Clinical Impact of Intratumoral EpCAM-Positive Cancer Stem Cell Heterogeneity in Patients with Hepatocellular Carcinoma

Backgrounds & Aims: Intratumoural heterogeneity of hepatocellular carcinoma (HCC) is of increasing translational interest. Dismal prognosis is frequently linked to HCC harbouring cancer stem cell (CSC)-features, represented by EpCAM-expression. However, to what extent intratumoural distribution of CSC-features impacts on recurrence after curative resection remains unknown. Hence, we aimed to investigate the spatial heterogeneity of CSC-features and its impact on clinical outcome, identifying high-risk patients amenable to adjuvant treatment.Methods: We designed a tissue microarray (TMA) from patients, who received liver resection between 2011 and 2017. Tumour specimens were sampled at multiple locations (n=3-8). EpCAM-positivity was assessed for intensity and proportion by applying a score dividing three groups: negative (E-/-), heterogeneous-positive (E-/+), homogeneous-positive (E+/+). The groups were further analysed with respect to time-to-recurrence (TTR) and recurrence-free-survival (RFS).Results: We included 341 tumour spots from 75 patients (77% male, median age 66 years, liver cirrhosis/fibrosis 74.6%). Risk factors were alcohol abuse in 23.9%, NASH 16.3%, HBV 14.1%, HCV 17.4% and others 28.3%, representing a typical Western cohort. E+/+ patients experienced a significantly shorter TTR and RFS compared to E+/- (and E-/-) patients (TTR 5 vs. 19 months, p=0.017; RFS 5 vs. 14 vs. 18 months, p=0.016). Only homogeneous EpCAM-positivity correlated with higher AFP levels (>400 ng/ml, p=0.024).Conclusions: Spatial heterogeneity of EpCAM-expression was markedly present. Only homogeneously positive EpCAM-expression correlated significantly with early recurrence, whereas heterogeneous EpCAM-expression was associated with clinical endpoints comparable to EpCAM-negativity. Similar to colorectal cancer, high or low risk features for recurrence could be decisive for adjuvant treatment.