Assessment of Different Circulating Tumor Cell Platforms for Uveal Melanoma: Potential Impact for Future Routine Clinical Practice

Liquid biopsy and circulating tumor cell (CTC) screening has gained interest over the last two decades for detecting almost all solid malignancies. To date, the major limitation in terms of the applicability of CTC screening in daily clinical practice is the lack of reproducibility due to the high number of platforms available that use various technologies (e.g., label-dependent versus label-free detection). Only a few studies have compared different CTC platforms. The aim of this study was to compare the efficiency of four commercially available CTC platforms (Vortex (VTX-1), ClearCell FX, ISET, and Cellsearch) for the detection and identification of uveal melanoma cells (OMM 2.3 cell line). Tumor cells were seeded in RPMI medium and venous blood from healthy donors, and then processed similarly using these four platforms. Melan-A immunochemistry was performed to identify tumor cells, except when the Cellsearch device was used (automated identification). The mean overall recovery rates (with mean recovered cells) were 39.2% (19.92), 22.2% (11.31), 8.9% (4.85), and 1.1% (0.20) for the ISET, Vortex (VTX-1), ClearCell FX, and CellSearch platforms, respectively. Although paramount, the recovery rate is not sufficient to assess a CTC platform. Other parameters, such as the purpose for using a platform (diagnosis, genetics, drug sensitivity, or patient-derived xenograft models), reproducibility, purity, user-friendliness, cost-effectiveness, and ergonomics, should also be considered before they can be used in daily clinical practice and are discussed in this article.

Circulating cancer giant cells with unique characteristics frequently found in patients with myelodysplastic syndromes (MDS)

Myelodysplastic syndromes (MDS) are incurable diseases characterized by dysplastic hematopoietic cells, cytopenias in the blood and an inherent tendency for transformation to secondary acute myeloid leukemia (AML). Since most therapies fail to prevent rapid clonal evolution and disease resistance, new and non-invasive predictive markers are needed to monitor patients and adapt the therapeutic strategy. By using ISET, a very sensitive approach to isolate cells larger than mature leukocytes from peripheral blood samples, we looked for cellular markers in 99 patients (158 samples) with MDS and 66 healthy individuals (76 samples) used as controls. We found a total of 680 Giant Cells, defined as cells having a size of 40 microns or larger in 46 MDS patients (80 samples) and 28 Giant Cells in 11 healthy individuals (11 samples). In order to understand if we had enriched from peripheral blood atypical cells of the megakaryocyte line, we studied the Giant Cells using immunolabeling with megakaryocytes and tumor-specific markers. We report that the Giant Cells we found in the peripheral blood of MDS patients primarily express tumor markers. Our results show that Polyploid Giant Cancer Cells (PGCC), similar to those described in solid tumors, are found in the peripheral blood of patients with MDS and suggest the working hypothesis that they could play a role in hematological malignancies.

A comparison of two methods for the detection of circulating tumour cells in patients with oral cavity cancer

BACKGROUND

Circulating tumour cells (CTCs) detected in patient blood samples are relevant as diagnostic and prognostic markers offering insights into tumour behaviour and guiding treatment of cancer at an individualised level. The aim of this study was to ascertain the feasibility of detecting CTCs in oral squamous cell carcinoma (OSCC) using two different methods so as to determine the optimal method for the study of this cancer.

METHODS

Comparison of the numbers of CTCs, circulating tumour micro-emboli (CTMs) and circulating tumour endothelial cells (CTECs), was undertaken in forty clinical samples of oral squamous cell carcinoma (OSCC) determined by filtration (ISET^® ) and in situ fluorescent immunostaining (i-FISH, Cytelligen^® ) immunostaining and in situ hybridisation.

RESULTS

i-FISH detected CTCs in 80% of samples compared with 40% of samples analysed by microfiltration. i-FISH detected CTCs in a further 40% of samples in which microfiltration did not detect CTCs. No CTC clusters were detected by microfiltration while i-FISH detected CTM in 12.5% of samples. i-FISH analysis detected CTECs in 20/40 samples.

CONCLUSION

These results highlight significant differences in detection of CTCs, CTM and CTECs between i-FISH and microfiltration when applied to OSCC samples, suggesting that technologies capable of detecting circulating aneuploid cells more accurately detect CTCs. i-FISH also detected CTM and CTEC not detected using ISET^® . With proven prognostic relevance in adenocarcinomas, accurate enumeration of CTCs, CTMs and CTECs may be a clinically useful tool in the management of OSCC and may aid in the reduction of false-negative diagnoses.

Optimization of the Enrichment of Circulating Tumor Cells for Downstream Phenotypic Analysis in Patients with Non-Small Cell Lung Cancer Treated with Anti-PD-1 Immunotherapy

The current study aimed at the optimization of circulating tumor cell (CTC) enrichment for downstream protein expression analyses in non-small cell lung cancer (NSCLC) to serve as a tool for the investigation of immune checkpoints in real time. Different enrichment approaches—ficoll density, erythrolysis, their combination with magnetic separation, ISET, and Parsortix—were compared in spiking experiments using the A549, H1975, and SKMES-1 NSCLC cell lines. The most efficient methods were tested in patients (n = 15) receiving immunotherapy targeting programmed cell death-1 (PD-1). Samples were immunofluorescently stained for a) cytokeratins (CK)/epithelial cell adhesion molecule (EpCAM)/leukocyte common antigen (CD45), and b) CK/programmed cell death ligand-1 (PD-L1)/ indoleamine-2,3-dioxygenase (IDO). Ficoll, ISET, and Parsortix presented the highest yields and compatibility with phenotypic analysis; however, at the patient level, they provided discordant CTC positivity (13%, 33%, and 60% of patients, respectively) and enriched for distinct CTC populations. IDO and PD-L1 were expressed in 44% and 33% and co-expressed in 19% of CTCs. CTC detection was associated with progressive disease (PD) (p = 0.006), reduced progression-free survival PFS (p = 0.007), and increased risk of relapse (hazard ratio; HR: 10.733; p = 0.026). IDO-positive CTCs were associated with shorter PFS (p = 0.039) and overall survival OS (p = 0.021) and increased risk of death (HR: 5.462; p = 0.039). The current study indicates that CTC analysis according to distinct immune checkpoints is feasible and may provide valuable biomarkers to monitor NSCLC patients treated with anti-PD-1 agents.

Detection of Circulating Tumor Cells in the Diagnostic Leukapheresis Product of Non-Small-Cell Lung Cancer Patients Comparing CellSearch® and ISET

Circulating tumor cells (CTCs) detected by CellSearch are prognostic in non-small-cell lung cancer (NSCLC), but rarely found. CTCs can be extracted from the blood together with mononuclear cell populations by diagnostic leukapheresis (DLA), therefore concentrating them. However, CellSearch can only process limited DLA volumes (≈2 mL). Therefore, we established a protocol to enumerate CTCs in DLA products with Isolation by SizE of Tumor cells (ISET), and compared CTC counts between CellSearch® and ISET. DLA was performed in NSCLC patients who started a new therapy. With an adapted protocol, ISET could process 10 mL of DLA. CellSearch detected CTCs in a volume equaling 2 × 108 leukocytes (mean 2 mL). CTC counts per mL were compared. Furthermore, the live cell protocol of ISET was tested in eight patients. ISET successfully processed all DLA products-16 with the fixed cell protocol and 8 with the live cell protocol. In total, 10-20 mL of DLA was processed. ISET detected CTCs in 88% (14/16), compared to 69% (11/16, p < 0.05) with CellSearch. ISET also detected higher number of CTCs (ISET median CTC/mL = 4, interquartile range [IQR] = 2-6, CellSearch median CTC/mL = 0.9, IQR = 0-1.8, p < 0.01). Cells positive for the epithelial cell adhesion molecule (EpCAM+) per mL were detected in similar counts by both methods. Eight patients were processed with the live cell protocol. All had EpCAM+, CD45-, CD235- cells isolated by fluorescence-activated cell sorting (FACS). Overall, ISET processed larger volumes and detected higher CTC counts compared to CellSearch. EpCAM+ CTCs were detected in comparable rates.

Filter-Adapted Fluorescent In Situ Hybridization (FA-FISH) for Filtration-Enriched Circulating Tumor Cells

Circulating tumor cells (CTCs) may represent an easily accessible source of tumor material to assess genetic aberrations such as gene-rearrangements or gene-amplifications and screen cancer patients eligible for targeted therapies. As the number of CTCs is a critical parameter to identify such biomarkers, we developed fluorescent in situ hybridization (FISH) for CTCs enriched on filters (filter-adapted-FISH, FA-FISH). Here, we describe the FA-FISH protocol, the combination of immunofluorescent staining (DAPI/CD45) and FA-FISH techniques, as well as the semi-automated microscopy method that we developed to improve the feasibility and reliability of FISH analyses in filtration-enriched CTC.

Early detection of poor outcome in patients with metastatic colorectal cancer: tumor kinetics evaluated by circulating tumor cells

BACKGROUND

Colorectal cancer (CRC) is the third most prevalent cancer worldwide. New prognostic markers are needed to identify patients with poorer prognosis, and circulating tumor cells (CTCs) seem to be promising to accomplish this.

PATIENTS AND METHODS

A prospective study was conducted by blood collection from patients with metastatic CRC (mCRC), three times, every 2 months in conjunction with image examinations for evaluation of therapeutic response. CTC isolation and counting were performed by Isolation by Size of Epithelial Tumor Cells (ISET).

RESULTS

A total of 54 patients with mCRC with a mean age of 57.3 years (31-82 years) were included. Among all patients, 60% (n=32) were carriers of wild-type KRAS (WT KRAS) tumors and 90% of them (n=29) were exposed to monoclonal antibodies along with systemic treatment. Evaluating CTC kinetics, when we compared the baseline (pretreatment) CTC level (CTC1) with the level at first follow-up (CTC2), we observed that CTC1-positive patients (CTCs above the median), who became negative (CTCs below the median) had a favorable evolution (n=14), with a median progression-free survival (PFS) of 14.7 months. This was higher than that for patients with an unfavorable evolution (CTC1- that became CTC2+; n=13, 6.9 months; P=0.06). Patients with WT KRAS with favorable kinetics had higher PFS (14.7 months) in comparison to those with WT KRAS with unfavorable kinetics (9.4 months; P=0.02). Moreover, patients whose imaging studies showed radiological progression had an increased quantification of CTCs at CTC2 compared to those without progression (P=0.04).

CONCLUSION

This study made possible the presentation of ISET as a feasible tool for evaluating CTC kinetics in patients with mCRC, which can be promising in their clinical evaluation.

MRP1 expression in CTCs confers resistance to irinotecan-based chemotherapy in metastatic colorectal cancer

Circulating tumor cells are important markers of tumor progression and can reflect tumor behavior in metastatic colorectal cancer (mCRC). Identification of proteins that confer resistance to treatment is an important step to predict response and better selection of treatment for patients. Multidrug resistance-associated protein 1 (MRP1) and Multidrug resistance-associated protein 4 (MRP4) play a role in irinotecan-resistance, and Excision Repair Cross-Complementation group 1 (ERCC1) expression can confer resistance to platinum compounds. Here, we included 34 patients with mCRC and most of them received FOLFIRI or FOLFOX chemotherapy (91.1%). CTCs were isolated by ISET(®) Technology and identified in 30 patients (88.2%), with a median of 2.0 CTCs/mL (0-31.0). We analyzed the immunocytochemical expression of MRP1, MRP4 and ERCC1 only in patients who had previously detectable CTCs, accordingly to treatment received (n = 19, 15 and 13 patients, respectively). Among patients treated with irinotecan-based chemotherapy, 4 out of 19 cases with MRP1 positive CTCs showed a worse progression free survival (PFS) in comparison to those with MRP1 negative CTCs (2.1 months vs. 9.1 months; p = 0.003). None of the other proteins studied in CTCs had significant association with PFS. We analyzed also histological sections of primary tumors and metastases by immunohistochemistry, and found no association with clinicopathological characteristics or with PFS. Our results show MRP1 as a potential biomarker of resistance to treatment with irinotecan when found in CTCs from mCRC patients. This is a small proof-of-principle study and these early findings need to be validated in a larger cohort of patients.

Circulating tumour cells as tumour biomarkers in melanoma: detection methods and clinical relevance

Circulating tumour cells (CTCs) are cells of solid tumour origin detectable in the peripheral blood. Their occurrence is considered a prerequisite step for establishing distant metastases. Metastatic melanoma was the first malignancy in which CTCs were detected and numerous studies have been published on CTC detection in melanoma at various stages of disease. In spite of this, there is no general consensus as to the clinical utility of CTCs in melanoma, largely due to conflicting results from heterogeneous studies and discrepancies in methods of detection between studies. In this review, we examine the possible clinical significance of CTCs in cutaneous, mucosal and ocular melanoma, focusing on detection methods and prognostic value of CTC detection.

Isolation, detection, and immunomorphological characterization of circulating tumor cells (CTCs) from patients with different types of sarcoma using isolation by size of tumor cells: a window on sarcoma-cell invasion

Background

Sarcomas are rare and heterogeneous neoplasms with poor prognosis that are thought to spread to distant organs mainly by hematogenous dissemination. However, circulating tumor cells (CTCs) have never been visualized in sarcomas.

Objectives

To investigate the feasibility of using isolation by size of tumor cells (ISET) for isolation, identification, and characterization of CTCs derived from patients with high-grade and metastatic sarcomas.

Patients and methods

We studied eleven patients with metastatic/recurrent or locally advanced soft-tissue sarcomas (STSs), six of whom had synovial sarcomas. Blood samples (8 mL) were collected from patients with advanced STS and treated by ISET, a marker- independent approach that isolates intact CTCs from blood, based on their larger size compared with leukocytes. CTCs were identified by cytomorphology and characterized by dual-color immunocytochemistry using antivimentin or anti-Pan CK, and anti-CD45.

Results

All patients with STS included in this study showed CTCs, with numbers ranging from two to 48 per 8 mL of blood.

Conclusion

This study shows the feasibility of isolating, identifying, and characterizing CTCs from patients with different types of sarcomas and the presence of circulating sarcoma cells in all the tested patients. Our results set the basis for further studies aimed at exploring the presence, number, and immunomolecular characteristics of CTCs in different types of sarcoma, and bring more light to the mechanisms of tumor invasion for these tumors.

Circulating tumor cells: advances in isolation and analysis, and challenges for clinical applications

Circulating tumor cells (CTCs) are rare cancer cells released from tumors into the bloodstream that are thought to have a key role in cancer metastasis. The presence of CTCs has been associated with worse prognosis in several major cancer types, including breast, prostate and colorectal cancer. There is considerable interest in CTC research and technologies for their potential use as cancer biomarkers that may enhance cancer diagnosis and prognosis, facilitate drug development, and improve the treatment of cancer patients. This review provides an update on recent progress in CTC isolation and molecular characterization technologies. Furthermore, the review covers significant advances and limitations in the clinical applications of CTC-based assays for cancer prognosis, response to anti-cancer therapies, and exploratory studies in biomarkers predictive of sensitivity and resistance to cancer therapies.

MALDI-target integrated platform for affinity-captured protein digestion

To address immunocapture of proteins in large cohorts of clinical samples high throughput sample processing is required. Here a method using the proteomic sample platform, ISET (integrated selective enrichment target) that integrates highly specific immunoaffinity capture of protein biomarker, digestion and sample cleanup with a direct interface to mass spectrometry is presented. The robustness of the on-ISET protein digestion protocol was validated by MALDI MS analysis of model proteins, ranging from 40 fmol to 1 pmol per nanovial. On-ISET digestion and MALDI MS/MS analysis of immunoaffinity captured disease-associated biomarker PSA (prostate specific antigen) from human seminal plasma are presented.

Circulating tumor cells in non-small cell lung carcinoma

Circulating tumor cells (CTCs) are associated with survival of cancer patients. Several methods have been developed to detect circulating tumor cells. The number of CTCs in NSCLC is lower than in other solid tumors. To date, trials are ongoing for a better understanding of CTCs. Besides association with prognosis, CTCs can be used to assess the efficacy of treatment and they are important substrates for molecular profiling of the tumor..