Expected clinical applications of circulating tumor cells in breast cancer

Tumor cell invasion and intravascular filtration lead to the presence of circulating tumor cells (CTCs) in peripheral blood. CTCs have, thus, been counted in patients with cancer to analyze metastatic mechanisms or in the hope of developing clinical applications for diagnosis and therapy; various CTC-related studies have been performed. However, the clinical significance of CTCs remains to be established because of the extremely small number of CTCs in peripheral blood as compared with the number of blood cells. Technical problems (e.g. reproducibility and reliability) in the detection of CTCs also remain to be solved. The use of flow cytometric analysis, which can be performed with tumor-cell markers such as anti-epithelial cell adhesion molecule antibodies and anti-cytokeratin antibodies and non-tumor-cell markers such as anti-CD45 antibodies has enhanced specificity for the detection of tumor cells. The CellSearch System^® can detect 1 CTC in 7.5 mL of peripheral blood, with high reproducibility. Its detection rate and accuracy for CTCs have been confirmed. In the United States, clinical trials have used this system to detect CTCs in patients with metastatic breast cancer, metastatic colorectal cancer, and metastatic prostate cancer, and CTCs have been confirmed to be a useful prognostic factor. This system was also suggested to be useful for monitoring treatment response in patients with metastatic breast cancer and was approved by the United States Food and Drug Administration in 2004. Measuring CTC counts can facilitate the early prediction of treatment response and thereby avoid unnecessary therapy. CTCs may also be a useful biomarker for molecular targeted agents, enabling the identification of patients most likely to respond to a given treatment and facilitating treatment selection. However, the widespread use of CTC monitoring as a routine examination requires a further improvement in measurement sensitivity, the establishment of criteria for quantitative and qualitative evaluations, and additional clear-cut evidence supporting the clinical significance of CTCs. We expect that CTCs will be established to be a new diagnostic and therapeutic index for breast cancer.     

Isolation of circulating epithelial and tumor progenitor cells with an invasive phenotype from breast cancer patients

Recent research advances show that tumor cell intravasation (entry into the circulation) and metastasis occur very early in breast cancer progression. Clinical studies also illustrate the potential importance of detection of circulating tumor cells (CTCs) in outcomes of patients with metastatic breast cancer. Whether these cells exhibit the invasiveness and express tumor stem or progenitor markers, hallmark of the metastatic phenotype, is less well characterized. To detect CTCs with the invasive phenotype and to explore their molecular features, we applied a functional cell separation method, called collagen adhesion matrix (CAM) assay, as enrichment and identification steps. The CAM‐coated device successfully recovered tumor cells spiked in 1 ml of blood with a 54% ± 9% (n = 18) recovery rate and 0.5–35% purity, and detected invasive tumor cells in 10/10 blood samples (100% yield) from patients with metastatic breast cancer with a range of 18–256 CTCs/ml and average of 126 ± 25 (mean ± SD) CTCs/ml. CTCs were detected in blood samples of 28/54 (52%) Stage I–III breast cancer patients with a mean count of 61 CTCs/ml. Furthermore, the relative frequency of these cells correlated to the staging, lymph node‐status and survival of patients with early stage breast cancer. CAM‐captured cells were capable of propagation in culture. Gene expression and multiplex flow cytometric analyses on CAM‐captured cells demonstrated the existence of distinct populations of CTCs including these of epithelial lineage and stem or progenitor cells. Thus, CAM‐initiated CTC detection provides advantages for examining invasiveness and tumor progenitor phenotypes.     

A novel platform for detection of CK+ and CK- CTCs

Metastasis is a complex, multistep process that begins with the epithelial-mesenchymal transition (EMT). Circulating tumor cells (CTC) are believed to have undergone EMT and thus lack or express low levels of epithelial markers commonly used for enrichment and/or detection of such cells. However, most current CTC detection methods target only EpCAM and/or cytokeratin (CK) to enrich epithelial CTCs, resulting in failure to recognize other, perhaps more important, CTC phenotypes that lack expression of these markers. Here, we describe a population of complex aneuploid CTCs that do not express CK or CD45 antigen in patients with breast, ovarian, or colorectal cancer. These cells were not observed in healthy subjects. We show that the primary epithelial tumors were characterized by similar complex aneuploidy, indicating conversion to an EMT phenotype in the captured cells. Collectively, our study provides a new method for highly efficient capture of previously unrecognized populations of CTCs. Significance: Current assays for CTC capture likely miss populations of cells that have undergone EMT. Capture and study of CTCs that have undergone EMT would allow a better understanding of the mechanisms driving metastasis.     

HER2 status predicts the presence of circulating tumor cells in patients with operable breast cancer

Introduction Circulating tumor cells (CTCs) correlate with worse prognosis in patients with metastatic breast cancer, but there are little data on CTCs in operable patients. We hypothesized that primary tumor characteristics would predict the likelihood of identifying CTCs in patients with operable breast cancer. Methods Clinical and pathological data from 92 patients with operable breast cancer were collected. The CellSearch system was used to detect CTCs in 30 ml of peripheral blood. CTCs were defined as nucleated cells lacking CD45 but expressing cytokeratins 8, 18, or 19. Univariate analysis was performed to determine if the presence of any primary tumor characteristic was predictive of CTCs. As a secondary objective we evaluated if nodal or bone marrow status was predictive of CTCs. Results Thirty-eight percent of patients (35/92) had evidence of CTCs, with a median number of 1.0 CTC per CTC positive patient (range 1–22). HER2 status was the sole primary tumor characteristic that reliably predicted the presence of CTCs (P = 0.01, risk ratio = 3.66). No significant association was found between the presence of CTCs and tumor size (T), estrogen receptor (ER) status, progesterone receptor (PR) status, grade, histologic type, degree of nodal involvement (N), lymphovascular invasion (LVI) or Ki-67 proliferation. Bone marrow micrometastases were found in 17/64 (26.6%) of the patients but did not correlate with the presence of CTCs. Conclusion HER2 status was the only primary tumor characteristic that correlated with the presence of CTCs. Long-term follow-up will be required to determine the significance of CTCs in operable breast cancer. Presented in part at the 2007 Society of Surgical Oncology Cancer Symposium.     

转移性乳腺癌循环肿瘤细胞的上皮间质转化水平对化疗疗效的预测意义

目的 检测转移性乳腺癌患者外周血循环肿瘤细胞（CTCs）不同亚型相关基因的表达,探讨其对化疗疗效的预测意义。方法 应用免疫磁性分选（MACS）技术联合逆转录 聚合酶链反应（RT-PCR）法检测58例转移性乳腺癌患者和10例健康人外周血中CTCs上皮型标志物上皮角蛋白（CK18、CK19）和间质型标志物（波形蛋白、纤连蛋白）mRNA的表达。分析上皮型标志物及间质型标志物表达与不同亚型乳腺癌之间的关系,并分别评估具有不同表型CTCs患者之间疗效的差异。结果 在10例健康志愿者的血液样本中,未检测出CK18、CK19、波形蛋白和纤连蛋白mRNA的表达。在58例转移性乳腺癌患者的血液样本中,检测出36例（62.1％）上皮角蛋白表达,19例（32.8％）间质型标志物表达。Luminal A组和HER-2阳性组的上皮型标志物阳性表达率高于三阴性乳腺癌组（P=0.008）,而间质型标志物阳性表达率则低于三阴性乳腺癌组（P＜0.001）。根据不同标志物的表达情况,将患者分为CKs+／EMT-组、CKs-／EMT-组、CKs+／EMT+组和CKs-／EMT+组,4组有效率依次为76.7％、55.6％、33.3％和15.4％,差异有统计学意义（P=0.002）。间质型标志物阴性者的化疗有效率高于间质型标志物阳性者（71.8% vs. 15.8%,P=0.000）。结论 转移性乳腺癌患者中部分CTCs将发生上皮间质转化而丢失上皮型细胞的表型,获得间质型细胞表型。间质型CTCs因具有更强的抵抗化疗药物的能力而存活,这可能是三阴性乳腺癌疗效不佳的原因之一。     

循环肿瘤细胞的异质性在转移性乳腺癌中的作用研究进展

循环肿瘤细胞（CTC）的计数可以预测转移性乳腺癌的预后,但其改善患者预后的能力在临床试验中尚未得到证实。目前研究专注于CTC的分子表征,作为肿瘤组织的“替代物”以非侵入性地方式评估癌症基因组表达及其在治疗过程中的演变。CTC中存在上皮-间质转化过程（EMT）,其特点为上皮标志物的缺失。EMT过程可以存在于侵袭性及耐药性较强的细胞,其计数和表征,能够引起肿瘤的复发和进展,具有较高的临床价值。本文深入探讨循环肿瘤细胞的异质性及在转移性乳腺癌上皮-间质转化过程中的作用。使其成为乳腺癌患者监测转移和预后的常规的检测指标,并有助于明确转移的机制,更有望发现乳腺癌转移治疗的新靶点。     

Determination of cut-offs for circulating tumor cell measurement in metastatic cancer

Evaluation of: Pierga JY, Hajage D, Bachelot T et al. High independent prognostic and predictive value of circulating tumor cells compared with serum tumor markers in a large prospective trial in first-line chemotherapy for metastatic breast cancer patients. Ann. Oncol. DOI: 10.1093/annonc/mdr263 (2011) (Epub ahead of print).

The metastatic transformation of epithelial tumors progresses through various steps leading to the generation of circulating tumor cells (CTCs). Measurement of CTCs in the peripheral blood is being increasingly recognized as a promising tool in breast oncology. Several studies have evaluated the prognostic significance of CTCs in newly diagnosed metastatic breast cancer (MBC) patients. The IC 2006-04 was a high-powered, prospective, multicenter, observational study conceived to assess CTC changes in women with MBC treated with first-line chemotherapy. Levels ≥5 CTCs/7.5 ml blood at baseline and before the second cycle of treatment were independent prognostic factors associated with shorter progression-free and overall survival. This study provides further level II evidence for the clinical and prognostic value of CTCs in MBC, confirming data from earlier small studies. It also provides proof that CTCs should be investigated in ongoing interventional trials to see if better patient outcomes can be attained by altering treatment based on CTC levels.     

PD-1/PD-L1信号通路在结直肠癌免疫逃逸及其治疗中作用的研究进展

结直肠癌是常见的消化系统肿瘤。近年来,免疫治疗是继放化疗及靶向治疗之后,结直肠癌治疗领域的新方向。而作为T细胞免疫反应的协同刺激信号通路,程序性死亡分子1（programmed death-1,PD-1）/PD-1配体（PD-1 ligand,PD-L1)信号通路在肿瘤的免疫治疗中起着至关重要的作用。PD-1/PD-L1信号通路被激活后,可参与肿瘤的免疫逃逸,与肿瘤的发生、发展密切相关。体内外实验证实,阻断该通路可增强机体内源性抗肿瘤免疫效应。本文就PD-1/PD-L1信号通路及其阻滞剂在结直肠癌领域中的研究进展作一综述。     

Detection of circulating tumour cells with a hybrid (epithelial/mesenchymal) phenotype in patients with metastatic non-small cell lung cancer

Background:

Circulating tumour cells (CTC) have a crucial role in metastasis formation and can consistently provide information on patient prognosis. Epithelial-mesenchymal transition (EMT) is considered as an essential process in the metastatic cascade, but there is currently very few data demonstrating directly the existence of the EMT process in CTCs.

Methods:

CTCs were enriched by blood filtration using ISET (isolation by size of epithelial tumour cells), triply labelled with fluorescent anti-vimentin, anti-pan-keratin antibodies and SYTOX orange nuclear dye, and examined by confocal microscopy in six patients with metastatic non-small cell lung cancer (NSCLC). In parallel, CTCs were morphocytologically identified by an experienced cytopathologist.

Results:

Isolated or clusters of dual CTCs strongly co-expressing vimentin and keratin were evidenced in all patients (range 5–88/5 ml). CTCs expressing only vimentin were detected in three patients, but were less frequent (range 3–15/5 ml). No CTC expressing only keratin was detected.

Conclusion:

We showed for the first time the existence of hybrid CTCs with an epithelial/mesenchymal phenotype in patients with NSCLC. Their characterisation should provide further insight on the significance of EMT in CTCs and on the mechanism of metastasis in patients with NSCLC.     

可手术乳腺癌循环肿瘤细胞与原发肿瘤临床病理特征的关系

目的探讨可手术乳腺癌患者外周血循环肿瘤细胞（CTCs）的阳性率及其与原发肿瘤临床病理特征的关系。方法以2010年9月至2011年5月期间南京医科大学第一附属医院收治的94例可手术乳腺癌患者为实验组,20例健康志愿者及20例乳腺良性疾病患者为对照组,抽取实验组及对照组患者的外周静脉血10ml,用密度梯度离心法富集分离单个核细胞,以多标志物（CK19、人乳腺珠蛋白、小黏蛋白）联合的实时荧光定量PCR法检测CTCs。采用皮尔逊x。检验分析可手术乳腺癌组与对照组外周血CTCs阳性率的差异,以及CTCs与原发肿瘤临床病理特征的关系。结果可手术乳腺癌组外周血CTCs阳性率显著高于对照组[56％（53／94）比5％（2／40）,X^2=30．62,P=0．00]。可手术乳腺癌患者外周血CTCs阳性率在不同的年龄、绝经状态、肿块大小、淋巴结转移、TNM分期、病理分级、病理类型、激素受体状态、HER-2表达、是否为三阴性乳腺癌、分子分型、P53表达、Ki67表达以及增殖细胞核抗原（PCNA）表达分组问差异无统计学意义（P值均〉0．05）。结论可手术乳腺癌患者外周血CTCs的阳性率较高,但其与原发肿瘤临床病理学特征无关系。     

Response Assessment With Molecular Characterization of Circulating Tumor Cells and Plasma MicroRNA Profiling in Patients With Locally Advanced Breast Cancer During Neoadjuvant Chemotherapy

BackgroundCells detaching from the primary tumor site are metastasis initiator cells, and the detection of CTC, known as liquid biopsy, is an important test of biomarkers of cancer progression. We investigated the molecular characterization of circulating tumor cells (CTCs), profiled the plasma microRNA (miR) content, and analyzed the relationship with the clinical outcomes by sampling the peripheral blood from patients with locally advanced breast cancer before and after neoadjuvant chemotherapy.Patients and MethodsMarkers of breast cancer, epithelial–mesenchymal transition (EMT), drug resistance, and stem cells were used for CTC isolation and characterization. Plasma miR profiles were obtained from selected patients with CTC positivity determined using next-generation sequencing.ResultsThe proportion of CTC, EMT, and stem cell marker positivity was 16.7%, 8.3%, and 25% before and 18.2%, 15.2%, and 9.1% after treatment, respectively. A significant correlation was found between the pretreatment CTCs and ALDH1 positivity (P = .0245). These CTCs with stemness properties were observed in most hormone receptor–positive, human epidermal growth factor receptor 2–negative cases and were also present with a high incidence in cases of early metastasis. miR-146b-5p and miR-199a-5p, which are involved in metastasis, invasion, and EMT, were accompanied by CTC positivity, and miR-4646-3p was associated with the development of early metastasis.ConclusionsMolecular characterization of CTCs and miR profiling of serial samples from patients with locally advanced breast cancer during neoadjuvant chemotherapy appears to be a very useful in predicting cure and clinical course and might be a key to developing new targeted therapies.     

Detection of circulating tumor cells in breast cancer may improve through enrichment with anti-CD146

Most assays to detect circulating tumor cells (CTCs) rely on EpCAM expression on tumor cells. Recently, our group reported that in contrast to other molecular breast cancer subtypes, ??normal-like?? cell lines lack EpCAM expression and are thus missed when CTCs are captured with EpCAM-based technology [J Natl Cancer Inst 101(1):61?C66, 2009]. Here, the use of CD146 is introduced to detect EpCAM-negative CTCs, thereby improving CTC detection. CD146 and EpCAM expression were assessed in our panel of 41 breast cancer cell lines. Cells from 14 cell lines, 9 of which normal-like, were spiked into healthy donor blood. Using CellSearch? technology, 7.5 ml whole blood was enriched for CTCs by adding ferrofluids loaded with antibodies against EpCAM and/or CD146 followed by staining for Cytokeratin and DAPI. Hematopoietic cells and circulating endothelial cells (CECs) were counterstained with CD45 and CD34, respectively. A similar approach was applied for blood samples of 20 advanced breast cancer patients. Eight of 9 normal-like breast cancer cell lines lacked EpCAM expression but did express CD146. Five of these 8 could be adequately recovered by anti-CD146 ferrofluids. Of 20 advanced breast cancer patients whose CTCs were enumerated with anti-EpCAM and anti-CD146 ferrofluids, 9 had CD146+ CTCs. Cells from breast cancer cell lines that lack EpCAM expression frequently express CD146 and can be recovered by anti-CD146 ferrofluids. CD146+ CTCs are present in the peripheral blood of breast cancer patients with advanced disease. Combined use of anti-CD146 and anti-EpCAM is likely to improve CTC detection in breast cancer patients.     

Detection of circulating urothelial cancer cells in the blood using the CellSearch System

BACKGROUND: Circulating tumor cells (CTCs) have been shown to aid in the therapeutic management of patients. But, only a few attempts have been made at the detection of urothelial cancer cells in the blood. The purpose of this study was to test the hypothesis that CTCs are detected in patients with urothelial cancers using newly developed CellSearch Assay. METHODS: Firstly, the bladder cancer cell lines were used to evaluate the reagents for immunocytochemical detection. After, mixed with peripheral blood mononuclear cells (PBMCs) of healthy volunteers, bladder cancer cells were stained with antibodies then multiparameter flow cytometric analysis was performed for the identification of bladder cancer cells in the PBMCs. Secondary, recovery of known numbers of spiked bladder cancer cells from whole blood was examined using CellSearch Assay. Finally, blood samples from nonmetastatic and metastatic urothelial cancer patients were investigated for CTC detection using CellSearch Assay. RESULTS: 1: Flow cytometric analysis revealed that it is possible to identify bladder cancer cells in PBMCs. 2: Sensitivity examination for detection of urothelial cancer cells with CellSearch Assay: Single regression analysis of the spiked number of cells vs. the recovered number of cells yielded a good correlation in this experiment. 3: Urothelial cancer cells were detected in 8 of fourteen patients (57.1%) with distant metastasis. Despite, no patient with nonmetastatic urothelial cancers showed positive result for this assay. CONCLUSION: This is the first report of attempt to detect circulating urothelial cancer cells in the peripheral blood of the patients with metastatic and nonmetastatic urothelial cancers by CellSearch Assay.     

Determination of cut-offs for circulating tumor cell measurement in metastatic cancer

The metastatic transformation of epithelial tumors progresses through various steps leading to the generation of circulating tumor cells (CTCs). Measurement of CTCs in the peripheral blood is being increasingly recognized as a promising tool in breast oncology. Several studies have evaluated the prognostic significance of CTCs in newly diagnosed metastatic breast cancer (MBC) patients. The IC 2006-04 was a high-powered, prospective, multicenter, observational study conceived to assess CTC changes in women with MBC treated with first-line chemotherapy. Levels ≥ 5 CTCs/7.5 ml blood at baseline and before the second cycle of treatment were independent prognostic factors associated with shorter progression-free and overall survival. This study provides further level II evidence for the clinical and prognostic value of CTCs in MBC, confirming data from earlier small studies. It also provides proof that CTCs should be investigated in ongoing interventional trials to see if better patient outcomes can be attained by altering treatment based on CTC levels.     

Evaluation of circulating tumor cells in patients with breast cancer: multi-institutional clinical trial in Japan

BACKGROUND: With the development of the CellSearch System, it has become possible to measure circulating tumor cell (CTC) levels with high reproducibility, and the CTC test is currently being used clinically for patients with metastatic breast cancer in the United States. It is imperative that the clinical significance of the CTC test also be examined in Japan. METHODS: Using the CellSearch System, CTC levels were evaluated in 57 healthy individuals and patients with benign breast disease; 30 patients with primary breast cancer (stages 1-3); and 38 patients with metastatic breast cancer. First, the relationship between CTC levels and the presence of metastasis was examined using a cutoff score of 2 CTCs per 7.5 ml whole blood. Then, the patients with metastatic breast cancer were divided into two groups, using a cutoff score of 5 CTCs per 7.5 ml blood, and progression-free survival (PFS) and overall survival (OS) were compared in the two groups. RESULTS: When the clinical cutoff score was set at 2 CTCs per 7.5 ml blood, 0% of the healthy individuals and patients with benign breast disease (0/57), 3.3% of the patients with primary breast cancer (1/30), and 50% of the patients with metastatic breast cancer (19/38) were identified as as having 2 CTCs per 7.5 ml blood. Additionally, with a cutoff score of 5 CTCs, 11 patients were reported to have 5 or more CTCs and both PFS (P = 0.0036) and OS (P = 0.04) were worse for this patient population than for the population with fewer than 5 CTCs. CONCLUSION: As concluded in a similar clinical trial in the United States, for patients with breast cancer, measuring CTC levels can be both an accurate indicator of metastases and an important measure of patient prognosis.     

Circulating tumor cells (CTCs) in breast cancer: a diagnostic tool for prognosis and molecular analysis

Metastatic breast cancer(MBC)is characterized by a combination of tumor growth,proliferation and metastatic progression and is typically managed with palliative intent.The benefit of standard systemic therapies is relatively limited and the disease is considered incurable suggesting the need to investigate the biological drivers of the various phases of the metastatic process in order to improve the selection of molecularly driven therapies.The detection,enumeration and molecular analysis of circulating tumor cells(CTCs)provide an intriguing opportunity to advance this knowledge.CTCs enumerated by the Food and Drugs Administration-cleared CellSearch TM system are an independent prognostic factor of progressionfree survival(PFS)and overall survival(OS)in MBC patients.Several published papers demonstrated the poor prognosis for MBC patients that presented basal CTC count ≥5 in 7.5mL of blood.Therefore,the enumeration of CTCs during treatment for MBC provides a tool with the ability to predict progression of disease earlier than standard timing of anatomical assessment using conventional radiological tests.During the metastatic process cancer cells exhibit morphological and phenotypic plasticity undergoing epithelialmesenchymal transition(EMT).This important phenomenon is associated with down regulation of epithelial marker(e.g.,EpCAM)with potential limitations in the applicability of current CTCs enrichment methods.Such observations translated in a number of investigations aimed at improving our capabilities to enumerate and perform molecular characterization of CTCs.Theoretically,the phenotypic analysis of CTCs can represent a "liquid" biopsy of breast tumor that is able to identify a new potential target against the metastatic disease and advance the development and monitoring of personalized therapies.     

Clinical significance of circulating tumor cells in breast cancer patients

Circulating tumor cells (CTCs) are defined as tumor cells circulating in the peripheral blood of patients, shed from either the primary tumors or its metastases. Many techniques have been developed in the recent years to identify CTCs in breast cancer patients, and trials have proved the prognostic significance of CTCs. In this study, we validated the CTC detection method of combining cell filtration and laser scanning cytometry (LSC), which was highly reproducible with increased sensitivity and accuracy. In 134 non-metastatic breast cancer patients analyzed, HER2 was found to be the only primary tumor characteristics that correlated with the presence of CTCs. 85 patients with definitive stage information were selected for association study between the disease stages and CTC numbers. The detection rate and the number of CTCs were correlated with the disease stages. Moreover, assessment of CTCs in 92 metastatic breast cancer patients was found to be able to predict the efficacy of chemotherapy. Increase in CTC numbers was an independent prognostic factor for treatment outcomes. Our results suggested that CTC assessment could be an indication of the disease progression and analysis of the properties of CTCs is likely to provide new insights into the biology of breast cancer and contribute to defining novel treatments and better prediction of clinical outcomes.