KRAS mutations in pancreatic circulating tumor cells: a pilot study.

Pancreatic ductal adenocarcinoma (PDAC) is most often diagnosed in a metastatic stage. Circulating tumor cells (CTC) in the blood are hypothesized as the means of systemic dissemination. We aimed to isolate and characterize CTC to evaluate their significance as prognostic markers in PDAC. Blood obtained from healthy donors and patients with PDAC before therapy was filtered with ScreenCell® filtration devices for size-based CTC isolation. Captured cells were analyzed by immunofluorescence for an epithelial to mesenchymal transition (EMT) marker (zinc finger E-box binding homebox 1 (ZEB1)) and an epithelial antigen (cytokeratin (CK)). Molecular analysis of parallel specimens evaluated the KRAS mutation status of the CTC. The survival of each patient after study was recorded. As demonstrated by either cytology or finding of a KRAS mutation, CTC were detected in 18 of 21 patients (86 %) with proven PDAC: 8 out of 10 patients (80 %) with early stage (UICC IIA/IIB) and 10 out of 11 (91 %) with late stage (UICC III/IV) disease. CTC were not found in any of the 10 control patients (p < 0.001). The presence of CTC did not adversely affect median survival: 16 months in CTC-positive (n = 18) vs. 10 months in CTC-negative (n = 3) patients. Neither ZEB1 nor cytological characteristics correlated with overall survival, although ZEB1 was found almost exclusively in CTC of patients with established metastases. Patients with a CTC KRAS mutation (CTC-KRAS (mut)) had a substantially better survival, 19.4 vs. 7.4 months than patients with wild type KRAS (p = 0.015). With ScreenCell filtration, CTC are commonly found in PDAC (86 %). Molecular and genetic characterization, including mutations such as KRAS, may prove useful for prognosis.

Author Correction: Pancreatic cancer: Circulating Tumor Cells and Primary Tumors show Heterogeneous KRAS Mutations.

A correction to this article has been published and is linked from the HTML version of this paper. The error has been fixed in the paper.

Pancreatic cancer: Circulating Tumor Cells and Primary Tumors show Heterogeneous KRAS Mutations.

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease. Circulating tumor cells (CTC) in the blood are hypothesized as the means of systemic tumor spread. Blood obtained from healthy donors and patients with PDAC was therefore subject to size-based CTC-isolation. We additionally compared Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations in pancreatic CTC and corresponding tumors, and evaluated their significance as prognostic markers. Samples from 68 individuals (58 PDAC patients, 10 healthy donors) were analyzed; CTCs were present in patients with UICC stage IA-IV tumors and none of the controls (p < 0.001). Patients with >3 CTC/ml had a trend for worse median overall survival (OS) than patients with 0.3­3 CTC/ml (P = 0.12). Surprisingly, CTCs harbored various KRAS mutations in codon 12 and 13. Patients with a KRAS G12V mutation in their CTC (n = 14) had a trend to better median OS (24.5 months) compared to patients with other (10 months), or no detectable KRAS mutations (8 months; P = 0.04). KRAS mutations in CTC and corresponding tumor were discordant in 11 of 26 "tumor-CTC-pairs" (42%), while 15 (58%) had a matching mutation; survival was similar in both groups (P = 0.36). Genetic characterization, including mutations such as KRAS, may prove useful for prognosis and understanding of tumor biology.