Introduction The persistence of circulating tumor cells (CTC) in breast cancer patients might be associated with stem cell like tumor cells which have been suggested to be the active source of metastatic spread in primary tumors. Furthermore, these cells also may undergo phenotypic changes, known as epithelialmesenchymal transition (EMT), which allows them to travel to the site of metastasis formation without getting affected by conventional treatment. Here we evaluated 226 blood samples of 39 metastatic breast cancer patients during a follow-up of palliative chemo-, antibody -or hormonal therapy for the expression of the stem cell marker ALDH1 and markers for EMT and correlated these findings with the presence of CTC and response to therapy.

Molecular profiling of CTC may offer superior prognostic information with regard to risk assessment for recurrence and predictive judgement of therapeutical regimens.

Circulating tumour cells (CTCs) serve as valuable biomarkers. However, EpCAM positive CTCs are less frequently detected in NSCLC patients compared to other epithelial tumours. First, EpCAM protein expression was analysed in primary and metastatic lung cancer tissue. In both groups 21% of the samples were EpCAM negative. Second, the CellSearch system identified 15% of patients (n = 48) as CTC positive whereas a multiplex RT-PCR for PIK3CA, AKT2, TWIST, and ALDH1 following EGFR, HER2 and EpCAM based enrichment detected CTCs in 29% of the patients. Interestingly, 86% of CTC positive patients were found to express ALDH1. Only 11% of the patients were CTC-positive by both techniques. CTC positivity was associated with patient disease state when assessed by the multiplex RT-PCR assay (p = 0.015). Patients harbouring tumours with an altered EGFR genotype were more frequently CTC-positive compared to patients with EGFR wildtype tumours. In subsets of patients, CTCs were found to express genes involved in resistance to therapy such as HER3 and MET. In conclusion, using multiple targets for CTC capture and identification increases the sensitivity of CTC detection in NSCLC patients, which can be explained by the presence of different CTC subtypes with distinct molecular features.

BACKGROUND Platinum resistance constitutes one of the most recognized clinical challenges for ovarian cancer. Notably, the detection of the primary tumor-based excision repair cross-complementation group 1 (ERCC1) protein by immunohistochemistry was recently shown to be inaccurate for the prediction of platinum resistance. On the basis of the previous finding that circulating tumor cells (CTC) in the blood of ovarian cancer patients are prognostically significant, and given our hypothesis that the negative prognostic impact of CTC may arise from a cellular phenotype associated with platinum resistance, we asked whether expression of the excision repair cross-complementation group 1 (ERCC1) gene in the form of the ERCC1 transcript in CTC may be a suitable blood-based biomarker for platinum resistance. METHODS The presence of CTC was analyzed by immunomagnetic CTC enrichment (n = 143 patients) targeting the epithelial epitopes epithelial cell adhesion molecule (EPCAM) (also known as GA733-2) and mucin 1, cell surface associated (MUC1), followed by multiplex reverse-transcription PCR to detect the transcripts EPCAM, MUC1, and mucin 16, cell surface associated (MUC16) (also known as CA125), including ERCC1 transcripts in a separate approach. ERCC1 expression in primary tumors was comparatively assessed by immunohistochemistry, using the antibody 8F1. RESULTS At primary diagnosis, the presence of CTC was observed in 14% of patients and constituted an independent predictor of overall survival (OS) (P = 0.041). ERCC1-positive CTC (ERCC1+CTC) were observed in 8% of patients and constituted an independent predictor, not only for OS but also for progression-free survival (PFS) (P = 0.026 and P = 0.009, respectively). More interestingly, we discovered the presence of ERCC1+CTC at primary diagnosis to be likewise an independent predictor of platinum resistance (P = 0.010), whereas ERCC1 expression in corresponding primary tumor tissue predicted neither platinum resistance nor prognosis. CONCLUSIONS The presence of ERCC1+CTC can serve as a blood-based diagnostic biomarker for predicting platinum resistance at primary diagnosis of ovarian cancer.

BackgroundAssuming that tumor cell dissemination requires a shift to a mesenchymal phenotype, we analyzed the incidence of epithelial-to-mesenchymal-transition (EMT)-like circulating tumor cells (CTCs) in ovarian cancer patients and inquired, how their molecular phenotypes respond to platinum-based chemotherapy and influence outcome.ResultsBefore surgery, overall detection rate for epithelial CTCs was 18%. EMT-like CTCs were more frequently observed (30%) and were mutually exclusive to epithelial CTCs in the majority of patients (82%). After chemotherapy, EMT-like CTCs increased up to 52%, accompanied by the “de novo” emergence of PI3Kα+/Twist+ EMT-like CTCs. Before surgery, PI3K+ EMT-like CTCs in combination with epithelial CTCs indicated decreased OS (p = 0.02) and FIGO I-III patients with residual tumor burden after surgery were more likely to be positive for EMT-like CTCs after chemotherapy (p = 0.02). In the latter group, epithelial CTCs alone significantly correlated with decreased PFS and OS (p = 0.02, p = 0.002), supported by an additional inclusion of PI3K+ CTCs (OS, p = 0.001).Materials and MethodsBlood samples of 91 ovarian cancer patients before surgery and 31 matched samples after adjuvant chemotherapy were evaluated for CTCs with the AdnaTest ovarian cancer and EMT-1, analyzing the epithelial-associated transcripts EpCAM, Muc-1 and CA125 and the EMT-associated transcripts PI3Kα, Akt-2 and Twist.ConclusionsPlatinum-based chemotherapy seems to select for EMT-like CTCs in ovarian cancer patients and provokes a shift towards PI3Kα and Twist expressing CTCs, which may reflect clonal tumor evolution towards therapy resistance. It has to be determined, whether this CTC subgroup may serve as a biomarker to identify patients at high risk.