The CellSearch® system (CS) enables standardized enrichment and enumeration of circulating tumor cells (CTCs) that are repeatedly assessable via non-invasive “liquid biopsy”. While the association of ...CTCs with poor clinical outcome for cancer patients has clearly been demonstrated in numerous clinical studies, utilizing CTCs for the identification of therapeutic targets, stratification of patients for targeted therapies and uncovering mechanisms of resistance is still under investigation. Here, we comprehensively review the current benefits and drawbacks of clinical CTC analyses for patients with metastatic and non-metastatic tumors. Furthermore, the review focuses on approaches beyond CTC enumeration that aim to uncover therapeutically relevant antigens, genomic aberrations, transcriptional profiles and epigenetic alterations of CTCs at a single cell level. This characterization of CTCs may shed light on the heterogeneity and genomic landscapes of malignant tumors, an understanding of which is highly important for the development of new therapeutic strategies.
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This study aimed to evaluate the prognostic impact of circulating tumor cells (CTC) detected in patients with operable or locally advanced breast cancer before and after neoadjuvant therapy (NT) ...within the clinical trial GeparQuattro.
Data on CTCs enumerated with the CellSearch system were available for 213 and 207 patients before and after NT, respectively. Associations of CTCs with disease-free survival (DFS) and overall survival (OS) were analyzed by nonparametric Kaplan-Meier estimates and parametric Cox regression.
After a median follow-up of 67.1 months, the detection of ≥1 CTC/7.5 mL and ≥2 CTCs/7.5 mL before NT was associated with reduced DFS (
= 0.031 and
< 0.0001, respectively) and OS (
= 0.0057 and
< 0.0001, respectively), whereas CTCs detected after NT did not correlate with DFS or OS. In parametric univariate and multivariate Cox models, ≥1 CTC/7.5 mL, ≥2 CTCs/7.5 mL, and absolute CTC numbers before NT revealed to be independent prognostic parameters of DFS and OS. CTC-negative patients with pathologic complete response (pCR) exhibited the best prognosis, whereas those with CTCs and less tumor response were at high risk of tumor relapse. In HER2 (ERBB2)-positive and triple-negative patients, ≥2 CTCs/7.5 mL detected before NT also were significantly associated with worse DFS and OS.
Detection of CTCs before NT is an independent prognostic factor of impaired clinical outcome, and combined with pCR, it could be helpful to stratify breast cancer patients for therapeutic interventions.
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The prognostic value of circulating tumor cells (CTC) detected in breast cancer patients is currently under debate. Different time points of blood collections and various CTC assays have been used in ...the past decades. Here, we conducted the first comprehensive meta-analysis of published literature on the prognostic relevance of CTC, including patients with early and advanced disease.
A comprehensive search for articles published between January 1990 and January 2012 was conducted; reviews of each study were conducted and data were extracted. The main outcomes analyzed were overall survival (OS) and disease-free survival (DFS) in early-stage breast cancer patients, as well as progression-free survival (PFS) and OS in metastatic breast cancer patients. Pooled hazard ratio (HR) and 95% confidence intervals (CIs) were calculated using the random and the fixed-effects models. Subgroup and sensitivity analyses were also conducted.
Forty-nine eligible studies enrolling 6,825 patients were identified. The presence of CTC was significantly associated with shorter survival in the total population. The prognostic value of CTC was significant in both early (DFS: HR, 2.86; 95% CI, 2.19-3.75; OS: HR, 2.78; 95% CI, 2.22-3.48) and metastatic breast cancer (PFS: HR, 1.78; 95% CI, 1.52-2.09; OS: HR, 2.33; 95% CI, 2.09-2.60). Further subgroup analyses showed that our results were stable irrespective of the CTC detection method and time point of blood withdrawal.
Our present meta-analysis indicates that the detection of CTC is a stable prognosticator in patients with early-stage and metastatic breast cancer. Further studies are required to explore the clinical utility of CTC in breast cancer.
Early dissemination, blood circulation, or homing of single tumor cells in bone marrow and other organs is usually undetectable at primary diagnosis, even by high resolution imaging technologies. ...However, ultrasensitive approaches now enable the detection of “occult” tumor cells. Many researchers are currently focusing on circulating tumor cells (CTC) in peripheral blood, and several publications have described associations of CTC in patients with metastatic cancer and worse prognosis. However, evidence has emerged that the currently used detection methods lack sensitivity or specificity to track all CTC, especially those that have lost characteristic epithelial features. Therefore, new developments in this field are of utmost interest and will be reviewed here. Moreover, molecular CTC analysis will provide insights into the selection of tumor cells and resistance mechanisms in patients undergoing systemic therapies. This information might support assessing individual prognosis, stratifying patients at risk to systemic therapies, and monitoring therapeutic efficacy.
Transcriptome analysis of circulating tumor cells (CTCs) holds great promise to unravel the biology of cancer cell dissemination and identify expressed genes and signaling pathways relevant to ...therapeutic interventions.
CTCs were enriched based on their EpCAM expression (CellSearch
) or by size and deformability (Parsortix
), identified by EpCAM and/or pan-keratin-specific antibodies, and isolated for single cell multiplex RNA profiling.
Distinct breast and prostate CTC expression signatures could be discriminated from RNA profiles of leukocytes. Some CTCs positive for epithelial transcripts (EpCAM and KRT19) also coexpressed leukocyte/mesenchymal associated markers (PTPRC and VIM). Additional subsets of CTCs within individual patients were characterized by divergent expression of genes involved in epithelial-mesenchymal transition (e.g., CDH2, MMPs, VIM, or ZEB1 and 2), DNA repair (RAD51), resistance to cancer therapy (e.g., AR, AR-V7, ERBB2, EGFR), cancer stemness (e.g., CD24 and CD44), activated signaling pathways involved in tumor progression (e.g., PIK3CA and MTOR) or cross talks between tumors and immune cells (e.g., CCL4, CXCL2, CXCL9, IL15, IL1B, or IL8).
Multimarker RNA profiling of single CTCs reveals distinct CTC subsets and provides important insights into gene regulatory networks relevant for cancer progression and therapy.
Circulating tumor cells (CTC) released into blood from primary cancers and metastases reflect the current status of tumor genotypes, which are prone to changes. Here, we conducted the first ...comprehensive genomic profiling of CTCs using array-comparative genomic hybridization (CGH) and next-generation sequencing. We used the U.S. Food and Drug Administration-cleared CellSearch system, which detected CTCs in 21 of 37 patients (range, 1-202/7.5 mL sample) with stage IV colorectal carcinoma. In total, we were able to isolate 37 intact CTCs from six patients and identified in those multiple colorectal cancer-associated copy number changes, many of which were also present in the respective primary tumor. We then used massive parallel sequencing of a panel of 68 colorectal cancer-associated genes to compare the mutation spectrum in the primary tumors, metastases, and the corresponding CTCs from two of these patients. Mutations in known driver genes e.g., adenomatous polyposis coli (APC), KRAS, or PIK3CA found in the primary tumor and metastasis were also detected in corresponding CTCs. However, we also observed mutations exclusively in CTCs. To address whether these mutations were derived from a small subclone in the primary tumor or represented new variants of metastatic cells, we conducted additional deep sequencing of the primary tumor and metastasis and applied a customized statistical algorithm for analysis. We found that most mutations initially found only in CTCs were also present at subclonal level in the primary tumors and metastases from the same patient. This study paves the way to use CTCs as a liquid biopsy in patients with cancer, providing more effective options to monitor tumor genomes that are prone to change during progression, treatment, and relapse.
Breast cancer patients often develop locoregional or distant recurrence years after mastectomy. Understanding the mechanism of metastatic recurrence after dormancy is crucial for improving the cure ...rate for breast cancer. Here, we characterize a bone metastasis dormancy model to show that aberrant expression of vascular cell adhesion molecule 1 (VCAM-1), in part dependent on the activity of the NF-κB pathway, promotes the transition from indolent micrometastasis to overt metastasis. By interacting with the cognate receptor integrin α4β1, VCAM-1 recruits monocytic osteoclast progenitors and elevates local osteoclast activity. Antibodies against VCAM-1 and integrin α4 effectively inhibit bone metastasis progression and preserve bone structure. These findings establish VCAM-1 as a promising target for the prevention and inhibition of metastatic recurrence in bone.
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► VCAM-1 expression is associated with early relapse and activation from dormancy ► VCAM-1 overexpression promotes bone metastasis by activating osteoclastogenesis ► VCAM-1-α4β1 binding facilitates adhesion of preosteoclasts to tumor cells ► VCAM-1 and α4 blocking antibodies reduce the progression of bone metastasis
Although clinically relevant, the detection rates of EpCAM positive CTCs in non-small cell lung cancer (NSCLC) are surprisingly low. To find new clinically informative markers for CTC detection in ...NSCLC, the expression of EGFR and HER3 was first analyzed in NSCLC tissue (n = 148). A positive EGFR and HER3 staining was observed in 52.3% and 82.7% of the primary tumors, and in 62.7% and 91.2% of brain metastases, respectively. Only 3.0% of the brain metastases samples were negative for both HER3 and EGFR proteins, indicating that the majority of metastases express these ERBB proteins, which were therefore chosen for CTC enrichment using magnetic cell-separation. Enrichment based on either EGFR or HER3 detected CTCs in 37.8% of the patients, while the combination of EGFR/HER3 enrichment with the EpCAM-based CellSearch technique detected a significantly higher number of 66.7% CTC-positive patients (Cohen's kappa = -0.280) which underlines the existence of different CTC subpopulations in NSCLC. The malignant origin of keratin-positive/CD45-negative CTC clusters and single CTCs detected after EGFR/HER3 based enrichment was documented by the detection of NSCLC-associated mutations. In conclusion, EGFR and HER3 expression in metastasized NSCLC patients have considerable value for CTC isolation plus multiple markers can provide a novel liquid biopsy approach.
The incidence and number of circulating tumor cells (CTCs) in the peripheral blood of colorectal cancer patients are lower than in other cancer types, which may point to a particular biology of ...colorectal cancer affecting CTC detection.
We detected CTCs in the peripheral and mesenteric blood of colorectal cancer patients by use of 2 independent technologies on the basis of different biological properties of colon cancer cells. Seventy-five patients diagnosed with localized (M0, n = 60) and metastatic (M1, n = 15) colorectal cancer were included. Peripheral and mesenteric blood samples were collected before tumor resection. We performed CTC enumeration with an EpCAM-independent enrichment method followed by the Epispot assay that detected only viable CK19-releasing CTCs. In parallel, we used the FDA-cleared EpCAM-dependent CellSearch® as the reference method.
The enumeration of CK19-releasing cells by the CK19-Epispot assay revealed viable CTCs in 27 of 41 (65.9%) and 41 of 74 (55.4%) (P = 0.04) patients in mesenteric and peripheral blood, respectively, whereas CellSearch detected CTCs in 19 of 34 (55.9%) and 20 of 69 (29.0%) (P = 0.0046) patients. In mesenteric blood, medians of 4 (range 0-247) and 2.7 CTCs (range 0-286) were found with Epispot and CellSearch (P = 0.2), respectively, whereas in peripheral blood, Epispot and CellSearch detected a median of 1.2 (range 0-92) and 0 CTCs (range 0-147) (P = 0.002).
A considerable portion of viable CTCs detectable by the Epispot assay are trapped in the liver as the first filter organ in CRC patients.
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