Tumour cell detection in G-CSF mobilised stem cell harvests of patients with breast cancer

The incidence of tumor cell contamination of peripheral blood stem cells: a meta-analysis to evaluate the impact of mobilization regimens and the influence on outcomes in breast cancer patients

Tumor cell contamination (TCC) of peripheral blood stem cells (PBSCs) is a major risk in the autologous PBSC transplant setting. However, the effect of different mobilization regimens (cytokines only versus cytokines + chemotherapy) on TCC of PBSCs and its impact on treatment outcomes have not been systematically reviewed. In the present meta-analysis, we aimed to investigate this effect in breast cancer patients since multiple studies have been conducted in this setting. We systematically searched MEDLINE and Cochrane Library up to May 2012. Seventeen studies (1,819 patients) were assessed. There was no significant difference in the incidence of TCC of PBSCs between the two mobilization regimens. When the analysis was restricted to granulocyte colony-stimulating factor as a cytokine, this difference was again not significant. We also found that TCC of PBSCs was associated with a higher annual recurrence rate in these patients. This suggests that there may be a significant risk for reinfusion of tumor cell-positive PBSCs, and whether it can increase the risk of disease recurrence needs to be determined. This study also raises important questions regarding the causes of TCC of PBSCs. These issues should be investigated systematically in PBSC transplant patients.

Role of stem cells in cancer therapy and cancer stem cells: a review

For over 30 years, stem cells have been used in the replenishment of blood and immune systems damaged by the cancer cells or during treatment of cancer by chemotherapy or radiotherapy. Apart from their use in the immuno-reconstitution, the stem cells have been reported to contribute in the tissue regeneration and as delivery vehicles in the cancer treatments. The recent concept of 'cancer stem cells' has directed scientific communities towards a different wide new area of research field and possible potential future treatment modalities for the cancer. Aim of this review is primarily focus on the recent developments in the use of the stem cells in the cancer treatments, then to discuss the cancer stem cells, now considered as backbone in the development of the cancer; and their role in carcinogenesis and their implications in the development of possible new cancer treatment options in future.

Micrometastases in apheresis products predict shorter progression-free and overall survival in patients with breast cancer undergoing high-dose chemotherapy (HDCT) and autologous blood stem cell transplantation (ABSCT)

The presence of cancer cells in autografts of breast cancer patients has been described to have prognostic value or directly lead to relapse. Previously, we demonstrated that apheresis products (APs) collected after induction chemotherapy have a significantly lower likelihood of tumor cell contamination. Here, we examine the prognostic value of micrometastases in autografts. Data from 83 patients with breast cancer treated with autologous blood stem cell transplantation were analyzed. Pan-cytokeratin-FITC conjugated antibodies were used to detect contaminating breast cancer cells in the APs. Progression and survival data analyzed on the basis of three or fewer cancer cells showed no significant differences in outcomes. Of the 83 patients, 11 had more than three cancer cells detectable in their APs. In total, 72 patients were shown to have less than three cells detectable. When patients with more than three cells were compared to patients with 0-3, we found statistically significant differences in progression-free survival. We also found a significant difference in overall survival (OS) between the two groups. No difference was observed in OS since the time of diagnosis. We conclude that patients with more than three contaminating cells in their APs have micrometastases and represent a poor prognosis group.

Preferential inactivation of paediatric solid tumour cells by sequential exposure to Merocyanine 540-mediated photodynamic therapy and Edelfosine: implications for the ex vivo purging of autologous haematopoietic stem cell grafts

Paediatric solid tumours exhibit steep dose-response curves to alkylating agents and are therefore considered candidates for high-dose chemotherapy and autologous stem cell support. There is growing evidence that autologous stem cell grafts from patients with solid tumours are frequently contaminated with live tumour cells. The objective of this study was to perform, in a preclinical purging model, an initial assessment of the safety and efficacy of a two-step purging procedure that combined Merocyanine 540-mediated photodynamic therapy (MC540-PDT) with a brief exposure to the alkyl-lysophospholipid, Edelfosine. Human and murine bone marrow cells and Neuro-2a murine neuroblastoma, SK-N-SH human neuroblastoma, SK-ES-1 and U-2 OS human osteosarcoma, G-401 and SK-NEP-1 human Wilms' tumour, and A-204 human rhabdomyosarcoma cells were exposed to a fixed dose of MC540-PDT followed by a brief incubation with graded concentrations of Edelfosine. Survival was subsequently assessed by in vitro clonal assay or, in the case of CD34-positive haematopoietic stem cells, by an immunohistochemical method. Combination purging with MC540-PDT and Edelfosine depleted all tumour cells by >4 log while preserving at least 15% of murine granulocyte/macrophage progenitors (CFU-GM), 34% of human CFU-GM, and 31% of human CD34-positive cells. The data suggest that combination purging with MC540-PDT and Edelfosine may be useful for the ex vivo purging of autologous stem cell grafts from patients with paediatric solid tumours.

Ovarian tumor cell detection in peripheral blood progenitor cells harvests by RT-PCR

BACKGROUND

To evaluate the frequency of tumor cell contamination in autologous peripheral-blood progenitor cells from patients with ovarian cancer, and to determine the impact of infusing such cells on relapses after high-dose chemotherapy.

METHODS

Seventy-three samples of peripheral-blood progenitor cells from 24 ovarian cancer patients were studied for contaminated tumor cells by cytokeratin 7 and cytokeratin 20 reverse transcriptase polymerase chain reaction.

RESULTS

Tumor cell contamination in peripheral-blood progenitor cells was detected in 11 of 24 patients (46%) and, among these, in four of 11 patients who received transplantations of peripheral-blood progenitor cells. There was no trend towards longer relapse-free survival in patients infused with cytokeratin-negative peripheral-blood progenitor cells as compared with positive ones. Interestingly, two of four patients who received transplantations of peripheral-blood progenitor cells containing tumor cells were free from progression at 20 and 41 months after transplantation.

CONCLUSION

Tumor cell contamination of peripheral-blood progenitor cells was frequently noted by transcriptase polymerase chain reaction in patients with ovarian cancer. The biological and clinical significance of this finding remains to be elucidated.

Disseminated breast cancer cells prior to and after high-dose therapy

Women with breast cancer in a distinct stage of disease can benefit from high-dose therapy (HDT) with autologous stem cell support; however, a significant number of these patients relapse despite this intensive treatment. This study investigates the persistence of malignancy on the single-cell level. A total of 194 data sets consisting of bone marrow and blood samples obtained prior to and after HDT and of aliquots of apheresis products were searched with immunocytochemistry and reverse transcriptase polymerase chain reaction (RT-PCR) for disseminated cancer cells. Presence of cancer cells in the marrow is frequent prior to and after HDT, but HDT reduces the amount of malignant cells in marrow significantly. In contrast, there was no effect on the number of circulating cancer cells. Reinfusion of contaminated apheresis products was surprisingly associated with a low number of malignant cells in bone marrow after HDT and vice versa. The impact of disseminated tumor cells in bone marrow, apheresis, and peripheral blood on disease-free survival after HDT could be investigated in a total of 165 samples. Surprisingly, neither the presence of tumor cells in marrow or blood nor in apheresis was associated with a bad prognosis in Kaplan-Meyer survival analysis. These results suggest that apheresis products and bone marrow should be regarded as different biological compartments for epithelial cancer cells. It can be concluded that complete elimination of disseminated cancer cells by HDT is not always possible. The theory of reinduction of metastatic breast cancer by accidentally reinfused contaminants is not supported by this study so far. However, further research is necessary to identify distinct cell populations with the potentially capacity to metastasize.

Kinetics of PBPC mobilization by cyclophosphamide, as compared with that by epirubicin/paclitaxel followed by G-CSF support: implications for optimal timing of PBPC harvest

BACKGROUND

Limited information is available on the mobilization kinetics of autologous PBPCs after induction with various chemotherapy regimens. With PBPC mobilization in patients with breast cancer used as a model for chemotherapy-induced PBPC recruitment, the kinetics of progenitor cells mobilized either with cyclophosphamide (CY) or epirubicin/paclitaxel (EPI-TAX) followed by the administration of G-CSF was compared.

STUDY DESIGN AND METHODS

The study included a total of 86 patients with breast cancer (stage II-IV) receiving either CY (n = 39) or EPI-TAX (n = 47), both followed by G-CSF support. The progenitor cell content in peripheral blood and apheresis components was monitored by flow cytometric enumeration of CD34+ cells. PBPC collection was started when the threshold of >20 x 10(6) CD34+ cells per L of peripheral blood was reached.

RESULTS

The PBPC collection was begun a median of 9 days after the administration of EPI-TAX followed by G-CSF support, as compared to a median of 13 days after mobilization with CY plus G-CSF. After treatment with CY, the total numbers of PBPCs peaked on Day 1 of apheresis, and they rapidly declined thereafter. In contrast, treatment with EPI-TAX followed by G-CSF administration led to a steady mobilization of CD34+ cells during leukapheresis. The difference in the mobilization patterns with CY and EPI-TAX resulted in a greater yield of CD34+ cells per L of processed blood volume. Compared to EPI-TAX, mobilization with CY required the overall processing of 30 percent less whole-blood volume to reach the target yield of > or = 10 x 10(6) CD34+ cells per kg of body weight. After a median of three apheresis procedures, however, both CY+G-CSF and EPI-TAX+G-CSF were equally effective in obtaining this target yield.

CONCLUSION

These results imply that specific PBPC mobilization as part of a given chemotherapy regimen should be taken into consideration before the planning of a PBPC harvest.

Influence of Preharvest Tumor Cell Contamination in Bone Marrow or Blood Does Not Predict Resultant Tumor Cell Contamination of Granulocyte Colony-Stimulating Factor Mobilized Stem Cells

Tumor cell contamination of stem cell collections harvested from breast cancer patients is a common phenomenon described by several investigators but with findings that vary among reports. Although so-called co-mobilization of these cells has been hypothesized, the origin of tumor cell contamination in stem cells is still unknown. A total of 47 G-CSF mobilized stem cell grafts from patients with nodal-positive (n = 30), chemosensitive metastatic (n = 11), and 5 women with inflammatory breast cancer were evaluated for cancer cells by immunocytochemistry. Additionally, 40 bone marrow aspirations and 23 peripheral blood samples collected prior to apheresis and after one to two cycles of conventional chemotherapy were available for examination. Tumor cell contamination of leukapheresis correlated best with preharvest blood state. This was valid when the nominal (positive/negative) presence of tumor cells in blood was compared to the nominal presence of tumor cells in apheresis samples and when the it was correlated to the tumor cell load of apheresis samples (TCL = tumor cells per 10(6) nucleated cells investigated). The correlation between blood and stem cells was better (nominal and quantitative) than that between marrow and stem cells, despite the larger sample size of marrow aspirations. The presence or absence of cancer cells in apheresis samples could not be safely predicted by the presence or absence of tumor cells in marrow or blood alone. Diagnostic specificity seems to improve from a combination of results from marrow and blood analysis. No correlation was found in quantitative analysis of tumor cell contamination between marrow and blood. In conclusion, the results suggest that blood and bone marrow represent different compartments for epithelial cancer cells and that contaminating tumor cells in stem cell harvests may be derived from the blood and/or marrow compartment. The tumor cell contamination of a stem cell harvest cannot be safely predicted by a preceding blood or marrow analysis.

Urokinase-like plasminogen activator receptor expression on disseminated breast cancer cells

Disseminated tumor cells are detected frequently in bone marrow, peripheral blood, and cytokine-mobilized peripheral blood cell products of women undergoing high-dose therapy for breast cancer. Several attempts were made to purge autografts from contaminating cancer cells; however, the biological and clinical impact of these contaminations has not been clarified so far. Expression of distinct phenotypes is a surrogate marker for metastatic behavior of cancer cells. The expression of the urokinase-like plasminogen activator receptor seems to be a factor of high importance. It is not expressed by normal mammary tissue. Disseminated cancer cells from marrow, blood, and stem cell products have been investigated by double-stain technique for urokinase-like plasminogen activator receptor (uPA-R) expressing cytokeratin-positive cells. uPA-R(+)/CK(+) cells could be found in all qualities of samples; however, significantly less in G-CSF-mobilized peripheral blood stem cells compared to samples of other provenance (p = 0.02). It can be concluded that epithelial cells of malignant phenotype occur in blood, marrow, and autografts of breast cancer patients. Populations of disseminated tumor cells are phenotypically heterogeneous. Reduced uPA-R expression on cancer cells from leukapheresis samples might suggest a less aggressive nature of these cells compared to disseminated cells found in bone marrow. Furthermore, the data suggest that the phenotype of tumor cell contamination in leukapheresis products differs significantly from those of disseminated cancer cells in bone marrow or blood.

Immunomagnetic tumor cell selection--implications for the detection of disseminated cancer cells

BACKGROUND

The optimal method for the detection of disseminated epithelial cancer cells has not yet been found. The standard method, using immunocytochemistry, offers a sensitivity of up to 10(-6). Molecular methods such as cytokeratin-19 RT-PCR are about 10 times as sensitive, but they are hampered by interference such as illegitimate gene expression.

STUDY DESIGN AND METHODS

Immunomagnetic bead selection of epithelial cancer cells using conjugates directed against the human epithelial antigen (HEA) followed by immunocytochemistry testing was investigated in this trial.

RESULTS

No cytokeratin-positive cells could be enriched from 56 control samples. In 104 clinical samples of bone marrow aspirations, PBPC collections, and venous blood obtained from breast cancer patients, the cytokeratin-positive rate increased significantly, from 29.9 percent before selection to 54.8 percent after enrichment. Even the yield of detected cancer cells was significantly higher after selection. Up to 2.5 x 10(8) MNCs were easily processed. However, the mean cancer cell recovery after HEA enrichment was only 24.4 percent. Subsequently, selected epithelial cells were successfully immunophenotyped by use of a double-stain technique detecting cytokeratin-positive cells and the urokinase-like plasminogen activator receptor.

CONCLUSION

HEA bead selection in combination with the standard immunocytochemistry method is a powerful and specific tool for the detection of disseminated cancer cells without false-positive results. Furthermore, it delivers enough cells for subsequent investigations such as characterization studies.