Lung cancer has one of the lowest survival outcomes of any cancer, and is the most common cause of cancer-related mortality worldwide. Early stage Non-Small Cell Lung Cancer (NSCLC) patients have an approximate 40% five year survival rate, largely depending on the development of metastasis. Currently, there is a significant unmet clinical need to identify early stage NSCLC patients at risk of developing metastasis, allowing more aggressive interventions. Previous work from our group and others has demonstrated that hypoxia in the primary tumor is a driver of metastatic dissemination through the secretion of factors into circulation.
Based on this knowledge, exosome secretion of a panel of hypoxic NSCLC cell lines was analyzed with nanoparticle tracking methods and compared to normoxic controls. Hypoxia was found to significantly induce exosome secretion, accompanied by the up-regulation of numerous pro-metastatic proteins as determined by Mass Spectrometry, including Galectin-3-Binding Protein. Hypoxia also modifies miRNA content of exosomes, shown by miRNA-sequencing with the identification of 18 unique miRNAs present only in exosomes derived from hypoxic NSCLC cells. These results have been used to generate an exosome-based signature for use in a clinical trial of early stage NSCLC patients to identify patients at risk of developing metastatic disease stages.
To accomplish this, exosomes were isolated from the plasma of controls and stage I/II NSCLC patients using a newly developed size exclusion chromatography technique. No significant difference in exosomes numbers was observed between NSCLC patients and healthy individuals. However, Galectin-3-Binding Protein was present at various abundances exclusively in NSCLC patients. These data are the first-in-man assessments of the capacity of plasma-derived exosomes to predict metastasis in early stage NSCLC patients.