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.

Retrospective Evaluation of the Use of Pembrolizumab in Malignant Mesothelioma in a Real-World Australian Population

INTRODUCTION

We investigated the efficacy and toxicity of pembrolizumab in patients with mesothelioma from a real-world Australian population. We aimed to determine clinical factors and predictive biomarkers that could help select patients who are likely to benefit from pembrolizumab.

METHOD

Patients with mesothelioma who were treated with pembrolizumab as part of the Insurance and Care New South Wales compensation scheme were included. Clinical information was collected retrospectively. Tumor biomarkers such as programmed death-ligand 1 (PD-L1), BAP1, and CD3-positive (CD3+) tumor-infiltrating lymphocytes (TILs) were examined using archival formalin-fixed paraffin-embedded tumor samples.

RESULTS

A total of 98 patients were included with a median age of 70 years (range, 46-91 y); 92% were men; 76% had epithelioid subtype; 21% had an Eastern Cooperative Oncology Group (ECOG) performance status of 0. Pembrolizumab was used as second-line or subsequent-line treatment in 94 patients and as first-line treatment in four patients. The overall response rate was 18%, and the disease control rate was 56%. The median progression-free survival (PFS) was 4.8 months (95% confidence interval: 3.6-6.2), and the median overall survival (OS) was 9.5 months (95% confidence interval: 6.6-13.7). Immune-related adverse events occurred in 27% of patients, of which nine (9%) were of grade 3 or higher. In the multivariable analysis, factors independently associated with longer PFS included baseline ECOG status of 0 (median PFS: 12 mo versus 4 mo, p < 0.01) and PD-L1 tumor proportion score of greater than or equal to 1% (median PFS: 6 mo versus 4 mo, p < 0.01). Baseline platelet count of less than or equal to 400 × 109/liter was independently associated with longer PFS and OS (median PFS: 6 mo versus 2 mo, p = 0.05; median OS: 10 mo versus 4 mo, p = 0.01), whereas lack of pretreatment dexamethasone was independently associated with OS but not PFS (median OS: 10 mo versus 3 mo, p = 0.01). The odds of response were higher for patients with baseline ECOG status of 0 (p = 0.02) and with greater than or equal to 5% CD3+ TILs in the tumor (p < 0.01). PD-L1 expression, BAP1 loss, and CD3+ TILs in the stroma were not significantly associated with the overall response rate.

CONCLUSIONS

Immunotherapy is a reasonable treatment option for patients with mesothelioma. Our results are comparable to other clinical trials investigating pembrolizumab in mesothelioma in terms of response. Good performance status assessment remains the most robust predictor for patient outcomes. CD3+ TILs in the tumor may help select patients that are likely to respond to pembrolizumab, whereas factors such as PD-L1 expression, baseline platelet count, and lack of pretreatment dexamethasone may help predict survival outcomes from pembrolizumab treatment.

Extracellular vesicles as biomarkers in malignant pleural mesothelioma: A review

Extracellular vesicles (EV) are secreted by all cells, including cancer cells, as a mode of intercellular transport and communication. The main types of EV known to date include exosomes, microvesicles and apoptotic bodies, as well as oncosomes and large oncosomes, which are specific to cancer cells. These different EV populations carry specific cargo from one cell to another to stimulate a specific response. They can be found in all body fluids and can be detected in liquid biopsies. EV released from mesothelioma cells can reveal important information about the molecules and signalling pathways involved in the development and progression of the tumour. The presence of tumour-derived EV in circulating body fluids makes them potential novel biomarkers for early diagnosis, prognostication and surveillance of cancer. In this review, we explore the characteristics and functional roles of EV reported in the literature, with a focus on their role in malignant pleural mesothelioma.

High BIN1 expression has a favorable prognosis in malignant pleural mesothelioma and is associated with tumor infiltrating lymphocytes

OBJECTIVES

A number of key immune regulators show prognostic value in malignant pleural mesothelioma (MPM), but the association between Bridging integrator 1 (BIN1), indoleamine 2,3 dioxygenase 1 (IDO1) and patient outcome has not been investigated. We aimed to determine the expression of BIN1 and IDO1, their association with other markers and impact on overall survival (OS) in MPM.

MATERIALS AND METHODS

The expression of BIN1, IDO1, CD3, CD20 and CD68 were evaluated by immunohistochemistry in 67 patients who underwent pleurectomy/decortication. Survival analyses were performed using the Kaplan Meier method and significant biomarkers were entered into a Cox Regression multivariate model, accounting for known prognostic factors such as age, gender, histological subtype, PD-L1 expression and neutrophil-to-lymphocyte ratio.

RESULTS

Immune markers were variably expressed in tumor cells, ranging from 0% to 100% for BIN1 (median: 89%), and 0% to 77.5% for IDO1 (median: 0%). Expression of markers of tumor-infiltrating lymphocytes (TILs) and macrophages ranged from 0% to more than 50%. BIN1 expression was high in 35 patients (51%) and was associated with increased OS (median: 12 vs 6 months for high and low BIN1 respectively,p = 0.03). Multivariate analysis showed BIN1 remained an independent prognostic indicator (HR 0.39; 95% CI: 0.18-0.82, p = 0.01). The majority of patients had immune inflamed tumors (77%) and there was a significant association between TILs and BIN1 (p = 0 < 0.01), PD-L1 (p=0.04) and CD68+ macrophages in the tumor (p < 0.01). There were no significant associations between PD-L1 and BIN1 or IDO1.

CONCLUSION

High BIN1 expression is a favorable prognostic biomarker and is associated with TILs in MPM.

An Update on Predictive Biomarkers for Treatment Selection in Non-Small Cell Lung Cancer

It is now widely established that management of lung cancer is much more complex and cannot be centered on the binary classification of small-cell versus non-small cell lung cancer (NSCLC). Lung cancer is now recognized as a highly heterogeneous disease that develops from genetic mutations and gene expression patterns, which initiate uncontrolled cellular growth, proliferation and progression, as well as immune evasion. Accurate biomarker assessment to determine the mutational status of driver mutations such as EGFR, ALK and ROS1, which can be targeted by specific tyrosine kinase inhibitors, is now essential for treatment decision making in advanced stage NSCLC and has shifted the treatment paradigm of NSCLC to more individualized therapy. Rapid advancements in immunotherapeutic approaches to NSCLC treatment have been paralleled by development of a range of potential predictive biomarkers that can enrich for patient response, including PD-L1 expression and tumor mutational burden. Here, we review the key biomarkers that help predict response to treatment options in NSCLC patients.

Fundamentals of siRNA and miRNA therapeutics and a review of targeted nanoparticle delivery systems in breast cancer

Gene silencing via RNA interference (RNAi) is rapidly evolving as a personalized approach to cancer treatment. The effector molecules-small interfering RNAs (siRNAs) and microRNAs (miRNAs)-can be used to silence or "switch off" specific cancer genes. Currently, the main barrier to implementing siRNA- and miRNA-based therapies in clinical practice is the lack of an effective delivery system that can protect the RNA molecules from nuclease degradation, deliver to them to tumor tissue, and release them into the cytoplasm of the target cancer cells, all without inducing adverse effects. Here, we review the fundamentals of RNAi, cell membrane transport pathways, and factors that affect intracellular delivery. We discuss the advantages and disadvantages of the various types of nanoparticle delivery systems, with a focus on those that have been investigated in breast cancer in vivo.