EGFR-Based Immunoisolation as a Recovery Target for Low-EpCAM CTC Subpopulation

Floating Immunomagnetic Microspheres for Highly Efficient Circulating Tumor Cell Isolation under Facile Magnetic Manipulation

Among circulating tumor cell enrichment strategies, immunomagnetic beads (IMBs) have received great attention due to their excellent performance. However, traditional strategies using IMBs normally require an additional mechanical stirring device to fully mix the IMBs and specimens, and this step may cause mechanical cellular damage. In this study, by changing the architecture and motion trajectory control strategy of the IMBs, floating immunomagnetic microspheres (FIMMs) and their matching rotary magnetic manipulation device were proposed to achieve highly efficient CTC capture under a cell-friendly condition. Generally, the FIMMs were prepared through layer-by-layer assembly of the individual functional components, and their stress state governed by either buoyancy or magnetic force was tuned by the rotary magnetic manipulation device. Consequently, recognition of FIMMs and target cells as well as CTC recovery can be simply realized through external magnetic manipulation. Accordingly, satisfactory enrichment efficiencies for CTCs with varied epithelial expression levels were obtained as 92.93 ± 3.23% for MCF-7, 79.93 ± 3.31% for A549, and 92.57 ± 5.22% for HepG2. Besides, an extremely low detection limitation of 5 cells mL^-1 can be achieved from complex sample conditions, even the whole blood. In addition, FIMMs successfully enriched 23-56 CTCs from 1.5 mL of blood samples from cancer patients.

Peptide-Functionalized Nanoemulsions as a Promising Tool for Isolation and Ex Vivo Culture of Circulating Tumor Cells

Circulating Tumor Cells (CTCs) are shed from primary tumors and travel through the blood, generating metastases. CTCs represents a useful tool to understand the biology of metastasis in cancer disease. However, there is a lack of standardized protocols to isolate and culture them. In our previous work, we presented oil-in-water nanoemulsions (NEs) composed of lipids and fatty acids, which showed a benefit in supporting CTC cultures from metastatic breast cancer patients. Here, we present Peptide-Functionalized Nanoemulsions (Pept-NEs), with the aim of using them as a tool for CTC isolation and culture in situ. Therefore, NEs from our previous work were surface-decorated with the peptides Pep10 and GE11, which act as ligands towards the specific cell membrane proteins EpCAM and EGFR, respectively. We selected the best surface to deposit a layer of these Pept-NEs through a Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D) method. Next, we validated the specific recognition of Pept-NEs for their protein targets EpCAM and EGFR by QCM-D and fluorescence microscopy. Finally, a layer of Pept-NEs was deposited in a culture well-plate, and cells were cultured on for 9 days in order to confirm the feasibility of the Pept-NEs as a cell growth support. This work presents peptide-functionalized nanoemulsions as a basis for the development of devices for the isolation and culture of CTCs in situ due to their ability to specifically interact with membrane proteins expressed in CTCs, and because cells are capable of growing on top of them.

Magnetic Iron Nanocubes Effectively Capture Epithelial and Mesenchymal Cancer Cells

Current methods for capturing circulating tumor cells (CTCs) are based on the overexpression of cytokeratin (CK) or epithelial cell-adhesion molecule (EpCAM) on cancer cells. However, during the process of metastasis, tumor cells undergo epithelial-to-mesenchymal transition (EMT) that can lead to the loss of CK/EpCAM expression. Therefore, it is vital to develop a capturing technique independent of CK/EpCAM expression on the cancer cell. To develop this technique, it is important to identify common secondary oncogenic markers overexpressed on tumor cells before and after EMT. We analyzed the biomarker expression levels in tumor cells, before and after EMT, and found two common proteins-human epidermal growth factor receptor 2 (Her2) and epidermal growth factor receptor (EGFR) whose levels remained unaffected. So, we synthesized immunomagnetic iron nanocubes covalently conjugated with antibodies of Her2 or EGFR to capture cancer cells irrespective of the EMT status. The nanocubes showed high specificity (6-9-fold) in isolating the cancer cells of interest from a mixture of cells spiked in serum. We characterized the captured cells for identifying their EMT status. Thus, we believe the results presented here would help in the development of novel strategies for capturing both primary and metastatic cancer cells from patients' blood to develop an effective treatment plan.

Sorting and gene mutation verification of circulating tumor cells of lung cancer with epidermal growth factor receptor peptide lipid magnetic spheres

Background

This study aimed to identify an efficient, simple, and specific method of detecting mutations in the epidermal growth factor receptor (EGFR) gene in isolated lung cancer circulating tumor cells (CTCs) and to improve the ability to obtain tumor tissue clinically.

Methods

EGFR peptide lipid magnetic spheres (EG‐P‐LMB) were prepared by reverse evaporation, and characterization and cell capture efficiency assessed. The peripheral blood samples of 30 lung cancer patients were isolated and identified with the EG‐P‐LMB using 20 healthy volunteers as controls. Finally, the isolated CTCs were tested for EGFR gene mutations, and the tissue samples selected for comparison.

Results

The prepared magnetic spheres had a smaller particle size and higher stability according to the particle size potential test. Their morphology was homogeneous by atomic force observation, and the UV test showed that there were peptides on the surface. The separation efficiency of EG‐P‐LMB was greater than 90% in PBS and greater than 80% in the blood simulation system. Compared with the tissue sample results, the positive rate of EGFR gene mutations was 94%. The CTC test results of 27 patients were consistent with the tissue test results of the corresponding patients, and the consistency with the tissue comparison test results was 90% (27/30).

Conclusions

EG‐P‐LMB can effectively capture CTCs in the peripheral blood of patients with lung cancer. CTC detection can accurately identify mutations in the EGFR gene and improve the ability to obtain tumor tissue in clinical practice.

Key points

Significant findings of the study

EG‐P‐LMB can effectively capture CTCs in the peripheral blood of patients with lung cancer. CTC detection can accurately identify mutations in the EGFR gene and improve the ability to obtain tumor tissue in clinical practice.

What this study adds

This study added EGFR peptide lipid magnetic spheres to capture CTCs in the blood. Genetic testing was performed and compared with tissues. It solves the problem of clinically difficult tumor tissue sampling.

Direct comparison of size-dependent versus EpCAM-dependent CTC enrichment at the gene expression and DNA methylation level in head and neck squamous cell carcinoma

We directly compared two different approaches used for Circulating Tumor Cell (CTC) isolation, a size-dependent microfluidic system versus an EpCAM-dependent positive selection for downstream molecular characterization of CTC both at the gene expression and DNA methylation level in Head and Neck Squamous Cell Carcinoma (HNSCC). A size-dependent microfluidic device (Parsortix, ANGLE) and an EpCAM-dependent positive immune-magnetic isolation procedure were applied in parallel, using 10 mL PB from 50 HNSCC patients and 18 healthy donors. Total RNA was isolated from enriched CTCs and RT-qPCR was used to study the expression levels of CK-19, PD-L1, EGFR, TWIST1, CDH2 and B2M (reference gene). Real time methylation specific PCR (MSP) was used to study the methylation status of RASSF1A and MLL3 genes. In identical blood draws, the label-free size-dependent CTC-isolation system was superior in terms of sensitivity when compared to the EpCAM-dependent CTC enrichment, since a significantly higher percentage of identical PB samples was found positive at the gene expression and DNA methylation level, while the specificity was not affected. Our results indicate that future studies focused on the evaluation of clinical utility of CTC molecular characterization in HNSCC should be based on size-dependent enrichment approaches.

A novel device to capture circulating tumor cells: Quantification and molecular analysis in lung cancer patients

Here, we describe a novel microfilter device to capture circulating tumor cells in an efficient and low-cost manner. Then, we validated the safety and clinical utility of the novel microfilter device. We next performed mutation analysis from circulating tumor cells collected from lung cancer patients using this new device. Our results indicate that this microfilter system can be used to investigate the genome landscape of circulating tumor cells collected from lung cancer patients. Further, our results highlight a proof-of-concept demonstration indicating that circulating tumor cell can be used for mutation profiling during tumor evolution, therapy prediction, and monitoring, with immediate clinical applicability.

Cancer marker-free enrichment and direct mutation detection in rare cancer cells by combining multi-property isolation and microfluidic concentration

Genetic analysis, rather than simply counting the number of circulating tumor cells (CTCs), which are rare cancer cells in peripheral blood, has great potential for non-invasive biopsy or "liquid biopsy." However, a practical problem in conventional enrichment of CTCs is that the isolated target cells are mixed with numerous residual leukocytes, and are suspended in a large volume. Hence, further isolation (i.e., cytokeratin (CK)-positive cell picking) or DNA purification is required for downstream genetic analysis after isolation. Here, we propose a novel cancer marker-free method of CTC enrichment by size-based Filtration and Immunomagnetic Negative selection followed by Dielectrophoretic concentration (CTC-FIND) for direct detection of genetic mutations in rare cancer cells suspended in whole blood. A combination of two independent isolation methods based on physical (filtration) and biochemical properties (immunomagnetic negative selection) in CTC-FIND allowed highly efficient cancer marker-free purification (5.1-log depletion of leukocytes). The isolated cells were trapped and concentrated using a microfluidic step-channel device using dielectrophoresis for discrimination and downstream genetic analysis. The feasibility of cancer marker-free enrichment by CTC-FIND was successfully demonstrated by directly detecting mutations in various cancer cells with a very high sensitivity of 1 cell per mL, including EpCAM and CK-negative cells, which were used to spike 8 mL of whole blood. Thus, CTC-FIND can be used with liquid biopsy to detect genetic mutations in wide-ranging CTC subsets, independent of cancer cell-specific marker expression.

A novel magnetic fluorescent biosensor based on graphene quantum dots for rapid, efficient, and sensitive separation and detection of circulating tumor cells

We describe a "turn-on" magnetic fluorescent biosensor based on graphene quantum dots (GQDs), Fe₃O₄, and molybdenum disulfide (MoS₂) nanosheets. It is used for rapid, efficient, and sensitive separation and detection of circulating tumor cells (CTCs). A facile approach (electrochemical synthesis method) for the preparation of photoluminescent GQDs functionalized with an aptamer [epithelial cell adhesion molecule (EpCAM) receptors] and a magnetic agent for one-step bioimaging and enrichment of CTCs is described. MoS₂ nanosheets, as a fluorescence quencher, and the aforementioned aptamer@Fe₃O₄@GQD complex were assembled to construct "turn-on" biosensing magnetic fluorescent nanocomposites (MFNs). This system exhibits low cytotoxicity and an average capture efficiency of 90%, which is higher than that of other magnetic nanoparticles on account of the one-step CTC separation method. In addition, the MFNs could quickly identify and label CTCs within 15 min, surpassing other one-step and two-step marker detection methods. Furthermore, because of the presence of aptamers, the MFNs have specific capability to capture CTCs (both low- and high-EpCAM-expressing cells). In addition, high-sensitivity detection of up to ten tumor cells in whole blood was achieved. Therefore, the MFNs have great potential to be used as universal biosensing nanocomposites for fluorescence-guided tumor cell enrichment and bioimaging. Graphical abstract ᅟ.

Efficient targeted cancer cell detection, isolation and enumeration using immuno-nano/hybrid magnetic microgels

Magnetic nano/hybrid structures have drawn ample attention in the field of biotechnology due to their excellent magnetic properties and biocompatibility.

Circulating Tumor Cells: Applications in Cytopathology

Circulating tumor cells (CTCs) are rare tumor cells found in the blood of patients with cancer that can be reliably detected by CTC technologies to provide prognostic, predictive, and diagnostic information. CTC sampling reflects intratumoral and intertumoral heterogeneity better than targeted biopsy. CTC samples are minimally invasive and amenable to repeated sampling, allowing real-time evaluation of tumor in response to therapy-related pressures and possibly early detection. Cytology is the most natural arena for integration of CTC testing. CTC technology may also be deployed to enhance and facilitate the practice of cytology and surgical pathology.

Polymer nanofiber-based microchips for EGFR mutation analysis of circulating tumor cells in lung adenocarcinoma

Background

Circulating tumor cells (CTCs) detection, an approach considered to be “liquid biopsy”, is a potential alternative method in clinical use for early diagnosis of solid tumor progression.

Methods

In this study, we developed a poly (lactic-co-glycolic acid) (PLGA) – nanofiber (PN)-NanoVelcro chip as an efficient device for simple and rapid capture of CTCs from peripheral blood. We evaluated the device performance by assessing the capture efficiency and purity. Single CTC was isolated via laser microdissection system for subsequent genetic analysis, with an aim to find the concordance of epidermal growth factor receptor (EGFR) mutations between tumor tissue and CTCs.

Results

PN-NanoVelcro chip exhibits great performance in capture efficiency and high purity. The genetic analysis results showed that most EGFR mutation in tumor tissue could also be detected in CTCs.

Conclusion

Compared to computed tomography image results, CTC detection can be implemented throughout the course of diseases and provides an accurate and earlier diagnosis of tumor progression, which make it possible for patients to acquire suitable and timely treatment.

Epidermal Growth Factor Receptor Status in Circulating Tumor Cells as a Predictive Biomarker of Sensitivity in Castration-Resistant Prostate Cancer Patients Treated with Docetaxel Chemotherapy

Objective: We examined whether epidermal growth factor receptor (EGFR) expression in circulating tumor cells (CTCs) can be used to predict survival in a population of bone-metastatic castration-resistant prostate cancer (mCRPC) patients treated with docetaxel chemotherapy. Methods: All patients with mCRPC who had experienced treatment failure with androgen-deprivation therapy and had received docetaxel chemotherapy were eligible. CTCs and EGFR expression in CTCs were enumerated with the CellSearch System in whole blood. This system is a semi-automated system that detects and enriches epithelial cells from whole blood using an EpCAM antibody-based immunomagnetic capture. In addition, the EGFR-positive CTCs were assessed using CellSearch^® Tumor Phenotyping Reagent EGFR. Results: The median CTC count at baseline before starting trial treatment was eight CTCs per 7.5 mL of blood (range 0–184). There were 37 patients (61.7%) who had ≥5 CTCs, with median overall survival of 11.5 months compared with 20.0 months for 23 patients (38.3%) with <5 CTCs (p < 0.001). A total of 15 patients (40.5%, 15/37) with five or more CTCs were subjected to automated immunofluorescence staining and cell sorting for EGFR protein. Patients with EGFR-positive CTCs had a shorter overall survival (OS) (5.5 months) than patients with EGFR-negative CTCs (20.0 months). CTCs, EGFR-positive CTCs, and alkaline phosphatase (ALP) were independent predictors of overall survival time (p = 0.002, p < 0.001, and p = 0.017, respectively). Conclusion: CTCs may be an independent predictor of OS in CRPC treated with docetaxel chemotherapy. The EGFR expression detected in CTCs was important for assessing the response to chemotherapy and predicting disease outcome.