Circulating Tumor Cells Phenotypes Research Articles

Circulating tumor cell copy-number heterogeneity in ALK-rearranged non-small-cell lung cancer resistant to ALK inhibitors

Gatekeeper mutations are identified in only 50% of the cases at resistance to Anaplastic Lymphoma Kinase (ALK)-tyrosine kinase inhibitors (TKIs). Circulating tumor cells (CTCs) are relevant tools to identify additional resistance mechanisms and can be sequenced at the single-cell level. Here, we provide in-depth investigation of copy number alteration (CNA) heterogeneity in phenotypically characterized CTCs at resistance to ALK-TKIs in ALK-positive non-small cell lung cancer. Single CTC isolation and phenotyping were performed by DEPArray or fluorescence-activated cell sorting following enrichment and immunofluorescence staining (ALK/cytokeratins/CD45/Hoechst). CNA heterogeneity was evaluated in six ALK-rearranged patients harboring ≥ 10 CTCs/20 mL blood at resistance to 1st and 3rd ALK-TKIs and one presented gatekeeper mutations. Out of 82 CTCs isolated by FACS, 30 (37%) were ALK+/cytokeratins-, 46 (56%) ALK-/cytokeratins+ and 4 (5%) ALK+/cytokeratins+. Sequencing of 43 CTCs showed highly altered CNA profiles and high levels of chromosomal instability (CIN). Half of CTCs displayed a ploidy >2n and 32% experienced whole-genome doubling. Hierarchical clustering showed significant intra-patient and wide inter-patient CTC diversity. Classification of 121 oncogenic drivers revealed the predominant activation of cell cycle and DNA repair pathways and of RTK/RAS and PI3K to a lower frequency. CTCs showed wide CNA heterogeneity and elevated CIN at resistance to ALK-TKIs. The emergence of epithelial ALK-negative CTCs may drive resistance through activation of bypass signaling pathways, while ALK-rearranged CTCs showed epithelial-to-mesenchymal transition characteristics potentially contributing to ALK-TKI resistance. Comprehensive analysis of CTCs could be of great help to clinicians for precision medicine and resistance to ALK-targeted therapies.

Epithelial circulating tumor cells with a heterogeneous phenotype are associated with metastasis in NSCLC

ObjectivesTo analyze the clinical relevance of heterogeneous phenotypes of peripheral circulating tumor cells (CTCs) in non-small cell lung cancer (NSCLC).Materials and MethodsCTCs in 5 mL venous blood were enriched using the Canpatrol™ CTC technique in 82 NSCLC patients. And then, CTCs were subjected to RNA in situ hybridization with a combination of epithelial (EpCAM and CK8/18/19) and mesenchymal (vimentin and TWIST1) markers.ResultsAccording to the fluorescent dots, CTCs were classified into three groups, including epithelial CTCs (E-CTC), hybrid epithelial/mesenchymal phenotypes (E/M-CTCs) and mesenchymal CTCs (M-CTCs). In 82 NSCLC cohort, only 2 patients didn’t detect CTCs, the overall CTCs detection rate was 97.5% (80/82). For 60 treatment naïve NSCLC, only one patient didn’t detect CTCs. The median number of total CTCs, hybrid E/M phenotype CTCs, E-CTCs and M-CTCs per 5 mL blood was 22 (range 1–90), 13 (range 0–83), 1 (range 0–17 and 0–47), respectively. Hybrid E/M CTCs, especially the e = m-CTCs, significantly differed between patients with and without distant metastasis. M-CTCs in advanced NSCLC patients were significantly more than the numbers observed in early stage patients. Patients with pure hybrid E/M-CTCs showed a lower proportion in distant metastasis positive cohort compared to negative ones (7% vs 22%), while patients with E + E/M CTCs (20% vs 9%) and E/M + M CTCs (33% vs 20%) showed a higher proportion. CTCs dynamic changes after treatment in 12 advanced NSCLC patients suggested that hybrid E/M-CTCs were related to the primary tumor size at baseline, while M-CTCs may suggest the progression of NSCLC.ConclusionWe concluded that E-CTCs with a hybrid E/M phenotype are associated to metastasis in therapy-naïve NSCLC patients.

Association of Circulating Tumor Cells with Inflammatory and Biomarkers in the Blood of Patients with Metastatic Castration-Resistant Prostate Cancer.

The identification of specific biomarkers that recognize the functional drivers of heterogeneity in prostate cancer (PCa) and personalized treatment remain challenging in systemic medicine. Liquid biopsy allows for the detection and analysis of personalized predictive biomarkers in single blood samples and specifies the current stage of cancer. The aim of our preliminary study was to investigate the association between an elevated circulating tumor cell (CTC) count and the levels of inflammatory factors (IL-6 and IL-8) and biomarkers (DKK-1, PSA, sHER2, and CD44) in patients with metastasized castration-resistant PCa (mCPRC) under chemotherapy and those with localized PCa. Such an association could be used as a component of cancer progression monitoring. We compared the sensitivity and specificity of two CTC isolation platforms. Twenty-eight patients (12 mCRPC and 16 localized PCa patients) were enrolled. Over the study period, the CTC detection rates were 84% with CellCollector® and 73.5% with CellSearch® System in mCPRC patients. The CTC counts determined by the CellSearch® System (CTC_CS) were correlated significantly with the DKK-1, sHER-2, and PSA concentrations in mCRPC patients. The CTC counts captured by CellCollector® demonstrated no significant association with the concentrations of the tested blood-based biomarkers. The CTC_CS count (AUC = 0.9 (95% CI: 0.72–1.0)) and the PSA level (AUC = 0.95 (95% CI: 0.83–1.0)) presented approximately the same sensitivity and specificity for the overall survival of mCRPC patients. For better personalized characterization, further research on CTC phenotyping and their interactions with tumor-associated blood-released factors is needed.

Abstract 2601: Using chaperonin containing TCP1 as a marker to track clinically relevant circulating tumor cells

Abstract Current methods for assessing circulating tumor cells (CTC) in blood focus on capture and enumeration with epithelial markers that provide little information about the aggressive and invasive potential of CTC. As a result, valuable knowledge that improves monitoring of cancer recurrence and metastasis is lacking. To provide actionable information on CTC, we developed a CTC identification method based on detection of the second subunit of Chaperonin Containing TCP1 (CCT2). CCT is a macromolecular protein folding complex composed of eight subunits (CCT1-8) that drives expression of many tumorigenic factors. Bioinformatic analysis in multiple cancers, such as breast cancer, revealed increased gene expression in tumor tissue compared to normal tissue for CCT1-8 (p< 0.0001), with the largest differences observed in CCT2 and CCT3. Genomic alteration of CCT2 inversely correlated with cancer patient survival, and depletion of CCT2 prevented growth of murine breast tumors. In a correlative study of blood and tumor tissues from metastatic breast cancer patients, high CTC counts positively correlated with detectable CCT2 in tumor tissues. These results support CCT2 as a possible marker for CTC. To determine this, antibodies to CCT2 were validated for use in the CellSearch System (CSS), currently the only FDA approved CTC enrichment platform, and tested with breast cancer cells spiked into healthy human blood. Recovery using CCT2 for identification, led to increased collection up to 6% of spiked breast cancer cells that would have been lost by standard CTC classification using cytokeratin (CK). With prognostic thresholds around 3-5 CTC/tube of blood, increased detection of even 1-2 more CTC can be significant for assessing patients' risks. Analysis in an open software program called ACCEPT (Automated CTC Classification, Enumeration and PhenoTyping) confirmed that the majority of recovered spiked cancer cells expressed CCT2. Flow cytometry analysis of spiked cancer cells confirmed that CCT2+ enriched cells expressed cancer markers CD44 or estrogen receptor (ER). These results show that the addition of CCT2 staining to a CTC detection protocol has positive implications for enumeration of CTC from blood, such as increased detection of CTC with low expression of epithelial markers. This experiment was repeated using small cell lung cancer cell lines with similar results. The combined bioinformatics, histologic and experimental results indicate that identification of CCT2-expressing CTC can be incorporated into CTC detection platforms to monitor those patients with a heightened risk for cancer recurrence or metastasis. Citation Format: Amanda Cox, Ana Martini, Eunkyung Lee, Rebecca Moroose, Amr Khaled, Annette R. Khaled. Using chaperonin containing TCP1 as a marker to track clinically relevant circulating tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2601.

Association of Preoperative NANOG-Positive Circulating Tumor Cell Levels With Recurrence of Hepatocellular Carcinoma.

BackgroundCancer stem cells (CSCs) and Circulating tumor cells (CTCs) have been proposed as fundamental causes for the recurrence of hepatocellular carcinoma (HCC). CTCs isolated from patients with HCC illustrate a unique Nanog expression profile analysis. The aim of this study was to enhance the prediction of recurrence and prognosis of the CTC phenotype in patients with HCC by combining Nanog expression into a combined forecasting model.Subjects, Materials, and MethodsWe collected 320 blood samples from 160 patients with HCC cancer before surgery and used CanPatrol™ CTC enrichment technology and in situ hybridization (ISH) to enrich and detect CTCs and CSCs. Nanog expression in all CTCs was also determined. In addition, RT-PCR and immunohistochemistry were used to study the expression of Nanog, E-Cadherin, and N-Cadherin in liver cancer tissues and to conduct clinical correlation studies.ResultsThe numbers of EpCAM mRNA+ CTCs and Nanog mRNA+ CTCs were strongly correlated with postoperative HCC recurrence (CTC number (P = 0.03), the total number of mixed CTCS (P = 0.02), and Nanog> 6.7 (P = 0.001), with Nanog > 6.7 (P = 0.0003, HR = 2.33) being the most crucial marker. There are significant differences in the expression of Nanog on different types of CTC: most Epithelial CTCs do not express Nanog, while most of Mixed CTC and Mesenchymal CTC express Nanog, and their positive rates are 38.7%, 66.7%, and 88.7%, respectively, (P=0.0001). Moreover, both CTC (≤/> 13.3) and Nanog (≤/>6.7) expression were significantly correlated with BCLC stage, vascular invasion, tumor size, and Hbv-DNA (all P < 0.05). In the young group and the old group, patients with higher Nanog expression had a higher recurrence rate. (P < 0.001).ConclusionsThe number of Nanog-positive cells showed positive correlation with the poor prognosis of HCC patients. The detection and analysis of CTC markers (EpCAM and CK8, 18, CD45 Vimentin,Twist and 19) and CSCs markers (NANOG) are of great value in the evaluation of tumor progression.

Evaluation of a marker independent isolation method for circulating tumor cells in esophageal adenocarcinoma.

The enrichment of circulating tumor cells (CTCs) from blood provides a minimally invasive method for biomarker discovery in cancer. Longitudinal interrogation allows monitoring or prediction of therapy response, detection of minimal residual disease or progression, and determination of prognosis. Despite inherent phenotypic heterogeneity and differences in cell surface marker expression, most CTC isolation technologies typically use positive selection. This necessitates the optimization of marker-independent CTC methods, enabling the capture of heterogenous CTCs. The aim of this report is to compare a size-dependent and a marker-dependent CTC-isolation method, using spiked esophageal cells in healthy donor blood and blood from patients diagnosed with esophageal adenocarcinoma. Using esophageal cancer cell lines (OE19 and OE33) spiked into blood of a healthy donor, we investigated tumor cell isolation by Parsortix post cell fixation, immunostaining and transfer to a glass slide, and benchmarked its performance against the CellSearch system. Additionally, we performed DEPArray cell sorting to infer the feasibility to select and isolate cells of interest, aiming towards downstream single-cell molecular characterization in future studies. Finally, we measured CTC prevalence by Parsortix in venous blood samples from patients with various esophageal adenocarcinoma tumor stages. OE19 and OE33 cells were spiked in healthy donor blood and subsequently processed using CellSearch (n = 16) or Parsortix (n = 16). Upon tumor cell enrichment and enumeration, the recovery rate ranged from 76.3 ± 23.2% to 21.3 ± 9.2% for CellSearch and Parsortix, respectively. Parsortix-enriched and stained cell fractions were successfully transferred to the DEPArray instrument with preservation of cell morphology, allowing isolation of cells of interest. Finally, despite low CTC prevalence and abundance, Parsortix detected traditional CTCs (i.e. cytokeratin+/CD45-) in 8/29 (27.6%) of patients with esophageal adenocarcinoma, of whom 50% had early stage (I-II) disease. We refined an epitope-independent isolation workflow to study CTCs in patients with esophageal adenocarcinoma. CTC recovery using Parsortix was substantially lower compared to CellSearch when focusing on the traditional CTC phenotype with CD45-negative and cytokeratin-positive staining characteristics. Future research could determine if this method allows downstream molecular interrogation of CTCs to infer new prognostic and predictive biomarkers on a single-cell level.

Heterogeneous Circulating Tumor Cells in Sarcoma: Implication for Clinical Practice.

Simple SummaryThe present review is aimed to discuss the relevance of assaying for the presence and isolation of circulating tumor cells (CTCs) in patients with sarcoma. Just a few studies have been performed to detect and enumerate viable CTCs in sarcoma and a majority of them still represent proof-of-concept studies, while more frequently tumor cells have been detected in the circulation by using the PCR-based method. Nevertheless, recent advances in technologies allowed detection of epithelial–mesenchymal transitioned CTCs from patients with mesenchymal malignancies, despite results being mostly preliminary. The possibility to identify CTCs holds a great promise for both applications of liquid biopsy in sarcoma for precision medicine, and for research purposes to pinpoint the mechanism of the metastatic process through the characterization of tumor mesenchymal cells. Coherently, clinical trials in sarcoma have been designed accordingly to detect CTCs, for diagnosis, identification of novel therapeutic targets and resistance mechanisms of systemic therapies, and patient stratification.Bone and soft tissue sarcomas (STSs) represent a group of heterogeneous rare malignant tumors of mesenchymal origin, with a poor prognosis. Due to their low incidence, only a few studies have been reported addressing circulating tumor cells (CTCs) in sarcoma, despite the well-documented relevance for applications of liquid biopsy in precision medicine. In the present review, the most recent data relative to the detection and isolation of viable and intact CTCs in these tumors will be reviewed, and the heterogeneity in CTCs will be discussed. The relevance of epithelial–mesenchymal plasticity and stemness in defining the phenotypic and functional properties of these rare cells in sarcoma will be highlighted. Of note, the existence of dynamic epithelial–mesenchymal transition (EMT)-related processes in sarcoma tumors has only recently been related to their clinical aggressiveness. Also, the presence of epithelial cell adhesion molecule (EpCAM)-positive CTC in sarcoma has been weakly correlated with poor outcome and disease progression, thus proving the existence of both epithelial and mesenchymal CTC in sarcoma. The advancement in technologies for capturing and enumerating all diverse CTCs phenotype originating from these mesenchymal tumors are presented, and results provide a promising basis for clinical application of CTC detection in sarcoma.

Circulating Tumor Cell Chromosomal Instability and Neuroendocrine Phenotype by Immunomorphology and Poor Outcomes in Men with mCRPC Treated with Abiraterone or Enzalutamide

While the detection of AR-V7 in circulating tumor cells (CTC) is associated with resistance to abiraterone or enzalutamide in men with metastatic castration-resistant prostate cancer (mCRPC), it only accounts for a minority of this resistance. Neuroendocrine (NE) differentiation or chromosomal instability (CIN) may be additional mechanisms that mediate resistance. PROPHECY was a multicenter prospective study of men with high-risk mCRPC starting abiraterone or enzalutamide. A secondary objective was to assess Epic CTC CIN and NE phenotypes before abiraterone or enzalutamide and at progression. The proportional hazards (PH) model was used to investigate the prognostic importance of CIN and NE in predicting progression-free survival and overall survival (OS) adjusting for CTC number (CellSearch), AR-V7, prior therapy, and clinical risk score. The PH model was utilized to validate this association of NE with OS in an external dataset of patients treated similarly at Memorial Sloan Kettering Cancer Center (MSKCC; New York, NY). We enrolled 118 men with mCRPC starting on abiraterone or enzalutamide; 107 were evaluable on the Epic platform. Of these, 36.4% and 8.4% were CIN positive and NE positive, respectively. CIN and NE were independently associated with worse OS [HR, 2.2; 95% confidence interval (CI), 1.2-4.0 and HR 3.8; 95% CI, 1.2-12.3, respectively] when treated with abiraterone/enzalutamide. The prognostic significance of NE positivity for worse OS was confirmed in the MSKCC dataset (n = 173; HR, 5.7; 95% CI, 2.6-12.7). A high CIN and NE CTC phenotype is independently associated with worse survival in men with mCRPC treated with abiraterone/enzalutamide, warranting further prospective controlled predictive studies to inform treatment decisions.

Circulating tumor cells after neoadjuvant chemotherapy are related with recurrence in esophageal squamous cell carcinoma.

Circulating tumor cells (CTCs) are known to be a systemic process of malignant progression of cancer cells and there is a possibility that analysis for CTCs as a liquid biopsy become predictive or prognostic tools for cancer patients. In the present study with the novel CTCs detection system (Celsee system®), we performed quantitative and qualitative analysis of CTCs in patients with esophageal squamous cell carcinoma (ESCC) receiving neoadjuvant chemotherapy (NAC) with 5FU + CDDP regimen. CTCs are defined as having both DAPI positive and CD45 negative. Vimentin-positive CTCs were defined as mesenchymal-type CTCs (M-CTCs), while epithelial-type CTCs (E-CTCs) were only positive for pan-cytokeratin. At the baseline, there are detectable amounts of CTCs in all patients (n = 30) at all stages, and there were no significant differences of total CTCs, E-CTCs, or M-CTCs numbers between stages. Of importance, among total CTCs, M-CTCs are more dominant than E-CTCs in number. Also, there was no significant change of detectable amounts and phenotype of CTCs before and after NAC (n = 24). Of note, early recurrent group indicated that there was an elevated total CTCs number before NAC and an increased M-CTCs after NAC in comparison to those in non-recurrent group. Quantitative and qualitative analysis of CTCs may provide useful complementary predictive and prognostic information in ESCC.

Abstract PD3-12: Efficacy of the tyrosine kinase inhibitor lapatinib in the treatment of patients with HER2-negative metastatic breast cancer and HER2-positive circulating tumor cells - results from the randomized phase III DETECT III trial

Abstract Background: It is well-known that tumor biology may change during the course of the disease due to clonal evolution, and such changes might have important implications for response to targeted treatments. Circulating tumor cells (CTCs) could serve as a real-time liquid biopsy to detect changes in tumor biology. It has been demonstrated that patients with HER2-negative metastatic breast cancer (MBC) may have discordant, HER2-positive CTCs in the peripheral blood. However, up to now there is no randomized clinical trial investigating whether treatment decisions based on CTC phenotype provide benefits in terms of improved outcome. The aim of the DETECT III study is to investigate whether patients with initially HER2-negative MBC and HER2-positive CTCs benefit from HER2-targeted therapy with the tyrosine kinase inhibitor lapatinib. In addition, the significance of CTCs as an early predictive marker for response to therapy will be analyzed. Methods: The randomized phase III DETECT III trial (NCT01619111) compares lapatinib in combination with standard therapy versus standard therapy alone in patients with initially HER2-negative MBC and HER2-positive CTCs. Efficacy of lapatinib treatment is evaluated by CTC clearance rate, progression-free survival (PFS) and overall survival (OS). In addition, we investigate the association between CTC results and both PFS and OS to assess the utility of CTCs as an early predictive marker for treatment response. CTC enumeration and phenotyping was performed using the CellSearch® technology (Menarini Silicon Biosystems; Bologna, Italy). Survival data are analyzed using log rank tests, univariable and adjusted multivariable cox regressions. Results: First results on CTC clearance rates, PFS and OS of 105 prospectively randomized patients will be presented. Conclusion: This first randomized clinical trial in breast cancer patients with treatment decisions being based on the phenotype of CTCs will show whether patients with HER2 negative MBC and HER2 positive CTCs benefit from additional HER2-targeted therapy with lapatinib. This finding might be increasingly important as novel HER2-targeted drugs become available. Citation Format: Tanja Fehm, Volkmar Mueller, Maggie Banys-Paluchowski, Peter A Fasching, Thomas WP Friedl, Andreas Hartkopf, Jens Huober, Christian Loehberg, Brigitte Rack, Sabine Riethdorf, Andreas Schneeweiss, Diethelm Wallwiener, Franziska Meier-Stiegen, Oliver Hoffmann, Lothar Müller, Pauline Wimberger, Eugen Ruckhaeberle, Jens Blohmer, Wolfgang Janni. Efficacy of the tyrosine kinase inhibitor lapatinib in the treatment of patients with HER2-negative metastatic breast cancer and HER2-positive circulating tumor cells - results from the randomized phase III DETECT III trial [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD3-12.

Abstract GS1-05: Hotspot ESR1 mutations rewire cell-cell adhesome to facilitate breast cancer metastasis

Abstract Background: Estrogen receptor alpha (ER/ESR1) mutations are found in 20-40% of endocrine resistant ER+ metastatic breast cancers, and they are associated with worse outcome. Preclinical studies have shown that they cause ligand-independent growth, resistance to endocrine therapy, and there is growing evidence for a role in metastasis. It is not known how ESR1 mutant cancer cells cause metastases and whether such a mechanism may indicate novel therapeutic options. Methods: ddPCR was used to detect hotspot ESR1 mutations. Transcriptome data were derived from cell line models and clinical samples. For in vitro phenotypic characterization, Y537S and D538G genome-edited MCF7 and T47D cell models from four different labs were used. Cell-cell adhesive properties were assessed using calcein-labelled adhesion, spontaneous cell aggregation and microfluidic aggregation assays. Altered expression of cell-cell adhesion genes detected in RNA seq data was validated via qRT-PCR, immunoblot and immune staining. Functional contributions of desmosome and gap junctions were tested by blocking peptide and carbenoxolone respectively. Mutant ER cistromes were profiled using ChIP-sequencing. Tail vein injection was performed on nude mice to evaluate metastasis in vivo. Mouse lung micro-metastatic foci were quantified using human-specific CK19 staining. Circulating tumor cells (CTCs) clustering propensity in vivo was assessed via intracardiac injection of ESR1 WT and mutant cells into nude mice following CTC microfilter capture. CTCs enumeration from breast cancer patients’ blood samples was performed using CellSearchTM system. Results: We identified a significant enrichment of ESR1 mutations in distant (12/48) vs local (0/27) recurrences, confirming the strong association of mutant ER with metastasis. Transcriptomic analysis revealed altered cell-to-cell interaction pathways in ESR1 mutant tumors compared to ESR1 WT tumors, suggesting a previously undescribed role of ESR1 mutations in reprogramming cell-cell adhesome. ESR1 mutant cells grown in suspension culture revealed more compact multicellular spheroids compared to WT cells. This observation was confirmed under both static and microfluidic conditions, indicative of increased cell-cell interactions. The effect was more pronounced in MCF7 compared to T47D cells, and it correlated with increased expression of multiple desmosome and gap junction pathway genes, which were also significantly enriched in ESR1 mutant tumors. Pharmacological blockade of desmosome and gap junctions significantly rescued enhanced cell-cell adhesion in ESR1 mutant cells. Mechanistically, our ER ChIP-seq did not identify any gained mutant ER binding sites in proximity to cell-cell adhesion gene loci, indicating indirect regulation by mutant ER. Consistent with this, expression of Connexin 43, one of the top upregulated gap junction components, was induced by cFOS found to be highly upregulated in ESR1 mutant cells. Tail vein injection of ESR1-mutant cells derived more distant macro- (MCF7) and micro- (T47D) metastases. Given increasing evidence for role of cell-cell attachment in CTC phenotypes, we tested CTC formation for ESR1 WT and mutant cells. In vivo studies showed MCF7 Y537S ESR1 mutant cells formed larger multi-cellular CTC clusters with increased compactness compared to WT CTCs. These preclinical data translated to clinical observation, where we observed an enrichment of CTC clusters in patients with ESR1 mutant-metastatic breast cancers. Conclusion: Hotspot ESR1 mutations induce expression of multiple desmosome and gap junction genes and confer increased cell-cell adhesion, which facilitate breast cancer metastasis via increased CTCs clustering propensity. These findings might guide approaches to test potential repurpose of drugs targeting gap junction in ER mutant tumors. Citation Format: Zheqi Li, Yang Wu, Amir Bahreini, Jian Chen, Ye Qin, Kevin M. Levine, Nilgun Tasdemir, Nolan Priedigkeit, Li Zhu, George C. Tseng, Yu Jiang, Benjamin Troness, Laki Buluwela, Simak Ali, Spencer Arnesen, Jason Gertz, Ben H. Park, Qiang Zhang, Lorenzo Gerratana, Andrew Davis, Jennifer M. Atkinson, Dorraya El-Ashry, Massimo Cristofanilli, Adrian V. Lee, Steffi Oesterreich. Hotspot ESR1 mutations rewire cell-cell adhesome to facilitate breast cancer metastasis [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr GS1-05.

The Blood Microenvironment Influences the Molecular Phenotypes of Circulating Tumor Cells in Head and Neck Squamous Cell Carcinoma.

Circulating tumor cells (CTCs) may be affected by the environment encountered during blood circulation. We aimed to explore the association between the molecular phenotype of CTCs and systemic inflammatory markers. CTCs isolated from patients with recurrent/metastatic head and neck squamous cell carcinoma by CD45-negative selection were analyzed for the expression of multiple genes. The correlations between gene expression levels in CTCs and systemic inflammation markers were examined. Thirty-five (83.3%) of the 42 patients were positive for CTCs. No significant differences in systemic inflammatory markers were observed between CTC-positive and CTC-negative patients. Notably, VIM or ZEB2 expression was strongly correlated with that of CD44 or ALDH1. PIK3CA, CD44, ALDH1A1, and PDCD1LG2 expression in CTCs was correlated with lymphocyte- and/or albumin-related systemic inflammatory markers. CTCs acquire a survival advantage through phenotypic alterations in the hostile blood environment, and evade circulatory immune surveillance.

A PLGA nanofiber microfluidic device for highly efficient isolation and release of different phenotypic circulating tumor cells based on dual aptamers.

The isolation of specific and sensitive circulating tumor cells (CTCs) is significant for applying them in cancer diagnosis and monitoring. In this work, dual aptamer-modified poly(lactic-co-glycolic acid) (PLGA) nanofiber-based microfluidic devices were fabricated to achieve the highly efficient capture and specific release of epithelial and mesenchymal CTCs of ovarian cancer. Dual aptamer targeting epithelial cell adhesion molecules (EpCAM) and N-cadherin proteins to improve the capture sensitivity, bovine serum albumin (BSA) to guarantee the capture purity and the nanofibers to increase the capture efficiency via synchronously and effectively capturing the epithelial and mesenchymal CTCs with good capture specificity and sensitivity from blood samples were used. We used the target cells including the ovarian cancer A2780 cells (N-cadherin-high, EpCAM-low) and OVCAR-3 cells (EpCAM-high, N-cadherin-low) to test the devices, which exhibited good capture efficiency (91% for A2780 cells, 89% for OVCAR-3 cells), release efficiency (95% for A2780 cells, 88% for OVCAR-3 cells), and sensitivity for rare cells (92% for A2780 cells, 88% for OVCAR-3 cells). Finally, the clinical blood samples of ovarian cancer patients were detected by the PLGA nanofiber-based microfluidic device, and 1 to 13 CTCs were successfully confirmed to be captured with the help of immunofluorescence staining identification. The results exhibited that the dual aptamer-modified PLGA nanofiber-based microfluidic device used as a tool for CTC capture has the potential for clinical application to guide the diagnosis, treatment, and prognosis of ovarian cancer patients.

Multifaceted modifications for a cell size-based circulating tumor cell scope technique hold the prospect for large-scale application in general populations.

Circulating tumor cells (CTCs) indicate the diagnosis and prognosis of cancer patients, together with benefiting individual treatment and anticancer drug development. However, their large-scale application in general population still requires systematically multifaceted modifications for currently proprietary new technologies based on filtration. We primitively utilized a cell size-based platform to evaluate the recovery efficiency of spiked abnormal cell lines and analyzed circulating abnormal cells (CACs). To dissect the subpopulations of CACs, we conducted immunofluorescent (IF) staining with a combination of unique biomarkers of CTCs and circulating endothelial cells (CECs). Furthermore, we improved the CTC screening system by assessing the feasibility of transferring CTCs for automatic IF analysis, together with simulating and optimizing the circumstances for long-term CTC storage and transportation. We detected CACs in 15 HD candidates with CTC characteristics such as abnormally large cytomorphology, high nuclear-cytoplasmic ratio, and positive for panCK or VIM staining. Thereafter, we improved accuracy of the platform by distinguishing CTCs from CECs, which satisfied the elementary requirement for small-scale CTC screening in HD candidates. Finally, large-scale CTC screening in general population was available after multifaceted modifications including automatic analysis by transferring CTCs onslides, choosing the appropriate blood-collecting tube, optimizing the conditions for long-term CTC storage and transportation, and evaluating the potential effect on the CTC phenotype. Hence, we systematically modified the scope of technique parameters, improved the accuracy of early cancer detection, and made it realizable for large-scale CTC or CEC screening in general population.

Abstract IA-02: Pancreatic cancer heterogeneity and plasticity: The mix of seed and soil

Abstract A series of transcriptomic analyses of human pancreatic ductal adenocarcinoma (PDAC) have consistently demonstrated multiple cancer subtypes with different functional behavior in preclinical models and patient outcomes in clinical studies. The two major molecular subtypes described in PDAC are the classical epithelial (E) and the quasi-mesenchymal (QM) subtypes, otherwise known as the basal-like or squamous subtype. Although a model of E and QM subtypes to dichotomize PDAC tumor behavior affords the simplicity of use in biomarker and functional studies, there has been increasing evidence of epithelial mesenchymal transition (EMT) transcriptional plasticity of PDAC cells in model systems as well as evidence from single cell RNA-seq studies. This suggests that the E and QM states are on a continuum that can result in interconverting cell types. We have utilized single cell technologies, functional model systems, and human tumor analysis to characterize the landscape of PDAC heterogeneity and the factors involved with cellular plasticity between E and QM states. Initial single cell RNA-seq studies in PDAC mouse models revealed that partial EMT is enriched in circulating tumor cells (CTCs) compared to primary tumor cells (Ting DT et al. Cell Reports 2014). These CTCs were also highly enriched for extracellular matrix (ECM) gene expression that were shared with stromal fibroblasts in the primary tumor indicating that the “seeds” of metastasis produce their own “soil”. Functional studies in patient derived PDAC cell lines and cancer associated fibroblasts (CAFs) revealed EMT heterogeneity was partially driven by the relative amounts of stromal CAFs (Ligorio M*, Sil S* et al. Cell 2019). Using RNA in situ hybridization (RNA-ISH) in human primary PDAC tumors and high content digital image analysis, we classified individual tumor cells for EMT and proliferative (PRO) phenotypes that were linked with relative stromal content and characterize the significant inter- and intra-tumoral heterogeneity of these cell types within distinct tumor glands. In addition, analysis of PDAC tumorspheres revealed a significant induction of EMT changes in response to FOLFIRINOX, which was also found in patient tumors that were resected after neoadjuvant FOLFIRINOX (Porter RL et al. PNAS 2019). Finally, we have recently characterized human PDAC CTCs that has identified 4 different stem cell genes (WNT5A/KLF4, LGALS3, LIN28B) that are enriched in these metastatic precursors and cluster separately between patients (Franses JW*, Philipp J* et al. Nature Communications 2020). Each of these CTC phenotypes are all associated with EMT features suggestive of different pathways that can achieve similar metastatic behavior. Altogether, single cell heterogeneity of PDAC is functionally linked with tumor stromal interactions, response to chemotherapy, and the ability to seed distant metastases. Citation Format: David T. Ting. Pancreatic cancer heterogeneity and plasticity: The mix of seed and soil [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr IA-02.

Abstract 5372: HER2 expression on tumor-derived extracellular vesicles and circulating tumor cells in metastatic breast cancer

Abstract Tumor-derived extracellular vesicles (tdEVs) and circulating tumor cells (CTCs) in blood of metastatic cancer patients associate with poor outcome. In this study, we explored the human epidermal growth factor receptor 2 (HER2) expression on CTCs and tdEVs of metastatic breast cancer patients. Blood samples from 98 patients (IC 2006-04 study) were originally processed with the CellSearch® system using the CTC kit and anti-HER2 as an additional marker in the staining cocktail. CTCs and tdEVs were automatically enumerated from the generated CellSearch image datasets using the open-source ACCEPT software. The HER2 status of the tissue was assessed by fluorescence in situ hybridization (FISH). The inclusion of anti-HER2 increased the percentage of informative samples with ≥1 detectable CTC and tdEV from 89% and 99% to 95 and 100%, respectively. CTCs and tdEVs were subdivided based on their cytokeratin (CK) and HER2 phenotype into CK+HER2-, CK-HER2+ and CK+HER2+. Inter- and intra- patient heterogeneity was found regarding the phenotype of CTCs and tdEVs with the majority of patients having all different subclasses present. CK- CTCs and tdEVs correlated equally well with clinical outcome as CK+ CTCs and tdEVs. Use of ≥7% HER2+CK+ tdEVs can predict HER2 expression of the tissue with 74% sensitivity and specificity, whereas the respective use of ≥23% HER2+CK+ CTCs leads to 65% sensitivity and 66% specificity. HER2 can be detected on CTCs and tdEVs not expressing CK, which have similar clinical relevance to CTCs and tdEVs expressing CK. tdEVs perform better than CTCs in predicting the HER2 status of the tissue. Funded by the NWO Applied and Engineering Sciences Cancer-ID project #14190, the EUFP7 CTCTrap project #305341 and the EU IMI CANCER-ID project # 115749-1. Citation Format: Afroditi Nanou, Leonie L. Zeune, Francois-Clement Bidard, Jean-Yves Pierga, Leon W. Terstappen. HER2 expression on tumor-derived extracellular vesicles and circulating tumor cells in metastatic breast cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5372.

A microfluidic device for differential capture of heterogeneous rare tumor cells with epithelial and mesenchymal phenotypes

Accumulating evidence suggests that the features associated with epithelial to mesenchymal transition (EMT) in circulating tumor cells (CTCs) reflect intrinsic metastatic potential and associate with therapy resistance. Thus, profiling the EMT phenotypes of CTCs is increasingly important for cancer diagnosis and prediction of therapeutic responses. However, rapid assessment of the EMT status of a global CTC population is still a challenge due to the difficulty in enriching and phenotyping CTCs simultaneously. Here, we report a microfluidic device consisting of an enrichment section and a capture section for differential capture of rare tumor cells from blood according to their EMT phenotypes. A row of micropillars was constructed in the enrichment section to provide cross-flows for the size-dependent filtration of cells. Thus, MCF-7 and MDA-MB-231 tumor cells mimicking CTCs were first separated from white blood cells through the micropillars and continually flowed into the capture section at a reduced velocity under a differential hydrodynamic pressure. In the capture section, the heterogeneous tumor cells were then phenotypically sorted and captured in two cascaded compartments functionalized with either an anti-EpCAM antibody or a cocktail of antibodies against mesenchymal markers including Axl, PD-L1, and EGFR. Direct counting of the captured cells in each compartment resulted in the enumeration of epithelial and mesenchymal subpopulations of the tumor cells without additional labeling. Furthermore, the captured tumor cells were successfully maintained for up to six days in the device with high viability and marked proliferation for downstream analysis. Thus, this integrated microfluidic device may have great potential in phenotyping EMT status of CTCs for precision cancer therapy.

Cellular Mechanisms of Circulating Tumor Cells During Breast Cancer Metastasis.

Circulating tumor cells (CTCs) are cancer cells that detach from the primary site and travel in the blood stream. A higher number of CTCs increases the risk of breast cancer metastasis, and it is inversely associated with the survival rates of patients with breast cancer. Although the numbers of CTCs are generally low and the majority of CTCs die in circulation, the survival of a few CTCs can seed the development of a tumor at a secondary location. An increasing number of studies demonstrate that CTCs undergo modification in response to the dynamic biophysical environment in the blood due in part to fluid shear stress. Fluid shear stress generates reactive oxygen species (ROS), triggers redox-sensitive cell signaling, and alters the function of intracellular organelles. In particular, the mitochondrion is an important target organelle in determining the metastatic phenotype of CTCs. In healthy cells, mitochondria produce adenosine triphosphate (ATP) via oxidative phosphorylation in the electron transport chain, and during oxidative phosphorylation, they produce physiological levels of ROS. Mitochondria also govern death mechanisms such as apoptosis and mitochondrial permeability transition pore opening to, in order eliminate unwanted or damaged cells. However, in cancer cells, mitochondria are dysregulated, causing aberrant energy metabolism, redox homeostasis, and cell death pathways that may favor cancer invasiveness. In this review, we discuss the influence of fluid shear stress on CTCs with an emphasis on breast cancer pathology, then discuss alterations of cellular mechanisms that may increase the metastatic potentials of CTCs.

Correlations between circulating tumor cell phenotyping and 18F-fluorodeoxyglucose positron emission tomography uptake in non-small cell lung cancer.

The epithelial-to-mesenchymal transition (EMT) phenotype-based subsets of circulating tumor cells (CTCs) might be predictors of tumor progression. We evaluated the clinical properties of different phenotypic CTCs in patients with non-small cell lung cancer (NSCLC). Secondly, we explored the association between different phenotypic CTCs and the uptake of 18F-fluorodeoxyglucose (FDG) by the primary tumor on a positron emission tomographic (PET) scan. Venous blood samples from 34 pathologically confirmed Stage IIB-IVB NSCLC patients were collected prospectively. CTCs were immunoassayed using a SE-i·FISH®CTC kit. We identified CTCs into cytokeratin positive (CK+) and cytokeratin negative (CK-) phenotypes. CTC classifications were correlated with the maximum standardized uptake value (SUVmax) measured by 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT). Overall survival (OS) and progression-free survival (PFS) curves were produced using the Kaplan-Meier method. CTCs were detected in 91.2% of NSCLC patients. CTC counting was associated with TNM stage (P = 0.014) and distant metastasis (P = 0.007). The number of CK-CTCs was also positively associated with TNM stage (P = 0.022) and distant metastasis (P = 0.007). Both total CTC counting and CK-CTC counting did not show association with SUVmax value (P = 0.959, P = 0.903). Kaplan-Meier survival analysis demonstrated that patients with ≥ 7 CTCs had shorter OS (P = 0.003) and PFS (P = 0.001)relativeto patients with < 7 CTCs). Notably, the number of CK-CTCs can act as independent risk factors for PFS (P = 0.044) and OS (P = 0.043) in NSCLC patients. However, SUVmax value was not associated with OS (P = 0.895) and PFS (P = 0.686). The CTC subpopulations could be useful evidence for testing metastasis and prognosis in NSCLC patients. The SUVmax value of the primary tumor was not related to prognosis in patients with NSCLC.

Relationship between circulating tumor cells undergoing EMT and short-term efficacy following interventional treatment in patients with hepatocellular carcinoma

ObjectiveA growing number of studies have indicated that epithelial-mesenchymal transition (EMT) phenotypes and the number of circulating tumor cells (CTCs) are significant indicators of tumor characteristics and treatment efficacy, and thus have a broad range of potential applications in the diagnosis and treatment of malignant tumors. The value of data on CTC phenotypes and CTC counts in the diagnosis of hepatocellular carcinoma (HCC) and assessment of efficacy after comprehensive interventional therapy remains unclear. MethodsData of 107 patients who exhibited space-occupying lesions in the liver on enhanced CT/MRI scans at the Guangdong Provincial People’s Hospital (a tertiary medical center) between August 2017 and October 2018, were retrospectively analyzed. All enrolled patients were treated with transcatheter arterial chemoembolization (TACE) combined with microwave ablation (MWA). An imFISH CTC assay was used to isolate and count CTCs with different EMT phenotypes in the patients’ peripheral blood, which facilitated an analysis of the value of CTC phenotype and CTC count data in the diagnosis or treatment of HCC. ResultsThe CTC count and EMT phenotypes in HCC patients were not associated with patient characteristics such as age, sex, Hepatitis B Virus (HBV)-DNA status, alcohol consumption history, Aspartate Transaminase (AST) to Platelet Ratio Index (APRI) score, Eastern Cooperative Oncology Group (ECOG) score, Child-Pugh score, alpha-fetoprotein (AFP), number and size of tumors, vascular invasion, or metastasis (P ​> ​0.05). The CTC count and EMT phenotypes in HCC patients before treatment were not predictive of short-term efficacy (P ​> ​0.05). Comprehensive interventional therapy reduced the total CTC count and mesenchymal CTC count (P ​= ​0.034 and 0.022, respectively). ConclusionTACE in combination with ablation reduced the total CTC count and mesenchymal CTC count. The CTC count and EMT phenotypes may be associated with long-term efficacy.