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BackgroundMesothelioma is increasingly recognised as a global health issue and the assessment of its global burden is warranted.ObjectivesTo descriptively analyse national mortality data and to use reported and estimated data to calculate the global burden of mesothelioma deaths.MethodsFor the study period of 1994 to 2014, we grouped 230 countries into 59 countries with quality mesothelioma mortality data suitable to be used for reference rates, 45 countries with poor quality data and 126 countries with no data, based on the availability of data in the WHO Mortality Database. To estimate global deaths, we extrapolated the gender-specific and age-specific mortality rates of the countries with quality data to all other countries.ResultsThe global numbers and rates of mesothelioma deaths have increased over time. The 59 countries with quality data recorded 15 011 mesothelioma deaths per year over the 3 most recent years with available data (equivalent to 9.9 deaths per million per year). From these reference data, we extrapolated the global mesothelioma deaths to be 38 400 per year, based on extrapolations for asbestos use.ConclusionsAlthough the validity of our extrapolation method depends on the adequate identification of quality mesothelioma data and appropriate adjustment for other variables, our estimates can be updated, refined and verified because they are based on commonly accessible data and are derived using a straightforward algorithm. Our estimates are within the range of previously reported values but higher than the most recently reported values.

Non-small cell lung cancer (NSCLC) is the leading cause of lung cancer deaths, with resistance to targeted therapies posing a major clinical challenge. Drug-tolerant persister (DTP) cells are key contributors to resistance, and targeting them offers new strategies to enhance existing treatments. MicroRNAs (miRNAs), particularly the tumour-suppressive miR-15/107 family, offer promise due to their ability to target multiple oncogenic pathways. This study evaluated a synthetic consensus miRNA mimic, conmiR-15/107, in NSCLC cell line models. Dose–response assays showed robust, dose-dependent growth inhibition in both EGFR-mutant (PC9) and KRAS-mutant (H358 and A549) lung adenocarcinoma cells, but not in the human bronchial epithelial cell line BEAS-2B. When combined with EGFR inhibitors (osimertinib and gefitinib) in PC9 cells, the mimics showed a higher rate of growth inhibition compared with the controls and reduced IC50 values. Similarly, conmiR-15/107 enhanced growth inhibition by the KRAS inhibitors sotorasib and adagrasib in H358 cells. RT-qPCR confirmed downregulation of conmiR-15/107 targets, including MEK1, BCL2 and BRCA1, suggesting a multi-target mechanism of action. Long-term assays showed that the mimics reduced the survival and delayed the proliferation of DTPs in osimertinib-treated PC9 cells as well as sotorasib-treated H358 cells. These findings support conmiR-15/107 as a potential adjunct to targeted therapy, capable of enhancing treatment efficacy and delaying resistance in lung adenocarcinoma.

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.

Background: Recent studies in non-small cell lung cancer (NSCLC) patients have demonstrated that first-line immunotherapy is associated with better therapeutic response than second-line treatment. So far, the mechanisms need to be explored. It prompted us to evaluate the association between first-line chemotherapy and subsequent immunotherapy in NSCLC as well as its underlying mechanisms at the genomic and transcriptomic level. Methods: We launched a prospective, observational clinical study, paired tumor biopsies before and after chemotherapy were collected from NSCLC patients without tyrosine kinase inhibitor (TKI)-related driver gene mutations. The analyses included genomic and transcriptional changes performed by next-generation sequencing (NGS)-based whole-exome sequencing (WES) and messager ribonucleic acid (mRNA) sequencing. Characteristic mutational alterations in 1574 genes were investigated based on mutational status, clinicopathological factors, and chemotherapy responses. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, neoantigen prediction and intratumoral heterogeneity evaluation were also performed. Results: Samples and information from 32 NSCLC patients without TKI-related driver gene mutations were obtained. We found that the total number of single nucleotide variants (SNV)/insertion-deletion (INDEL) mutations did not change significantly after chemotherapy. The tumor mutation burden (TMB) decreased significantly after chemotherapy in smoking patients and the decreased TMB correlated with a better survival of smoking patients. The change in copy number variations (CNVs) exhibited a decreasing trend during chemotherapy. Subsequent analysis at mRNA level revealed a significant decrease in the expression levels of genes related to antigen processing and presentation as well as other factors relevant for response to immunotherapy. Pathway enrichment analysis confirmed that the immune-related signaling pathways or biological processes were decreased after first-line chemotherapy. Conclusions: Our study presents an explanation for the unsatisfactory results of immunotherapy when given after chemotherapy, and suggests that first-line chemotherapy is able to influence the tumor microenvironment and decrease the efficacy of subsequent immunotherapy. The study was registered at ClinicalTrials.gov, number NCT03764917, and has completed enrolment; patients are still in follow-up.

TargomiRs are minicells (EnGeneIC Dream Vectors) loaded with miR-16-based mimic microRNA (miRNA) and targeted to EGFR that are designed to counteract the loss of the miR-15 and miR-16 family miRNAs, which is associated with unsuppressed tumour growth in preclinical models of malignant pleural mesothelioma. We aimed to assess the safety, optimal dosing, and activity of TargomiRs in patients with malignant pleural mesothelioma. In this first-in-man, open-label, dose-escalation phase 1 trial at three major cancer centres in Sydney (NSW, Australia), we recruited adults (aged ≥18 years) with a confirmed diagnosis of malignant pleural mesothelioma, measurable disease, radiological signs of progression after previous chemotherapy, Eastern Cooperative Oncology Group performance status of 0 or 1, life expectancy of 3 months or more, immunohistochemical evidence of tumour EGFR expression, and adequate bone marrow, liver, and renal function. Patients were given TargomiRs via 20 min intravenous infusion either once or twice a week (3 days apart) in a traditional 3 + 3 dose-escalation design in five dose cohorts. The dose-escalation steps planned were 5 × 109, 7 × 109, and 9 × 109 TargomiRs either once or twice weekly, but after analysis of data from the first eight patients, all subsequent patients started protocol treatment at 1 × 109 TargomiRs. The primary endpoints were to establish the maximum tolerated dose of TargomiRs as measured by dose-limiting toxicity, define the optimal frequency of administration, and objective response (defined as the percentage of assessable patients with a complete or partial response), duration of response (defined as time from the first evidence of response to disease progression in patients who achieved a response), time to response (ie, time from start of treatment to the first evidence of response) and overall survival (defined as time from treatment allocation to death from any cause). Analyses were based on the full analysis set principle, including every patient who received at least one dose of TargomiRs. The study was closed for patient entry on Jan 3, 2017, and registered with ClinicalTrials.gov, number NCT02369198, and the Australian Registry of Clinical Trials, number ACTRN12614001248651. Between Sept 29, 2014, and Nov 24, 2016, we enrolled 27 patients, 26 of whom received at least one TargomiR dose (one patient died before beginning treatment). Overall, five dose-limiting toxicities were noted: infusion-related inflammatory symptoms and coronary ischaemia, respectively, in two patients given 5 × 109 TargomiRs twice weekly; anaphylaxis and cardiomyopathy, respectively, in two patients given 5 × 109 TargomiRs once weekly but who received reduced dexamethasone prophylaxis; and non-cardiac pain in one patient who received 5 × 109 TargomiRs once weekly. We established that 5 × 109 TargomiRs once weekly was the maximum tolerated dose. TargomiR infusions were accompanied by transient lymphopenia (25 [96%] of 26 patients), temporal hypophosphataemia (17 [65%] of 26 patients), increased aspartate aminotransferase or alanine aminotranferase (six [23%] of 26 patients), and increased alkaline phosphatase blood concentrations (two [8%]). Cardiac events occurred in five patients: three patients had electrocardiographic changes, one patient had ischaemia, and one patient had Takotsubo cardiomyopathy. Of the 22 patients who were assessed for response by CT, one (5%) had a partial response, 15 (68%) had stable disease, and six (27%) had progressive disease. The proportion of patients who achieved an objective response was therefore one (5%) of 22, and the duration of the objective response in that patient was 32 weeks. Median overall survival was 200 days (95% CI 94–358). During the trial, 21 deaths occurred, of which 20 were related to tumour progression and one was due to bowel perforation. The acceptable safety profile and early signs of activity of TargomiRs in patients with malignant pleural mesothelioma support additional studies of TargomiRs in combination with chemotherapy or immune checkpoint inhibitors. Asbestos Diseases Research Foundation.

miRNAs are responsible for post-transcriptional control of gene expression, and are frequently downregulated in cancer. It has become well established that restoring miRNA levels can inhibit tumor growth, and many studies have demonstrated this in preclinical models. This in turn has led to the first clinical trials of miRNA replacement therapy. This special report focuses on the development of TargomiRs - miRNA mimics delivered by targeted bacterial minicells - and the very first clinical experience of a miRNA replacement therapy in thoracic cancer patients in the Phase I MesomiR-1 trial.

The presence of cell-free microRNAs (miRNAs) has been detected in a range of body fluids. The miRNA content of plasma/serum in particular has been proposed as a potential source of novel biomarkers for a number of diseases. Nevertheless, the quantification of miRNAs from plasma or serum is made difficult due to inefficient isolation and lack of consensus regarding the optimal reference miRNA. The effect of haemolysis on the quantification and normalisation of miRNAs in plasma has not been investigated in great detail. We found that levels of miR-16, a commonly used reference gene, showed little variation when measured in plasma samples from healthy volunteers or patients with malignant mesothelioma or coronary artery disease. Including samples with evidence of haemolysis led to variation in miR-16 levels and consequently decreased its ability to serve as a reference. The levels of miR-16 and miR-451, both present in significant levels in red blood cells, were proportional to the degree of haemolysis. Measurements of the level of these miRNAs in whole blood, plasma, red blood cells and peripheral blood mononuclear cells revealed that the miRNA content of red blood cells represents the major source of variation in miR-16 and miR-451 levels measured in plasma. Adding lysed red blood cells to non-haemolysed plasma allowed a cut-off level of free haemoglobin to be determined, below which miR-16 and miR-451 levels displayed little variation between individuals. In conclusion, increases in plasma miR-16 and miR-451 are caused by haemolysis. In the absence of haemolysis the levels of both miR-16 and miR-451 are sufficiently constant to serve as normalisers.

Malignant mesothelioma (MM) is a treatment-resistant tumor originating in the mesothelial lining of the pleura or the abdominal cavity with very limited treatment options. More effective therapeutic approaches are urgently needed to improve the poor prognosis of MM patients. Chimeric Antigen Receptor (CAR) T cell therapy has emerged as a novel potential treatment for this incurable solid tumor. The tumor-associated antigen mesothelin (MSLN) is an attractive target for cell therapy in MM, as this antigen is expressed at high levels in the diseased pleura or peritoneum in the majority of MM patients and not (or very modestly) present in healthy tissues. Clinical trials using anti-MSLN CAR T cells in MM have shown that this potential therapeutic is relatively safe. However, efficacy remains modest, likely due to the MM tumor microenvironment (TME), which creates strong immunosuppressive conditions and thus reduces anti-MSLN CAR T cell tumor infiltration, efficacy and persistence. Various approaches to overcome these challenges are reviewed here. They include local (intratumoral) delivery of anti-MSLN CAR T cells, improved CAR design and co-stimulation, and measures to avoid T cell exhaustion. Combination therapies with checkpoint inhibitors as well as oncolytic viruses are also discussed. Preclinical studies have confirmed that increased efficacy of anti-MSLN CAR T cells is within reach and offer hope that this form of cellular immunotherapy may soon improve the prognosis of MM patients.

Malignant pleural mesothelioma (MPM) is an almost invariably fatal, asbestos-related malignancy arising from the mesothelial membrane lining the thoracic cavities. Despite some improvements in treatment, therapy is not considered curative and median survival following diagnosis is less than 1 year. Although still classed as a rare cancer, the incidence of MPM is increasing, and the limited progress in treating the disease makes the identification of new therapies a priority. As there is evidence for expression of the integrins αvβ3 and αvβ5 in MPM, there is a rationale for investigating the effects on MPM of cilengitide, a synthetic peptide inhibitor of integrin αv heterodimer with high specificity for αvβ3 and αvβ5. In mesothelial cells (MC) and 7 MPM cell lines, growth inhibition by cilengitide was associated with the expression level of its target integrins. Furthermore, cilengitide caused cell detachment and subsequent death of anoikis-sensitive cells. It also suppressed invasion of MPM cells in monolayer and three-dimensional cultures. Gene knockdown experiments indicated that these effects of cilengitide were, at least partly, due to antagonism of αvβ3 and αvβ5.