelioma

Mesothelioma is an incurable, asbestos-exposure-related cancer that typically affects the lining or pleura of the lungs. Symptoms typically develop many decades after initial asbestos exposure, leaving an enduring legacy of disease. The current disease burden is peaking worldwide and thus there is a massive unmet clinical need for curative therapies. Recently, immune checkpoint blockade-based therapy has been adopted as a first-line of treatment for mesothelioma. Vaccine-induced augmentation of immune responses unleashed during checkpoint blockade may provide further clinical benefit in mesothelioma. In this study, we explore the human leukocyte antigen class I landscape (or immunopeptidome) of mesothelioma in patient-derived cell lines and clinical material (pleural effusion samples). We identify a range of peptide antigens derived from targets including cancer testis antigens, endogenous retroviruses as well as novel post-translational modification of peptides. This information will facilitate the characterization of the immune response to these antigens to determine which class of antigen is most immunogenic and has the potential to be tested in future vaccine studies.

Immunotherapy of mesothelioma: the evolving change of a long-standing therapeutic dream

Pleural mesothelioma (PM) is an aggressive and rare disease, characterized by a very poor prognosis. For almost two decades, the world standard treatment regimen for unresectable PM has consisted of a platinum-based drug plus pemetrexed, leading to an overall survival of approximately 12 months. The dramatic therapeutic scenario of PM has recently changed with the entry into the clinic of immune checkpoint inhibition, which has proven to be an effective approach to improve the survival of PM patients. The aim of the present review is to provide a comprehensive overview of the most promising immunotherapeutic-based strategies currently under investigation for advanced PM.

Comparison of immunotherapy mediated by apoptotic bodies, microvesicles and exosomes: apoptotic bodies' unique anti-inflammatory potential

Immunotherapy, including immunostimulation and immunosuppression, has seen significant development in the last 10 years. Immunostimulation has been verified as effective in anti-cancer treatment, while immunosuppression is used in the treatment of autoimmune disease and inflammation. Currently, with the update of newly-invented simplified isolation methods and the findings of potent triggered immune responses, extracellular vesicle-based immunotherapy is very eye-catching. However, the research on three main types of extracellular vesicles, exosomes, microvesicles and apoptotic bodies, needs to be more balanced. These three subtypes share a certain level of similarity, and at the same time, they have their own properties caused by the different methods of biogensis. Herein, we summarized respectively the status of immunotherapy based on each kind of vesicle and discuss the possible involved mechanisms. In conclusion, we highlighted that the effect of the apoptotic body is clear and strong. Apoptotic bodies have an excellent potential in immunosuppressive and anti-inflammatory therapies .

Immunogenic cell death triggered by impaired deubiquitination in multiple myeloma relies on dysregulated type I interferon signaling

Introduction

Proteasome inhibition is first line therapy in multiple myeloma (MM). The immunological potential of cell death triggered by defects of the ubiquitin-proteasome system (UPS) and subsequent perturbations of protein homeostasis is, however, less well defined.

Methods

In this paper, we applied the protein homeostasis disruptors bortezomib (BTZ), ONX0914, RA190 and PR619 to various MM cell lines and primary patient samples to investigate their ability to induce immunogenic cell death (ICD).

Results

Our data show that while BTZ treatment triggers sterile type I interferon (IFN) responses, exposure of the cells to ONX0914 or RA190 was mostly immunologically silent. Interestingly, inhibition of protein de-ubiquitination by PR619 was associated with the acquisition of a strong type I IFN gene signature which relied on key components of the unfolded protein and integrated stress responses including inositol-requiring enzyme 1 (IRE1), protein kinase R (PKR) and general control nonderepressible 2 (GCN2). The immunological relevance of blocking de-ubiquitination in MM was further reflected by the ability of PR619-induced apoptotic cells to facilitate dendritic cell (DC) maturation via type I IFN-dependent mechanisms.

Conclusion

Altogether, our findings identify de-ubiquitination inhibition as a promising strategy for inducing ICD of MM to expand current available treatments.

Immunotherapy approaches for malignant pleural mesothelioma

Over the past decade, immune-checkpoint inhibitors (ICIs) have revolutionized the treatment of cancer. In mesothelioma, a rare cancer with a dismal prognosis generally caused by exposure to asbestos, treatment with single or dual ICIs results in robust improvements in overall survival over previous standard-of-care therapies, both in the first-line and relapsed disease settings. Predictive biological features that underpin response to ICIs remain poorly understood; however, insights into the immune microenvironment and genomic landscape of mesothelioma as well as into their association with response or acquired resistance to ICIs are emerging. Several studies of rational combinations involving ICIs with either another ICI or a different agent are ongoing, with emerging evidence of synergistic antitumour activity. Non-ICI-based immunotherapies, such as peptide-based vaccines and mesothelin-targeted chimeric antigen receptor T cells, have demonstrated promising efficacy. Moreover, results from pivotal trials of dendritic cell vaccines and viral cytokine delivery, among others, are eagerly awaited. In this Review, we comprehensively summarize the key steps in the development of immunotherapies for mesothelioma, focusing on strategies that have led to randomized clinical evaluation and emerging predictors of response. We then forecast the future treatment opportunities that could arise from ongoing research.

Dendritic cell-based immunotherapy in mesothelioma

Mesothelioma is a rare thoracic malignancy with a dismal prognosis. Current treatment options are scarce and clinical outcomes are rather disappointing. Due to the immunogenic nature of mesothelioma, several studies have investigated immunotherapeutic strategies to improve the prognosis of patients with mesothelioma. In the last decade, progress in knowledge of the modulation of the immune system to attack the tumor has been remarkable, but the optimal strategy for immunotherapy has yet to be unraveled. Because of their potent antigen-presenting capacity, dendritic cells are acknowledged as a promising agent in immunotherapeutic approaches in a number of malignancies. This review gives an update and provides a future perspective in which immunotherapy may improve the outcome of mesothelioma therapy.

New roads open up for implementing immunotherapy in mesothelioma

Treatment options for malignant mesothelioma are limited, and the results with conventional therapies have been rather disappointing to this date. Chemotherapy is the only evidence-based treatment for mesothelioma patients in good clinical condition, with an increase in median survival of only 2 months. Therefore, there is urgent need for a different approach to battle this malignancy. As chronic inflammation precedes mesothelioma, the immune system plays a key role in the initiation of this type of tumour. Also, many immunological cell types can be found within the tumour at different stages of the disease. However, mesothelioma cells can evade the surveillance capacity of the immune system. They build a protective tumour microenvironment to harness themselves against the immune system's attacks, in which they even abuse immune cells to act against the antitumour immune response. In our opinion, modulating the immune system simultaneously with the targeting of mesothelioma tumour cells might prove to be a superior treatment. However, this strategy is challenging since the tumour microenvironment possesses numerous forms of defence strategies. In this paper, we will discuss the interplay between immunological cells that can either inhibit or stimulate tumour growth and the challenges associated with immunotherapy. We will provide possible strategies and discuss opportunities to overcome these problems.

Cytotoxic T-cells as imaging probes for detecting glioma

Tumor vaccination using tumor-associated antigen-primed dendritic cells (DCs) is in clinical trials. Investigators are using patients' own immune systems to activate T-cells against recurrent or metastatic tumors. Following vaccination of DCs or attenuated tumor cells, clinical as well as radiological improvements have been noted due to migration and accumulation of cytotoxic T-cells (CTLs). CTLs mediated tumor cell killing resulted in extended survival in clinical trails and in preclinical models. Besides administration of primed DCs or attenuated or killed tumors cells to initiate the generation of CTLs, investigators have started making genetically altered T-cells (CTLs) to target specific tumors and showed in vivo migration and accumulation in the implanted or recurrent tumors using different imaging modalities. Our groups have also showed the utilization of both in vivo and in vitro techniques to make CTLs against glioma and used them as imaging probes to determine the sites of tumors. In this short review, the current status of vaccination therapy against glioma and utilization of CTLs as in vivo imaging probes to determine the sites of tumors and differentiate recurrent glioma from radiation necrosis will be discussed.

What's the place of immunotherapy in malignant mesothelioma treatments?

Malignant pleural mesothelioma (MPM) is a rare malignancy of the pleura with a very poor prognosis. Treatments evaluated for malignant mesothelioma, including chemotherapy, radiotherapy and surgery are of limited efficacy. However, the fact that the tumors of some patients with MPM regress spontaneously or respond to immunotherapy suggests that the immune system may respond to MPM under some circumstances. In this respect, animal studies have demonstrated immunoreactivity of MPM to different immunotherapies. In the case of MPM, several clinical studies have demonstrated a correlation between the presence of a lymphocyte infiltrate and a better prognosis and humoral response directed against specific antigens related to tumor. Thus, MPM immunotherapy is undoubtedly a highly promising but also very challenging approach to the treatment of this disease that has slipped through the defense lines of the immune system. This article reviews past and recent developments of the clinical strategies that concern immunotherapy of mesothelioma.

Measles virus induces oncolysis of mesothelioma cells and allows dendritic cells to cross-prime tumor-specific CD8 response

Despite conventional medical and surgical treatments, malignant pleural mesothelioma (MPM) remains incurable. Oncovirotherapy (i.e., the use of replication-competent virus for cancer treatment) is currently explored in clinical trials. In this study, we investigated the antineoplastic potential of a new oncolytic viral agent, a live-attenuated measles virus (MV) strain derived from the Edmonston vaccine lineage (Schwarz strain). We evaluated both oncolytic activity and immunoadjuvant properties of the MV vaccine strain on mesothelioma tumor cells. Infectivity, syncytium formation, and cytolytic activity of MV were studied on a panel of mesothelioma cells derived from pleural effusions of MPM patients. We observed that MV infected preferentially MPM cell lines in comparison with nontransformed mesothelial cells, leading to an efficient killing of a significant fraction of tumor cells. A cytoreductive activity was also evidenced through formation of multinuclear cellular aggregates (syncytia). The susceptibility of MPM cell lines to measles infection was assessed by the analysis of cell surface expression of the MV vaccine receptor (CD46). We also evaluated whether MV infection of mesothelioma cells could elicit an autologous antitumor immune response. We showed that MV Schwarz strain induced apoptotic cell death of infected mesothelioma cells, which were efficiently phagocytosed by dendritic cells (DC). Loading of DCs with MV-infected MPM cells induced DC spontaneous maturation, as evidenced by the increased expression of MHC and costimulatory molecules along with the production of proinflammatory cytokines. Priming of autologous T cells by DCs loaded with MV-infected MPM cells led to a significant proliferation of tumor-specific CD8 T cells. Altogether, these data strongly support the potential of oncolytic MV as an efficient therapeutic agent for mesothelioma cancer.

Peptide Epitopes from the Wilms' Tumor 1 Oncoprotein Stimulate CD4+and CD8+T Cells That Recognize and Kill Human Malignant Mesothelioma Tumor Cells

PURPOSE

Wilms' tumor 1 protein (WT1), a transcription factor overexpressed in malignant mesothelioma, leukemias, and other solid tumors, is an ideal target for immunotherapy. WT1 class I peptide epitopes that were identified and shown to stimulate CD8(+) T cells are being tested as vaccine candidates in several clinical trials. The induction and maintenance of a robust memory CD8(+) cytotoxic T-cell response requires CD4(+) T-cell help.

EXPERIMENTAL DESIGN

Three HLA class II peptide epitopes of WT1 with high predictive affinities to multiple HLA-DRB1 molecules were identified using the SYFPEITHI algorithm. Due to the highly polymorphic nature of the HLA class II alleles, such reactivity is critical in the development of a broadly useful therapeutic. One of the WT1 CD4(+) peptide epitopes, 122-140, comprises a previously identified CD8(+) peptide epitope (126-134). By mutating residue 126 from an arginine to a tyrosine, we embedded a synthetic immunogenic analogue CD8(+) epitope (126-134) inside the longer peptide (122-140). This analogue was previously designed to improve immunogenicity and induce a potent CD8(+) response.

RESULTS

WT1 peptides 328-349 and 423-441 are able to stimulate a peptide-specific CD4(+) response that can recognize WT1(+) tumor cells in multiple HLA-DRB1 settings as determined by IFN-gamma enzyme-linked immunospot assays. The mutated WT1 peptide epitope 122-140 is able to induce CD4(+) and cytotoxic CD8(+) WT1-specific T-cell responses that can recognize the native WT1 epitopes on the surface of human WT1(+) cancer cells. Cross-priming experiments showed that antigen-presenting cells pulsed with either mesothelioma or leukemia tumor lysates can process and present each of the CD4(+) peptides identified.

CONCLUSIONS

These studies provide the rationale for using the WT1 CD4(+) peptides in conjunction with CD8(+) peptide epitopes to vaccinate patients with WT1-expressing cancers.

Lymphohistiocytoid Variant of Malignant Mesothelioma of the Pleura: A Series of 22 Cases

The lymphohistiocytoid variant of diffuse malignant mesothelioma is rare with very few cases described in the literature. It is characterized by mesothelial cells with a histiocytelike appearance and an associated dense lymphoid infiltrate. We studied clinicopathologic features and immunohistochemical patterns of a series of 22 cases. The histiocytelike cells had a mesothelial immunophenotype: AE1/AE3 (100%), calretinin (100%), CK5/6 (46%), and EMA (52%). The prominent lymphoid component showed a cytotoxic T-cell immunophenotype. Prognosis was similar to that of a large series of epithelioid diffuse malignant mesotheliomas. Formely, it was classified within the sarcomatoid type. We suggest that it should be reclassified as an epithelioid variant because of its similar behavioural characteristics. There was no evidence of Epstein-Barr virus-related infection.

Soluble mesothelin-related peptides in the diagnosis of malignant pleural mesothelioma

BACKGROUND

Diagnosis of malignant pleural mesothelioma is a challenging issue. Potential markers in mesothelioma diagnosis include soluble mesothelin-related peptides (SMRPs) and osteopontin, but no subsequent validation has been published yet.

METHODS

We prospectively evaluated SMRPs in serum and pleural effusion from patients with mesothelioma (n = 74), pleural metastasis of carcinomas (n = 35), or benign pleural lesions associated with asbestos exposure (n = 28), recruited when first suspected for mesothelioma.

FINDINGS

Mean serum SMRP level was higher in patients with mesothelioma (2.05 +/- 2.57 nM/L [median +/- interquartile range]) than in patients with metastasis (1.02 +/- 1.79 nM/L) or benign lesions (0.55 +/- 0.59 nM/L). The area under the receiver operating characteristic curve (AUC) for serum SMRP was 0.872 for differentiating mesothelioma and benign lesions, cut-off = 0.93 nM/L (sensitivity = 80%, specificity = 82.6%). The AUC for serum SMRP differentiating metastasis and mesothelioma was 0.693, cut-off = 1.85 nM/L (sensitivity = 58.3%, specificity = 73.3%). SMRP values in pleural fluid were higher than in serum in all groups (mesothelioma: 46.1 +/- 83.2 nM/L; benign lesions: 6.4 +/- 11.1 nM/L; metastasis: 6.36 +/- 21.73 nM/L). The AUC for pleural SMRP-differentiating benign lesions and mesothelioma was 0.831, cut-off = 10.4 nM/L (sensitivity = 76.7%, specificity = 76.2%). The AUC for pleural SMRP-differentiating metastasis and mesothelioma was 0.793.

INTERPRETATION

We show that SMRPs may be a promising marker for mesothelioma diagnosis when measured either in serum or pleural fluid. The diagnostic value of SMRPs was similar in both types of samples, but pleural fluid SMRPs may better discriminate mesothelioma from pleural metastasis.

Identification of a new member of the CD20/FcepsilonRIbeta family overexpressed in tolerated allografts

We identified a novel rat gene specifically overexpressed in tolerated heart allografts in a model of tolerance induced by donor-specific blood transfusion (DST). We named this gene TORID, for tolerance-related and induced transcript. We show that TORID expression can be attributed to non-T cells infiltrating tolerated grafts. Interestingly, TORID overexpression was also observed in long-term grafts from a different model of tolerance in which chronic rejection does not occur. Comparison of the predicted amino acid sequence of TORID and of its human counterpart LR8 showed an homology with the four-transmembrane CD20/FcepsilonRIbeta family proteins. We investigated TORID expression in naive rat immune cells and lymphoid tissues. TORID was found to be preferentially expressed in cells of the myeloid lineage such as macrophages and dendritic cells (DCs). Its expression dramatically decreased following activation/maturation. Similar results were obtained in human monocyte-derived DCs. Interestingly, TORID overexpression in bone marrow-derived DCs alters expression of MHC II and CD86 and production of IL12p40 following activation. These results suggest that TORID may be involved in the control of DC maturation and may, therefore, play a role in the induction or maintenance of allograft tolerance.

Lymphocytes in pleural disease

PURPOSE OF REVIEW

Lymphocytic pleural effusions are characterised by divergent cellular responses depending on the etiology of disease. The pathogenic role of lymphocytes in pleural disease, however, remains unclear. This review provides a basic description of the functions of the different lymphocyte subsets within the pleural space and then summarises recent studies of lymphocyte biology in pleural disease.

RECENT FINDINGS

The mechanisms of lymphocyte trafficking into the pleural space have been clarified. Specific adhesion molecules (such as intercellular adhesion molecule-1 and vascular cell adhesion molecule-1) and chemokines (CXCL13, interleukin-8, and monocyte chemotactic protein-1) have been identified as important factors involved in the accumulation of lymphocytes during inflammatory pleuritis. Both cellular and soluble factors may contribute to impaired T-cell immunity in malignant pleural effusions. Studies of natural killer cell and gammadelta T-cell biology indicate that these lymphocyte subsets may also play a role in the pathogenesis of pleural disease. The dominant Th1 response characterised by tuberculous pleuritis may allow for rapid diagnosis of disease. Furthermore, strategies for improving cytotoxic T-cell and natural killer cell function show promise for treatment of malignant pleural disease.

SUMMARY

Recent work has provided insight into the pathogenesis of disease in lymphocytic pleural effusions. Further study of specific cellular responses may offer significant opportunities in the diagnosis and management of these disorders.

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.

METHODS

Malignant mesothelioma was induced in mice by intraperitoneal injection of the AB1 mesothelioma cell line, leading to death within 28 days. For immunotherapy, dendritic cells were pulsed overnight either with AB1 tumor cell line lysate, AB1-derived exosomes, or ex vivo AB1 tumor lysate, and injected either before (Days -14 and -7) at the day of (Day 0) or after (Days +1 and +8) tumor implantation.

MAIN RESULTS

Mice receiving tumor lysate-pulsed dendritic cells before tumor implantation demonstrated protective antitumor immunity with prolonged survival (> 3 months) and even resisted secondary tumor challenge. Tumor protection was associated with strong tumor-specific cytotoxic T-lymphocyte responses. Adoptive transfer of splenocytes or purified CD8+ T lymphocytes transferred tumor protection to unimmunized mice in vivo. When given after tumor implantation in a therapeutic setting, pulsed dendritic cells prevented mesothelioma outgrowth. With higher tumor load and delayed administration after tumor implantation, dendritic cells were no longer effective.

CONCLUSIONS

We demonstrate in this murine model that immunotherapy using pulsed dendritic cells may emerge as a powerful tool to control mesothelioma outgrowth. In the future, immunotherapy using dendritic cells could be used as adjuvant to control local recurrence after multimodality treatment for malignant mesothelioma.