Malignant mesothelioma: Advances in immune checkpoint inhibitor and mesothelin-targeted therapies

Global burden of mesothelioma attributable to occupational asbestos exposure in 204 countries and territories: 1990-2019

Malignant mesothelioma, a rare and aggressive cancer primarily caused by occupational asbestos exposure, has a poor prognosis. This study leverages the Global Burden of Disease (GBD) 2019 dataset to analyze the burden of mesothelioma linked to occupational asbestos exposure from 1990 to 2019. The analysis includes the number of mesothelioma deaths and disability-adjusted life years (DALYs) attributable to occupational asbestos exposure, focusing on trends in age-standardized mortality rate (ASMR) and age-standardized disability-adjusted life-year rate (ASDR) by year, age, sex, country, region, and Socio-demographic Index (SDI). In 2019, 91.7% of mesothelioma deaths and 85.2% of DALYs were attributable to occupational asbestos exposure, resulting in 26,820 (95% UI 24,312-28,622) deaths and 569,429 (95% UI 509,956-617,484) DALYs. Despite a decline in ASMR and ASDR from 1990 to 2019, the absolute number of deaths and DALYs almost doubled. The United States reported the highest number of mesothelioma deaths, while China had the highest number of DALYs. Age-specific mortality rates and DALYs decreased in the 25-74 age group but increased in the 75+ age group. In conclusion, occupational asbestos exposure remains the primary cause of mesothelioma worldwide, with an increasing number of deaths and DALYs. The highest incidence rates are observed in high-income areas, and rates are rising in low-income areas. It is crucial to raise awareness about the hazards of asbestos to reduce the global burden of mesothelioma linked to occupational exposure.

Efficacy and safety of bispecific antibodies vs. immune checkpoint blockade combination therapy in cancer: a real-world comparison

Emerging tumor immunotherapy methods encompass bispecific antibodies (BSABs), immune checkpoint inhibitors (ICIs), and adoptive cell immunotherapy. BSABs belong to the antibody family that can specifically recognize two different antigens or epitopes on the same antigen. These antibodies demonstrate superior clinical efficacy than monoclonal antibodies, indicating their role as a promising tumor immunotherapy option. Immune checkpoints are also important in tumor immunotherapy. Programmed cell death protein-1 (PD-1) is a widely acknowledged immune checkpoint target with effective anti-tumor activity. PD-1 inhibitors have demonstrated notable therapeutic efficacy in treating hematological and solid tumors; however, more than 50% of patients undergoing this treatment exhibit a poor response. However, ICI-based combination therapies (ICI combination therapies) have been demonstrated to synergistically increase anti-tumor effects and immune response rates. In this review, we compare the clinical efficacy and side effects of BSABs and ICI combination therapies in real-world tumor immunotherapy, aiming to provide evidence-based approaches for clinical research and personalized tumor diagnosis and treatment.

Clinical outcomes of stereotactic body radiation therapy for malignant pleural mesothelioma

BACKGROUND

The objective of this study is to determine the outcomes and toxicities of patients with malignant pleural mesothelioma (MPM) treated with stereotactic body radiotherapy (SBRT).

MATERIALS AND METHODS

Data were extracted from an institutional tumor registry for patients diagnosed with mesothelioma and treated with SBRT. Kaplan-Meier and Cox regression analyses were employed to determine local control (LC) and overall survival (OS).

RESULTS

Forty-four patients with 59 total treated tumors from December 2006 to April 2022 were identified. Fifty-one (86.4 %) cases had oligoprogressive disease (five sites or less). The median prescription dose delivered was 3000 cGy in 5 fractions (range: 2700-6000 cGy in 3-8 fractions). Fifty-one (86.4 %) tumors were in the pleura, 4 (6.8 %) spine, 2 (3.4 %) bone, 1 (1.7 %) brain, and 1 (1.7 %) pancreas. The median follow-up from SBRT completion for those alive at last follow-up was 28 months (range: 14-52 months). The most common toxicities were fatigue (50.8 %), nausea (22.0 %), pain flare (15.3 %), esophagitis (6.8 %), dermatitis (6.8 %), and pneumonitis (5.1 %). There were no grade ≥ 3 acute or late toxicities. There were 2 (3.4 %) local failures, one of the pleura and another of the spine. One-year LC was 92.9 % (95 % CI: 74.6-98.2 %) for all lesions and 96.3 % (95 % CI: 76.5-99.5 %) for pleural tumors. One-year LC was 90.9 % (95 % CI: 68.1-97.6 %) for epithelioid tumors and 92.1 % (95 % CI: 72.1-98.0 %) for oligoprogressive tumors. One-year OS from time of SBRT completion was 36.4 % (95 % CI: 22.6-50.3 %). On multivariable analysis, KPS was the lone significant predictor for OS (p = 0.029).

CONCLUSIONS

Our single-institutional experience on patients with MPM suggests that SBRT is safe with a low toxicity profile and potentially achieve good local control.

Specific Targeting of Mesothelin-Expressing Malignant Cells Using Nanobody-Functionalized Magneto-Fluorescent Nanoassemblies

Introduction

Most current anti-cancer therapies are associated with major side effects due to a lack of tumor specificity. Appropriate vectorization of drugs using engineered nanovectors is known to increase local concentration of therapeutic molecules in tumors while minimizing their side effects. Mesothelin (MSLN) is a well-known tumor associated antigen overexpressed in many malignancies, in particular in malignant pleural mesothelioma (MPM), and various MSLN-targeting anticancer therapies are currently evaluated in preclinical and clinical assays. In this study, we described, for the first time, the functionalization of fluorescent organic nanoassemblies (NA) with a nanobody (Nb) targeting MSLN for the specific targeting of MSLN expressing MPM cancer cells.

Methods

Cell lines from different cancer origin expressing or not MSLN were used. An Nb directed against MSLN was coupled to fluorescent NA using click chemistry. A panel of endocytosis inhibitors was used to study targeted NA internalization by cells. Cancer cells were grown in 2D or 3D and under a flow to evaluate the specificity of the targeted NA. Binding and internalization of the targeted NA were studied using flow cytometry, confocal microscopy and transmission electron microscopy.

Results

We show that the targeted NA specifically bind to MSLN-expressing tumor cells. Moreover, such functionalized NA appear to be internalized more rapidly and in significantly larger proportions compared to naked ones in MSLN+ MPM cells, thereby demonstrating both the functionality and interest of the active targeting strategy. We demonstrated that targeted NA are mainly internalized through a clathrin-independent/dynamin-dependent endocytosis pathway and are directed to lysosomes for degradation. A 3D cell culture model based on MSLN-expressing multicellular tumor spheroids reveals NA penetration in the first superficial layers.

Conclusion

Altogether, these results open the path to novel anticancer strategies based on MSLN-activated internalization of NA incorporating drugs to promote specific accumulation of active treatments in tumors.

Targeting AXL in Mesothelioma: from functional characterization to clinical implication

Malignant pleural mesothelioma (MM) is a highly aggressive and lethal cancer with a poor survival rate. Current treatment approaches primarily rely on chemotherapy and radiation, but their effectiveness is limited. Consequently, there is an urgent need for alternative treatment strategies, a comprehensive understanding of the molecular mechanisms underlying MM, and the identification of potential therapeutic targets. Extensive studies over the past decade have emphasized the role of Axl in driving tumor development and metastasis, while high levels of Axl expression have been associated with immune evasion, drug resistance, and reduced patient survival in various cancer types. Ongoing clinical trials are investigating the efficacy of Axl inhibitors for different cancers. However, the precise role of Axl in MM progression, development, and metastasis, as well as its regulatory mechanisms within MM, remain inadequately understood. This review aims to comprehensively investigate the involvement of Axl in MM. We discuss Axl role in MM progression, development, and metastasis, along with its specific regulatory mechanisms. Additionally, we examined the Axl associated signaling pathways, the relationship between Axl and immune evasion, and the clinical implications of Axl for MM treatment. Furthermore, we discussed the potential utility of liquid biopsy as a non-invasive diagnostic technique for early detection of Axl in MM. Lastly, we evaluated the potential of a microRNA signature that targets Axl. By consolidating existing knowledge and identifying research gaps, this review contributes to a better understanding of Axl's role in MM and sets the stage for future investigations and the development of effective therapeutic interventions.

The past, present, and future of targeted therapeutic approaches in patients with diffuse pleural mesotheliomas

Despite our growing understanding of the genomic landscape of diffuse pleural mesotheliomas (DPM), there has been limited success in targeted therapeutic strategies for the disease. This review summarizes attempts to develop targeted therapies in DPM, focusing on the following targets being clinically explored in recent and ongoing clinical trials: vascular endothelial growth factor, mesothelin, BRCA1-associated protein 1, Wilms tumor 1 protein, NF2/YAP/TAZ, CDKN2, methylthioadenosine phosphorylase, v-domain Ig suppressor T-cell activation, and argininosuccinate synthetase 1. Although preclinical data for these targets are promising, few have efficaciously translated to benefit our patients. Future efforts should seek to expand the availability of preclinical models that faithfully recapitulate DPM biology, develop clinically relevant biomarkers, and refine patient selection criteria for clinical trials.

Coexistence of a novel STRN-ALK, NBEA-ALK double-fusion in an ovarian malignant mesothelioma patient: a case report and review

Primary ovarian mesothelioma (POM) is a rare malignant tumor with poor prognosis. Although anaplastic lymphoma kinase gene (ALK) double-fusion partners have been found in various tumors, it is rarely reported in mesothelioma. In this article, we describe the coexistence of a novel STRN-ALK, neurobeachin (NBEA)-ALK double-fusion in a patient with primary ovarian mesothelioma. A 30-year-old woman was found to have pelvic masses for more than a year. Color Doppler ultrasound showed mixed mass in the left ovary and multiple solid masses in the right ovary. the patient underwent laparoscopic surgery, including total hysterectomy, bilateral salpingo-oopherectomy, pelvic lymph node and abdominal aortic lymph node resection, omentum resection and abdominal focus resection. Pathologic examination revealed bilateral ovarian malignant mesothelioma and no evidence of malignancy in the resected bilateral round/broad ligaments, bilateral parametrial tissues, vaginal stump, bilateral fallopian tubes, pelvic and paraaortic lymph nodes. Immunohistochemistry showed that it was positive for Calretinin, VIM, WT1, PAX8, mesothelin, CK5/6, PCK, CK7, MLH1, PMS2, MSH2, MSH6, weakly positive for BAP1, while being negative for Napsin A, P504S, CEA, D2-40, GATA3. The sequencing analysis identified STRN-ALK (intron3:intron19) and NBEA-ALK (intron1:intron16) double-ALK fusion. To the best of our knowledge, this is the first report that a novel NBEA-ALK and EML4-ALK coexist in one patient with POM. The patient has completed 6 cycles of continuous chemotherapy and is in stable condition. Whether ALK inhibitors can bring promising benefits to POM patients in the future deserves further study.

Case report: Rare intrapulmonary malignant mesothelioma complicated with myositis

Malignant pleural mesothelioma is an uncommon aggressive tumor. Its incidence is even lower when the lung parenchyma is the primary site. Myositis is a common paraneoplastic syndrome, but it rarely presents with malignant pleural mesothelioma. This report presents a rare intrapulmonary malignant mesothelioma complicated by cancer-associated myositis. The patient presented with limb muscle weakness as the first symptom and was diagnosed with intrapulmonary malignant mesothelioma complicated by cancer-associated myositis on the basis of clinical, histological, immunohistochemical, and radiological findings. The patient responded poorly to conventional hormone therapy and died of respiratory failure within 2 months after the first presence of limb muscle weakness.

Survival analysis and development of a prognostic nomogram for patients with malignant mesothelioma in different anatomic sites

Background

Malignant mesothelioma (MMe) is a rare and fatal cancer with a poor prognosis. Our study aimed to compare the overall survival (OS) of MMe patients across various sites and develop a prognostic model to provide a foundation for individualized management of MMe patients.

Methods

From the Surveillance, Epidemiology, and End Results (SEER) database, 1,772 individuals with malignant mesothelioma (MMe) were identified. The X-tile software was used to identify the optimal cut-off point for continuous variables. The Kaplan–Meier method was employed to compare the survival of MMe across different sites. The Cox proportional hazards model was applied to identify the independent risk factors of overall survival (OS) and a nomogram was constructed.

Results

In the survival analysis, MMe originating from the reproductive organs and hollow organs showed a relatively better prognosis than those originating from soft tissue, solid organs, and pleura. Age, gender, location, histological type, grade of differentiation, extent of disease, lymph node status, lymph node ratio (LNR), and chemotherapy were all found to be independent risk variables for the prognosis of MMe patients (P<0.05) in a multivariate Cox analysis and were included in the construction of nomogram. In the training and testing sets, the C-index of the nomogram was 0.701 and 0.665, respectively, and the area under the ROC curve (AUROC) of the 1-, 3-, and 5-year overall survival rate was 0.749, 0.797, 0.833 and 0.730, 0.800, 0.832, respectively. The calibration curve shows that the nomogram is well-calibrated.

Conclusions

This is the first research to examine the prognosis of MMe patients based on the location. However, previous studies often focused on malignant pleural mesothelioma or malignant peritoneal mesothelioma with high incidence. Furthermore, a nomograph with good prediction efficiency was established according to the variables that influence patient survival outcomes, which provides us with a reference for clinical decision-making.

Identification of Tumor Antigens and Immune Subtypes of Malignant Mesothelioma for mRNA Vaccine Development

BACKGROUND

mRNA-based cancer vaccines have been considered a promising anticancer therapeutic approach against various cancers, yet their efficacy for malignant mesothelioma (MESO) is still not clear. The present study is designed to identify MESO antigens that have the potential for mRNA vaccine development, and to determine the immune subtypes for the selection of suitable patients.

METHODS

A total of 87 MESO datasets were used for the retrieval of RNA sequencing and clinical data from The Cancer Genome Atlas (TCGA) databases. The possible antigens were identified by a survival and a genome analysis. The samples were divided into two immune subtypes by the application of a consensus clustering algorithm. The functional annotation was also carried out by using the DAVID program. Furthermore, the characterization of each immune subtype related to the immune microenvironment was integrated by an immunogenomic analysis. A protein-protein interaction network was established to categorize the hub genes.

RESULTS

The five tumor antigens were identified in MESO. FAM134B, ALDH3A2, SAV1, and RORC were correlated with superior prognoses and the infiltration of antigen-presenting cells (APCs), while FN1 was associated with poor survival and the infiltration of APCs. Two immune subtypes were identified; TM2 exhibited significantly improved survival and was more likely to benefit from vaccination compared with TM1. TM1 was associated with a relatively quiet microenvironment, high tumor mutation burden, and enriched DNA damage repair pathways. The immune checkpoints and immunogenic cell death modulators were also differentially expressed between two subtypes. Finally, FN1 was identified to be the hub gene.

CONCLUSIONS

FAM134B, ALDH3A2, SAV1, RORC, and FN1 are considered as possible and effective mRNA anti-MESO antigens for the development of an mRNA vaccine, and TM2 patients are the most suitable for vaccination.

Gene Expression Analysis of Biphasic Pleural Mesothelioma: New Potential Diagnostic and Prognostic Markers

Biphasic is the second most common histotype of pleural mesothelioma (PM). It shares epithelioid and sarcomatoid features and is challenging to diagnose. The aim of this study was to identify biphasic PM markers to improve subtyping and prognosis definition. The expression levels of 117 cancer genes, evaluated using the nanoString system, were compared between the three major histotypes (epithelioid, sarcomatoid, and biphasic), and expression differences within biphasic PM were evaluated in relation to the percentage of epithelioid components. Biphasic PM overexpressed CTNNA1 and TIMP3 in comparison to sarcomatoid, and COL16A1 and SDC1 in comparison to epithelioid PM. CFB, MSLN, CLDN15, SERPINE1, and PAK4 were deregulated among all histotypes, leading to the hypothesis of a gradual expression from epithelioid to sarcomatoid PM. According to gene expression, biphasic PM samples were divided in two clusters with a significant difference in the epithelioid component. ADCY4, COL1A1, and COL4A2 were overexpressed in the biphasic group with a low percentage of epithelioid component. Survival analysis using TCGA data showed that high COL1A1 and COL4A2 expression levels correlate with poor survival in PM patients. Herein, we identified markers with the potential to improve diagnosis and prognostic stratification of biphasic PM, which is still an orphan tumor.

The Collagen Receptor uPARAP in Malignant Mesothelioma: A Potential Diagnostic Marker and Therapeutic Target

Malignant mesothelioma (MM) is a highly aggressive cancer with limited therapeutic options. We have previously shown that the endocytic collagen receptor, uPARAP, is upregulated in certain cancers and can be therapeutically targeted. Public RNA expression data display uPARAP overexpression in MM. Thus, to evaluate its potential use in diagnostics and therapy, we quantified uPARAP expression by immunohistochemical H-score in formalin-fixed paraffin-embedded bioptic/surgical human tissue samples and tissue microarrays. We detected pronounced upregulation of uPARAP in the three main MM subtypes compared to non-malignant reactive mesothelial proliferations, with higher expression in sarcomatoid and biphasic than in epithelioid MM. The upregulation appeared to be independent of patients’ asbestos exposure and unaffected after chemotherapy. Using immunoblotting, we demonstrated high expression of uPARAP in MM cell lines and no expression in a non-malignant mesothelial cell line. Moreover, we showed the specific internalization of an anti-uPARAP monoclonal antibody by the MM cell lines using flow cytometry-based assays and confocal microscopy. Finally, we demonstrated the sensitivity of these cells towards sub-nanomolar concentrations of an antibody-drug conjugate formed with the uPARAP-directed antibody and a potent cytotoxin that led to efficient, uPARAP-specific eradication of the MM cells. Further studies on patient cohorts and functional preclinical models will fully reveal whether uPARAP could be exploited in diagnostics and therapeutic targeting of MM.

Antibody-Antineoplastic Conjugates in Gynecological Malignancies: Current Status and Future Perspectives

In the last decade, antibody-drug conjugates (ADCs), normally formed by a humanized antibody and a small drug via a chemical cleavable or non-cleavable linker, have emerged as a potential treatment strategy in cancer disease. They allow to get a selective delivery of the chemotherapeutic agents at the tumor level, and, consequently, to improve the antitumor efficacy and, especially to decrease chemotherapy-related toxicity. Currently, nine antibody-drug conjugate-based formulations have been already approved and more than 80 are under clinical trials for the treatment of several tumors, especially breast cancer, lymphomas, and multiple myeloma. To date, no ADCs have been approved for the treatment of gynecological formulations, but many formulations have been developed and have reached the clinical stage, especially for the treatment of ovarian cancer, an aggressive disease with a low five-year survival rate. This manuscript analyzes the ADCs formulations that are under clinical research in the treatment of gynecological carcinomas, specifically ovarian, endometrial, and cervical tumors.

Immunotherapeutic Approaches in Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare and aggressive malignant disease affecting the mesothelium, commonly associated to asbestos exposure. The current therapeutic actions, based on cisplatin/pemetrexed treatment, are limited due to the late stage at which most patients are diagnosed and to the intrinsic chemo-resistance of the tumor. Another relevant point is the absence of approved therapies in the second line setting following progression of MPM after chemotherapy. Considering the poor prognosis of the disease and the fact that the incidence of this tumor is expected to increase in the next decade, novel therapeutic approaches are urgently needed. In the last few years, several studies have investigated the efficacy and safety of immune-checkpoint inhibitors (ICIs) in the treatment of unresectable advanced MPM, and a number of trials with immunotherapeutic agents are ongoing in both first line and second line settings. In this review, we describe the most promising emerging immunotherapy treatments for MPM (ICIs, engineered T cells to express chimeric antigen receptors (CARs), dendritic cells (DCs) vaccines), focusing on the biological and immunological features of this tumor as well as on the issues surrounding clinical trial design.

Pathological Characterization of Tumor Immune Microenvironment (TIME) in Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare and highly aggressive disease that arises from pleural mesothelial cells, characterized by a median survival of approximately 13-15 months after diagnosis. The primary cause of this disease is asbestos exposure and the main issues associated with it are late diagnosis and lack of effective therapies. Asbestos-induced cellular damage is associated with the generation of an inflammatory microenvironment that influences and supports tumor growth, possibly in association with patients' genetic predisposition and tumor genomic profile. The chronic inflammatory response to asbestos fibers leads to a unique tumor immune microenvironment (TIME) composed of a heterogeneous mixture of stromal, endothelial, and immune cells, and relative composition and interaction among them is suggested to bear prognostic and therapeutic implications. TIME in MPM is known to be constituted by immunosuppressive cells, such as type 2 tumor-associated macrophages and T regulatory lymphocytes, plus the expression of several immunosuppressive factors, such as tumor-associated PD-L1. Several studies in recent years have contributed to achieve a greater understanding of the pathogenetic mechanisms in tumor development and pathobiology of TIME, that opens the way to new therapeutic strategies. The study of TIME is fundamental in identifying appropriate prognostic and predictive tissue biomarkers. In the present review, we summarize the current knowledge about the pathological characterization of TIME in MPM.