Background: Using liver-derived circulating tumor cells (CTC) as “liquid biopsy” may be a promising approach for individualizing and monitoring treatment in patients with HCC. However, this is challenged by cellular heterogeneity. Therefore, we wanted to assess whether CTC subtypes are identifiable in the peripheral blood of patients with HCC and whether their distribution is associated with clinical characteristics.
Methods: CTC were enriched from peripheral venous blood using density gradient centrifugation and subsequent depletion with immunomagnetic beads. CTC enriched suspensions were spun onto glass slides and stained by immunofluorescence or immunocytochemistry. Epithelial CTC were concomitantly selected for qRT-PCR based molecular analysis.
Results: We were able to detect cells with epithelial, mesenchymal, stem cell-like and mixed characteristics and a remarkable variation in the size range. The distribution of these subgroups varied significantly between different patient groups and was associated with clinical outcome. Kaplan-Meier log rank test showed that a change in the ratio of epithelial to mesenchymal cells was associated with longer median time to progression (TTP; 2 months, p=0.01; [HR]=0.18). Furthermore, we were able to identify IGFBP1 as a potential molecular marker for TTP after radioembolisation (p=0.04; HR<0.1). Here, ROC analysis resulted in sensitivity and specificity of 80% (AUC=0.8; CI 0.44-0.98; p=0.03).
Conclusions: Our data suggest that different CTC populations are identifiable in peripheral blood of patients with HCC and that these individual cell type profiles may have distinct clinical implications, e.g. epithelial cells as markers of aggressiveness. CTC may also be usable for identifying new molecular markers.