Frequency of Circulating Tumor Cells (CTC) in Patients with Brain Metastases: Implications as a Risk Assessment Marker in Oligo-Metastatic Disease

Exploring the Molecular Tumor Microenvironment and Translational Biomarkers in Brain Metastases of Non-Small-Cell Lung Cancer

Brain metastases represent a significant clinical challenge in the treatment of non-small-cell lung cancer (NSCLC), often leading to a severe decline in patient prognosis and survival. Recent advances in imaging and systemic treatments have increased the detection rates of brain metastases, yet clinical outcomes remain dismal due to the complexity of the metastatic tumor microenvironment (TME) and the lack of specific biomarkers for early detection and targeted therapy. The intricate interplay between NSCLC tumor cells and the surrounding TME in brain metastases is pivotal, influencing tumor progression, immune evasion, and response to therapy. This underscores the necessity for a deeper understanding of the molecular underpinnings of brain metastases, tumor microenvironment, and the identification of actionable biomarkers that can inform multimodal treatment approaches. The goal of this review is to synthesize current insights into the TME and elucidate molecular mechanisms in NSCLC brain metastases. Furthermore, we will explore the promising horizon of emerging biomarkers, both tissue- and liquid-based, that hold the potential to radically transform the treatment strategies and the enhancement of patient outcomes.

Oligometastasis: Expansion of Curative Treatments in the Field of Oncology

Oligometastasis is defined as the presence of several limited metastatic lesions and is generally limited to three or fewer than five metastatic lesions. Previously, the treatment of metastatic cancer aimed to alleviate symptoms rather than cure them; however, the use of immunotherapy or targeted therapy has greatly improved patient life expectancy. Additionally, the effectiveness and safety of local treatment have recently been proven for oligometastatic cancers and have significantly improved patient survival and decreased recurrence rates. A few metastatic studies on lung cancer have demonstrated the usefulness of combining radiation therapy and immunotherapy. Recently, local and targeted therapy combinations have shown promising results in treating non-small cell lung cancer, predominantly caused by the epidermal growth factor receptor and anaplastic lymphoma kinase gene mutations, suggesting the potential of these new treatment strategies. It is well known that oligometastasis has better clinical results than polymetastasis; however, research on the biological profile of oligometastasis is still lacking. Studies using circulating tumor DNA and circulating tumor cells are at the initial stages of providing a better understanding of oligometastatic cancers, and the biological characteristics of these cancers may be revealed based on more diverse studies. With the development of these treatments, the prognosis for patients with oligometastatic cancers is steadily improving, and if the biological profile is revealed, customized treatment may be provided.

Development and clinical validation of a microfluidic-based platform for CTC enrichment and downstream molecular analysis

Background

Although many CTC isolation and detection methods can provide information on cancer cell counts, downstream gene and protein analysis remain incomplete. Therefore, it is crucial to develop a technology that can provide comprehensive information on both the number and profile of CTC.

Methods

In this study, we developed a novel microfluidics-based CTC separation and enrichment platform that provided detailed information about CTC.

Results

This platform exhibits exceptional functionality, achieving high rates of CTC recovery (87.1%) and purification (∼4 log depletion of WBCs), as well as accurate detection (95.10%), providing intact and viable CTCs for downstream analysis. This platform enables successful separation and enrichment of CTCs from a 4 mL whole-blood sample within 15 minutes. Additionally, CTC subtypes, selected protein expression levels on the CTC surface, and target mutations in selected genes can be directly analyzed for clinical utility using immunofluorescence and real-time polymerase chain reaction, and the detected PD-L1 expression in CTCs is consistent with immunohistochemical assay results.

Conclusion

The microfluidic-based CTC enrichment platform and downstream molecular analysis together provide a possible alternative to tissue biopsy for precision cancer management, especially for patients whose tissue biopsies are unavailable.

Research Progress on Nanomaterials for Tissue Engineering in Oral Diseases

Due to their superior antibacterial properties, biocompatibility and high conductivity, nanomaterials have shown a broad prospect in the biomedical field and have been widely used in the prevention and treatment of oral diseases. Also due to their small particle sizes and biodegradability, nanomaterials can provide solutions for tissue engineering, especially for oral tissue rehabilitation and regeneration. At present, research on nanomaterials in the field of dentistry focuses on the biological effects of various types of nanomaterials on different oral diseases and tissue engineering applications. In the current review, we have summarized the biological effects of nanoparticles on oral diseases, their potential action mechanisms and influencing factors. We have focused on the opportunities and challenges to various nanomaterial therapy strategies, with specific emphasis on overcoming the challenges through the development of biocompatible and smart nanomaterials. This review will provide references for potential clinical applications of novel nanomaterials in the field of oral medicine for the prevention, diagnosis and treatment of oral diseases.

Liquid biopsy for brain metastases and leptomeningeal disease in patients with breast cancer

A significant subset of patients with metastatic breast cancer develops brain metastasis. As efficacy of systemic therapies has improved and patients live longer with metastatic breast cancer, the incidence of breast cancer brain metastases has increased. Brain metastases pose a clinical challenge in diagnosis, treatment, and monitoring across all breast cancer subtypes, and better tools are needed. Liquid biopsy, which enables minimally invasive sampling of a patient's cancer, has the potential to shed light on intra-cranial tumor biology and to improve patient care by enabling therapy tailoring. Here we review current evidence for the clinical validity of liquid biopsy in patients with breast cancer brain metastases, with a focus on circulating tumor cells and circulating tumor DNA.

Role of Nanomedicine-Based Therapeutics in the Treatment of CNS Disorders

Central nervous system disorders, especially neurodegenerative diseases, are a public health priority and demand a strong scientific response. Various therapy procedures have been used in the past, but their therapeutic value has been insufficient. The blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier is two of the barriers that protect the central nervous system (CNS), but are the main barriers to medicine delivery into the CNS for treating CNS disorders, such as brain tumors, Parkinson's disease, Alzheimer's disease, and Huntington's disease. Nanotechnology-based medicinal approaches deliver valuable cargos targeting molecular and cellular processes with greater safety, efficacy, and specificity than traditional approaches. CNS diseases include a wide range of brain ailments connected to short- and long-term disability. They affect millions of people worldwide and are anticipated to become more common in the coming years. Nanotechnology-based brain therapy could solve the BBB problem. This review analyzes nanomedicine's role in medication delivery; immunotherapy, chemotherapy, and gene therapy are combined with nanomedicines to treat CNS disorders. We also evaluated nanotechnology-based approaches for CNS disease amelioration, with the intention of stimulating the immune system by delivering medications across the BBB.

Isolation, Detection and Analysis of Circulating Tumour Cells: A Nanotechnological Bioscope

Cancer is one of the dreaded diseases to which a sizeable proportion of the population succumbs every year. Despite the tremendous growth of the health sector, spanning diagnostics to treatment, early diagnosis is still in its infancy. In this regard, circulating tumour cells (CTCs) have of late grabbed the attention of researchers in the detection of metastasis and there has been a huge surge in the surrounding research activities. Acting as a biomarker, CTCs prove beneficial in a variety of aspects. Nanomaterial-based strategies have been devised to have a tremendous impact on the early and rapid examination of tumor cells. This review provides a panoramic overview of the different nanotechnological methodologies employed along with the pharmaceutical purview of cancer. Initiating from fundamentals, the recent nanotechnological developments toward the detection, isolation, and analysis of CTCs are comprehensively delineated. The review also includes state-of-the-art implementations of nanotechnological advances in the enumeration of CTCs, along with future challenges and recommendations thereof.

The Implication of Liquid Biopsy in the Non-small Cell Lung Cancer: Potential and Expectation

Nowadays, lung cancer has remained the most lethal cancer, despite great advances in diagnosis and treatment. However, a large proportion of patients were diagnosed with locally advanced or metastatic disease and have poor prognosis. Immunotherapy and targeted drugs have greatly improved the survival and prognosis of patients with advanced lung cancer. However, how to identify the optimal patients to accept those therapies and how to monitor therapeutic efficacy are still in dispute. In the past few decades, tissue biopsy, including percutaneous fine needle biopsy and surgical excision, has still been the gold standard for examining the gene mutation such as EGFR, ALK, ROS, and PD-1/PD/L1, which can indicate the follow-up treatment. Nevertheless, the biopsy techniques mentioned above were invasive and unrepeatable, which were not suitable for advanced patients. Liquid biopsy, accounting for heterogeneity compared with tissue biopsy, is an alternative technique for monitoring the mutation, and a large quantity of research has demonstrated its feasibility to detect the circulating tumor cell, cell-free DNA, circulating tumor DNA, and extracellular vesicles from peripheral venous blood. The proposal of the concept of precision medicine brings a novel medical model developed with the rapid progress of genome sequencing technology and the cross-application of bioinformation, which was based on personalized medicine. The emerging method of liquid biopsy might contribute to promoting the development of precision medicine. In this review, we intend to describe the liquid biopsy in non-small cell lung cancer in detail in the aspect of screening, diagnosis, monitoring, treatment, and drug resistance.

Circulating tumor cells and extracellular vesicles as liquid biopsy markers in neuro-oncology: prospects and limitations

For many tumor entities, tumor biology and response to therapy are reflected by components that can be detected and captured in the blood stream. The so called “liquid biopsy” has been stratified over time into the analysis of circulating tumor cells (CTC), extracellular vesicles (EVs), and free circulating components such as cell-free nucleic acids or proteins. In neuro-oncology, two distinct areas need to be distinguished, intrinsic brain tumors and tumors metastatic to the brain. For intrinsic brain tumors, specifically glioblastoma, CTCs although present in low abundance, contain highly relevant, yet likely incomplete biological information for the whole tumor. For brain metastases, CTCs can have clinical relevance for patients especially with oligometastatic disease and brain metastasis in cancers like breast and lung cancer. EVs shed from the tumor cells and the tumor environment provide complementary information. Sensitive technologies have become available that are able to detect both, CTCs and EVs in the peripheral blood of patients with intrinsic and metastatic brain tumors despite the blood brain barrier. In reference to glioblastoma EVs, being shed by tumor cells and microenvironment and being more diffusible than CTCs may yield a more complete reflection of the whole tumor compared to low-abundance CTCs representing only a fraction of the multiclonal tumor heterogeneity. We here review the emerging aspects of CTCs and EVs as liquid biopsy biomarkers in neuro-oncology.

Differences in actionable genomic alterations between brain metastases and non‑brain metastases in patients with non‑small cell lung cancer

Brain metastases (BM) have been closely associated with increased morbidity and poor survival outcomes in patients with non‑small cell lung cancer (NSCLC). Excluding risk factors in histological subtypes, genomic alterations, including epidermal growth factor receptor mutations and anaplastic lymphoma kinase (ALK) rearrangements have been also regarded as greater risk factors for BM in the aspect of molecular subtypes. In the present study, 69 tumor tissues and 51 peripheral blood samples from patients with NSCLC were analyzed using a hybridization capture‑based next‑generation sequencing (NGS) panel, including 95 known cancer genes. Among the 90 patients with stage IV NSCLC, 26 cases suffered from BM and 64 cases did not. In total, 174 somatic mutations in 35 mutated genes were identified, and 12 of these genes were concurrently present in the BM group and the non‑BM group. Importantly, five mutated genes including ALK, cytidine deaminase (CDA), SMAD family member 4 (SMAD4), superoxide dismutase 2 (SOD2) and Von Hippel‑Lindau tumor suppressor (VHL) genes were uniquely detected in the BM group, and they were enriched in the Hippo signaling pathway, pyrimidine metabolism and pantothenate and co‑enzyme A (CoA) biosynthesis, as demonstrated using Kyoto Encyclopedia of Genes and Genomes enrichment analysis. RNA polymerase II transcription regulator complex and promyelocytic leukemia nuclear body were the top functional categories according to the Gene Ontology enrichment analysis in the BM group and non‑BM group, respectively. Furthermore, 43.33% (13/30) of mutated genes were detected by both tumor tissue deoxyribonucleic acid (DNA) and plasma‑derived circulating tumor DNA (ctDNA) in the non‑BM group, while this percentage was only limited to 29.41% (5/17) in the BM group. To summarize, significant differences in somatic mutations, somatic interactions, key signaling pathways, functional biological information, and clinical actionability for the therapy of targeted agents were founded between the BM group and the non‑BM group, and ctDNA analysis may by applied as a more credible alternative for genomic profiling in patients with advanced NSCLC without BM, due to its higher consistency for genomic profiling between ctDNA analysis and tissue DNA analysis.

Investigating the Retained Inhibitory Effect of Cobimetinib against p.P124L Mutated MEK1: A Combined Liquid Biopsy and in Silico Approach

The systemic treatment of metastatic melanoma has radically changed, due to an improvement in the understanding of its genetic landscape and the advent of targeted therapy. However, the response to BRAF/MEK inhibitors is transitory, and big efforts were made to identify the mechanisms underlying the resistance. We exploited a combined approach, encompassing liquid biopsy analysis and molecular dynamics simulation, for tracking tumor evolution, and in parallel defining the best treatment option. The samples at different time points were collected from a BRAF-mutant melanoma patient who developed an early resistance to dabrafenib/trametinib. The analysis of the circulating tumor DNA (ctDNA) identified the MEK1 p.P124L mutation that confers resistance to trametinib. With an in silico modeling, we identified cobimetinib as an alternative MEK inhibitor, and consequently suggested a therapy switch to vemurafenib/cobimetinib. The patient response was followed by ctDNA tracking and circulating melanoma cell (CMC) count. The cobimetinib administration led to an important reduction in the BRAF p.V600E and MEK1 p.P124L allele fractions and in the CMC number, features suggestive of a putative response. In summary, this study emphasizes the usefulness of a liquid biopsy-based approach combined with in silico simulation, to track real-time tumor evolution while assessing the best treatment option.

Application and prospect of single-cell sequencing in cancer metastasis

Cancer metastasis is a complicated process driven by internal genetic variations and developed through interactions with the external environment. This process usually causes therapeutic resistance and results in a low survival rate. In recent years, single-cell sequencing has become a popular method for revealing the tumor evolutionary genetic lineage, intra-tumoral heterogeneity and tumor microenvironment of the metastasis process. So as to find more therapeutic targets for clinical application, the spatial transcriptomics method has become a new rising field of cancer studies, which promotes the combination between clinical medicine and molecular biology. In future prospects, more accurate and personalized treatment models will come into reality.

Tumour invasion and dissemination

Activating invasion and metastasis are one of the primary hallmarks of cancer, the latter representing the leading cause of death in cancer patients. Whilst many advances in this area have been made in recent years, the process of cancer dissemination and the underlying mechanisms governing invasion are still poorly understood. Cancer cells exhibit multiple invasion strategies, including switching between modes of invasion and plasticity in response to therapies, surgical interventions and environmental stimuli. The ability of cancer cells to switch migratory modes and their inherent plasticity highlights the critical challenge preventing the successful design of cancer and anti-metastatic therapies. This mini-review presents current knowledge on the critical models of tumour invasion and dissemination. We also discuss the current issues surrounding current treatments and arising therapeutic opportunities. We propose that the establishment of novel approaches to study the key biological mechanisms underlying the metastatic cascade is critical in finding novel targets that could ultimately lead to complete inhibition of cancer cell invasion and dissemination.

Liquid biopsies to occult brain metastasis

Brain metastasis (BrM) is a major problem associated with cancer-related mortality, and currently, no specific biomarkers are available in clinical settings for early detection. Liquid biopsy is widely accepted as a non-invasive method for diagnosing cancer and other diseases. We have reviewed the evidence that shows how the molecular alterations are involved in BrM, majorly from breast cancer (BC), lung cancer (LC), and melanoma, with an inception in how they can be employed for biomarker development. We discussed genetic and epigenetic changes that influence cancer cells to breach the blood-brain barrier (BBB) and help to establish metastatic lesions in the uniquely distinct brain microenvironment. Keeping abreast with the recent breakthroughs in the context of various biomolecules detections and identifications, the circulating tumor cells (CTC), cell-free nucleotides, non-coding RNAs, secretory proteins, and metabolites can be pursued in human body fluids such as blood, serum, cerebrospinal fluid (CSF), and urine to obtain potential candidates for biomarker development. The liquid biopsy-based biomarkers can overlay with current imaging techniques to amplify the signal viable for improving the early detection and treatments of occult BrM.

Clinical Validation of a Circulating Tumor Cell Assay Using Density Centrifugation and Automated Immunofluorescence Microscopy

OBJECTIVES

The US Food and Drug Administration (FDA)-approved CELLSEARCH assay (Menarini Silicon Biosystems) for circulating tumor cells (CTCs) relies on expression of an epithelial cell adhesion molecule to enrich for CTCs. We sought to validate a CTC assay (RareCyte) for clinical use that instead collects a buffy coat preparation enriched for CTCs.

METHODS

Normal peripheral blood specimens spiked with cultured breast and prostate cancer cells and 47 clinical samples were used to validate assay performance. Specimens were enriched for buffy coat cells and applied onto 8 glass slides. The slides were immunofluorescently stained and imaged by automated microscopy and computer-aided image analysis.

RESULTS

The assay was 100% specific for detecting spiked tumor cells. For samples spiked with 25, 50, and 125 cells, the percentage coefficients of variation were 42%, 21%, and 3.7%, respectively. Linearity studies demonstrated a slope of 0.99, an intercept of 1.6, and R2 of 0.96. Recoveries at the 25-, 50-, and 125-cell levels were 92%, 111%, and 100%, respectively. Clinical samples run on both CELLSEARCH and RareCyte correlated with an R2 of 0.8 after log-transformation and demonstrated 87.5% concordance using the CELLSEARCH criteria for predicting adverse outcomes.

CONCLUSIONS

The RareCyte CTC assay has comparable performance to the FDA-cleared method and is ready for further clinical validation studies.

Intracranial Metastatic Disease: Present Challenges, Future Opportunities

Intracranial metastatic disease (IMD) is a prevalent complication of cancer that significantly limits patient survival and quality of life. Over the past half-century, our understanding of the epidemiology and pathogenesis of IMD has improved and enabled the development of surveillance and treatment algorithms based on prognostic factors and tumor biomolecular characteristics. In addition to advances in surgical resection and radiation therapy, the treatment of IMD has evolved to include monoclonal antibodies and small molecule antagonists of tumor-promoting proteins or endogenous immune checkpoint inhibitors. Moreover, improvements in the sensitivity and specificity of imaging as well as the development of new serological assays to detect brain metastases promise to revolutionize IMD diagnosis. In this review, we will explore current treatment principles in patients with IMD, including the emerging role of targeted and immunotherapy in select primary cancers, and discuss potential areas for further investigation.

Emerging Biomarkers for Diagnosis, Prevention and Treatment of Brain Metastases-From Biology to Clinical Utility

Primary malignancies of the lung, skin (melanoma), and breast have higher propensity for metastatic spread to the brain. Advances in molecular tumour profiling have aided the development of targeted therapies, stereotactic radiotherapy, and immunotherapy, which have led to some improvement in patient outcomes; however, the overall prognosis remains poor. Continued research to identify new prognostic and predictive biomarkers is necessary to further impact patient outcomes, as this will enable better risk stratification at the point of primary cancer diagnosis, earlier detection of metastatic deposits (for example, through surveillance), and more effective systemic treatments. Brain metastases exhibit considerable inter- and intratumoural heterogeneity-apart from distinct histology, treatment history and other clinical factors, the metastatic brain tumour microenvironment is incredibly variable both in terms of subclonal diversity and cellular composition. This review discusses emerging biomarkers; specifically, the biological context and potential clinical utility of tumour tissue biomarkers, circulating tumour cells, extracellular vesicles, and circulating tumour DNA.

Molecular Mechanisms Related with Oligometastatic Prostate Cancer-Is It Just a Matter of Numbers?

During the last decade, the body of knowledge regarding the oligometastatic state has increased exponentially. Several molecular frameworks have been established, aiding our understanding of metastatic spread caused by genetically unstable cells that adapt to a tissue environment which is distant from the primary tumor. In the current narrative review, we provide an overview of the current treatment landscape of oligometastatic cancer, focusing on the current biomarkers used in the identification of true oligometastatic disease and highlighting the impact of molecular imaging on stage shift in different scenarios. Finally, we address current and future directions regarding the use of genetic and epigenetic targeting treatments in oligometastatic prostate cancer.

Clinical Biomarkers for Early Identification of Patients with Intracranial Metastatic Disease

Simple Summary

The development of brain metastases, or intracranial metastatic disease (IMD), is a serious and life-altering complication for many patients with cancer. While there have been substantial advancements in the treatments available for IMD and in our understanding of its pathogenesis, conventional methods remain insufficient to detect IMD at an early stage. In this review, we discuss current research on biomarkers specific to IMD. In particular, we highlight biomarkers that can be easily accessed via the bloodstream or cerebrospinal fluid, including circulating tumor cells and DNA, as well as advanced imaging techniques. The continued development of these assays could enable clinicians to detect IMD prior to the development of IMD-associated symptoms and ultimately improve patient prognosis and survival.

Abstract

Nearly 30% of patients with cancer will develop intracranial metastatic disease (IMD), and more than half of these patients will die within a few months following their diagnosis. In light of the profound effect of IMD on survival and quality of life, there is significant interest in identifying biomarkers that could facilitate the early detection of IMD or identify patients with cancer who are at high IMD risk. In this review, we will highlight early efforts to identify biomarkers of IMD and consider avenues for future investigation.

Diagnostic and prognostic biomarkers in oligometastatic non-small cell lung cancer: a literature review

Objective

This review aims to summarize the possibilities of recently discovered molecular diagnostic techniques in lung cancer, by evaluating their impact on diagnosis, monitoring, and prognosis in oligometastatic disease.

Background

Oligometastatic non-small cell lung cancer (OM-NSCLC) is currently defined based on morphological rather than biological features. Major advances in the detection of molecular biomarkers in cell-free tumoral DNA and the models of oncogene addiction make as feasible an early diagnosis and guide the therapeutic decision-making progress to improve the prognosis.

Methods

This narrative review EXAMINES current approaches of diagnosis, monitoring, and prognosis of OM-NSCLC and describes the fast-evolving therapeutic scenario of this disease. We provide an overview of the powerful capability of liquid biopsy techniques applied to blood and fluid and we focus on the technological advancement of circulant biomolecular factors in OM NSCLC pathology, starting from apparently simpler models such as oncogene addicted tumors to evaluate themselves in the light of treatment with immune-checkpoint inhibitors.

Conclusions

A better understanding of spatial and temporal evolution of oligometastatic diseases would contribute to a more accurate diagnosis and tailored treatment. Data from prospective clinical trials in the early stage of disease, coupled with knowledge of genetic characteristics of lung tumors, are warranted. These efforts would lead to improving the possibility to eradicate the residual disease in these low burden tumoral settings, thus enhancing the definitive cure perspectives.

Future Directions in the Use of SAbR for the Treatment of Oligometastatic Cancers

The role of local therapy as a sole therapy or part of a combined approach in treating metastatic cancer continues to evolve. The most obvious requirements for prudent implementation of local therapies like stereotactic ablative radiotherapy (SAbR) to become mainstream in treating oligometastases are (1) Clear guidance as to what particular patients might benefit, and (2) Confirmation of improvements in outcome after such treatments via clinical trials. These future directional requirements are non-negotiable. However, innovation and research offer many more opportunities to understand and improve therapy. Identifying candidates and personalizing their therapy can be afforded via proteomic, genomic and epigenomic characterization techniques. Such molecular profiling along with liquid biopsy opportunities will both help select best therapies and facilitate ongoing monitoring of response. Technologies both to find targets and help deliver less-toxic therapy continue to improve and will be available in the marketplace. These technologies include molecular-based imaging (eg, PET-PSMA), FLASH ultra-high dose rate platforms, Grid therapy, PULSAR adaptive dosing, and MRI/PET guided linear accelerators. Importantly, a treatment approach beyond oligometastastic could evolve including a rationale for using SAbR in the oligoprogressive, oligononresponsive, oligobulky and oligolethal settings as well as expansion beyond oligo- toward even plurimetastastic disease. In any case, lessons learned and experiences required by the implementation of using SAbR in oligometastatic cancer will be revisited.

CD74 and CD44 Expression on CTCs in Cancer Patients with Brain Metastasis

Up to 40% of advance lung, melanoma and breast cancer patients suffer from brain metastases (BM) with increasing incidence. Here, we assessed whether circulating tumor cells (CTCs) in peripheral blood can serve as a disease surrogate, focusing on CD44 and CD74 expression as prognostic markers for BM. We show that a size-based microfluidic approach in combination with a semi-automated cell recognition system are well suited for CTC detection in BM patients and allow further characterization of tumor cells potentially derived from BM. CTCs were found in 50% (7/14) of breast cancer, 50% (9/18) of non-small cell lung cancer (NSCLC) and 36% (4/11) of melanoma patients. The next-generation sequencing (NGS) analysis of nine single CTCs from one breast cancer patient revealed three different CNV profile groups as well as a resistance causing ERS1 mutation. CD44 and CD74 were expressed on most CTCs and their expression was strongly correlated, whereas matched breast cancer BM tissues were much less frequently expressing CD44 and CD74 (negative in 46% and 54%, respectively). Thus, plasticity of CD44 and CD74 expression during trafficking of CTCs in the circulation might be the result of adaptation strategies.

Current status of gastrointestinal tract cancer brain metastasis and the use of blood-based cancer biomarker biopsy

Brain metastasis (BM) frequently occurs in patients with cutaneous melanoma, lung, and breast cancer; although, BM rarely arises from cancers of the gastrointestinal tract (GIT). The reported incidence of GIT cancer BM is less than 4%. In the last few years, effective systemic therapy has prolonged the survival of GIT patients and consequently, the incidence of developing BM is rising. Therefore, the epidemiology and biology of BM arising from GIT cancer requires a more comprehensive understanding. In spite of the development of new therapeutic agents for patients with metastatic GIT cancers, survival for patients with BM still remains poor, with a median survival after diagnosis of less than 4 months. Limited evidence suggests that early detection of isolated intra-cranial lesions will enable surgical resection plus systemic and/or radiation therapy, which may lead to an increase in overall survival. Novel diagnostic methods such as blood-based biomarker biopsies may play a crucial role in the early detection of BM. Circulating tumor cells and circulating cell-free nucleic acids are known to serve as blood biomarkers for early detection and treatment response monitoring of multiple cancers. Blood biopsy may improve early diagnosis and treatment monitoring of GIT cancers BM, thus prolonging patients' survivals.

Circulating Tumor Cells for Glioma

Liquid biopsy has entered clinical applications for several cancers, including metastatic breast, prostate, and colorectal cancer for CTC enumeration and NSCLC for EGFR mutations in ctDNA, and has improved the individualized treatment of many cancers, but relatively little progress has been made in validating circulating biomarkers for brain malignancies. So far, data on circulating tumor cells about glioma are limited, the application of circulating tumor cells as biomarker for glioma patients has only just begun. This article reviews the research status and application prospects of circulating tumor cells in gliomas. Several detection methods and research results of circulating tumor cells about clinical research in gliomas are briefly discussed. The wide application prospect of circulating tumor cells in glioma deserves further exploration, and the research on more sensitive and convenient detection methods is necessary.

Prospective Assessment of the Association Between Circulating Tumor Cells and Control of Brain Disease After Focal Radiation Therapy of Breast Cancer Brain Metastases

Purpose

Predicting the risk of early distant brain failure (DBF) is in demand for management decisions in patients who are candidates for local treatment of brain metastases. This study aimed to analyze the association between circulating tumor cells (CTCs) and brain disease control after stereotactic radiation therapy/radiosurgery (SRT) for breast cancer brain metastasis (BCBM).

Methods and Materials

We prospectively assessed CTCs before (CTC1) and 4 to 5 weeks after (CTC2) SRT and their relationship with the number of new lesions (NL) suggestive of BCBM before SRT. CTC were quantified and analyzed by immunocytochemistry to evaluate the expression of the proteins COX2, EGFR, ST6GALNAC5, NOTCH1, and HER2. Distant brain failure-free survival (DBFFS), the primary endpoint, diffuse DBFFS (D-DBFFS), and overall survival were estimated. Analysis for DBF within 6 months, with death as competing risk, was performed.

Results

Patients were included between 2016 and 2018. CTCs were detected in all 39 patients before and in 34 of 35 patients after SRT. After median follow-up of 16.6 months, median DBFFS, D-DBFFS, and overall survival were 15.3, 14.1, and 19.5 months, respectively. DBF at 6 months was 40% with CTC1 ≤0.5 and 8.82% with CTC1 >0.5 CTC/mL (P = .007), and D-DBF at 6 months was 40% with CTC1 ≤0.5 and 0 with CTC1 >0.5 CTC/mL (P = .005) and 25% with NL/CTC1 >6.8 and 2.65% with NL/CTC1 ≤6.8 (P = .063). On multivariate analysis, DBFFS was inferior with CTC1 ≤0.5 (hazard ratio, 8.27; 95% confidence interval, 2.12-32.3; P = .002), and D-DBFFS was inferior with CTC1 ≤0.5 (hazard ratio, 10.22; 95% confidence interval, 1.99-52.41; P = .005). Protein expression was not associated with outcomes.

Conclusions

These data suggest that CTC1 and NL/CTC1 may have a role as a biomarker of early diffuse DBF and as a subsequent guide between focal or whole-brain radiation therapy in patients with BCBM.

Characterization of Oligometastatic Disease in a Real-World Nationwide Cohort of 3447 Patients With de Novo Metastatic Breast Cancer

Background

Observational studies in metastatic breast cancer (MBC) show that long-term overall survival (OS) is associated with limited tumor burden, or oligo-MBC (OMBC). However, a uniform definition of OMBC is lacking. In this real-world nationwide cohort, we aimed to define the optimal OMBC threshold and factors associated with survival in patients with OMBC.

Methods

3535 patients aged younger than 80 years at diagnosis of de novo MBC in the Netherlands between January 2000 and December 2007 were included. Detailed clinical, therapy, and outcome data were collected from medical records of a sample of the patients. Using inverse-sampling-probability weighting, the analysis cohort (n = 3447) was constructed. We assessed OS according to number of metastases at diagnosis to determine the optimal OMBC threshold. Next, we applied Cox regression models with inverse-sampling-probability weighting to study associations with OS and progression-free survival in OMBC. All statistical tests were 2-sided.

Results

Compared with more than 5 distant metastases, adjusted hazard ratios for OS (with 95% confidence interval [CI] based on robust standard errors) for 1, 2-3, and 4-5 metastases were 0.70 (95% CI = 0.52 to 0.96), 0.63 (95% CI = 0.45 to 0.89), and 0.91 (95% CI = 0.61 to 1.37), respectively. Ten-year OS estimates for patients with no more than 3 vs more than 3 metastases were 14.9% and 3.4% (P < .001). In multivariable analyses, premenopausal andperimenopausal status, absence of lung metastases, and local therapy of metastases (surgery and/or radiotherapy) added to systemic therapy were statistically significantly associated with better OS and progression-free survival in OMBC, independent of local therapy of the primary tumor.

Conclusion

OMBC defined as MBC limited to 1-3 metastases was associated with favorable OS. In OMBC, local therapy of metastases was associated with better OS, particularly if patients were premenopausal or perimenopausal without lung metastases.

Cytoplasm protein GFAP magnetic beads construction and application as cell separation target for brain tumors

Background

It is very important to develop a highly efficient cerebrospinal fluid (CSF) detection system with diagnosis and prediction function, for which the detection of circulating tumor cells (CTCs) in CSF is a good choice. In contrast to the past use of epithelial EpCAM as CTCs separation target, a cytoplasm protein of GFAP antibody was first selected to construct highly-sensitive immunomagnetic liposome beads (IMLs). The validation and efficiency of this system in capturing CTCs for brain tumors were measured both in vitro and in vivo. The associations between the numbers of CTCs in patients with their clinical characteristics were further analyzed.

Results

Our data show that CTCs can be successfully isolated from CSF and blood samples from 32 children with brain tumors. The numbers of CTCs in CSF were significantly higher than those in blood. The level of CTCs in CSF was related to the type and location of the tumor rather than its stage. The higher the CTCs number is, the more possibly the patient will suffer from poor prognosis. Genetic testing in GFAP CTC-DNA by sanger sequencing, q-PCR and NGS methods indicated that the isolated CTCs (GFAP+/EGFR+) are the related tumor cell. For example, the high expression of NPR3 gene in CSF CTCs was consistent with that of tumor tissue.

Conclusions

The results indicated that GFAP-IML CTCs isolation system, combined with an EGFR immunofluorescence assay of antitumor marker, can serve as a brand-new method for the identification of CTCs for brain tumors. Via lumbar puncture, a minimally invasive procedure, this technique may play a significant role in the clinical diagnosis and drug evaluation of brain tumors.

Discovery of Targetable Genetic Alterations in NSCLC Patients with Different Metastatic Patterns Using a MassARRAY-Based Circulating Tumor DNA Assay

Circulating tumor DNA (ctDNA) has shown great promise as a minimally invasive liquid biopsy for personalized cancer diagnostics especially among metastatic patients. Here, we used a novel sensitive assay to detect clinically relevant mutations in ctDNA in blood plasma from metastatic non-small cell lung cancer (NSCLC) patients, including patients with a limited oligo-brain metastatic disease. We analyzed 66 plasma samples from 56 metastatic NSCLC patients for 74 hotspot mutations in five genes commonly mutated in NSCLC using a novel MassARRAY-based lung cancer panel with a turnaround time of only 3 days. Mutations in plasma DNA could be detected in 28 out of 56 patients (50.0%), with a variant allele frequency (VAF) ranging between 0.1% and 5.0%. Mutations were detected in 50.0% of patients with oligo-brain metastatic disease, although the median VAF was lower (0.4%) compared to multi-brain metastatic patients (0.9%) and patients with extra-cranial metastatic progression (1.2%). We observed an overall concordance of 86.4% (n = 38/44) for EGFR status between plasma and tissue. The MassARRAY technology can detect clinically relevant mutations in plasma DNA from metastatic NSCLC patients including patients with limited, oligo-brain metastatic disease.

Liquid biopsies: Potential and challenges

The analysis of tumor cells or tumor cell products obtained from blood or other body fluids ("liquid biopsy" [LB]) provides a broad range of opportunities in the field of oncology. Clinical application areas include early detection of cancer or tumor recurrence, individual risk assessment and therapy monitoring. LB allows to portray the entire disease as tumor cells or tumor cell products are released from all metastatic or primary tumor sites, providing comprehensive and real-time information on tumor cell evolution, therapeutic targets and mechanisms of resistance to therapy. Here, we focus on the most prominent LB markers, circulating tumor cells (CTCs) and circulating tumor-derived DNA (ctDNA), in the blood of patients with breast, prostate, lung and colorectal cancer, as the four most frequent tumor types in Europe. After a brief introduction of key technologies used to detect CTCs and ctDNA, we discuss recent clinical studies on these biomarkers for early detection and prognostication of cancer as well as prediction and monitoring of cancer therapies. We also point out current methodological and biological limitations that still hamper the implementation of LB into clinical practice.

The Role of Local Treatment in Oligometastatic and Oligoprogressive Cancer

BACKGROUND

Systemic treatment is standard for most types of cancer with disseminated metastases. The role of local treatment (LT) of individual tumor foci in patients with oligometastatic disease is unclear and the object of current scientific studies.

METHODS

This review is based on pertinent publications retrieved by a selective search in PubMed.

RESULTS

Four randomized trials have shown that radical local treatment confers an advantage with respect to overall survival (OS), compared to systemic treatment alone, in patients with oligometastatic disease. In patients with synchronous metastases and a stable primary tumor, LT prolongs the median overall survival by approximately two years. A single randomized trial for oligometastatic small-cell lung cancer did not show any prolongation of overall survival. Local treatment increased the frequency of grade III side effects by approximately 10%.

CONCLUSION

Although local treatment already has a place in many guidelines on the basis of the findings of a small number of prospective and retrospective studies, a option of local treatment should be considered by an interdisciplinary tumor board individually for suitable patients.

Long-term survival results after treatment for oligometastatic brain disease

Aim

The aim of this study was to characterize the survival results of patients with up to four brain metastases after intense local therapy (primary surgery or stereotactic radiotherapy) if extracranial metastases were absent or limited to one site, e.g. the lungs.

Background

Oligometastatic disease has repeatedly been reported to convey a favorable prognosis.

Material and methods

This retrospective study included 198 German and Norwegian patients treated with individualized approaches, always including brain radiotherapy. Information about age, extracranial spread, number of brain metastases, performance status and other variables was collected. Uni- and multivariate tests were performed.

Results

Median survival was 16.5 months (single brain metastasis) and 9.8 months (2-4, comparable survival for 2, 3 and 4), respectively (p = 0.001). After 5 years, 15 and 2% of the patients were still alive. In patients alive after 2 years, added median survival was 23 months and the probability of being alive 5 years after treatment was 26%. In multivariate analysis, extracranial metastases were not significantly associated with survival, while primary tumor control was.

Conclusion

Long-term survival beyond 5 years is possible in a minority of patients with oligometastatic brain disease, in particular those with a single brain metastasis. The presence of extracranial metastases to one site should not be regarded a barrier towards maximum brain-directed therapy.

Insights into brain metastasis: Recent advances in circulating tumor cell research

Background

How tumor cells disseminate to brain and establish brain metastasis remains partly an unsolved problem. This devastating complication of many cancers is initiated by a rare subset of the circulating tumor cells (CTCs) shed into the blood stream. Thus, the profiling of the molecular properties in these brain metastasis‐initiating CTCs is essential to uncover the mechanisms underlying brain metastasis.

Recent Findings

Important efforts to improve the enrichment and detection of CTCs enabled the detailed molecular and functional analysis of CTCs that drive brain metastasis. In this review, we highlight key findings on existing preclinical studies that provide insights toward a comprehensive picture of brain metastasis‐precursors in CTCs and the potential clinical implications.

Conclusion

A deeper understanding of the brain metastasis precursors should help to stratify high‐risk patients and improve preventive therapeutic strategies. Although all these preclinical evidences have yet to be translated into patients, they provide considerable hope to benefit patients with brain metastases in the future.

The role of contextual signal TGF-β1 inducer of epithelial mesenchymal transition in metastatic lung adenocarcinoma patients with brain metastases: an update on its pathological significance and therapeutic potential

Lung adenocarcinoma (LA) is the most common cause of cancer-related death worldwide. Despite the advances over last decade in new targeted therapies, cancer genetics, diagnostics, staging, and surgical techniques as well as new chemotherapy and radiotherapy protocols, the death rate from LA remains high. The tumour microenvironment is composed of several cytokines, one of which is transforming growth factor β1 (TGF-β1), which modulates and mediates the expression of epithelial-mesenchymal transition (EMT), correlated with invasive growth in LAs, and exhibits its pleiotropic effects through binding to transmembrane receptors TβR-1 (also termed activin receptor-like kinases – ALKs) and TβR-2. Accordingly, there is an urgent need to elucidate the molecular mechanisms associated with the tumoural spreading process and therapeutic resistance of this serious pathology. In this review, we briefly discuss the current role of contextual signal TGF-β1 inducer of epithelial mesenchymal transition in metastatic lung adenocarcinoma patients with brain metastases, and give an overview of our current mechanistic understanding of the TGF-β1-related pathways in brain metastases progression, TGF-β1 pathway inhibitors that could be used for clinical treatment, and examination of models used to study these processes. Finally, we summarise the current progress in the therapeutic approaches targeting TGF-β1.

Unravelling tumour heterogeneity by single-cell profiling of circulating tumour cells

Single-cell technologies have contributed to unravelling tumour heterogeneity, now considered a hallmark of cancer and one of the main causes of tumour resistance to cancer therapies. Liquid biopsy (LB), defined as the detection and analysis of cells or cell products released by tumours into the blood, offers an appealing minimally invasive approach that allows the characterization and monitoring of tumour heterogeneity in individual patients. Here, we will review and discuss how circulating tumour cell (CTC) analysis at single-cell resolution provides unique insights into tumour heterogeneity that are not revealed by analysis of circulating tumour DNA (ctDNA) derived from LBs. The molecular analysis of CTCs provides complementary information to that of genomic aberrations determined using ctDNA to fully describe many different cellular components (for example, DNA, RNA, proteins and metabolites) that can influence tumour heterogeneity.

EpCAMlow Circulating Tumor Cells: Gold in the Waste

The CellSearch® system which is still considered the gold standard for the enumeration of circulating tumor cells (CTC) utilizes antibodies against the epithelial cell adhesion molecule (EpCAM) for CTC enrichment. Recently, CTC discarded by the CellSearch® system due to their low EpCAM expression have been isolated and analyzed. We here sought to discuss technical and biological issues concerning the isolation and characterization of EpCAM^low CTC, highlighting the enormous potential of this subpopulation discarded by CellSearch®, which might instead reveal an unexpected clinical significance in tumor types where CTC enumeration has never been validated for prognostic and predictive purpose.

Clonality of circulating tumor cells in breast cancer brain metastasis patients

Background

The incidence of brain metastases in breast cancer (BCBM) patients is increasing. These patients have a very poor prognosis, and therefore, identification of blood-based biomarkers, such as circulating tumor cells (CTCs), and understanding the genomic heterogeneity could help to personalize treatment options.

Methods

Both EpCAM-dependent (CellSearch® System) and EpCAM-independent Ficoll-based density centrifugation methods were used to detect CTCs from 57 BCBM patients. DNA from individual CTCs and corresponding primary tumors and brain metastases were analyzed by next-generation sequencing (NGS) in order to evaluate copy number aberrations and single nucleotide variations (SNVs).

Results

CTCs were detected after EpCAM-dependent enrichment in 47.7% of the patients (≥ 5 CTCs/7.5 ml blood in 20.5%). The CTC count was associated with ERBB2 status (p = 0.029) of the primary tumor as well as with the prevalence of bone metastases (p = 0.021). EpCAM-independent enrichment revealed CTCs in 32.6% of the patients, especially among triple-negative breast cancer (TNBC) patients (70.0%). A positive CTC status after enrichment of either method was significantly associated with decreased overall survival time (p < 0.05). Combining the results of both enrichment methods, 63.6% of the patients were classified as CTC positive. In three patients, the matched tumor tissue and single CTCs were analyzed by NGS showing chromosomal aberrations with a high genomic clonality and mutations in pathways potentially important in brain metastasis formation.

Conclusion

The detection of CTCs, regardless of the enrichment method, is of prognostic relevance in BCBM patients and in combination with molecular analysis of CTCs can help defining patients with higher risk of early relapse and suitability for targeted treatment.

Electronic supplementary material

The online version of this article (10.1186/s13058-019-1184-2) contains supplementary material, which is available to authorized users.

Surgical stress and cancer progression: the twisted tango

Surgical resection is an important avenue for cancer treatment, which, in most cases, can effectively alleviate the patient symptoms. However, accumulating evidence has documented that surgical resection potentially enhances metastatic seeding of tumor cells. In this review, we revisit the literature on surgical stress, and outline the mechanisms by which surgical stress, including ischemia/reperfusion injury, activation of sympathetic nervous system, inflammation, systemically hypercoagulable state, immune suppression and effects of anesthetic agents, promotes tumor metastasis. We also propose preventive strategies or resolution of tumor metastasis caused by surgical stress.

EGFR and HER3 expression in circulating tumor cells and tumor tissue from non-small cell lung cancer patients

Although clinically relevant, the detection rates of EpCAM positive CTCs in non-small cell lung cancer (NSCLC) are surprisingly low. To find new clinically informative markers for CTC detection in NSCLC, the expression of EGFR and HER3 was first analyzed in NSCLC tissue (n = 148). A positive EGFR and HER3 staining was observed in 52.3% and 82.7% of the primary tumors, and in 62.7% and 91.2% of brain metastases, respectively. Only 3.0% of the brain metastases samples were negative for both HER3 and EGFR proteins, indicating that the majority of metastases express these ERBB proteins, which were therefore chosen for CTC enrichment using magnetic cell-separation. Enrichment based on either EGFR or HER3 detected CTCs in 37.8% of the patients, while the combination of EGFR/HER3 enrichment with the EpCAM-based CellSearch technique detected a significantly higher number of 66.7% CTC-positive patients (Cohen’s kappa = −0.280) which underlines the existence of different CTC subpopulations in NSCLC. The malignant origin of keratin-positive/CD45-negative CTC clusters and single CTCs detected after EGFR/HER3 based enrichment was documented by the detection of NSCLC-associated mutations. In conclusion, EGFR and HER3 expression in metastasized NSCLC patients have considerable value for CTC isolation plus multiple markers can provide a novel liquid biopsy approach.