Enlarged extracellular vesicles are a negative prognostic factor in patients undergoing TACE for primary or secondary liver cancer–a case series

BACKGROUND: Transarterial chemoembolization (TACE) has evolved as a standard treatment option in patients with intermediate stage, unresectable HCC [Barcelona Clinic Liver Cancer (BCLC) stage B] as well as in patients with liver metastases, when surgery or systemic therapy is considered not appropriate. Concentration and sizes of extracellular vesicles (EVs) recently emerged as novel diagnostic and prognostic biomarkers in patients with liver cancer, but no data on its prognostic relevance in the context of TACE exists. Here, we evaluate pre-interventional EVs as a potential biomarker in patients undergoing TACE for primary and secondary hepatic malignancies. METHODS: Vesicle size distribution and concentration were measured by nanoparticle tracking analysis (NTA) in patient sera before and after TACE in 38 patients. RESULTS: Extracellular vesicle size distribution measured before TACE is of prognostic significance with respect to overall survival in patients after TACE. Overall survival is significantly reduced when initial vesicle size (X50) is in the upper quartile (>145.65nm). Median overall survival in patients in the upper quartile was only 314 days, compared to 799 days in patients with vesicle size in the first to third quartile (<145.65nm; p = 0.007). Vesicle size was also shown to be a significant prognostic marker for overall survival in Cox regression analysis [HR 1.089, 95% CI: 1.021–1.162, p = 0.010]. In addition, a significant correlation was observed between initial EVs concentration/BMI (r(S) = 0.358, p = 0.029), X50/IL-8-concentration (r(S) = 0.409, p = 0.011) and X50/CRP-concentration (r(S) = 0.404, p = 0.016). In contrast, with regard to immediate tumor response after TACE, EVs concentration and size did not differ. SUMMARY: Sizes (but not concentrations) of EVs represent a novel prognostic marker in patients receiving TACE for primary and secondary hepatic malignancies since patients with enlarged EVs display a significantly impaired prognosis after TACE.