Molecular analysis of circulating tumors cells: Biomarkers beyond enumeration

Simulation-Guided Rational Design of DNA Walker-Based Theranostic Platform

Biomolecule-functionalized nanoparticles represent a type of promising biomaterials in biomedical applications owing to their excellent biocompatibility and versatility. DNA-based reactions on nanoparticles have enabled emerging applications including intelligent biosensors, drug delivery, and biomimetic devices. Among the reactions, strand hybridization is the critical step to control the sensitivity and specificity of biosensing, and the efficiency of drug delivery. However, a comprehensive understanding of DNA hybridization on nanoparticles is still lacking, which may differ from the process in homogeneous solutions. To address this limitation, coarse-grained model-based molecular dynamic simulation is harnessed to disclose the critical factors involved in intermolecular hybridization. Based on simulation guidance, DNA walker-based smart theranostic platform (DWTP) based on "on-particle" hybridization is developed, showing excellent consistency with simulation. DWTP is successfully applied for highly sensitive miRNA 21 detection and tumor-specific miRNA 21 imaging, driven by tumor-endogenous APE 1 enzyme. It enables the precise release of antisense oligonucleotide triggered by tumor-endogenous dual-switch miRNA 21 and APE 1, facilitating effective gene silencing therapy with high biosafety. The simulation of "on-particle" DNA hybridization has improved the corresponding biosensing performance and the release efficiency of therapeutic agents, representing a conceptually new approach for DNA-based device design.

Organ preservation in muscle-invasive urothelial bladder cancer

PURPOSE OF REVIEW

The most common definitive treatment for muscle-invasive bladder cancer (MIBC) is radical cystectomy. However, removing the bladder and surrounding organs poses risks of morbidity that can reduce quality of life, and raises the risk of death. Treatment strategies that preserve the organs can manage the local tumor and mitigate the risk of distant metastasis. Recent data have demonstrated promising outcomes in several bladder-preservation strategies.

RECENT FINDINGS

Bladder preservation with trimodality therapy (TMT), combining maximal transurethral resection of the bladder tumor, chemotherapy, and radiotherapy (RT), was often reserved for nonsurgical candidates for radical cystectomy. Recent meta-analyses show that outcomes of TMT and radical cystectomy are similar. More recent bladder-preservation approaches include combining targeted RT (MRI) and immune checkpoint inhibitors (ICIs), ICIs and chemotherapy, and selecting patients based on genomic biomarkers and clinical response to systemic therapies. These are all promising strategies that may circumvent the need for radical cystectomy.

SUMMARY

MIBC is an aggressive disease with a high rate of systemic progression. Current management includes neoadjuvant cisplatin-based chemotherapy and radical cystectomy with lymph node dissection. Novel alternative strategies, including TMT approaches, combinations with RT, chemotherapy, and/or ICIs, and genomic biomarkers, are in development to further advance bladder-preservation options for patients with MIBC.

High-Fidelity Sensitive Tracing Circulating Tumor Cell Telomerase Activity

Dynamic tracing of intracellular telomerase activity plays a crucial role in cancer cell recognition and correspondingly in earlier cancer diagnosis and personalized precision therapy. However, due to the complexity of the required reaction system and insufficient loading of reaction components into cells, achieving a high-fidelity determination of telomerase activity is still a challenge. Herein, an Aptamer-Liposome mediated Telomerase activated poly-Molecular beacon Arborescent Nanoassembly(ALTMAN) approach was described for direct high-fidelity visualization of telomerase activity. Briefly, intracellular telomerase activates molecular beacons, causing their hairpin structures to unfold and produce fluorescent signals. Furthermore, multiple molecular beacons can self-assemble, forming arborescent nanostructures and leading to exponential amplification of fluorescent signals. Integrating the enzyme-free isothermal signal amplification successfully increased the sensitivity and reduced interference by leveraging the skillful design of the molecular beacon and the extension of the telomerase-activated TTAGGG repeat sequence. The proposed approach enabled ultrasensitive visualization of activated telomerase exclusively with a prominent detection limit of 2 cells·μL-1 and realized real-time imaging of telomerase activity in living cancer cells including blood samples from breast cancer patients and urine samples from bladder cancer patients. This approach opens an avenue for establishing a telomerase activity determination and in situ monitoring technique that can facilitate both telomerase fundamental biological studies and cancer diagnostics.

Circulating and Imaging Biomarkers of Radium-223 Response in Metastatic Castration-Resistant Prostate Cancer

PURPOSE

Radium-223 improves overall survival (OS) and reduces skeletal events in patients with bone metastatic castration-resistant prostate cancer (CRPC), but relevant biomarkers are lacking. We evaluated automated bone scan index (aBSI) and circulating tumor cell (CTC) analyses as potential biomarkers of prognosis and activity.

PATIENTS AND METHODS

Patients with bone metastatic CRPC were enrolled on a prospective single-arm study of standard radium-223. 99mTc-MDP bone scan images at baseline, 2 months, and 6 months were quantitated using aBSI. CTCs at baseline, 1 month, and 2 months were enumerated and assessed for RNA expression of prostate cancer-specific genes using microfluidic enrichment followed by droplet digital polymerase chain reaction.

RESULTS

The median OS was 21.3 months in 22 patients. Lower baseline aBSI and minimal change in aBSI (<+0.7) from baseline to 2 months were each associated with better OS (P = .00341 and P = .0139, respectively). The higher baseline CTC count of ≥5 CTC/7.5 mL was associated with worse OS (median, 10.1 v 32.9 months; P = .00568). CTCs declined at 2 months in four of 15 patients with detectable baseline CTCs. Among individual genes in CTCs, baseline expression of the splice variant AR-V7 was significantly associated with worse OS (hazard ratio, 5.20 [95% CI, 1.657 to 16.31]; P = .00195). Baseline detectable AR-V7, higher aBSI, and CTC count ≥5 CTC/7.5 mL continued to have a significant independent negative impact on OS after controlling for prostate-specific antigen or alkaline phosphatase.

CONCLUSION

Quantitative bone scan assessment with aBSI and CTC analyses are prognostic markers in patients treated with radium-223. AR-V7 expression in CTCs is a particularly promising prognostic biomarker and warrants validation in larger cohorts.

Viscoelastic-Sorting Integrated Deformability Cytometer for High-Throughput Sorting and High-Precision Mechanical Phenotyping of Tumor Cells

The counts and phenotypes of circulating tumor cells (CTCs) in whole blood are useful for disease monitoring and prognostic assessment of cancer. However, phenotyping CTCs in the blood is difficult due to the presence of a large number of background blood cells, especially some blood cells with features similar to those of tumor cells. Herein, we presented a viscoelastic-sorting integrated deformability cytometer (VSDC) for high-throughput label-free sorting and high-precision mechanical phenotyping of tumor cells. A sorting chip for removing large background blood cells and a detection chip for detecting multiple cellular mechanical properties were integrated into our VSDC. Our VSDC has a sorting efficiency and a purity of over 95% and over 81% for tumor cells, respectively. Furthermore, multiple mechanical parameters were used to distinguish tumor cells from white blood cells using machine learning. An accuracy of over 97% for identifying tumor cells was successfully achieved with the highest identification accuracy of 99.4% for MCF-7 cells. It is envisioned that our VSDC will open up new avenues for high-throughput and label-free single-cell analysis in various biomedical applications.

The Utilization of Optically Induced Dielectrophoresis (ODEP)-Based Cell Manipulation in a Microfluidic System for the Purification and Sorting of Circulating Tumor Cells (CTCs) with Different Sizes

The analysis of circulating tumor cells (CTCs) at the molecular level holds great promise for several clinical applications. For this goal, the harvest of high-purity, size-sorted CTCs with different subtypes from a blood sample are important. For this purpose, a two-step CTC isolation protocol was proposed, by which the immunomagnetic beads-based cell separation was first utilized to remove the majority of blood cells. After that, an optically induced dielectrophoresis (ODEP) microfluidic system was developed to (1) purify the CTCs from the remaining magnetic microbeads-bound blood cells and to (2) sort and separate the CTCs with different sizes. In this study, the ODEP microfluidic system was designed and fabricated. Moreover, its optimum operation conditions and performance were explored. The results exhibited that the presented technique was able to purify and sort the cancer cells with two different sizes from a tested cell suspension in a high-purity (93.5% and 90.1% for the OECM 1 and HA22T cancer cells, respectively) manner. Overall, this study presented a technique for the purification and sorting of cancer cells with different sizes. Apart from this application, the technique is also useful for other applications in which the high-purity and label-free purification and sorting of cells with different sizes is required.

Rapid detection of EGFR mutation in CTCs based on a double spiral microfluidic chip and the real-time RPA method

Circulating tumor cells (CTCs) are cells shed from primary or metastatic tumors and spread into the peripheral bloodstream. Mutation detection in CTCs can reveal vital genetic information about the tumors and can be used for "liquid biopsy" to indicate cancer treatment and targeted medication. However, current methods to measure the mutations in CTCs are based on PCR or DNA sequencing which are cumbersome and time-consuming and require sophisticated equipment. These largely limited their applications especially in areas with poor healthcare infrastructure. Here we report a simple, convenient, and rapid method for mutation detection in CTCs, including an example of a deletion at exon 19 (Del19) of the epidermal growth factor receptor (EGFR). CTCs in the peripheral blood of NSCLC patients were first sorted by a double spiral microfluidic chip with high sorting efficiency and purity. The sorted cells were then lysed by proteinase K, and the E19del mutation was detected via real-time recombinase polymerase amplification (RPA). Combining the advantages of microfluidic sorting and real-time RPA, an accurate mutation determination was realized within 2 h without professional operation or complex data interpretation. The method detected as few as 3 cells and 1% target variants under a strongly interfering background, thus, indicating its great potential in the non-invasive diagnosis of E19del mutation for NSCLC patients. The method can be further extended by redesigning the primers and probes to detect other deletion mutations, insertion mutations, and fusion genes. It is expected to be a universal molecular diagnostic tool for real-time assessment of relevant mutations and precise adjustments in the care of oncology patients.

Circulating tumour cells in the -omics era: how far are we from achieving the 'singularity'?

Over the past decade, cancer diagnosis has expanded to include liquid biopsies in addition to tissue biopsies. Liquid biopsies can result in earlier and more accurate diagnosis and more effective monitoring of disease progression than tissue biopsies as samples can be collected frequently. Because of these advantages, liquid biopsies are now used extensively in clinical care. Liquid biopsy samples are analysed for circulating tumour cells (CTCs), cell-free DNA, RNA, proteins and exosomes. CTCs originate from the tumour, play crucial roles in metastasis and carry information on tumour heterogeneity. Multiple single-cell omics approaches allow the characterisation of the molecular makeup of CTCs. It has become evident that CTCs are robust biomarkers for predicting therapy response, clinical development of metastasis and disease progression. This review describes CTC biology, molecular heterogeneity within CTCs and the involvement of EMT in CTC dynamics. In addition, we describe the single-cell multi-omics technologies that have provided insights into the molecular features within therapy-resistant and metastasis-prone CTC populations. Functional studies coupled with integrated multi-omics analyses have the potential to identify therapies that can intervene the functions of CTCs.

Distribution and Clinical Analysis of EpCAM+/Vimentin+ Circulating Tumor Cells in High-Risk Population and Cancer Patients

Circulating Tumor Cells (CTCs) are already present in the peripheral blood of patients with early tumors and even precancerous lesions. The objective of this study was to determine the count of CTCs in peripheral blood from high-risk population(HRP), healthy subjects and patients with Pan-cancer. The CTCs in the peripheral blood from HRP and cancer patients were enriched and identified based on the positive sorting method by epithelial cell adhesion molecular (EpCAM) liposome magnetic bead (Ep-LMB) and Vimentin liposome magnetic bead (Vi-LMB). Simultaneously, further analysis was carried out focusing on the clinical characteristics of patients by collecting the peripheral blood samples from healthy subjects as the parallel control. According to the results, the prepared LMBs had high specificity and stability, resulting in an average (Av) proliferation rate of over 90% for each cell line, and the average capture rate of higher than 80%. In terms of CTCs count detection in clinical blood samples, the average count was 0.9 (Ep: Av=0.6, Vi: Av=0.3), 2.4 (Ep: Av=1.4, Vi: Av=0.8) and 7.3 (Ep: Av=4.0, Vi: Av=3.3) in healthy subjects, HRP and total cancer patients, respectively. Besides, there was no obvious difference in the average count of CTCs among patients with different cancer types. While count of CTCs in the aforementioned cancer patients was statistically different from that in healthy subjects and patients with HRP. The survival time of cancer patients whose number of CTCs is greater than the average is significantly increased. Collectively, the study confirmed that CTCs can achieve early tumor detection and auxiliary diagnosis, and its number is related to the occurrence and development of tumors, and CTCs can be detected in HRP and sub-health population.

Detection of circulating tumor cells: Advances and critical concerns

Metastasis is the main cause of cancer-related death and the major challenge in cancer treatment. Cancer cells in circulation are termed circulating tumor cells (CTCs). Primary tumor metastasis is likely due to CTCs released into the bloodstream. These CTCs extravasate and form fatal metastases in different organs. Analyses of CTCs are clarifying the biological understanding of metastatic cancers. These data are also helpful to monitor disease progression and to inform the development of personalized cancer treatment-based liquid biopsy. However, CTCs are a rare cell population with 1-10 CTCs per ml and are difficult to isolate from blood. Numerous approaches to detect CTCs have been developed based on the physical and biological properties of the cells. The present review summarizes the progress made in detecting CTCs.

Circulating tumor cell detection and single-cell analysis using an integrated workflow based on ChimeraX® -i120 Platform: A prospective study

Circulating tumor cell (CTC) analysis holds great potential to be a noninvasive solution for clinical cancer management. A complete workflow that combined CTC detection and single‐cell molecular analysis is required. We developed the ChimeraX^®‐i120 platform to facilitate negative enrichment, immunofluorescent labeling, and machine learning‐based identification of CTCs. Analytical performances were evaluated, and a total of 477 participants were enrolled to validate the clinical feasibility of ChimeraX^®‐i120 CTC detection. We analyzed copy number alteration profiles of isolated single cells. The ChimeraX^®‐i120 platform had high sensitivity, accuracy, and reproducibility for CTC detection. In clinical samples, an average value of > 60% CTC‐positive rate was found for five cancer types (i.e., liver, biliary duct, breast, colorectal, and lung), while CTCs were rarely identified in blood from healthy donors. In hepatocellular carcinoma patients treated with curative resection, CTC status was significantly associated with tumor characteristics, prognosis, and treatment response (all P < 0.05). Single‐cell sequencing analysis revealed that heterogeneous genomic alteration patterns resided in different cells, patients, and cancers. Our results suggest that the use of this ChimeraX^®‐i120 platform and the integrated workflow has validity as a tool for CTC detection and downstream genomic profiling in the clinical setting.

Bladder preservation: Translating discovery for clinical impact in urothelial cancer

Muscle-invasive bladder cancer can be treated with either radical cystectomy or bladder preservation approaches, and there is a need for reliable biomarkers to guide the optimal choice of therapy. The recent elucidation of the genomic landscape and biological drivers of bladder cancer has enabled the identification of tumor molecular features that may be helpful in driving clinical decision-making. Here, we summarize recent efforts to develop molecular biomarkers that could be leveraged to guide therapeutic decisions, post-treatment monitoring, and the optimal use of bladder preservation approaches for the effective treatment of muscle-invasive bladder cancer.

Circulating tumour cell enumeration does not correlate with Miller-Payne grade in a cohort of breast cancer patients undergoing neoadjuvant chemotherapy

Purpose

The association between pathological complete response (pCR) in patients receiving neoadjuvant chemotherapy (NAC) for breast cancer and Circulating Tumour Cells (CTCs) is not clear. The aim of this study was to assess whether CTC enumeration could be used to predict pathological response to NAC in breast cancer as measured by the Miller–Payne grading system.

Methods

Twenty-six patients were recruited, and blood samples were taken pre- and post-NAC. CTCs were isolated using the ScreenCell device and stained using a modified Giemsa stain. CTCs were enumerated by 2 pathologists and classified as single CTCs, doublets, clusters/microemboli and correlated with the pathological response as measured by the Miller–Payne grading system. χ² or ANOVA was performed in SPSS 24.0 statistics software for associations.

Results

89% of patients had invasive ductal carcinoma (IDC) and 11% invasive lobular carcinoma (ILC). At baseline 85% of patients had CTCs present, median 7 (0–161) CTCs per 3 ml of whole blood. Post-chemotherapy, 58% had an increase in CTCs. This did not correlate with the Miller–Payne grade of response. No significant association was identified between the number of CTCs and clinical characteristics; however, we did observe a correlation between pre-treatment CTC counts and body mass index, p < 0.05.

Conclusions

Patients with a complete response to NAC still had CTCs present, suggesting enumeration is not sufficient to aid surgery stratification. Additional characterisation and larger studies are needed to further characterise CTCs isolated pre- and post-chemotherapy. Long-term follow-up of these patients will determine the significance of CTCs in NAC breast cancer patients.

Electronic supplementary material

The online version of this article (10.1007/s10549-020-05658-7) contains supplementary material, which is available to authorized users.

Microfluidics for label-free sorting of rare circulating tumor cells

A review discussing the working principles and performances of label-free CTC sorting methods.

Molecular biomarkers in bladder preservation therapy for muscle-invasive bladder cancer

Although muscle-invasive bladder cancer is commonly treated with radical cystectomy, a standard alternative is bladder preservation therapy, consisting of maximum transurethral bladder tumour resection followed by radiotherapy with concurrent chemotherapy. Although no successfully completed randomised comparisons are available, the two treatment paradigms seem to have similar long-term outcomes; however, clinicopathologic parameters can be insufficient to provide clear guidance in the selection of one treatment over the other. Recent advances in the molecular understanding of bladder cancer have led to the identification of new predictive biomarkers that ultimately might help guide the tailored selection of therapy on the basis of the intrinsic biology of the tumour. In this Review, we discuss the existing evidence for molecular alterations and genomic signatures as prognostic or predictive biomarkers for bladder preservation therapy. If validated in prospective clinical trials, such biomarkers could enable the identification of subgroups of patients who are more likely to benefit from one treatment over another, and guide the use of combination therapies that include other modalities, such as immunotherapy, which might act synergistically with radiotherapy.

Immunomagnetic isolation of circulating melanoma cells and detection of PD-L1 status

Personalised medicine targeted to specific biomarkers such as BRAF and c-Kit has radically improved the success of melanoma therapy. More recently, further advances have been made using therapies targeting the immune response. In particular, therapies targeting the PD-1/PD-L1 or CTLA-4 axes alone or in combination have shown more sustained responses in 30–60% of patients. However, these therapies are associated with considerable toxicities and useful biomarkers to predict responders and non-responders are slow to emerge. Here we developed a reliable melanoma circulating tumor cell (CTC) detection method with PD-L1 evaluation on CTCs. A set of melanoma cell surface markers was tested as candidates for targeted melanoma CTC isolation and a melanoma specific immunostaining-based CTC identification protocol combined with PD-L1 detection was established. In vitro testing of the effect of exposure to blood cells on melanoma cell PD-L1 expression was undertaken. Immunomagnetic targeting isolated melanoma CTCs in up to 87.5% of stage IV melanoma patient blood samples and 3 8.6% of these had some PD-L1 expressing CTCs. Our in vitro data demonstrate PD-L1 induction on melanoma cells in the blood.This study established a robust, reliable method to isolate melanoma CTCs and detect expression of PD-L1 on these cells.