Abstract 68P
Background
Extracellular vesicles (EVs) are lipid membrane-enclosed, nanosized particles secreted by cells to regulate intercellular communication. EVs released by cancer cells are valuable carriers of tumor information and are considered as having promising potential as biomarkers in cancer diagnosis, prognostication, and surveillance. In our study, we investigated the diagnostic and prognostic value of blood circulating EV expressing cancer stem cell markers in a cohort of advanced cancer patients.
Methods
This prospective observational study enrolled patients with histologically or cytologically confirmed diagnosis of advanced cancer. Patients were recruited from January 2016 to February 2021. Identification, enumeration, and phenotypic characterization of EVs from whole fresh blood samples were obtained by applying a recently patented simplified polychromatic flow cytometry method based on a combined EV staining with a lipophilic cationic dye (LCD) and phalloidin. EV subpopulations were identified based on their positivity to selected cancer stem cell markers, including CD133, EPCAM, CD90 and CD29.
Results
A total of 195 cancer patients (lung cancer [n= 81]; colorectal cancer [n=56]; melanoma [n=24]; pancreatic cancer [n=8]; breast cancer [n=7]; other malignancies [n=19]) and 55 healthy controls (HCs) were enrolled. Median blood concentration of circulating CD133+ EPCAM- EV was significantly higher in the overall cancer population (median EVs/μl= 100.2; 95 % CI 74.2 – 129.4) compared to HCs (median EVs/μl= 19.6; 95 % CI 8,40-32,20) (p. 0.0000001). Blood concentration of CD133+ EPCAM- EVs was not correlated with age (p. 0.90), sex (p. 0.66), cancer subtype (0.64), number of metastatic sites (p. 0.41) and line of treatment (0.08) in cancer patients. Survival analysis revealed a correlation between high CD133+ EPCAM- EV concentration (>74 EVs/μl) and worse overall survival in colorectal cancer patients (HR= 3.15 [95 % CI 1.36-7.33]; p. 0.008).
Conclusions
Overall, our results suggest a potential role of blood circulating EVs with a cancer stem cell-phenotype as a prognostic tool in cancer population.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
University “G. d'Annunzio” Chieti-Pescara.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.