Anti-Mesothelin CAR T cell therapy for malignant mesothelioma

Nanotechnology in Advancing Chimeric Antigen Receptor T Cell Therapy for Cancer Treatment

Chimeric antigen receptor (CAR) T cell therapy has emerged as a groundbreaking treatment for hematological cancers, yet it faces significant hurdles, particularly regarding its efficacy in solid tumors and concerning associated adverse effects. This review provides a comprehensive analysis of the advancements and ongoing challenges in CAR-T therapy. We highlight the transformative potential of nanotechnology in enhancing CAR-T therapy by improving targeting precision, modulating the immune-suppressive tumor microenvironment, and overcoming physical barriers. Nanotechnology facilitates efficient CAR gene delivery into T cells, boosting transfection efficiency and potentially reducing therapy costs. Moreover, nanotechnology offers innovative solutions to mitigate cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). Cutting-edge nanotechnology platforms for real-time monitoring of CAR-T cell activity and cytokine release are also discussed. By integrating these advancements, we aim to provide valuable insights and pave the way for the next generation of CAR-T cell therapies to overcome current limitations and enhance therapeutic outcomes.

Optimizing CAR-T cell Culture: Differential effects of IL-2, IL-12, and IL-21 on CAR-T cells

BACKGROUND

Chimeric antigen receptor (CAR)-T therapy has demonstrated sustained clinical remission in numerous hematologic malignancies and has expanded to encompass solid tumors and autoimmune diseases. While progress is being made in establishing optimal culture conditions for CAR-T cells, the identification of the most effective cytokine for promoting their persistence in vitro remains elusive.

METHODS

Here, we employed scRNA-seq (single-cell RNA sequencing) analysis to investigate the potential alterations in biological processes within CAR-T cells following exposure to cytokines (IL-2, IL-12, and IL-21) and antigens. Transcriptomic changes in diverse CAR-T groups were compared following various treatments, with a focus on epigenetic modifications, metabolic shifts, cellular senescence, and exhaustion.

RESULTS

Our study reveals that CAR-T cells treated with antigen, IL-2, and IL-12 exhibit signs of exhaustion and senescence, whereas those treated with IL-21 do not display these characteristics. The activities of glycolysis and epigenetic changes were significantly increased by treatments with antigens, IL-2, and IL-12, while IL-21 treatment maintained the oxidative phosphorylation (OXPHOS) of CAR-T cells.

CONCLUSIONS

Our findings suggest that IL-21 may play a role in preventing senescence and could be utilized in combination with other strategies, such as IL-2 and IL-12, for CAR-T culture.

The rare occurrence of unifocal peritoneal mesothelioma: a case report, literature review, and future directions

Background

Mesothelioma is a rare, aggressive disease originating from mesothelial cells and carries a poor prognosis. Mesothelioma may arise from the pleura, pericardium, or peritoneum. Peritoneal mesothelioma (PM) usually spreads in a diffuse manner; however, a localized unifocal form of PM may occur. Literature on unifocal mesothelioma remains scarce.

Case Description

Herein, we highlight a case of localized epithelioid PM in an 81-year-old gentleman with the unique challenges faced during management. The pelvic mass was 7 cm, well-circumscribed, and hyper-vascular with fibrous attachments to the abdominal wall. The patient had a peritoneal cancer index (PCI) of 4 on initial diagnostic laparoscopy. Diagnosis was confirmed by histology. Resection of the mass with a partial omentectomy was performed. Months later, the patient developed recurrence detected on follow-up imaging in the peri-splenic region. The patient underwent cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC) for 60 minutes using mitomycin C and cisplatin followed by an uneventful recovery. Our case report is followed by a review of literature on disease pathophysiology, treatment options, and recently promising immunotherapy approaches.

Conclusions

CRS and HIPEC remains the standard treatment regimen for patients with PM. Nonetheless, a more nuanced approach might be indicated in specific patients with localized unifocal PM. Disease distribution and burden may impact the decision on surgical management in selected patients.

Mesothelin expression correlates with elevated inhibitory immune activity in patients with colorectal cancer

The expression of the protein Mesothelin (MSLN) is highly variable in several malignancies, including colorectal cancer (CRC), and high levels are associated with aggressive clinicopathological features and worse patient survival. Colorectal cancer is both a common and deadly cancer; being the third most common in incidence and second most common cause of cancer-related death. While systemic therapy remains the primary therapeutic option for most patients with stage IV (metastatic; m) CRC, their disease eventually becomes treatment refractory, and 85% succumb within 5 years. Microsatellite-stable (MSS) CRC tumors, which constitute more than 90% of patients with mCRC, are generally refractory to immunotherapeutic interventions. In our current work, we characterize MSLN levels in CRC, specifically correlating expression with clinical outcomes in relevant CRC subtypes, and explore how MSLN expression impacts the status of immune activation and suppression in the peritumoral microenvironment. Higher MSLN expression is prevalent in CMS1 and CMS4 CRC subtypes and correlates with higher gene mutation rates across the patient cohorts. Further, MSLN-high patients exhibit increased M1/M2 macrophage infiltration, PD-L1 staining, immune-inhibitory gene expression, enrichment in inflammatory, TGF-β, IL6/JAK/STAT3, IL2/STAT5 signaling pathways, and mutation in KRAS and FBXW7. Together, these results suggest that MSLN protein is a potential target for antigen-specific therapy and supports investigation into its tumorigenic effects to identify possible therapeutic interventions for patients with high MSLN expressing MSS CRC.

Infusion and delivery strategies to maximize the efficacy of CAR-T cell immunotherapy for cancers

Chimeric antigen receptor (CAR) T-cell therapy has achieved substantial clinical outcomes for tumors, especially for hematological malignancies. However, extending the duration of remission, reduction of relapse for hematological malignancies and improvement of the anti-tumor efficacy for solid tumors are challenges for CAR-T cells immunotherapy. Besides the endeavors to enhance the functionality of CAR-T cell per se, optimization of the infusion and delivery strategies facilitates the breakthrough of the hurdles that limited the efficacy of this cancer immunotherapy. Here, we summarized the infusion and delivery strategies of CAR-T cell therapies under pre-clinical study, clinical trials and on-market status, through which the improvements of safety and efficacy for hematological and solid tumors were analyzed. Of note, novel infusion and delivery strategies, including local-regional infusion, biomaterials bearing the CAR-T cells and multiple infusion technique, overcome many limitations of CAR-T cell therapy. This review provides hints to determine infusion and delivery strategies of CAR-T cell cancer immunotherapy to maximize clinical benefits.

Application of CAR-T cell therapy targeting mesothelin in solid tumor treatment

Chimeric antigen receptor (CAR)-T-cell therapy is one of the most effective immunotherapies. CAR-T-cell therapy has achieved great success in the treatment of hematological malignancies. However, due to the characteristics of solid malignant tumors, such as on-target effects, off-tumor toxicity, an immunosuppressive tumor microenvironment (TME), and insufficient trafficking, CAR-T-cell therapy for solid tumors is still in the exploration stage. Mesothelin (MSLN) is a molecule expressed on the surface of various solid malignant tumor cells that is suitable as a target of tumor cells with high MSLN expression for CAR-T-cell therapy. This paper briefly described the development of CAR-T cell therapy and the structural features of MSLN, and especially summarized the strategies of structure optimization of MSLN-targeting CAR-T-cells and the enhancement methods of MSLN-targeting CAR-T cell anti-tumor efficacy by summarizing some preclinical experiment and clinical trials. When considering MSLN-targeting CAR-T-cell therapy as an example, this paper summarizes the efforts made by researchers in CAR-T-cell therapy for solid tumors and summarizes feasible treatment plans by integrating the existing research results.

Advances in Immunotherapy for Malignant Pleural Mesothelioma: From Emerging Strategies to Translational Insights

MPM stands as a rare malignancy necessitating improved therapeutic strategies due to its limited treatment choices and unfavorable prognosis. The advent of immune checkpoint inhibitors has heralded a paradigm shift in the therapeutic landscape of MPM, offering promising avenues across diverse clinical scenarios. In the context of advanced stages of the disease, Immune check-point inhibitors targeting programmed cell death protein 1 (PD-1) and cytotoxic T-lymphocyte-as-sociated protein 4 (CTLA-4), have exhibited encouraging potential in clinical trials, particularly manifesting efficacy among patients exhibiting disease progression following chemotherapy regimens. Innovative combination regimens, exemplified by the concurrent administration of nivolumab and ipilimumab, have demonstrated marked improvement in survival and patient's benefits. A deeper comprehension of the intricate genetic underpinnings of MPM, encompassing key mutations such as cyclin-dependent kinase inhibitor 2A (CDKN2A), neurofibromin 2 (NF2), and BRCA1-associated protein 1 (BAP1) mutations, has elucidated novel avenues for targeted therapeutic interventions. This review accentuates the transformative capacity of immunotherapy in revolutionizing the therapeutic outlook for MPM, thereby potentially translating into augmented survival rates and offering glimpses of new approaches on the horizon. Despite the persisting challenges, the synergistic crossroads of interdisciplinary research and collaborative clinical endeavors portend a hopeful landscape for MPM treatment.

Targeted Therapy in Mesotheliomas: Uphill All the Way

Mesothelioma (MM) is an aggressive and lethal disease with few therapeutic opportunities. Platinum-pemetrexed chemotherapy is the backbone of first-line treatment for MM. The introduction of immunotherapy (IO) has been the only novelty of the last decades, allowing an increase in survival compared to standard chemotherapy (CT). However, IO is not approved for epithelioid histology in many countries. Therefore, therapy for relapsed MM remains an unmet clinical need, and the prognosis of MM remains poor, with an average survival of only 18 months. Increasing evidence reveals MM complexity and heterogeneity, of which histological classification fails to explain. Thus, scientific focus on possibly new molecular markers or cellular targets is increasing, together with the search for target therapies directed towards them. The molecular landscape of MM is characterized by inactivating tumor suppressor alterations, the most common of which is found in CDKN2A, BAP1, MTAP, and NF2. In addition, cellular targets such as mesothelin or metabolic enzymes such as ASS1 could be potentially amenable to specific therapies. This review examines the major targets and relative attempts of therapeutic approaches to provide an overview of the potential prospects for treating this rare neoplasm.

Current Advancements in Anti-Cancer Chimeric Antigen Receptor T Cell Immunotherapy and How Nanotechnology May Change the Game

Chimeric antigen receptor (CAR)-T cell immunotherapy represents a cutting-edge advancement in the landscape of cancer treatment. This innovative therapy has shown exceptional promise in targeting and eradicating malignant tumors, specifically leukemias and lymphomas. However, despite its groundbreaking successes, (CAR)-T cell therapy is not without its challenges. These challenges, particularly pronounced in the treatment of solid tumors, include but are not limited to, the selection of appropriate tumor antigens, managing therapy-related toxicity, overcoming T-cell exhaustion, and addressing the substantial financial costs associated with treatment. Nanomedicine, an interdisciplinary field that merges nanotechnology with medical science, offers novel strategies that could potentially address these limitations. Its application in cancer treatment has already led to significant advancements, including improved specificity in drug targeting, advancements in cancer diagnostics, enhanced imaging techniques, and strategies for long-term cancer prevention. The integration of nanomedicine with (CAR)-T cell therapy could revolutionize the treatment landscape by enhancing the delivery of genes in (CAR)-T cell engineering, reducing systemic toxicity, and alleviating the immunosuppressive effects within the tumor microenvironment. This review aims to explore how far (CAR)-T cell immunotherapy has come alone, and how nanomedicine could strengthen it into the future. Additionally, the review will examine strategies to limit the off-target effects and systemic toxicity associated with (CAR)-T cell therapy, potentially enhancing patient tolerance and treatment outcomes.

CAR-T Cell Therapy in Ovarian Cancer: Where Are We Now?

The success of chimeric antigen receptor T-cell (CAR-T) therapies in the treatment of hematologic malignancies has led to the investigation of their potential in the treatment of solid tumors, including ovarian cancer. While the immunosuppressive microenvironment of ovarian cancer has been a barrier in their implementation, several early phase clinical trials are currently evaluating CAR-T cell therapies targeting mesothelin, folate receptor a, HER2, MUC16, and B7H3. Ongoing challenges include cytokine-associated and "on-target, off-tumor" toxicities, while most common adverse events include cytokine release syndrome, hemophagocytic lymphohistiocytosis/macrophage activation-like syndrome (HLH/MAS), and neurotoxicity. In the present review, we summarize the current status of CAR-T therapy in ovarian cancer and discuss future directions.

Adoptive T Cell Therapy in Solid Tumors: State-of-the Art, Current Challenges, and Upcoming Improvements

In solid tumors, three main complementary approaches of adoptive T-cell therapies were successively developed: tumor-infiltrating lymphocytes, chimeric antigen receptor engineered T cells, and high-affinity T-cell receptor engineered T cells. In this review, we summarized rational and main results of these three adoptive T-cell therapies in solid tumors field and gave an overview of encouraging data and their limits. Then, we listed the major remaining challenges (including tumor antigen loss, on-target/off-tumor effect, tumor access difficulties and general/local immunosubversion) and their lines of research. Finally, we gave insight into the ongoing trials in solid tumor.

Mesothelin expression correlates with elevated inhibitory immune activity in patients with colorectal cancer

The expression of the protein Mesothelin (MSLN) is highly variable in several malignancies including colorectal cancer (CRC) and high levels are associated with aggressive clinicopathological features and worse patient survival. CRC is both a common and deadly cancer; being the third most common in incidence and second most common cause of cancer related death. While systemic therapy remains the primary therapeutic option for most patients with stage IV (metastatic; m) CRC, their disease eventually becomes treatment refractory, and 85% succumb within 5 years. Microsatellite-stable (MSS) CRC tumors, which affect more than 90% of patients with mCRC, are generally refractory to immunotherapeutic interventions. In our current work, we characterize MSLN levels in CRC, specifically correlating expression with clinical outcomes in relevant CRC subtypes and explore how MSLN expression impacts the status of immune activation and suppression in the peritumoral microenvironment. High MSLN expression is highly prevalent in CMS1 and CMS4 CRC subtypes as well as in mCRC tissue and correlates with higher gene mutation rates across the patient cohorts. Further, MSLN-high patients exhibit increased M1/M2 macrophage infiltration, PD-L1 staining, immune-inhibitory gene expression, enrichment in inflammatory, TGF-β, IL6/JAK/STAT3, IL2/STAT5 signaling pathways and mutation in KRAS and FBXW7. Together, these results suggest MSLN protein is a potential target for antigen-specific therapy and supports investigation into its tumorigenic effects to identify possible therapeutic interventions for patients with high MSLN expressing MSS CRC.

The Current Treatment Landscape of Malignant Pleural Mesothelioma and Future Directions

The incidence of malignant pleural mesothelioma is expected to increase globally. New treatment options for this malignancy are eagerly awaited to improve the survival and quality of life of patients. The present article highlights the results of recent advances in this field, analyzing data from several relevant trials. The heterogeneous tumor microenvironment and biology, together with the low mutational burden, pose a challenge for treating such tumors. So far, no single biomarker has been soundly correlated with targeted therapy development; thus, combination strategies are often required to improve outcomes. Locally applied vaccines, the expansion of genetically engineered immune cell populations such as T cells, the blockage of immune checkpoints that inhibit anti-tumorigenic responses and chemoimmunotherapy are among the most promising options expected to change the mesothelioma treatment landscape.

Established and new treatment roadmaps for pleural mesothelioma: opinions of the Turkish Collaborative Group

Pleural mesothelioma (PM) is a cancer of the pleural surface, which is aggressive and may be rapidly fatal. PM is a rare cancer worldwide, but is a relatively common disease in Turkey. Asbestos exposure is the main risk factor and the most common underlying cause of the disease. There have been significant improvements in diagnoses and treatments of many malignancies; however, there are still therapeutic challenges in PM. In this review, we aimed to increase the awareness of health care professionals, oncologists, and pulmonologists by underlining the unmet needs of patients with PM and by emphasizing the need for a multidisciplinary treatment and management of PM. After reviewing the general information about PM, we further discuss the treatment options for patients with PM using immunotherapy and offer evidence for improvements in the clinical outcomes of these patients because of these newer treatment modalities.

Development of mesothelioma-specific oncolytic immunotherapy enabled by immunopeptidomics of murine and human mesothelioma tumors

Malignant pleural mesothelioma (MPM) is an aggressive tumor with a poor prognosis. As the available therapeutic options show a lack of efficacy, novel therapeutic strategies are urgently needed. Given its T-cell infiltration, we hypothesized that MPM is a suitable target for therapeutic cancer vaccination. To date, research on mesothelioma has focused on the identification of molecular signatures to better classify and characterize the disease, and little is known about therapeutic targets that engage cytotoxic (CD8+) T cells. In this study we investigate the immunopeptidomic antigen-presented landscape of MPM in both murine (AB12 cell line) and human cell lines (H28, MSTO-211H, H2452, and JL1), as well as in patients' primary tumors. Applying state-of-the-art immuno-affinity purification methodologies, we identify MHC I-restricted peptides presented on the surface of malignant cells. We characterize in vitro the immunogenicity profile of the eluted peptides using T cells from human healthy donors and cancer patients. Furthermore, we use the most promising peptides to formulate an oncolytic virus-based precision immunotherapy (PeptiCRAd) and test its efficacy in a mouse model of mesothelioma in female mice. Overall, we demonstrate that the use of immunopeptidomic analysis in combination with oncolytic immunotherapy represents a feasible and effective strategy to tackle untreatable tumors.

Secretion of 4-1BB Ligand Crosslinked to PD-1 Checkpoint Inhibitor Potentiates Chimeric Antigen Receptor T Cell Solid Tumor Efficacy

Chimeric antigen receptor (CAR) T cell therapy has transformed the treatment of hematological malignancies but has yet to achieve similar success in solid tumors due to a lack of persistence and function in the tumor microenvironment. We previously reported the augmentation of CAR T cell therapy in an engineered solid tumor model through the secretion of anti-PD-1 single-chain fragment variable region (scFv), as shown by enhanced CAR T cell antitumor efficacy, expansion, and vitality. We have since improved the platform to create a superior cellular product-CAR T cells secreting single-chain trimeric 4-1BB ligand fused to anti-PD-1 scFv (αPD1-41BBL). 4-1BB signaling promotes cytotoxic T lymphocyte proliferation and survival but targeting 4-1BB with agonist antibodies in the clinic has been hindered by low antitumor activity and high toxicity. CAR T cells using 4-1BB endodomain for costimulatory signals have demonstrated milder antitumor response and longer persistence compared to CAR T cells costimulated by CD28 endodomain. We have, for the first time, engineered CD28-costimulated CAR T cells to secrete a fusion protein containing the soluble trimeric 4-1BB ligand. In vitro and in vivo, CAR19.αPD1-41BBL T cells exhibited reduced inhibitory receptor upregulation, enhanced persistence and proliferation, and a less differentiated memory status compared to CAR T cells without additional 4-1BB:4-1BBL costimulation. Accordingly, CAR19.αPD1-41BBL T cell-treated mice displayed significantly improved tumor growth control and overall survival. Spurred on by our preclinical success targeting CD19 as a model antigen, we produced mesothelin-targeting CAR T cells and confirmed the enhanced solid tumor efficacy of αPD1-41BBL-secreting CAR T cells.

Sophisticated genetically engineered macrophages, CAR-Macs, in hitting the bull's eye for solid cancer immunotherapy approaches

Studies have begun to employ macrophages engineered with chimeric antigen receptor (CAR-Macs) against solid tumors since they can enter solid tumor tissue and interact with approximately all cellular components in the tumor microenvironment. The chimeric antigen receptor (CAR) has emerged as an appealing strategy for improving immune cells' ability to detect cancer. Tumor-associated macrophages (TAMs) generated with CAR designs exhibit appropriate potency based on their capacity to enter solid tumors and communicate through the inhibitory tumor microenvironment. CAR-Macs technology is a new therapeutic method for attacking cancer cells by switching pro-tumoral M2 macrophages to anti-tumoral M1 macrophages, enhancing macrophage phagocytosis, or increasing antigen presentation activity. CAR-Macs may have a prevailing impact on surrounding immune cells, indicating that they retain anti-tumor activity in the presence of human M2 macrophages, demonstrating their use in CAR technology. Understanding the biology of TAM and targeting novel domains for the advanced CAR-Macrophage platform, it will be feasible to add a new dimension to immunotherapy techniques used exclusively in solid malignancies. This review describes how CAR-Macs technologies modulate CAR-Macrophage production, potential target biomarkers on these platforms, their role in immunotherapeutic approaches, and tumor microenvironment.

CAR designs for solid tumors: overcoming hurdles and paving the way for effective immunotherapy

Chimeric antigen receptor T cell (CAR-T) therapy has revolutionized immunotherapy by modifying patients' immune cells genetically. By expressing CARs, these modified cells can specifically identify and eliminate tumor cells. The success of CAR-T therapy in hematological malignancies, such as leukemia and lymphoma, has been remarkable. Numerous studies have reported improved patient outcomes and increased survival rates. However, the application of CAR-T therapy in treating solid tumors faces significant challenges. Solid tumors possess complex microenvironments containing stromal cells, extracellular matrix components, and blood vessels. These factors can impede the infiltration and persistence of CAR-T cells within the tumor. Additionally, the lack of target antigens exclusively expressed on tumor cells raises concerns about off-target effects and potential toxicity. This review aims to discuss advancements achieved by CAR-T therapy in solid tumors and the clinical outcomes in the realm of solid tumors.

Revolutionizing cancer treatment: a comprehensive review of CAR-T cell therapy

Chimeric antigen receptor (CAR)-T cell therapy is a promising new treatment for cancer that involves genetically modifying a patient's T-cells to recognize and attack cancer cells. This review provides an overview of the latest discoveries and clinical trials related to CAR-T cell therapy, as well as the concept and applications of the therapy. The review also discusses the limitations and potential side effects of CAR-T cell therapy, including the high cost and the risk of cytokine release syndrome and neurotoxicity. While CAR-T cell therapy has shown promising results in the treatment of hematologic malignancies, ongoing research is needed to improve the efficacy and safety of the therapy and expand its use to solid tumors. With continued research and development, CAR-T cell therapy has the potential to revolutionize cancer treatment and improve outcomes for patients with cancer.

Chimeric Antigen Receptor (CAR) T-Cell Therapy for Patients with Lung Cancer: Current Perspectives

Immunotherapy using chimeric antigen receptor (CAR)-engineered T-cells has achieved unprecedented efficacy in selected hematological cancers. However, solid tumors such as lung cancer impose several additional challenges to the attainment of clinical success using this emerging therapeutic modality. Lung cancer is the biggest cause of cancer-related mortality worldwide, accounting for approximately 1.8 million deaths worldwide each year. Obstacles to the development of CAR T-cell immunotherapy for lung cancer include the selection of safe tumor-selective targets, accounting for the large number of candidates that have been evaluated thus far. Tumor heterogeneity is also a key hurdle, meaning that single target-based approaches are susceptible to therapeutic failure through the emergence of antigen null cancers. There is also a need to enable CAR T-cells to traffic efficiently to sites of disease, to infiltrate tumor deposits and to operate within the hostile tumor microenvironment formed by solid tumors, resisting the onset of exhaustion. Multiple immune, metabolic, physical and chemical barriers operate at the core of malignant lesions, with potential for further heterogeneity and evolution in the face of selective therapeutic pressures. Although the extraordinarily adaptable nature of lung cancers has recently been unmasked, immunotherapy using immune checkpoint blockade can achieve long-term disease control in a small number of patients, establishing clinical proof of concept that immunotherapies can control advanced lung carcinomas. This review summarizes pre-clinical CAR T-cell research that is specifically focused on lung cancer in addition to published and ongoing clinical trial activity. A number of advanced engineering strategies are also described which are designed to bridge the gap to the attainment of meaningful efficacy using genetically engineered T-cells.

Rapid nanobody-based imaging of mesothelin expressing malignancies compatible with blocking therapeutic antibodies

Introduction

Mesothelin (MSLN) is overexpressed in a wide variety of cancers with few therapeutic options and has recently emerged as an attractive target for cancer therapy, with a large number of approaches currently under preclinical and clinical investigation. In this respect, developing mesothelin specific tracers as molecular companion tools for predicting patient eligibility, monitoring then response to mesothelin-targeting therapies, and tracking the evolution of the disease or for real-time visualisation of tumours during surgery is of growing importance.

Methods

We generated by phage display a nanobody (Nb S1) and used enzymatic approaches were used to site-directed conjugate Nb S1 with either ATTO 647N fluorochrome or NODAGA chelator for fluorescence and positron emission tomography imaging (PET) respectively.

Results

We demonstrated that Nb S1 displays a high apparent affinity and specificity for human mesothelin and demonstrated that the binding, although located in the membrane distal domain of mesothelin, is not impeded by the presence of MUC16, the only known ligand of mesothelin, nor by the therapeutic antibody amatuximab. In vivo experiments showed that both ATTO 647N and [68Ga]Ga-NODAGA-S1 rapidly and specifically accumulated in mesothelin positive tumours compared to mesothelin negative tumours or irrelevant Nb with a high tumour/background ratio. The ex vivo biodistribution profile analysis also confirmed a significantly higher uptake of Nb S1 in MSLN-positive tumours than in MSLNlow tumours.

Conclusion

We demonstrated for the first time the use of an anti-MSLN nanobody as PET radiotracer for same day imaging of MSLN+ tumours, targeting an epitope compatible with the monitoring of amatuximab-based therapies and current SS1-derived-drug conjugates.

Stromal depletion by TALEN-edited universal hypoimmunogenic FAP-CAR T cells enables infiltration and anti-tumor cytotoxicity of tumor antigen-targeted CAR-T immunotherapy

Adoptive cell therapy based on chimeric antigen receptor (CAR)-engineered T-cells has proven to be lifesaving for many cancer patients. However, its therapeutic efficacy has so far been restricted to only a few malignancies, with solid tumors proving to be especially recalcitrant to efficient therapy. Poor intra-tumor infiltration by T cells and T cell dysfunction due to a desmoplastic, immunosuppressive microenvironment are key barriers for CAR T-cell success against solid tumors. Cancer-associated fibroblasts (CAFs) are critical components of the tumor stroma, evolving specifically within the tumor microenvironment (TME) in response to tumor cell cues. The CAF secretome is a significant contributor to the extracellular matrix and a plethora of cytokines and growth factors that induce immune suppression. Together they form a physical and chemical barrier which induces a T cell-excluding 'cold' TME. CAF depletion in stroma rich solid tumors can thus provide an opportunity to convert immune evasive tumors susceptible to tumor-antigen CAR T-cell cytotoxicity. Using our TALEN-based gene editing platform we engineered non-alloreactive, immune evasive CAR T-cells (termed UCAR T-cells) targeting the unique CAF marker Fibroblast Activation Protein, alpha (FAP). In an orthotopic mouse model of triple-negative breast cancer (TNBC) composed of patient derived-CAFs and tumor cells, we demonstrate the efficacy of our engineered FAP UCAR T-cells in CAF depletion, reduction of desmoplasia and successful tumor infiltration. Furthermore, while previously resistant, pre-treatment with FAP UCAR T-cells now sensitized these tumors to Mesothelin (Meso) UCAR T-cell infiltration and anti-tumor cytotoxicity. Combination therapy of FAP UCAR, Meso UCAR T cells and the checkpoint inhibitor anti-PD-1 significantly reduced tumor burden and prolonged mice survival. Our study thus proposes a novel treatment paradigm for successful CAR T-cell immunotherapy against stroma-rich solid tumors.

Small and Large Extracellular Vesicles Derived from Pleural Mesothelioma Cell Lines Offer Biomarker Potential

Pleural mesothelioma, previously known as malignant pleural mesothelioma, is an aggressive and fatal cancer of the pleura, with one of the poorest survival rates. Pleural mesothelioma is in urgent clinical need for biomarkers to aid early diagnosis, improve prognostication, and stratify patients for treatment. Extracellular vesicles (EVs) have great potential as biomarkers; however, there are limited studies to date on their role in pleural mesothelioma. We conducted a comprehensive proteomic analysis on different EV populations derived from five pleural mesothelioma cell lines and an immortalized control cell line. We characterized three subtypes of EVs (10 K, 18 K, and 100 K), and identified a total of 4054 unique proteins. Major differences were found in the cargo between the three EV subtypes. We show that 10 K EVs were enriched in mitochondrial components and metabolic processes, while 18 K and 100 K EVs were enriched in endoplasmic reticulum stress. We found 46 new cancer-associated proteins for pleural mesothelioma, and the presence of mesothelin and PD-L1/PD-L2 enriched in 100 K and 10 K EV, respectively. We demonstrate that different EV populations derived from pleural mesothelioma cells have unique cancer-specific proteomes and carry oncogenic cargo, which could offer a novel means to extract biomarkers of interest for pleural mesothelioma from liquid biopsies.

Immunomodulatory effect of locoregional therapy in the tumor microenvironment

Cancer immunotherapy appears to be a promising treatment option; however, only a subset of patients with cancer responds favorably to treatment. Locoregional therapy initiates a local antitumor immune response by disrupting immunosuppressive components, releasing immunostimulatory damage-associated molecular patterns, recruiting immune effectors, and remodeling the tumor microenvironment. Many studies have shown that locoregional therapy can produce specific antitumor immunity alone; nevertheless, the effect is relatively weak and transient. Furthermore, increasing research efforts have explored the potential synergy between locoregional therapy and immunotherapy to enhance the long-term systemic antitumor immune effect and improve survival. Therefore, further research is needed into the immunomodulatory effects of locoregional therapy and immunotherapy to augment antitumor effects. This review article summarizes the key components of the tumor microenvironment, discusses the immunomodulatory role of locoregional therapy in the tumor microenvironment, and emphasizes the therapeutic potential of locoregional therapy in combination with immune checkpoint inhibitors.

Emerging Role of Immunomonitoring to Predict the Clinical Outcome of Patients With Malignant Pleural Mesothelioma Treated With Radical Radiation Therapy

PURPOSE

The present study aimed at evaluating the baseline immune profile and the immunomodulating effects of radical hemithoracic radiation therapy (RT) in patients affected by malignant pleural mesothelioma (MPM) to identify potential predictive biomarkers of therapy response, toxicity development, and eligibility for further immunotherapeutic treatments.

METHODS AND MATERIALS

Blood samples were collected from 55 patients with MPM, enrolled in a phase 3 trial comparing radical hemithoracic RT (interventional arm, n = 28) with local palliative RT (control arm, n = 27). Immunomonitoring was performed before RT, at the end of treatment, and 1 month after therapy, characterizing natural killer cells, B and T lymphocytes, activated CD4 and CD8 T cells, interferon-γ- and tumor necrosis factor-α-producing T helper (Th) 1 cells, regulatory T cells, and Th17 and Th22 lymphocytes, through flow cytometry. Serum levels of interleukin (IL)-6, -8, -10 and mesothelin were quantified through Enzyme-Linked Immunosorbent Assay (ELISA) assays at the same time points. Variations in the immune parameters were investigated by Friedman test and Wilcoxon signed rank post hoc test with Bonferroni correction for multiple testing, while the prognostic effect of immune biomarkers was evaluated through Kaplan-Meier method and Spearman's correlation analysis.

RESULTS

Major immune variations were noticed after radical RT compared with palliative treatment, in particular an improvement in activated T cells and in interferon-γ-producing Th1 cells after RT. In the interventional arm, baseline high levels of Th22 and IL-10 and an increase in T cells were associated with an improved survival, whereas a fold increase in serum mesothelin correlated with the development of severe toxicity. An improvement of immunosuppressive regulatory T cells was observed in both arms of treatment.

CONCLUSIONS

The immunomonitoring performed in patients with MPM revealed potential prognostic biomarkers for radical hemithoracic RT treatment and identified specific immune signatures induced by RT immunomodulation, which could suggest a synergistic effect with an immunotherapeutic treatment.

Challenges of Anti-Mesothelin CAR-T-Cell Therapy

Chimeric antigen receptor (CAR)-T-cell therapy is a kind of adoptive T-cell therapy (ACT) that has developed rapidly in recent years. Mesothelin (MSLN) is a tumor-associated antigen (TAA) that is highly expressed in various solid tumors and is an important target antigen for the development of new immunotherapies for solid tumors. This article reviews the clinical research status, obstacles, advancements and challenges of anti-MSLN CAR-T-cell therapy. Clinical trials on anti-MSLN CAR-T cells show that they have a high safety profile but limited efficacy. At present, local administration and introduction of new modifications are being used to enhance proliferation and persistence and to improve the efficacy and safety of anti-MSLN CAR-T cells. A number of clinical and basic studies have shown that the curative effect of combining this therapy with standard therapy is significantly better than that of monotherapy.

CAR Based Immunotherapy of Solid Tumours-A Clinically Based Review of Target Antigens

Immunotherapy with CAR-engineered immune cells has transformed the management of selected haematological cancers. However, solid tumours have proven much more difficult to control using this emerging therapeutic modality. In this review, we survey the clinical impact of solid tumour CAR-based immunotherapy, focusing on specific targets across a range of disease indications Among the many candidates which have been the subject of non-clinical CAR T-cell research, clinical data are available for studies involving 30 of these targets. Here, we map out this clinical experience, highlighting challenges such as immunogenicity and on-target off-tumour toxicity, an issue that has been both unexpected and devastating in some cases. We also summarise how regional delivery and repeated dosing have been used in an effort to enhance impact and safety. Finally, we consider how emerging armouring systems and multi-targeted CAR approaches might be used to enhance tumour access and better enable discrimination between healthy and transformed cell types.

Targeted thorium-227 conjugates as treatment options in oncology

Targeted alpha therapy (TAT) is a promising approach for addressing unmet needs in oncology. Inherent properties make α-emitting radionuclides well suited to cancer therapy, including high linear energy transfer (LET), penetration range of 2-10 cell layers, induction of complex double-stranded DNA breaks, and immune-stimulatory effects. Several alpha radionuclides, including radium-223 (²²³Ra), actinium-225 (²²⁵Ac), and thorium-227 (²²⁷Th), have been investigated. Conjugation of tumor targeting modalities, such as antibodies and small molecules, with a chelator moiety and subsequent radiolabeling with α-emitters enables specific delivery of cytotoxic payloads to different tumor types. ²²³Ra dichloride, approved for the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC) with bone-metastatic disease and no visceral metastasis, is the only approved and commercialized alpha therapy. However, ²²³Ra dichloride cannot currently be complexed to targeting moieties. In contrast to ²²³Ra, ²²⁷Th may be readily chelated, which allows radiolabeling of tumor targeting moieties to produce targeted thorium conjugates (TTCs), facilitating delivery to a broad range of tumors. TTCs have shown promise in pre-clinical studies across a range of tumor-cell expressing antigens. A clinical study in hematological malignancy targeting CD22 has demonstrated early signs of activity. Furthermore, pre-clinical studies show additive or synergistic effects when TTCs are combined with established anti-cancer therapies, for example androgen receptor inhibitors (ARI), DNA damage response inhibitors such as poly (ADP)-ribose polymerase inhibitors or ataxia telangiectasia and Rad3-related kinase inhibitors, as well as immune checkpoint inhibitors.

NAV-001, a high-efficacy antibody-drug conjugate targeting mesothelin with improved delivery of a potent payload by counteracting MUC16/CA125 inhibitory effects

Subsets of tumor-produced cell surface and secreted proteins can bind to IgG1 type antibodies and suppress their immune-effector activities. As they affect antibody and complement-mediated immunity, we call these proteins humoral immuno-oncology (HIO) factors. Antibody-drug conjugates (ADCs) use antibody targeting to bind cell surface antigens, internalize into the cell, then kill target cells upon liberation of the cytotoxic payload. Binding of the ADC antibody component by a HIO factor may potentially hamper ADC efficacy due to reduced internalization. To determine the potential effects of HIO factor ADC suppression, we evaluated the efficacy of a HIO-refractory, mesothelin-directed ADC (NAV-001) and a HIO-bound, mesothelin-directed ADC (SS1). The HIO factor MUC16/CA125 binding to SS1 ADC was shown to have a negative effect on internalization and tumor cell killing. The MUC16/CA125 refractory NAV-001 ADC was shown to have robust killing of MUC16/CA125 expressing and non-expressing tumor cells in vitro and in vivo at single, sub-mg/kg dosing. Moreover, NAV-001-PNU, which contains the PNU-159682 topoisomerase II inhibitor, demonstrated good stability in vitro and in vivo as well as robust bystander activity of resident cells while maintaining a tolerable safety profile in vivo. Single-dose NAV-001-PNU demonstrated robust tumor regression of a number of patient-derived xenografts from different tumor types regardless of MUC16/CA125 expression. These findings suggest that identification of HIO-refractory antibodies to be used in ADC format may improve therapeutic efficacy as observed by NAV-001 and warrants NAV-001-PNU's advancement to human clinical trials as a monotherapy to treat mesothelin-positive cancers.

The current landscape of CAR T-cell therapy for solid tumors: Mechanisms, research progress, challenges, and counterstrategies

The successful outcomes of chimeric antigen receptor (CAR) T-cell therapy in treating hematologic cancers have increased the previously unprecedented excitement to use this innovative approach in treating various forms of human cancers. Although researchers have put a lot of work into maximizing the effectiveness of these cells in the context of solid tumors, few studies have discussed challenges and potential strategies to overcome them. Restricted trafficking and infiltration into the tumor site, hypoxic and immunosuppressive tumor microenvironment (TME), antigen escape and heterogeneity, CAR T-cell exhaustion, and severe life-threatening toxicities are a few of the major obstacles facing CAR T-cells. CAR designs will need to go beyond the traditional architectures in order to get over these limitations and broaden their applicability to a larger range of malignancies. To enhance the safety, effectiveness, and applicability of this treatment modality, researchers are addressing the present challenges with a wide variety of engineering strategies as well as integrating several therapeutic tactics. In this study, we reviewed the antigens that CAR T-cells have been clinically trained to recognize, as well as counterstrategies to overcome the limitations of CAR T-cell therapy, such as recent advances in CAR T-cell engineering and the use of several therapies in combination to optimize their clinical efficacy in solid tumors.

Considerations for design, manufacture, and delivery for effective and safe T-cell engager therapies

T-cell engager (TCE) molecules provide a targeted immunotherapy approach to treat hematologic malignancies and solid tumors. Since the approval of the CD19-targeted BiTE® (bispecific T-cell engager) molecule blinatumomab, multiple TCE molecules against different targets have been developed in several tumor types, with the approval of three additional TCE molecules in 2022. Some of the initial challenges, such as the need for continuous intravenous administration and low productivity, have been addressed in subsequent iterations of the platform by advancing half-life extended, Fc-based molecules. As clinical data from these molecules emerge, additional optimization of formats and manufacturability will be necessary. Ongoing efforts are focused on further improving TCE efficacy, safety, and convenience of administration.

Oncolytic herpes simplex virus delivery of dual CAR targets of CD19 and BCMA as well as immunomodulators to enhance therapeutic efficacy in solid tumors combined with CAR T cell therapy

BACKGROUND

The CAR T-cell therapy is a promising approach to treating hematologic malignancies. However, the application in solid tumors still has many tough challenges, including heterogenicity in antigen expressions and immunosuppressive tumor microenvironment (TME). As a new cancer treatment modality, oncolytic virotherapy can be engineered to circumvent these obstacles for CAR T cell therapy in solid tumors.

METHODS

In this study, an oHSV T7011 is engineered to drive ectopic expression of dual-antigens, extracellular domains of CD19 and BCMA, on the solid tumor cell surface to be targeted by approved CAR T cells. In addition, multiple immunomodulators, CCL5, IL-12, and anti-PD-1 antibody are also included to modulate the TME. The antitumor activities of T7011 in combination with CD19 or BCMA CAR T-cell were evaluated in vitro and in vivo.

RESULTS

The expression of CD19 or BMCA on the tumor cell surface could be detected after T7011 infection. The level of CCL5 in TME was also increased. Efficacy studies demonstrated that combination with T7011 and CAR-TCD19 or CAR-TBCMA cells showed significant synergistic anti-tumor responses in several solid tumor models.

CONCLUSION

These studies indicated that the new generation of oHSV T7011 can be a promising combinational therapy with CD19 or BCMA-specific CAR T cells for the treatment of a broad range of solid tumors.

Approved gene therapies in Australia: coming to a store near you

Gene therapy has been promising paradigm‐shifting advances in medical science for over two decades. Broadly, it is defined as a human therapy in which an existing defective gene function is added to, replaced, edited or disrupted to achieve a clinical benefit, up to and including a potential lifelong cure. Although originally set out to treat monogenic disorders, gene therapy has since been utilised to treat neoplasia, cardiovascular and neurodegenerative diseases, as well as infections. The realisation of this therapy has been dependent on the achievement of fundamental milestones in medicine, from determining the human genome sequence to identifying effective vehicles for the gene of interest, ultimately facilitating gene delivery in humans. In this review, six approved gene and cell therapies available in Australia are described. Their efficacy, adverse effects, limitations and eligibility are discussed, as well as an overview of cost and future directions.

Chimeric Antigen Receptor (CAR)-T Cell Immunotherapy Against Thoracic Malignancies: Challenges and Opportunities

Different from surgery, chemical therapy, radio-therapy and target therapy, Chimeric antigen receptor-modified T (CAR-T) cells, a novel adoptive immunotherapy strategy, have been used successfully against both hematological tumors and solid tumors. Although several problems have reduced engineered CAR-T cell therapeutic outcomes in clinical trials for the treatment of thoracic malignancies, including the lack of specific antigens, an immunosuppressive tumor microenvironment, a low level of CAR-T cell infiltration into tumor tissues, off-target toxicity, and other safety issues, CAR-T cell treatment is still full of bright future. In this review, we outline the basic structure and characteristics of CAR-T cells among different period, summarize the common tumor-associated antigens in clinical trials of CAR-T cell therapy for thoracic malignancies, and point out the current challenges and new strategies, aiming to provide new ideas and approaches for preclinical experiments and clinical trials of CAR-T cell therapy for thoracic malignancies.

Locoregional delivery of CAR-T cells in the clinic

Cellular therapies utilizing T cells expressing chimeric antigen receptors (CARs) have garnered significant interest due to their clinical success in hematological malignancies. Unfortunately, this success has not been replicated in solid tumors, with only a small fraction of patients achieving complete responses. A number of obstacles to effective CAR-T cell therapy in solid tumors have been identified including tumor antigen heterogeneity, poor T cell fitness and persistence, inefficient trafficking and inability to penetrate into the tumor, immune-related adverse events due to on-target/off-tumor toxicity, and the immunosuppressive tumor microenvironment. Many preclinical studies have focused on improvements to CAR design to try to overcome some of these hurdles. However, a growing body of work has also focused on the use of local and/or regional delivery of CAR-T cells as a means to overcome poor T cell trafficking and inefficient T cell penetration into tumors. Most trials that incorporate locoregional delivery of CAR-T cells have targeted tumors of the central nervous system - repurposing an Ommaya/Rickham reservoir for repeated delivery of cells directly to the tumor cavity or ventricles. Hepatic artery infusion is another technique used for locoregional delivery to hepatic tumors. Locoregional delivery theoretically permits increased numbers of CAR-T cells within the tumor while reducing the risk of immune-related systemic toxicity. Studies to date have been almost exclusively phase I. The growing body of evidence indicates that locoregional delivery of CAR-T cells is both safe and feasible. This review focuses specifically on the use of locoregional delivery of CAR-T cells in clinical trials.

MSLN Correlates With Immune Infiltration and Chemoresistance as a Prognostic Biomarker in Ovarian Cancer

Mesothelin (MSLN) is a glycoprotein with various expression degrees in different tumors including mesothelioma, ovarian cancer, pancreatic cancer, etc. MSLN is considered to play an important role in cell survival, proliferation, and tumor progression. Although the expression of MSLN in tumors makes it a potential therapeutic target, its mechanism of action is still unclear, especially its correlation with immune cells infiltration in the tumor microenvironment has not been investigated. In this study, we detected the overexpression of MSLN in ovarian cancer using database analysis and tissue-array staining. We further evaluated the diagnostic value of MSLN and found it was associated with poor overall survival in ovarian cancer. In addition, the high expression of MSLN was significantly related to the immune-related genes and chemoresistant genes. We confirmed the overexpression of MSLN in the chemoresistant ovarian cancer cell lines. Our research suggests that MSLN participates in a variety of pathways related to the suppression of immune activation and promotion of chemoresistance, leading to a poor prognosis in ovarian cancer.

C3aR costimulation enhances the antitumor efficacy of CAR-T cell therapy through Th17 expansion and memory T cell induction

Although chimeric antigen receptor (CAR)-modified adoptive T cell therapy is a promising immunotherapy for hematological malignancies, the efficacy improvement in relapsed/refractory acute lymphoblastic leukemia (ALL) with extramedullary infiltration and in multiple myeloma (MM) is still warranted. Since C3aR activation can promote the expansion of tumor-killing Th17 cells, we hypothesized that incorporating C3aR as a costimulatory domain would augment the antitumor activity of CAR-T. In this study, we introduced the C3aR domain into a CAR and generated BB-ζ-C3aR CAR-T targeting CD19 or BCMA. These new CAR-T exhibited a potent cytolytic ability to eradicate tumor cells expressing CD19 or BCMA in vitro. When administered intravenously to ALL or MM xenograft mouse models, BB-ζ-C3aR CAR-T reduced the tumor burden and improved the survival rate. Of note, these CAR-T could effectively eradicate subcutaneous CD19⁺ tumor cells, highlighting the therapeutic potential in extramedullary leukemia. Mechanistically, BB-ζ-C3aR CAR-T tended to exhibit a Th17 phenotype favoring tumor killing and suppressed Tregs. In addition, the induction of memory T cell in the BB-ζ-C3aR CAR-T cells indicated their long-term effects. Together, our findings suggest that the application of C3aR costimulation boosts the ability of CAR-T to eradicate aggressive tumor cells via Th17 expansion and memory T cell induction.

Mesothelin: An Immunotherapeutic Target beyond Solid Tumors

Simple Summary

This review summarizes the current knowledge on mesothelin’s function, its role in cancer, and opportunities for immunotherapeutic targeting of mesothelin. Immunotherapies including monoclonal antibodies, antibody–drug conjugates, chimeric antigen receptor T and NK-cells, targeted alpha therapies, and bispecific T cell engaging molecules are reviewed. We show future directions for mesothelin targeting in hematological malignancies, including acute myeloid leukemia.

Abstract

Modern targeted cancer therapies rely on the overexpression of tumor associated antigens with very little to no expression in normal cell types. Mesothelin is a glycosylphosphatidylinositol-anchored cell surface protein that has been identified in many different tumor types, including lung adenocarcinomas, ovarian carcinomas, and most recently in hematological malignancies, including acute myeloid leukemia (AML). Although the function of mesothelin is widely unknown, interactions with MUC16/CA125 indicate that mesothelin plays a role in the regulation of proliferation, growth, and adhesion signaling. Most research on mesothelin currently focuses on utilizing mesothelin to design targeted cancer therapies such as monoclonal antibodies, antibody–drug conjugates, chimeric antigen receptor T and NK cells, bispecific T cell engaging molecules, and targeted alpha therapies, amongst others. Both in vitro and in vivo studies using different immunotherapeutic modalities in mesothelin-positive AML models highlight the potential impact of this approach as a unique opportunity to treat hard-to-cure AML.

The next wave of cellular immunotherapies in pancreatic cancer

Pancreatic cancer is an aggressive disease that is predicted to become the second leading cause of cancer-related death worldwide by 2030. The overall 5-year survival rate is around 10%. Pancreatic cancer typically presents late with locally advanced or metastatic disease, and there are limited effective treatments available. Cellular immunotherapy, such as chimeric antigen receptor (CAR) T cell therapy, has had significant success in treating hematological malignancies. However, CAR T cell therapy efficacy in pancreatic cancer has been limited. This review provides an overview of current and ongoing CAR T cell clinical studies of pancreatic cancer and the major challenges and strategies to improve CAR T cell efficacy. These strategies include arming CAR T cells; developing off-the-shelf allogeneic CAR T cells; using other immune CAR cells, like natural killer cells and tumor-infiltrating lymphocytes; and combination therapy. Careful incorporation of preclinical models will enhance management of affected individuals, assisting incorporation of cellular immunotherapies. A multifaceted, personalized approach involving cellular immunotherapy treatment is required to improve pancreatic cancer outcomes.

Current Management and Future Perspective in Pleural Mesothelioma

Pleural mesothelioma is an aggressive malignancy arising from pleural mesothelial cell lining, predominantly associated with prior exposure to asbestos. The ban on asbestos use has led to its lower incidence in many countries, but globally the disease burden is expected to rise. Therefore, well-planned research is needed to develop more effective, tolerable and affordable drugs. The development of novel treatment has been too slow, with only two regimens of systemic therapy with robust phase 3 data approved formally to date. The treatment scenario for resectable disease remains controversial. However, recent developments in the understanding of disease and clinical trials have been encouraging, and may add better treatment options in the coming years. In this review, we discuss the current treatment options for pleural mesothelioma and shed light on some recent studies and ongoing trials.

Novel and Future Treatment Options in Mesothelioma: A Systematic Review

Mesothelioma is a rare tumor, frequently associated with asbestos exposure, arising from pleura and peritoneum. Traditionally, diagnosis and treatment have been difficult in a clinical setting. The treatment is based on a trimodal approach involving surgery, chemotherapy, and radiotherapy. The introduction of chemotherapy improved the overall survival. However, the regimen of pemetrexed/cisplatin doublet has not been changed as a standard treatment since 2004. Novel combinations of ipilimumab and nivolumab have only been approved for clinical use in late 2020. The aim of this review was to systematically summarize findings on novel treatment options in mesothelioma. We searched available medical databases online, such as PubMed and Clinicaltrials.gov, to systematically review the literature on novel approaches in immunotherapy, vaccines, and Chimeric Antigen Receptor (CAR)-T cell therapy in mesothelioma. We manually screened 1127 articles on PubMed and 450 trials on ClinicalTrials.gov, and 24 papers and 12 clinical trials published in the last ten years were included in this review. Immunotherapy that was swiftly introduced to treat other thoracic malignancies was slow to reach desirable survival endpoints in mesothelioma, possibly due to limited patient numbers. Novel treatment approaches, such as CAR-T cell therapy, are being investigated. As the incidence of mesothelioma is still rising globally, novel treatment options based on a better understanding of the tumor microenvironment and the genetic drivers that modulate it are needed to support future precision-based therapies.

Mesothelin-specific CAR-T cell therapy that incorporates an HLA-gated safety mechanism selectively kills tumor cells

Background

Mesothelin (MSLN) is a classic tumor-associated antigen that is expressed in lung cancer and many other solid tumors. However, MSLN is also expressed in normal mesothelium which creates a significant risk of serious inflammation for MSLN-directed therapeutics. We have developed a dual-receptor (Tmod™) system that exploits the difference between tumor and normal tissue in a subset of patients with defined heterozygous gene loss (LOH) in their tumors.

Methods

T cells engineered with the MSLN CAR Tmod construct described here contain (1) a novel MSLN-activated CAR and (2) an HLA-A*02-gated inhibitory receptor (blocker). A*02 binding is intended to override T-cell cytotoxicity, even in the presence of MSLN. The Tmod system is designed to treat heterozygous HLA class I patients, selected for HLA LOH. When A*02 is absent from tumors selected for LOH, the MSLN Tmod cells are predicted to mediate potent killing of the MSLN(+)A*02(−) malignant cells.

Results

The sensitivity of the MSLN Tmod cells is comparable with a benchmark MSLN CAR-T that was active but toxic in the clinic. Unlike MSLN CAR-T cells, the Tmod system robustly protects surrogate “normal” cells even in mixed-cell populations in vitro and in a xenograft model. The MSLN CAR can also be paired with other HLA class I blockers, supporting extension of the approach to patients beyond A*02 heterozygotes.

Conclusions

The Tmod mechanism exemplified by the MSLN CAR Tmod construct provides an alternative route to leverage solid-tumor antigens such as MSLN in safer, more effective ways than previously possible.

Cancer-Homing CAR-T Cells and Endogenous Immune Population Dynamics

Chimeric antigen receptor (CAR) therapy is based on patient blood-derived T cells and natural killer cells, which are engineered in vitro to recognize a target antigen in cancer cells. Most CAR-T recognize target antigens through immunoglobulin antigen-binding regions. Hence, CAR-T cells do not require the major histocompatibility complex presentation of a target peptide. CAR-T therapy has been tremendously successful in the treatment of leukemias. On the other hand, the clinical efficacy of CAR-T cells is rarely detected against solid tumors. CAR-T-cell therapy of cancer faces many hurdles, starting from the administration of engineered cells, wherein CAR-T cells must encounter the correct chemotactic signals to traffic to the tumor in sufficient numbers. Additional obstacles arise from the hostile environment that cancers provide to CAR-T cells. Intense efforts have gone into tackling these pitfalls. However, we argue that some CAR-engineering strategies may risk missing the bigger picture, i.e., that a successful CAR-T-cell therapy must efficiently intertwine with the complex and heterogeneous responses that the body has already mounted against the tumor. Recent findings lend support to this model.

[T cell-based immunotherapies in solid tumors]

In solid tumors, adoptive T cell therapies based on ex vivo amplification of antitumor T cell are represented by three main complementary approaches : (i) tumor infiltrating lymphocytes (TILs) which are amplified in vitro before reinjection to the patient, (ii) chimeric antigen receptor (CAR) engineered T cells and (iii) T cell receptor (TCR) engineered T cells. Despite encouraging results, some obstacles remain, such as optimal target selection and tumor microenvironment. In this Review, we discuss pros and cons of these different therapeutic strategies that may open new perspectives in the treatment of solid tumors.

Dual Targeting CAR-T Cells with Optimal Costimulation and Metabolic Fitness enhance Antitumor Activity and Prevent Escape in Solid Tumors

Chimeric antigen receptor (CAR) T cells showed great activity in hematologic malignancies. However, heterogeneous antigen expression in tumor cells and suboptimal CAR-T cell persistence remain critical aspects to achieve clinical responses in patients with solid tumors. Here we show that CAR-T cells targeting simultaneously two tumor-associated antigens and providing transacting CD28 and 4-1BB costimulation, while sharing the sane CD3ζ-chain cause rapid antitumor effects in in vivo stress conditions, protection from tumor re-challenge and prevention of tumor escape due to low antigen density. Molecular and signaling studies indicate that T cells engineered with the proposed CAR design demonstrate sustained phosphorylation of T cell receptor-associated (TCR) signaling molecules and a molecular signature supporting CAR-T cell proliferation and long-term survival. Furthermore, metabolic profiling of CAR-T cells displayed induction of glycolysis that sustains rapid effector T cell function, but also preservation of oxidative functions, which are critical for T cell long-term persistence.

Hitting the Bull's-Eye: Mesothelin's Role as a Biomarker and Therapeutic Target for Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive cancer with limited treatment options and poor prognosis. MPM originates from the mesothelial lining of the pleura. Mesothelin (MSLN) is a glycoprotein expressed at low levels in normal tissues and at high levels in MPM. Many other solid cancers overexpress MSLN, and this is associated with worse survival rates. However, this association has not been found in MPM, and the exact biological role of MSLN in MPM requires further exploration. Here, we discuss the current research on the diagnostic and prognostic value of MSLN in MPM patients. Furthermore, MSLN has become an attractive immunotherapy target in MPM, where better treatment strategies are urgently needed. Several MSLN-targeted monoclonal antibodies, antibody-drug conjugates, immunotoxins, cancer vaccines, and cellular therapies have been tested in the clinical setting. The biological rationale underpinning MSLN-targeted immunotherapies and their potential to improve MPM patient outcomes are reviewed.