Malignant pleural mesothelioma: an update on investigation, diagnosis and treatment

An Overview of Asbestos and Malignant Pleural Mesothelioma: An Iranian Perspective

Asbestos refers to a group of minerals that appears naturally in the environment as bundles of fibers. The incidence rate of asbestos-related diseases has considerably increased as well as the amount of asbestos utilization in few countries. Malignant pleural mesothelioma (MPM) is a rare type of aggressive and life threatening neoplasm which arise from various serous surfaces: pleura, peritoneum, tunica vaginalis and pericardium. The first case of MPM was reported in 1947. MPM etiologically is associated to the exposure of asbestos fibers. This form of malignancy is difficult to diagnose in paraclinical work-ups because mesothelioma could occur within 10-20 years of the first-time exposure to asbestos. The burden of MPM is not yet to be wholly understood. The toxic side effects of asbestos on environment and people compelled the European countries to accept the French view upon this matter. However, this approach has not been accepted by some developing countries. This review provides a brief points and facts in relation to MPM and asbestos in Iran.

CAR T-cell therapy for lung cancer and malignant pleural mesothelioma

Immunotherapy is a promising field that harnesses the power of the immune system as a therapeutic agent for cancer treatment. Beneficial outcomes shown in patients with non-small cell lung cancer (NSCLC) and malignant pleural mesothelioma (MPM) with relatively higher tumor-infiltrating T cells, combined with impressive responses obtained in a cohort of patients with NSCLC following checkpoint blockade therapy, lays a strong foundation to promote effector immune responses in these patients. One such approach being investigated is administration of tumor antigen-targeted T cells with transduction of a chimeric antigen receptor (CAR). CARs are synthetic receptors that enhance T-cell antitumor effector function and have gained momentum to investigate in solid tumors based on recent successes of clinical trials treating patients with B-cell hematologic malignancies. This review summarizes target antigens for CAR T-cell therapy that are being investigated in preclinical studies and clinical trials for both NSCLC and MPM patients. We discuss the rationale for combination immunotherapies for NSCLC and MPM patients. Additionally, we have highlighted the challenges and strategies for overcoming the obstacles facing translation of CAR T-cell therapy to solid tumors.

Oncolytic Viral Therapy for Mesothelioma

The limited effectiveness of conventional therapy for malignant pleural mesothelioma demands innovative approaches to this difficult disease. Even with aggressive multimodality treatment of surgery, radiation, and/or chemotherapy, the median survival is only 1–2 years depending on stage and histology. Oncolytic viral therapy has emerged in the last several decades as a rapidly advancing field of immunotherapy studied in a wide spectrum of malignancies. Mesothelioma makes an ideal candidate for studying oncolysis given the frequently localized pattern of growth and pleural location providing access to direct intratumoral injection of virus. Therefore, despite being a relatively uncommon disease, the multitude of viral studies for mesothelioma can provide insight for applying such therapy to other malignancies. This article will begin with a review of the general principles of oncolytic therapy focusing on antitumor efficacy, tumor selectivity, and immune system activation. The second half of this review will detail results of preclinical models and human studies for oncolytic virotherapy in mesothelioma.

Targeting microRNA to improve diagnostic and therapeutic approaches for malignant mesothelioma

Malignant mesothelioma is an aggressive and often fatal cancer associated with asbestos exposure. The disease originates in the mesothelial lining of the serosal cavities, most commonly affecting the pleura. Survival rates are low as diagnosis often occurs at an advanced stage and current treatments are limited. Identifying new diagnostic and therapeutic targets for mesothelioma remains a priority, particularly for the new wave of victims exposed to asbestos through do-it-yourself renovations and in countries where asbestos is still mined and used. Recent advances have demonstrated a biological role for the small but powerful gene regulators microRNA (miRNA) in mesothelioma. A number of potential therapeutic targets have been identified. MiRNA have also become popular as potential biomarkers for mesothelioma due to their stable expression in bodily fluid and tissues. In this review, we highlight the current challenges associated with the diagnosis and treatment of mesothelioma and discuss how targeting miRNA may improve diagnostic, prognostic and therapeutic approaches.

Promising investigational drug candidates in phase I and phase II clinical trials for mesothelioma

INTRODUCTION

Malignant mesothelioma is a rare and lethal malignancy primarily affecting the pleura and peritoneum. Mesothelioma incidence is expected to increase worldwide and current treatments remain ineffective, leading to poor prognosis. Within this article potential targets to improve the quality of life of the patients and assessment of further avenues for research are discussed. Areas covered: This review highlights emerging therapies currently under investigation for malignant mesothelioma with a specific focus on phase I and phase II clinical trials. Three main areas are discussed: immunotherapy (immune checkpoint blockade and cancer vaccines, among others), multitargeted therapy (such as targeting pro-angiogenic genes) and gene therapy (such as suicide gene therapy). For each, clinical trials are described to detail the current or past investigations at phase I and II. Expert opinion: The approach of applying existing treatments from other cancers does not show significant benefit, with the most promising outcome being an increase in survival of 2.7 months following combination of chemotherapy with bevacizumab. It is our opinion that the hypoxic microenvironment, the role of the stroma, and the metabolic status of mesothelioma should all be assessed and characterised to aid in the development of new treatments to improve patient outcomes.

Pleural diseases

PURPOSE OF REVIEW

Due to the increasing burden of pleural diseases worldwide, a personalized cost-effective management of these conditions is essential to optimize the healthcare sources. The current review is focused on latest evidence in diagnostic work-up and management of pleural diseases.

RECENT FINDINGS

Recent research highlights the increasing role of thoracic ultrasound in both diagnostic and therapeutic interventions and the potential suitability of cytological sampling from pleural effusions for molecular analysis, essential requirement for a satisfactory test in the era of personalized anticancer therapy. The thoracoscopic approach, by means of rigid or semirigid instruments, remains the gold standard, and attractive tools to increase diagnostic yield in semirigid pleuroscopy include insulated-tip diathermic knife and cryprobe. Talc pleurodesis and indwelling pleural catheters are the most effective interventions, and their combination, likely to result in additional benefits, is currently under investigation.

SUMMARY

Because of the huge variety of possible clinical settings, a proper management of pleural diseases should be tailored on a case-by-case basis and requires a multidisciplinary approach. Recent advances in technologies has conferred to interventional pulmonology an increasing relevant role in this context, leading to the development of a dedicated subspecialty, and training programs are urgently needed to standardize skills and care pathways.