Advances in treatment of mesothelioma

Deciphering signaling pathway interplay via miRNAs in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a highly invasive form of lung cancer that adversely affects the pleural and other linings of the lungs. MPM is a very aggressive tumor that often has an advanced stage at diagnosis and a bad prognosis (between 7 and 12 months). When people who have been exposed to asbestos experience pleural effusion and pain that is not explained, MPM should be suspected. After being diagnosed, most MPM patients have a one- to four-year life expectancy. The life expectancy is approximately six months without treatment. Despite the plethora of current molecular investigations, a definitive universal molecular signature has yet to be discovered as the causative factor for the pathogenesis of MPM. MicroRNAs (miRNAs) are known to play a crucial role in the regulation of gene expression at the posttranscriptional level. The association between the expression of these short, non-coding RNAs and several neoplasms, including MPM, has been observed. Although the incidence of MPM is very low, there has been a significant increase in research focused on miRNAs in the past few years. In addition, miRNAs have been found to have a role in various regulatory signaling pathways associated with MPM, such as the Notch signaling network, Wnt/β-catenin, mutation of KRAS, JAK/STAT signaling circuit, protein kinase B (AKT), and Hedgehog signaling pathway. This study provides a comprehensive overview of the existing understanding of the roles of miRNAs in the underlying mechanisms of pathogenic symptoms in MPM, highlighting their potential as viable targets for therapeutic interventions.

Fluorescence in situ hybridization detection of chromosome 22 monosomy in pleural effusion cytology for the diagnosis of mesothelioma

BACKGROUND

Malignant pleural mesothelioma (MPM) is characterized by mutations in several genes, including cyclin-dependent kinase-inhibitor 2A/p16 in the 9p21 locus, BRCA1-associated protein 1 (BAP1), and neurofibromatosis type 2 (NF2) in the 22q12 locus. Recent studies indicate that fluorescence in situ hybridization (FISH) detects hemizygous loss of NF2 in tissue specimens of MPM. The authors investigated whether NF2 FISH, either alone or in combination with other diagnostic assays (9p21 FISH, methylthioadenosine phosphorylase [MTAP] immunohistochemistry [IHC], and BAP1 IHC), effectively distinguishes MPM cells from reactive mesothelial cells (RMCs) in cell blocks prepared from pleural effusions.

METHODS

FISH assays were used to examine the deletion status of NF2 and 9p21, and IHC was used to determine the expression of MTAP and BAP1 in cell blocks from 54 cases with MPM and 18 cases with RMCs.

RESULTS

Hemizygous NF2 loss (chromosome 22 monosomy or hemizygous deletion) showed 51.9% sensitivity (48.1% for chromosome 22 monosomy and 3.7% for hemizygous deletion) and 100% specificity in differentiating MPM cells from RMCs. Combinations of NF2 FISH, 9p21 FISH, and BAP1 IHC assays yielded greater sensitivity (98.1%) than any assay alone (9p21 FISH, 61.1%; MTAP IHC, 52.8%; or BAP1 IHC, 60.4%). The level of hemizygous NF2 loss in cell blocks positively correlated with that in corresponding tissues. Furthermore, to overcome cytologic specimen-specific challenges, FISH combined with cytokeratin AE1/AE3 immunofluorescence was necessary in 25.9% of MPM cases for FISH assessment of predominantly scattered MPM cells.

CONCLUSIONS

NF2 FISH alone or in combination with other diagnostic assays effectively differentiates MPM cells from RMCs in cell blocks prepared from pleural effusions.

Genomic-based ancillary assays offer improved diagnostic yield of effusion cytology with potential challenges in malignant pleural mesothelioma

BRCA1-associated protein 1 (BAP1) or methylthioadenosine phosphorylase (MTAP) immunohistochemistry (IHC) or 9p21 fluorescence in situ hybridization (FISH) are useful for the diagnosis of malignant pleural mesothelioma (MPM). However, the effect of these assays on the diagnostic yield of effusion cytology in MPM cases with suspicious cytomorphology or the diagnostic challenges in BAP1 or MTAP IHC have not been fully elucidated. Two cohorts of cytologic preparations obtained from pleural effusions were examined: MPM cases in cohort 1 were used to evaluate whether BAP1 or MTAP IHC or 9p21 FISH increase the diagnostic yield of effusion cytology; cohort 2 included cases suspicious for MPM, to which BAP1 or MTAP IHC was applied to clarify the challenges in the clinical assessment of these assays. In cohort 1 (n = 28), either assay elevated 62.5% of class II or III cases to class V. In cohort 2 (n = 139), 21.7% of BAP1 immunocytochemistry in smears and 10.6% of BAP1 IHC and 9.4% of MTAP IHC in cell blocks, were identified to be challenging. The application of genomic-based assays increased the diagnostic yield of effusion cytology in the diagnosis of MPM. However, diagnostic challenges limit the application of these assays in some cases.

Patient experiences of participation in a radical thoracic surgical trial: findings from the Mesothelioma and Radical Surgery Trial 2 (MARS 2)

BACKGROUND

The Mesothelioma and Radical Surgery Trial (MARS 2) aims to evaluate a surgical procedure by comparing chemotherapy and surgery against chemotherapy alone. The pilot study for MARS 2 evaluated the viability of recruitment. Challenges have been reported in conducting clinical research into thoracic surgical treatments and evidence is required to improve our understanding of patient experiences of trial procedures, trial treatments and the factors that influence participation.

METHODS

This longitudinal qualitative study was nested within the MARS 2 pilot. Semi-structured telephone interviews were conducted with 15 participants in the MARS 2 trial. Interviews were conducted post-randomisation, post-surgery (surgery arm) and at 6 and 12 months. Altogether, 41 interviews were carried out. The data were analysed using framework techniques.

RESULTS

Challenges were identified regarding the volume and complexity of information given to participants, and their understanding of clinical equipoise and randomisation. Factors influencing participation included having an opportunity to undergo surgery, a self-assessment of their ability to cope with trial treatments, maintaining a positive approach and altruism. Obstacles included the logistics of traveling for treatment in an unfamiliar setting. Negative consequences of trial participation included increased uncertainty amplified by multiple care providers and unclear transition arrangements after the trial.

CONCLUSIONS

Participants' descriptions provided insights that have implications for care for mesothelioma trial patients. The need for healthcare staff to be alert to the potential for misunderstanding, particularly when presenting treatment options, was identified. Patients perceived and derived benefits from taking part in the trial but experienced some negative consequences. These should be anticipated and managed proactively.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02040272 . Registered on 20 January 2014.

Mortality among workers exposed to asbestos at the shipyard of Genoa, Italy: a 55 years follow-up

BACKGROUND

Exposure to asbestos remains a global issue due to its massive use in the twentieth century and its long environmental persistence. Exposure to asbestos still occurs during dismantling of ships and vessels, buildings renovation, mining operations, and is reported in developing countries. Current estimate report exposure of hundreds of million people in occupational settings in countries where its use remains unregulated.

METHODS

We conducted a historical prospective cohort mortality study aimed at estimating mortality from specific causes, the temporal changes of pleural and lung cancer mortality, and the attributable fraction (AF) of lung cancer deaths following asbestos exposure. The study included 3984 shipyard workers employed at the shipyard of Genoa, Italy, between 1960 and 1981 and followed up to December 2014. Standardized Mortality Ratios (SMR) and their 95% confidence intervals (95%CI) were computed.

RESULTS

Overall deaths recorded were 3331 (83.6%). Excess mortality was observed for all cancers (SMR = 127, 95%CI:120-134), pleural mesothelioma (575, 469-697), cancers of the larynx (183, 134-244) and of the lung (154, 139-170), and for respiratory tract diseases (127, 114-141), including asbestosis (2277, 1525-3270). Ninety out of 399 deaths (22.6%) from lung cancer were attributed to asbestos exposure. The estimated lung cancer AF was 49.3% in workers with the highest SMR for pleural cancer. Median latency times for pleural and lung cancer were 42.8 years (minimum latency: 9.3 years) and 38.7 years (minimum latency: 6 years). The peak of mesothelioma incidence, expected in Italy in the period 2015-2024, was confirmed.

CONCLUSIONS

The long follow-up period of our study allowed the detection of a substantial disease burden following asbestos exposure. These findings support the urgent need for the prevention of asbestos related diseases through the implementation of asbestos ban worldwide, including those countries where asbestos is still mined, manufactured and used.

Downregulation of miR-99a/let-7c/miR-125b miRNA cluster predicts clinical outcome in patients with unresected malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive tumor with a dismal overall survival (OS) and to date no molecular markers are available to guide patient management. This study aimed to identify a prognostic miRNA signature in MPM patients who did not undergo tumor resection. Whole miRNA profiling using a microarray platform was performed using biopsies on 27 unresected MPM patients with distinct clinical outcome: 15 patients had short survival (OS<12 months) and 12 patients had long survival (OS>36 months). Three prognostic miRNAs (mir-99a, let-7c, and miR-125b) encoded at the same cluster (21q21) were selected for further validation and tested on publicly available miRNA sequencing data from 72 MPM patients with survival data. A risk model was built based on these 3 miRNAs that was validated by quantitative PCR in an independent set of 30 MPM patients. High-risk patients had shorter median OS (7.6 months) as compared with low-risk patients (median not reached). In the multivariate Cox model, a high-risk score was independently associated with shorter OS (HR=3.14; 95% CI, 1.18–8.34; P=0.022). Our study identified that the downregulation of the miR-99a/let-7/miR-125b miRNA cluster predicts poor outcome in unresected MPM.

Chemosensitivity and resistance testing in malignant effusions with focus on primary malignant mesothelioma and metastatic adenocarcinoma

Cell based chemosensitivity and resistance testing is an attractive approach that offers functional measurement of drug response ex vivo with the ultimate goal to guide the choice of chemotherapy for various cancers. Thus, it has a great potential to select patients for the optimal treatment option, thereby offering a tool for personalized cancer therapy. Despite several decades of intensive scientific efforts ex-vivo tests are still not incorporated in the standard of care. Limited access to fresh tumor tissue, unsatisfactory models and single readout as endpoint constitute major hindrance. Thus, establishing and validating clinically useful and reliable model systems still remains a major challenge. Here we present malignant effusions as valuable sources for ex-vivo chemosensitivity and resistance testing. Accumulation of a malignant effusion in the pleura, peritoneum or pericardium is often the first diagnostic material for both primary malignant mesothelioma and a broad spectrum of metastatic adenocarcinoma originating from lung-, breast-, ovary- and gastro-intestinal organs as well as lymphoma. In contrast to biopsies, in these effusions malignant cells are easily accessible and often abundant. Effusion derived cells can occur dissociated or forming three-dimensional papillary structures that authentically recapitulate the biology of the corresponding tumor tissue and offer models for ex vivo testing. In addition, effusions have the advantage of being available prior to or concurrent with the pathological review, thus constituting an excellent source of viable cells for simultaneous molecular profiling, biomarker analysis and for establishing primary cells for studying tumor biology and resistance mechanisms. For a reliable test, however, a careful validation is needed, taking into account the inherited heterogeneity of malignant tumors, but also the complex interplay between malignant and benign cells, which are always present in this setting.