Evaluation of different methods for the detection of minimal residual disease in blood and bone marrow of patients with primary breast cancer: importance for clinical use?

Extracorporeal tumor cell filtration during extended liver surgery: first clinical use of leukocyte depletion filters--case series

Background

During oncologic surgery, intraoperative manipulation of tumor tissue is almost unpreventable and causes a high risk of tumor cell dissemination into venous blood. A tumor cell-reducing effect of leukocyte adhesion filter systems has been shown under in vitro conditions.

Methods

In a first clinical attempt, leukocyte adhesion filters were integrated into veno-venous bypass systems in four patients undergoing extended liver surgery for secondary hepatic malignancies.

Practicability, handling, and safety aspects as well as potency of cell removal and clinical side effects of the filter system were analyzed.

Results

All patients tolerated the application of the system without problems during operative and postoperative follow-up. Immunohistochemical staining of perioperative blood samples detected cytokeratin positive (CK+) cells in three cases during the hepatic mobilization.

Conclusions

Effectiveness of CK+ cell depletion and safety of the procedure was shown. The presented surgical technique represents a safe and innovative tool; however, clinical significance has to be examined in a larger patient cohort.

Bone marrow micrometastasis in breast cancer: review of detection methods, prognostic impact and biological issues

Immunocytochemical detection of disseminated tumour cells in the bone marrow of patients with primary breast cancer at surgery has been shown to be an independent prognostic factor in single institutional studies and in a large pooled analysis. However, bone marrow sampling and assessment of disseminated tumour cells is not a routine procedure in the clinical management of patients with breast cancer, but will certainly play a role in the near future for risk stratification and monitoring of therapeutic efficacy. Accurate identification of disseminated tumour cells in bone marrow must be based on standardised methodologies and procedures. This review describes these methodologies and the standardised morphological criteria used for disseminated tumour cell detection. The prognostic value of circulating tumour cells detection in peripheral blood is demonstrated in patients with metastatic disease but remains to be substantiated at early stage. The significance of disseminated tumour cells in bone marrow and in the blood for the prediction of response to therapy is briefly summarised. Finally, this review addresses the main biological questions raised by disseminated tumour cells, in particular understanding tumour dormancy and identifying metastatic stem cells.

Chemokine receptor CXCR4 expression in breast cancer as a potential predictive marker of isolated tumor cells in bone marrow

Interactions between the CXCR4 chemokine receptor in breast cancer cells and the ligand CXCL12/SDF-1alpha are thought to play an important role in breast cancer metastases. In this pilot study, CXCR4 expression along with other biomarkers including HER2-neu and EGFR, were measured in primary tumor samples of patients with operable breast cancer to test whether any of these biomarkers alone and in combination could indicate breast cancer with high likelihood of metastasizing to bone marrow. Cytokeratin (CK) positive cells in bone marrow were identified by flow-cytometry following enrichment with CK 7/8 antibody-coupled magnetic beads. Primary tumors (n = 18) were stained with specific antibodies for CXCR4, HER2-neu, EGFR, and PCNA using an indirect avidin-biotin horseradish peroxidase method. The majority of the patients had T2/T3 tumors (72%), or lymph node involvement (67%) as pathologic characteristics that were more indicative of high-risk breast cancer. High CXCR4 cytoplasmic expression was found in 7 of 18 patients (39%), whereas 6 of 18 patients (33%) were found to have CK positivity in bone marrow. The median number of CK(+) cells was 236 (range, 20-847) per 5 x 10(4) enriched BM cells. The presence of CK(+) cells in bone marrow was found to be associated with increased expression of CXCR4 alone or in addition to EGFR and/or HER2-neu expression (P = 0.013, P = 0.005, and P = 0.025, respectively) in primary tumors. Furthermore, three patients with high CK positivity (>236 CK(+) per 5 x 10(4) enriched bone marrow cells) in bone marrow exclusively expressed high levels of CXCR4 with EGFR/HER2-neu (P = 0.001). Our data suggest that high CXCR4 expression in breast cancer may be a potential marker in predicting isolated tumor cells in bone marrow. CXCR4 coexpression with EGFR/HER2-neu might further predict a particular subset of patients with high CK positivity in bone marrow.

Evaluation of multiparameter flow cytometry for the detection of breast cancer tumor cells in blood samples

We comparatively evaluated different cytokeratin (CK) reagents analyzed by flow cytometry (FCM) for the identification of the best combination of DNA/CK staining for detecting minimal numbers of breast cancer cells in peripheral blood (PB). In 59 primary breast cancer tumors, we comparatively analyzed the reactivity for up to 6 different anti-CK reagents using multiparameter FCM: anti-CK7, anti-CK20, anti-pan-CK, anti-CK8/CK18, anti-CK8, and anti-CK18. Afterward, dilutional experiments of Michigan Cancer Foundation (MCF)7 breast cancer cells in PB were performed, and the sensitivity of a DNA/CK18 staining was evaluated. Our results showed that anti-CK18 reagents were those providing the brightest and more sensitive staining for primary breast cancer tumor cells by FCM. Dilutional experiments of MCF cells in PB showed that the DNA/anti-CK18 double staining was highly specific for the identification of epithelial cells; its sensitivity ranged between 10(-6) and 10(-7) (detection of 1 tumor cell among 10(6) to 10(7) nucleated blood cells). Combined assessment of DNA cell contents and reactivity for CK18 by FCM is a sensitive method for the specific identification of breast cancer cells in PB.

Peri-operative filtration of disseminated cytokeratin positive cells in patients with colorectal liver metastasis

BACKGROUND

Liver resection is the only potential cure for patients with colorectal liver metastasis. However, more than 30% of patients will develop tumour recurrence, probably caused by tumour cells disseminated before or during surgery. As prevention of cell dissemination is barely obtainable, alternative concepts have to be discussed.

METHODS

The potential of leukocyte adhesion filters for the removal of cytokeratin positive cells (CK+) from blood was studied in 18 patients undergoing liver resection for colorectal liver metastasis. Blood sampling was done via a liver venous catheter during hepatic mobilisation. Filtration was done with an in-line WBF2 filter system. To define the relation between surgery and cell release we compared patients' pre-operative and intra-operative blood and bone marrow (BM) samples with their CK expression using immunochemical staining.

RESULTS

CK+ cells were detected in BM samples of nine of 14 patients before surgery, indicating early dissemination. In ten of 18 patients CK+ cells were detected in blood samples during hepatic mobilisation; all ten patients underwent major liver surgery (R0 resection). In those patients recurrent disease was observed more often (P < or = 0.05). In 17 of 18 patients CK+ cells were not detectable after filtration procedure, which indicated cell adhesion to the filter medium.

CONCLUSION

Liver resection due to metastasis leads to frequent intra-operative tumour cell shedding. As the detection of CK+ cells is correlated with disease recurrence, modification of surgical techniques to prevent cell dissemination, and additional therapeutic concepts such as advanced filtration technology, have to be discussed.

Monitoring the Circulating Levels of the HER2/neu Oncoprotein in Breast Cancer

The HER2/neu oncoprotein is a major target for the development of new cancer therapies and is similar to the estrogen receptor, which guides hormone therapy. The HER2/neu status is used to guide therapy decisions in patients with HER2/neu-overexpressing breast cancer tumors. The HER2/neu oncogene, or c-erbB-2, encodes a transmembrane receptor protein that is expressed on normal epithelial cells and can be overexpressed in breast cancer cells. Studies have shown that the extracellular domain (ECD) of the HER2/neu oncoprotein is released from the cell and can be measured in the circulation of women with breast cancer. Enzyme-linked immunosorbent assay methods used to measure the circulating HER2/neu ECD have shown that the prevalence of elevated ECD levels is approximately 18.1% in women with primary breast cancer and approximately 45.6% in women with metastatic breast cancer (MBC). Many studies have monitored the circulating ECD levels after surgery and indicate that increasing ECD levels can indicate recurrence of breast cancer earlier than clinical diagnosis. Studies in women with MBC showed that serial changes in circulating HER2/neu ECD levels paralleled the clinical course of disease, regardless of the treatment regimen. Several studies identified a subgroup of patients with MBC who had HER2/neu-negative disease by tissue testing but developed elevated ECD levels with MBC. In contrast to tissue testing, which is a one-time event, monitoring the circulating levels of the HER2/neu ECD in patients with breast cancer provides a real-time assessment of the HER2/neu status and provides important information for managing the therapy of patients with MBC.

Detection of breast cancer cells in the peripheral blood is positively correlated with estrogen-receptor status and predicts for poor prognosis

We investigated whether detection of cytokeratin-positive (CK+) cells in the peripheral blood (PB) of breast cancer patients before chemotherapy could be a prognostic factor. Blood from a total of 92 breast cancer patients was evaluated for the presence of CK+ cells. Blood samples were collected before chemotherapy. Patients entered in the study included: neoadjuvant (n = 25), adjuvant (n = 42) and metastatic (n = 25). Blood samples (10 ml) were centrifuged using a double density-gradient to recovering the mononuclear cell (MNC) and granulocyte cell (GC) fractions. Subsequently, positive immunomagnetic cell separation was carried out to isolating CK+ cells. The enriched cell fraction was cytocentrifuged and then immunocytochemically labeled using an anti-cytokeratin antibody. Our results indicated that breast tumor cells sediment with both MNC and GC fractions. We therefore recommend examination of both fractions in all enrichment protocols. CK+ cells in PB were identified in 57 of 92 (62%) patients when MNC and GC fractions were assessed (range = 1-61 cells, median = 8). No CK+ cells were detected in blood samples of 16 healthy donors. There were significant differences in the presence of CK+ cells according to estrogen receptor expression (p = 0.049), and lymph node status (p = 0.033), but not to the age, menopausal status, type of patient (neoadjuvant, adjuvant or metastatic), TNM stage, histological type, progesterone receptor expression, c-erbB2 expression, p53 expression or Ki67 expression. Regarding the relationship between tumor size (T) and the presence of CK+ cells, a borderline significant trend was observed (p = 0.07). The median follow-up of the patients was 21 months and statistical analysis (Kaplan-Meier analysis) showed that using the method we present, the detection of CK+ cells in PB before starting the chemotherapy in breast cancer patients was significantly correlated with both progression-free survival (p = 0.058) and overall survival (p = 0.003). In conclusion, the present study suggests that detection of CK+ cells in PB before chemotherapy might identify breast cancer patients with poor prognosis.

An ultrasensitive tumor enriched flow-cytometric assay for detection of isolated tumor cells in bone marrow of patients with breast cancer

BACKGROUND

An ultrasensitive tumor enriched flow-cytometric assay was used to determine its feasibility in detection of isolated tumor cells (ITC) in bone marrow (BM) of patients with breast cancer.

METHODS

Epithelial cells were removed by magnetic microbeads conjugated with an anti-cytokeratin 7/8 monoclonal antibody to enrich tumor cells in BM samples. A specific gate for MCF-7 breast cancer cells (gate(MCF-7 cells)) was also taken into consideration in addition to a gate including all enriched BM cells (gate(enriched BM cells)) in flow-cytometric analysis to enhance the specificity of the method.

RESULTS

Nineteen patients with stage I/II were evaluated. Ten patients (53%) were found to have cytokeratin positive (CK(+)) cells according to the gate(enriched BM cells) whereas 6 patients (32%) had CK(+) cells when the gate(MCF-7 cells) was taken into account.

CONCLUSIONS

New strategies in nonmorphological ultrasensitive techniques might be useful to categorize patients with ITCs having different tumor morphology and characteristics.