Malignant Pleural Mesothelioma: Current Understanding of the Immune Microenvironment and Treatments of a Rare Disease

SIMPLE SUMMARY: Malignant pleural mesothelioma is a rare disease with an annual incidence of around 3000 cases a year in the United States. Most cases are caused by asbestos exposure, with a latency period of up to 40 years but overall survival of approximately only 6–12 months after the time of diagnosis. Often, the treatment is multimodal and consists of surgery, chemotherapy, and radiation. While the survival benefit of treatment is impactful, overall prolongation remains marginal. Nevertheless, the advent of new treatment approaches involving the interactions of targeted immune therapies and the tumor microenvironment appear to offer some promise. Furthering our understanding of these complex interactions in conjunction with the host immune system will likely prove to be pivotal in advancing current treatment options for malignant pleural mesothelioma. ABSTRACT: Malignant pleural mesothelioma is a rare disease with an annual incidence of around 3000 cases a year in the United States. Most cases are caused by asbestos exposure, with a latency period of up to 40 years. Pleural mesothelioma is an aggressive disease process with overall survival of roughly 6–12 months after the time of diagnosis. It is divided into three subtypes: epithelioid, mixed type, and sarcomatoid type, with the epithelioid subtype having the best overall survival. Often, the treatment is multimodality with surgery, chemotherapy, and radiation. The survival benefit is improved but remains marginal. New treatment options involving targeted immune therapies appear to offer some promise. The tumor microenvironment is the ecosystem within the tumor that interacts and influences the host immune system. Understanding this complex interaction and how the host immune system is involved in the progression of the disease process is important to define and guide potential treatment options for this devastating and rare disease.