Development of Novel Biomarkers for Diagnosis of Malignant Pleural Effusion

About This Grant

Abstract /Summary: Malignant pleural effusion (MPE) affects 200,000 individuals in the United States annually and lung cancer is the most common cancer to metastasize to the pleura. Unfortunately, cytologic examination of the pleural fluid (PF) obtained during thoracentesis only has a diagnostic sensitivity of ~50% with marginal increase upon serial sampling and limited by the need to detect malignant cells which are sparse in the PF. More invasive procedures such as thoracoscopic pleural biopsy are often required, but these procedures are associated with potential complications, hospital stay and delayed diagnosis and treatment. There is an urgent need to develop novel approaches to complement PF cytology. To address this need, we examined the potential of tumor cell products, specifically extracellular vesicles (EVs) and non-vesicular particles, for MPE diagnosis. In previous studies, we have detected and characterized EVs in PF and have identified and validated distinct EV microRNA (miRNA) signatures discriminating cytology-positive (C+) lung adenocarcinoma induced MPE (LA-MPE) from non-malignant pleural effusion (non-MPE). Additionally, because epithelial-derived surface markers are not native in the pleural space, we analyzed the expression of epithelial cell adhesion molecule (EpCAM), in cell- free PF of LA-MPE to identify tumor-derived EVs. We showed significantly higher EpCAM expression in (C+) LA-MPE compared to non-MPE. An essential next step is the evaluation of extracellular miRNA and proteins within the cytology-negative (C-) MPE populations, where current tests fail or are highly invasive. To Accomplish this goal, we will leverage samples from a diverse PF biorepository (current n=313) including (C+) and (C-) MPE and non-MPE with 35% African/Black participants and detailed tumor-specific and clinical data. Specific Aims will: 1) identify differentially expressed extracellular miRNA among patients with (C-) LA-MPE and non-MPE and validate the identified miRNA signature in an independent validation cohort, 2) identify differentially expressed extracellular proteins (particularly epithelial-derived proteins) among patients with (C-) LA-MPE and non-MPE. In addition, we will identify protein expression in (C+) and (C-) MPE due to breast cancer and compare protein expression among groups. We will evaluate the combined discriminating role of protein and miRNA expression among (C-) LA-MPE and non-MPE. Development of a diagnostic classifier, using a cell-free biofluid enriched with tumor-cell products that requires drainage and is underutilized is paradigm shifting and a crucial missing step in our MPE management which will be addressed through our proposal. Most biomarkers to date are examined in (C+) MPEs of heterogeneous populations and lack reproducibility or confirmation in (C-) MPE groups. We aim to close this gap and focus on (C-) LA-MPE populations where our findings could be clinically relevant and practice changing. This work will lead to an R01- level grant focusing on PF tumor-derived EVs and EV cargo in diagnosis, disease monitoring and prognosis of metastatic cancers of varying tissue type to the pleura.