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. Cancer Res; 73(10); 2965-75. Ó2013 AACR.

Glioblastoma multiforme (GBM) is the most frequent and aggressive brain tumor in adults. The dogma that GBM spread is restricted to the brain was challenged by reports on extracranial metastases after organ transplantation from GBM donors. We identified circulating tumor cells (CTCs) in peripheral blood (PB) from 29 of 141 (20.6%) GBM patients by immunostaining of enriched mononuclear cells with antibodies directed against glial fibrillary acidic protein (GFAP). Tumor cell spread was not significantly enhanced by surgical intervention. The tumor nature of GFAP-positive cells was supported by the absence of those cells in healthy volunteers and the presence of tumor-specific aberrations such as EGFR gene amplification and gains and losses in genomic regions of chromosomes 7 and 10. Release of CTCs was associated with EGFR gene amplification, suggesting a growth potential of these cells. We demonstrate that hematogenous GBM spread is an intrinsic feature of GBM biology.

BACKGROUND: Molecular characterization of circulating tumor cells (CTCs) is pivotal to increasing the diagnostic specificity of CTC assays and investigating therapeutic targets and their downstream pathways on CTCs. We focused on epidermal growth factor receptor (EGFR) and genes relevant for its inhibition in patients with colorectal cancer (CRC).

With the increasing number of available predictive biomarkers, clinical management of cancer is becoming increasingly reliant on the accurate serial monitoring of tumor genotypes. We tested whether tumor-specific copy number changes can be inferred from the peripheral blood of patients with cancer. To this end, we determined the plasma DNA size distribution and the fraction of mutated plasma DNA fragments with deep sequencing and an ultrasensitive mutation-detection method, i.e., the Beads, Emulsion, Amplification, and Magnetics (BEAMing) assay. When analyzing the plasma DNA of 32 patients with Stage IV colorectal carcinoma, we found that a subset of the patients (34.4%) had a biphasic size distribution of plasma DNA fragments that was associated with increased circulating tumor cell numbers and elevated concentration of mutated plasma DNA fragments. In these cases, we were able to establish genome-wide tumor-specific copy number alterations directly from plasma DNA. Thus, we could analyze the current copy number status of the tumor genome, which was in some cases many years after diagnosis of the primary tumor. An unexpected finding was that not all patients with progressive metastatic disease appear to release tumor DNA into the circulation in measurable quantities. When we analyzed plasma DNA from 35 patients with metastatic breast cancer, we made similar observations suggesting that our approach may be applicable to a variety of tumor entities. This is the first description of such a biphasic distribution in a surprisingly high proportion of cancer patients which may have important implications for tumor diagnosis and monitoring.

Multimarker RNA profiling of single CTCs reveals distinct CTC subsets and provides important insights into gene regulatory networks relevant for cancer progression and therapy.

IntroductionThe management of metastatic breast cancer needs improvement. As clinical evaluation is not very accurate in determining the progression of disease, the analysis of circulating tumor DNA (ctDNA) has evolved to a promising noninvasive marker of disease evolution. Indeed, ctDNA was reported to represent a highly sensitive biomarker of metastatic cancer disease directly reflecting tumor burden and dynamics. However, at present little is known about the dynamic range of ctDNA in patients with metastatic breast cancer.MethodsIn this study, 74 plasma DNA samples from 58 patients with metastasized breast cancer were analyzed with a microfluidic device to determine the plasma DNA size distribution and copy number changes in the plasma were identified by whole-genome sequencing (plasma-Seq). Furthermore, in an index patient we conducted whole-genome, exome, or targeted deep sequencing of the primary tumor, metastases, and circulating tumor cells (CTCs). Deep sequencing was done to accurately determine the allele fraction (AFs) of mutated DNA fragments.ResultsAlthough all patients had metastatic disease, plasma analyses demonstrated highly variable AFs of mutant fragments. We analyzed an index patient with more than 100,000 CTCs in detail. We first conducted whole-genome, exome, or targeted deep sequencing of four different regions from the primary tumor and three metastatic lymph node regions, which enabled us to establish the phylogenetic relationships of these lesions, which were consistent with a genetically homogeneous cancer. Subsequent analyses of 551 CTCs confirmed the genetically homogeneous cancer in three serial blood analyses. However, the AFs of ctDNA were only 2% to 3% in each analysis, neither reflecting the tumor burden nor the dynamics of this progressive disease. These results together with high-resolution plasma DNA fragment sizing suggested that differences in phagocytosis and DNA degradation mechanisms likely explain the variable occurrence of mutated DNA fragments in the blood of patients with cancer.ConclusionsThe dynamic range of ctDNA varies substantially in patients with metastatic breast cancer. This has important implications for the use of ctDNA as a predictive and prognostic biomarker.Electronic supplementary materialThe online version of this article (doi:10.1186/s13058-014-0421-y) contains supplementary material, which is available to authorized users.

What’s known on the subject? and What does the study add? Circulating tumour cells (CTC) have prognostic relevance for patients with different metastatic carcinomas. Detection of CTC using the CellSearch system has also been reported in bladder cancer, but mainly in patients with metastatic disease. This is the largest report demonstrating that detection of CTC in non‐metastatic bladder cancer patients is feasible using the CellSearch system. Presence of CTC may be predictive for early systemic disease. OBJECTIVE To prospectively detect and evaluate the biological significance of circulating tumour cells (CTC) in patients with bladder cancer, especially in those patients with non‐metastatic, advanced bladder cancer (NMABC). PATIENTS AND METHODS Between July 2007 and January 2009, blood samples of 50 consecutive patients with localized bladder cancer and five patients with metastatic disease scheduled for cystectomy were prospectively investigated for CTC. Peripheral blood (7.5 ml) was drawn before cystectomy. Detection of CTC was performed using the USA Food and Drug Administration‐approved CellSearchTM system. Data were compared with the clinical and histopathological findings. RESULTS CTC were detected in 15 of 50 patients (30%) with non‐metastatic disease and five of five patients with metastatic disease. The overall mean number of CTC was 33.7 (range: 1–372; median: 2). In non‐metastatic patients, the mean number of CTC was 3.1 (range: 1–11; median: 1). Except for a univariate association between CTC with vessel infiltration (P= 0.047), all other common clinical and histopathological parameters did not reveal a significant correlation with CTC detection. A median 1‐year follow up was available for 53 patients (96.4%). Ten out of 19 preoperatively CTC‐positive patients died as a result of cancer progression. CTC‐positive patients showed significantly worse overall (P= 0.001), progression‐free (P < 0.001) and cancer specific survival (P < 0.001) compared to preoperatively CTC‐negative patients. CONCLUSION This is the largest study demonstrating that detection of CTC in NMABC patients is feasible using the CellSearchTM system. Our findings suggest that the presence of CTC may be predictive for early systemic disease.

The presence of disseminated tumor cells (DTCs) in bone marrow (BM) identifies breast cancer patients with less favorable outcome. Furthermore, molecular characterization is required to investigate the malignant potential of these cells. This study presents a single‐cell array comparative genomic hybridization (SCaCGH) method providing molecular analysis of immunomorphologically detected DTCs. The resolution limit of the method was estimated using the cancer cell line SK‐BR‐3 on 44 and 244k arrays. The technique was further tested on 28 circulating tumor cells and four hematopoietic cells (HCs) from peripheral blood (n = 8 patients). The SCaCGH method was finally applied to 24 DTCs, three immunopositive cells morphologically classified as probable HCs from breast cancer patients and five HC controls from BM (n = 7 patients plus n = 1 healthy donor). The frequency of copy number changes of the DTCs revealed similarities with primary breast tumor samples. Three of the patients had available profiles for DTCs and the corresponding tumor tissue from primary surgery. More than two‐third of the analyzed DTCs disclosed equivalent changes, both to each other and to the corresponding primary disease, whereas the rest of the cells showed balanced profiles. The probable HCs revealed either balanced profiles (n = 2) or changes comparable to the tumor tissue and DTCs (n = 1), indicating morphological overlap between HCs and DTCs. Similar aberration patterns were visible in DTCs collected at diagnosis and at 3 years relapse‐free follow‐up. SCaCGH may be a powerful tool for the molecular characterization of DTCs.