Cerebrospinal fluid circulating tumor cells: a novel tool to diagnose leptomeningeal metastases from epithelial tumors

Advances in the diagnosis, evaluation, and management of leptomeningeal disease

Leptomeningeal metastasis (LM) is a devastating complication of cancer with variable clinical presentation and limited benefit from existing treatment options. In this review, we discuss advances in LM diagnostics and therapeutics with the potential to reverse this grim course. Emerging cerebrospinal fluid circulating tumor cell and cell-free tumor DNA analysis technologies will improve diagnosis of LM, while providing crucial genetic information, capturing tumor heterogeneity, and quantifying disease burden. Circulating tumor cells and cell-free tumor DNA have utility as biomarkers to track disease progression and treatment response. Treatment options for LM include ventriculoperitoneal shunting for symptomatic relief, radiation therapy including whole-brain radiation and focal radiation for bulky leptomeningeal involvement, and systemic and intrathecal medical therapies, including targeted and immunotherapies based on tumor mutational profiling. While existing treatments for LM have limited efficacy, recent advances in liquid biopsy together with increasing availability of targeted treatments will lead to rational multimodal individualized treatments and improved patient outcomes.

Leptomeningeal Metastases from Solid Tumors: Recent Advances in Diagnosis and Molecular Approaches

Leptomeningeal metastases (LM) from solid tumors represent an unmet need of increasing importance due to an early use of MRI for diagnosis and improvement of outcome of some molecular subgroups following targeted agents and immunotherapy. In this review, we first discussed factors limiting the efficacy of targeted agents in LM, such as the molecular divergence between primary tumors and CNS lesions and CNS barriers at the level of the normal brain, brain tumors and CSF. Further, we reviewed pathogenesis and experimental models and modalities, such as MRI (with RANO and ESO/ESMO criteria), CSF cytology and liquid biopsy, to improve diagnosis and monitoring following therapy. Efficacy and limitations of targeted therapies for LM from EGFR-mutant and ALK-rearranged NSCLC, HER2-positive breast cancer and BRAF-mutated melanomas are reported, including the use of intrathecal administration or modification of traditional cytotoxic compounds. The efficacy of checkpoint inhibitors in LM from non-druggable tumors, in particular triple-negative breast cancer, is discussed. Last, we focused on some recent techniques to improve drug delivery.

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.

[Auxiliary Diagnostic Value of Tumor Markers in the Cerebrospinal Fluid and Blood for Leptomeningeal Metastasis from Non-small Cell Lung Cancer]

背景与目的

软脑膜转移（leptomeningeal metastasis, LM）是指恶性肿瘤细胞浸润软脑膜，并在脑脊液（cerebrospinal fluid, CSF）中播散，预后极差，是晚期非小细胞肺癌（non-small cell lung cancer, NSCLC）患者致死的重要原因之一，因此早期的诊断和及时的治疗具有重要意义，CSF细胞学是LM诊断的金标准，但常常伴随着检测敏感性低、无法评估疗效等问题。本文旨在探讨血清及CSF中肿瘤标志物（tumor markers, TM）在NSCLC伴LM患者诊治的临床价值。

方法

选取NSCLC伴LM患者19例，另选同期27例神经系统良性肿瘤（nonmalignant neurological diseases, NMNDs）患者作为对照组。观察比较两组患者血清和CSF中癌胚抗原（carbohydrate antigen, CEA）、糖类抗原125（carbohydrate antigen-125, CA125）、细胞角蛋白19片断抗原（cytokeratin 19 fragments, CYFRA21-1）和神经元烯醇化酶（neurone specific enolase, NSE）检测水平和检出阳性率，比较不同组TM的敏感性和特异性，并分析血清与CSF中TM检出情况相关性，最后动态监测2例LM患者血清和CSF中TM水平，分别评估颅外和颅内治疗疗效。

结果

LM组CSF和血清中TM水平和检出阳性率均高于对照组（P < 0.05），同时LM组CSF中CEA、CYFRA21-1、NSE水平高于血清，差异有统计学意义（P < 0.05）。CSF中TM检出阳性率与血清差异不具有统计学意义（P > 0.05）。CSF中CYFRA21-1敏感性最高（88.2%），CEA特异性最好（92.3%），联合指标中CEA或NSE任一项超过临界值则敏感性和阴性预测值为100%，特异性为74.1%。CYFRA21-1和NSE同时超过临界值时特异性和阳性预测值为100%，敏感性为78.9%。亚组分析显示，CSF细胞学阳性人群TM检出阳性率超过有磁共振成像（magnetic resonance imaging, MRI）异常的人群，但不具有统计学差异（P > 0.05）。LM组血清与CSF中TM检出阳性率不一致。另外，脑室中CSF与腰穿中CSF具有相同的生化性质，动态监测血清和CSF中TM浓度，可分别评估颅外和颅内病灶的疗效。

结论

血清和CSF中TM为NSCLC伴LM患者增加了一个早期辅助诊断指标，动态监测可评估治疗疗效，值得临床推广应用。

Leptomeningeal disease in pancreas ductal adenocarcinoma: A manifestation of longevity

BACKGROUND

/Objectives: Pancreatic adenocarcinoma (PDAC) metastatic to the leptomeninges is a rare and lethal event. Leptomeningeal disease (LMD) research is limited in PDAC, and insights into clinical descriptors, possible disease predictors, and treatment strategies is necessitated.

METHODS

Memorial Sloan Kettering databases were queried with Institutional Review Board approval to identify patients with LMD and PDAC treated between January 2000 and June 2020. Medical record review was used to abstract clinical, genomic, pathologic, and radiographic data. Overall survival was calculated from date of PDAC diagnosis to date of death. Previously published literature on LMD from PDAC was reviewed.

RESULTS

Four patients with LMD from PDAC were identified, two males and two females. Age at diagnosis ranged from 57 to 68 years. All four patients had predominant lung metastasis and a relatively low burden of intra-abdominal disease. Somatic testing indicated alterations typical of PDAC and no PDAC defining pathogenic germline mutations were identified. An extended clinical course prior to LMD diagnosis was observed in all patients, ranging from 16 to 148 months. Upon diagnosis of LMD, three patients elected for supportive care and one patient received a limited course of craniospinal radiation. The median survival following diagnosis of LMD was 1.6 months (range 0.5-2.8 months).

CONCLUSIONS

LMD from PDAC is a rare occurrence that may be more frequent in patients with lung metastasis and/or a more indolent clinical course. Following diagnosis of LMD, prognosis is poor, and survival is short. New treatment strategies for this manifestation of PDAC are needed.

The Underlying Biology and Therapeutic Vulnerabilities of Leptomeningeal Metastases in Adult Solid Cancers

Metastasis to the central nervous system occurs in approximately 20% of patients with advanced solid cancers such as lung cancer, breast cancer, and melanoma. While central nervous system metastases most commonly form in the brain parenchyma, metastatic cancer cells may also reside in the subarachnoid space surrounding the brain and spinal cord to form tumors called leptomeningeal metastases. Leptomeningeal metastasis involves cancer cells that reach the subarachnoid space and proliferate in the cerebrospinal fluid compartment within the leptomeninges, a sequela associated with a myriad of symptoms and poor prognosis. Cancer cells exposed to cerebrospinal fluid in the leptomeninges must contend with a unique microenvironment from those that establish within the brain or other organs. Leptomeningeal lesions provide a formidable clinical challenge due to their often-diffuse infiltration within the subarachnoid space. The molecular mechanisms that promote the establishment of leptomeningeal metastases have begun to be elucidated, demonstrating that it is a biological entity distinct from parenchymal brain metastases and is associated with specific molecular drivers. In this review, we outline the current state of knowledge pertaining to the diagnosis, treatment, and molecular underpinnings of leptomeningeal metastasis.

Detection of Aneuploidy in Cerebrospinal Fluid from Patients with Breast Cancer Can Improve Diagnosis of Leptomeningeal Metastases

PURPOSE

Detection of leptomeningeal metastasis is hampered by limited sensitivities of currently used techniques: MRI and cytology of cerebrospinal fluid (CSF). Detection of cell-free tumor DNA in CSF has been proposed as a tumor-specific candidate to detect leptomeningeal metastasis at an earlier stage. The aim of this study was to investigate mutation and aneuploidy status in CSF-derived cell-free DNA (cfDNA) of patients with breast cancer with a clinical suspicion of leptomeningeal metastasis.

EXPERIMENTAL DESIGN

cfDNA was isolated from stored remnant CSF and analyzed by targeted next-generation sequencing (NGS; n = 30) and the modified fast aneuploidy screening test-sequencing system (mFAST-SeqS; n = 121). The latter method employs selective amplification of long interspaced nuclear elements sequences that are present throughout the genome and allow for fast and cheap detection of aneuploidy. We compared these results with the gold standard to diagnose leptomeningeal metastasis: cytology.

RESULTS

Leptomeningeal metastasis was cytology proven in 13 of 121 patients. Low DNA yields resulted in insufficient molecular coverage of NGS for the majority of samples (success rate, 8/30). The mFAST-SeqS method, successful in 112 of 121 (93%) samples, detected genome-wide aneuploidy in 24 patients. Ten of these patients had cytology-proven leptomeningeal metastasis; 8 additional patients were either concurrently diagnosed with central nervous system metastases by radiological means or developed these soon after the lumbar puncture. The remaining six cases were suspected of leptomeningeal metastasis, but could not be confirmed by cytology or imaging. Aneuploidy was associated with development of leptomeningeal metastasis and significantly worse overall survival.

CONCLUSIONS

Aneuploidy in CSF-derived cfDNA may provide a promising biomarker to improve timely detection of leptomeningeal metastasis.

Quantitative cerebrospinal fluid circulating tumor cells are a potential biomarker of response for proton craniospinal irradiation for leptomeningeal metastasis

BACKGROUND

Leptomeningeal metastasis (LM) involves cerebrospinal fluid (CSF) seeding of tumor cells. Proton craniospinal irradiation (pCSI) is potentially effective for solid tumor LM. We evaluated whether circulating tumor cells (CTCs) in the CSF (CTCCSF), blood (CTCblood), and neuroimaging correlate with outcomes after pCSI for LM.

METHODS

We describe a single-institution consecutive case series of 58 patients treated with pCSI for LM. Pre-pCSI CTCs, the change in CTC post-pCSI (Δ CTC), and MRIs were examined. Central nervous system progression-free survival (CNS-PFS) and overall survival (OS) from pCSI were determined using Kaplan Meier analysis, Cox proportional-hazards regression, time-dependent ROC analysis, and joint modeling of time-varying effects and survival outcomes.

RESULTS

The median CNS-PFS and OS were 6 months (IQR: 4-9) and 8 months (IQR: 5-13), respectively. Pre-pCSI CTCCSF < 53/3mL was associated with improved CNS-PFS (12.0 vs 6.0 months, P < .01). Parenchymal brain metastases (n = 34, 59%) on pre-pCSI MRI showed worse OS (7.0 vs 13 months, P = .01). Through joint modeling, CTCCSF was significantly prognostic of CNS-PFS (P < .01) and OS (P < .01). A Δ CTC-CSF≥37 cells/3mL, the median Δ CTC-CSF at nadir, showed improved CNS-PFS (8.0 vs 5.0 months, P = .02) and further stratified patients into favorable and unfavorable subgroups (CNS-PFS 8.0 vs 4.0 months, P < .01). No associations with CTCblood were found.

CONCLUSION

We found the best survival observed in patients with low pre-pCSI CTCCSF and intermediate outcomes for patients with high pre-pCSI CTCCSF but large Δ CTC-CSF. These results favor additional studies incorporating pCSI and CTCCSF measurement earlier in the LM treatment paradigm.

Circulating tumor cell characterization of lung cancer brain metastases in the cerebrospinal fluid through single-cell transcriptome analysis

BACKGROUND

Brain metastases explain the majority of mortality associated with lung cancer, which is the leading cause of cancer death. Cytology analysis of the cerebrospinal fluid (CSF) remains the diagnostic gold standard, however, the circulating tumor cells (CTCs) in CSF (CSF-CTCs) are not well defined at the molecular and transcriptome levels.

METHODS

We established an effective CSF-CTCs collection procedure and isolated individual CSF cells from five lung adenocarcinoma leptomeningeal metastases (LUAD-LM) patients and three controls. Three thousand seven hundred ninety-two single-cell transcriptomes were sequenced, and single-cell RNA sequencing (scRNA-seq) gene expression analysis was used to perform a comprehensive characterization of CSF cells.

RESULTS

Through clustering and expression analysis, we defined CSF-CTCs at the transcriptome level based on epithelial markers, proliferation markers, and genes with lung origin. The metastatic-CTC signature genes are enriched for metabolic pathway and cell adhesion molecule categories, which are crucial for the survival and metastases of tumor cells. We discovered substantial heterogeneity in patient CSF-CTCs. We quantified the degree of heterogeneity and found significantly greater among-patient heterogeneity compared to among-cell heterogeneity within a patient. This observation could be explained by spatial heterogeneity of metastatic sites, cell-cycle gene, and cancer-testis antigen (CTA) expression profiles as well as the proportion of CTCs displaying mesenchymal and cancer stem cell properties. In addition, our CSF-CTCs transcriptome profiling allowed us to determine the biomarkers during the progression of an LM patient with cancer of unknown primary site (CUP).

CONCLUSIONS

Our results will provide candidate genes for an RNA-based digital detection of CSF-CTCs from LUAD-LM and CUP-LM cases, and shed light on the therapy and mechanism of LUAD-LM.

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.

Leptomeningeal disease in melanoma patients: An update to treatment, challenges, and future directions

In February 2018, the Melanoma Research Foundation and the Moffitt Cancer Center hosted the Second Summit on Melanoma Central Nervous System Metastases in Tampa, Florida. The meeting included investigators from multiple academic centers and disciplines. A consensus summary of the progress and challenges in melanoma parenchymal brain metastases was published (Eroglu et al., Pigment Cell & Melanoma Research, 2019, 32, 458). Here, we will describe the current state of basic, translational, clinical research, and therapeutic management, for melanoma patients with leptomeningeal disease. We also outline key challenges and barriers to be overcome to make progress in this deadly disease.

Cerebrospinal fluid circulating tumor cells as a quantifiable measurement of leptomeningeal metastases in patients with HER2 positive cancer

PURPOSE

The CellSearch® system has been used to identify circulating tumor cells (CTCs) in cerebrospinal fluid (CSF) to diagnose leptomeningeal metastasis (LM) in patients with epithelial cancers. Using this system, we prospectively explored sequential CSF CTC enumeration in patients with LM from HER2+ cancers receiving intrathecal (IT) trastuzumab to capture dynamic changes in CSF CTC enumeration.

METHODS

CSF from patients enrolled in an IRB-approved phase I/II dose escalation trial of IT trastuzumab for LM in HER2+ cancer (NCT01325207) was obtained on day 1 of each cycle and was evaluated by the CellSearch® platform for CTC enumeration. The results were correlated with CSF cytology from the same sample, along with clinical and radiographic response.

RESULTS

Fifteen out of 34 patients with HER2+ LM were enrolled in CSF CTC analysis; 14 were women. Radiographic LM was documented in 14 (93%) patients; CSF cytology was positive in 6 (40%) and CSF CTCs were identified in 13 (87%). Median CSF CTC was 22 CTCs (range 0-200 +) per 3 ml. HER2/neu expression analysis of CTCs was performed in 8 patients; 75% had confirmed expression of HER2/neu positivity in CSF and HER2/neu expression was absent in 25%. Four of 10 patients received 7 or more cycles of IT trastuzumab; in 3 of these patients, increase in CSF CTCs enumeration from baseline was detected 2-3 months prior to changes seen on MRI, and while CSF cytology remained negative.

CONCLUSION

Our study demonstrates that enumeration of CSF CTCs may provide dynamic, quantitative assessment of tumor burden in the central nervous system compartment during treatment for LM and prior to changes on MRI or CSF cytology.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT01325207; registered March 29th, 2011.

A retrospective, quantitative assessment of disease burden in patients with leptomeningeal metastases from non-small-cell lung cancer

BACKGROUND

Improvements in detection and molecular characterization of leptomeningeal metastasis from lung cancer (LC-LM) coupled with cerebrospinal fluid (CSF)-penetrating targeted therapies have altered disease management. A barrier to formal study of these therapies in LM is quantification of disease burden. Also, outcomes of patients with targetable mutations in LC-LM are not well defined. This study employs molecular and radiographic measures of LM disease burden and correlates these with outcome.

METHODS

We reviewed charts of 171 patients with LC-LM treated at Memorial Sloan Kettering. A subset had MRI and CSF studies available. Radiographic involvement (n = 76) was scored by number of gadolinium-enhancing sites in 8 locations. CSF studies included cytopathology, circulating tumor cell (CTC) quantification (n = 16), and cell-free DNA (cfDNA) analysis (n = 21). Clinical outcomes were compared with Kaplan-Meier log-rank test and Cox proportional hazards methodologies.

RESULTS

Median overall survival was 4.2 months (95% CI: 3.6-4.9); 84 patients (49%) harbored targetable mutations. Among bevacizumab-naïve patients with MRI and CSF cytology at time of LC-LM diagnosis, extent of radiographic involvement correlated with risk of death (hazard ratio [HR]: 1.16; 95% CI: 1.02-1.33; P = 0.03), as did CSF CTC (HR: 3.39, 95% CI: 1.01-11.37; P = 0.048) and CSF cfDNA concentration (HR: 2.58; 95% CI: 0.94-7.05; P = 0.06). Those without a targetable mutation were almost 50% more likely to die (HR: 1.49; 95% CI: 1.06-2.11; P = 0.02).

CONCLUSIONS

Extent of radiographic involvement and quantification of CSF CTC and cfDNA show promise as prognostic indicators. These findings support molecular characterization and staging for clinical management, prognostication, and clinical trial stratification of LC-LM.

Novel methods to diagnose leptomeningeal metastases in breast cancer

Leptomeningeal metastases (LM) in breast cancer patients are rare but often accompanied by devastating neurological symptoms and carry a very poor prognosis, even if treated. To date, two diagnostic methods are clinically used to diagnose LM: gadolinium MRI of the brain and/or spinal cord and cytological examination of cerebrospinal fluid (CSF). Both techniques are, however, hampered by limited sensitivities, often leading to a long diagnostic process requiring repeated lumbar punctures and MRI examinations. To improve the detection rate of LM, numerous studies have assessed new techniques. In this review, we present the current workup to diagnose LM, set out an overview of novel techniques to diagnose LM, and give recommendations for future research.

Management of leptomeningeal metastases in non-small cell lung cancer

In leptomeningeal metastasis (LM), malignant lung cancer cells reach the sanctuary site of the leptomeningeal space through haematogenous or lymphatic route and thrive in the leptomeninges because of restricted access of chemotherapeutic agents across the blood brain barrier. The incidence of LM is 3%-5% in non-small cell lung cancer (NSCLC) patients; the incidence is higher in patients with anaplastic lymphoma kinase (ALK) gene rearrangement or epidermal growth factor receptor (EGFR) mutations. However, the real-world burden of undiagnosed cases may be higher. LM diagnosis is based on clinical, radiological, and cytological testing. Disease management remains a challenge because of low central nervous system penetration of drugs. The prognosis of NSCLC patients with LM is poor with an overall survival (OS) of 3 months with contemporary treatment and <11 months with novel therapies. Therapy goals in this patient population are to improve or stabilize neurologic status, improve quality of life, and prolong survival while limiting the toxicity of chemotherapeutic regimens. We reviewed therapeutic options for management of LM in NSCLC patients with or without genetic mutations. Radiotherapy, systemic, or intrathecal chemotherapy, and personalized molecularly targeted therapy prolong the OS in patients with LM. Newer third generation EGFR-tyrosine kinase inhibitors have considerable brain penetration property and have been vital in increasing the OS especially in patients with EGFR mutations. Sequential or combination therapy third generation EGFR agents with radiotherapy or chemotherapy might be effective in increasing the quality of life and overall survival.

Leptomeningeal metastatic cells adopt two phenotypic states

Background

Leptomeningeal metastasis (LM), or spread of cancer cells into the cerebrospinal fluid (CSF), is characterized by a rapid onset of debilitating neurological symptoms and markedly bleak prognosis. The lack of reproducible in vitro and in vivo models has prevented the development of novel, LM‐specific therapies. Although LM allows for longitudinal sampling of floating cancer cells with a spinal tap, attempts to culture patient‐derived leptomeningeal cancer cells have not been successful.

Aim

We, therefore, employ leptomeningeal derivatives of human breast and lung cancer cell lines that reproduce both floating and adherent phenotypes of human LM in vivo and in vitro.

Methods and Results

We introduce a trypsin/EDTA‐based fractionation method to reliably separate the two cell subsets and demonstrate that in vitro cultured floating cells have decreased proliferation rate, lower ATP content, and are enriched in distinct metabolic signatures. Long‐term fractionation and transcriptomic analysis suggest high degree plasticity between the two phenotypes in vitro. Floating cells colonize mouse leptomeninges more rapidly and associate with shortened survival. In addition, patients harboring LM diagnosed with CSF disease alone succumbed to the disease earlier than patients with adherent (MRI positive) disease.

Conclusion

Together, these data support mechanistic evidence of a metabolic adaptation that allows cancer cells to thrive in their natural environment but leads to death in vitro.

Circulating epithelial tumor cell analysis in CSF in patients with leptomeningeal metastases

OBJECTIVE

The primary objective was to determine the sensitivity and specificity of epithelial cell adhesion molecule (EpCAM) immunoflow cytometry circulating tumor cells (CTC) analysis in CSF in patients with suspected leptomeningeal metastases (LM). The secondary objective was to explore the distribution of driver mutations in the primary tumor, plasma, cell free CSF (cfCSF), and isolated CTC from CSF in non-small cell lung cancer (NSCLC).

METHODS

We tested the performance of the CTC assay vs CSF cytology in a prospective study in 81 patients with a clinical suspicion of LM but a nonconfirmatory MRI. In an NSCLC subcohort, we analyzed circulating tumor (ct)DNA of the selected driver mutations by digital droplet PCR (ddPCR).

RESULTS

The sensitivity of the CTC assay was 94% (95% confidence interval [CI] 80-99) and the specificity was 100% (95% CI 91-100) at the optimal cutoff of 0.9 CTC/mL. The sensitivity of cytology was 76% (95% CI 58-89). Twelve of the 23 patients with NSCLC had mutated epidermal growth factor receptor (EGFR). All 5 tested patients with LM demonstrated the primary EGFR driver mutation in cfCSF. The driver mutation could also be detected in CTC isolated from CSF.

CONCLUSION

CTC in CSF are detected with a high sensitivity for the diagnosis of LM. ddPCR can determine EGFR mutations in both cfCSF and isolated CTC from CSF of patients with EGFR-mutated NSCLC and LM.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that EpCAM-based immunoflow cytometry analysis of CSF accurately identifies patients with LM.

Integration of rare cell capture technology into cytologic evaluation of cerebrospinal fluid specimens from patients with solid tumors and suspected leptomeningeal metastasis

INTRODUCTION

Dissemination of tumor to the leptomeninges, subarachnoid space, and cerebrospinal fluid (CSF) is termed leptomeningeal metastasis (LM) and occurs in approximately 5% of patients with solid tumors. LM is associated with dismal clinical prognosis, and routine cytologic and radiologic methods for diagnosing LM have limited sensitivity. The CellSearch immunomagnetic rare cell capture assay is FDA-approved to detect circulating tumor cells (CTCs) in peripheral blood, but whether it may have a role in identifying CSF CTCs is still unclear.

MATERIAL AND METHODS

CSF specimens from 20 patients with clinically suspected solid tumor LM collected from 2 institutions between October 2016 and January 2019 were evaluated with routine CSF cytology and underwent concurrent CTC testing with the CellSearch assay (Menarini-Silicon Biosystems, Huntingdon Valley, PA). The results of CTC testing were compared to routine CSF cytology and radiologic studies for detecting LM.

RESULTS

The CellSearch assay achieved a sensitivity of 88.9% and specificity of 100% for detecting LM (using a threshold of 1 CTC/mL of CSF as the definition of a positive CTC result). One patient with negative CSF cytology but positive CTCs developed positive cytology 37 days later.

CONCLUSIONS

In this proof-of-principle pilot study, we demonstrate that the CellSearch assay can be successfully integrated with the routine CSF cytologic workflow to aid in the diagnosis of solid tumor LM. Importantly, CTCs detected by this rare cell capture assay are found in a subset of patients with non-positive routine CSF cytology, which may have significant implications for patient management.

Current Advances and Future Perspectives of Cerebrospinal Fluid Biopsy in Midline Brain Malignancies

OPINION STATEMENT

Malignancies arising in midline brain structures, including lymphomas, teratomas, germinomas, diffuse midline gliomas, and medulloblastomas typically respond to systemic therapies, and excessive surgical excision can result in serious complications, so that total surgical removal is not routinely performed. Identifying tumor specific biomarkers that can facilitate diagnosis at early stage and allow for dynamic surveillance of the tumor is of great clinical importance. However, existing standard methods for biopsy of these brain neoplasms are high risk, time consuming, and costly. Thus, less invasive and more rapid diagnosis tests are urgently needed to detect midline brain malignancies. Currently, tools for cerebrospinal biopsy of midline brain malignancies mainly include circulating tumor DNA, circulating tumor cells, and extracellular vesicles. Circulating tumor DNA achieved minimally invasive biopsy in several brain malignancies and has advantages in detecting tumor-specific mutations. In the field of tumor heterogeneity, circulating tumor cells better reflect the genome of tumors than surgical biopsy specimens. They can be applied for the diagnosis of leptomeningeal metastasis. Extracellular vesicles contain lots of genetic information about cancer cells, so they have potential in finding therapeutic targets and studying tumor invasion and metastasis.

New Frontiers in Diagnosis and Therapy of Circulating Tumor Markers in Cerebrospinal Fluid In Vitro and In Vivo

One of the greatest challenges in neuro-oncology is diagnosis and therapy (theranostics) of leptomeningeal metastasis (LM), brain metastasis (BM) and brain tumors (BT), which are associated with poor prognosis in patients. Retrospective analyses suggest that cerebrospinal fluid (CSF) is one of the promising diagnostic targets because CSF passes through central nervous system, harvests tumor-related markers from brain tissue and, then, delivers them into peripheral parts of the human body where CSF can be sampled using minimally invasive and routine clinical procedure. However, limited sensitivity of the established clinical diagnostic cytology in vitro and MRI in vivo together with minimal therapeutic options do not provide patient care at early, potentially treatable, stages of LM, BM and BT. Novel technologies are in demand. This review outlines the advantages, limitations and clinical utility of emerging liquid biopsy in vitro and photoacoustic flow cytometry (PAFC) in vivo for assessment of CSF markers including circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), microRNA (miRNA), proteins, exosomes and emboli. The integration of in vitro and in vivo methods, PAFC-guided theranostics of single CTCs and targeted drug delivery are discussed as future perspectives.

Characteristics of Diffuse Leptomeningeal Glioneuronal Tumor With First-Episode Headache and Rapid Blindness Misdiagnosed as Viral Meningoencephalitis

Diffuse leptomeningeal glioneuronal tumor has a high degree of malignancy and high mortality. The purpose of this paper is to describe the characteristics of atypical diffuse leptomeningeal glioneuronal tumor and analyze the causes of misdiagnosis as viral meningoencephalitis. An adolescent female patient presented with headache, nausea, vomiting, sharp vision loss and cognitive dysfunction. After poor therapeutic effect of standard antiviral treatment, further inspection found that malignant cells were detected by cerebrospinal fluid (CSF) cytology; and enhanced magnetic resonance imaging (MRI) showed extensive enhancement of the leptomeningeal. In conclusions, when patient with unexplained high intracranial pressure, it is necessary to be alert to the diagnosis of diffuse leptomeningeal glioneuronal tumor. Multiple examinations of fresh CSF are helpful to increase the positive detection rate of tumor cells. Early diagnosis and active treatment are conducive to improving survival rate.

Review: Peering through a keyhole: liquid biopsy in primary and metastatic central nervous system tumours

Tumour molecular profiling by liquid biopsy is being investigated for a wide range of research and clinical purposes. The possibility of repeatedly interrogating the tumour profile using minimally invasive procedures is helping to understand spatial and temporal tumour heterogeneity, and to shed a light on mechanisms of resistance to targeted therapies. Moreover, this approach has been already implemented in clinical practice to address specific decisions regarding patients’ follow‐up and therapeutic management. For central nervous system (CNS) tumours, molecular profiling is particularly relevant for the proper characterization of primary neoplasms, while CNS metastases can significantly diverge from primary disease or extra‐CNS metastases, thus compelling a dedicated assessment. Based on these considerations, effective liquid biopsy tools for CNS tumours are highly warranted and a significant amount of data have been accrued over the last few years. These results have shown that liquid biopsy can provide clinically meaningful information about both primary and metastatic CNS tumours, but specific considerations must be taken into account, for example, when choosing the source of liquid biopsy. Nevertheless, this approach is especially attractive for CNS tumours, as repeated tumour sampling is not feasible. The aim of our review was to thoroughly report the state‐of‐the‐art regarding the opportunities and challenges posed by liquid biopsy in both primary and secondary CNS tumours.

Liquid biopsy in central nervous system metastases: a RANO review and proposals for clinical applications

Liquid biopsies collect and analyze tumor components in body fluids, and there is an increasing interest in the investigation of liquid biopsies as a surrogate for tumor tissue in the management of both primary and secondary brain tumors. Herein we critically review available literature on spinal fluid and plasma circulating tumor cells (CTCs) and cell-free tumor (ctDNA) for diagnosis and monitoring of leptomeningeal and parenchymal brain metastases. We discuss technical issues and propose several potential applications of liquid biopsies in different clinical settings (ie, for initial diagnosis, for assessment during treatment, and for guidance of treatment decisions). Last, ongoing clinical studies on CNS metastases that include liquid biopsies are summarized, and recommendations for future clinical studies are provided.

A Case of Leptomeningeal Carcinomatosis from Aggressive Metastatic Prostate Cancer

Leptomeningeal carcinomatosis (LC) is a rare leptomeningeal spread of diffusely metastatic tumors. It occurs more commonly with hematologic tumors, less commonly with solid tumors, and is exceedingly rare in prostate cancer. Due to its scarcity, it has traditionally been difficult to diagnose LC but advancement of MRI has helped considerably. However, even with technological improvements, pre-mortem diagnosis of LC remains difficult and controversial. Our case is a 71-year-old male with prostate cancer with bone metastases who presented to our facility with altered mental status (AMS), lower extremity weakness, and worsening diarrhea. The diarrhea was responsive to antibiotic therapy, but his AMS did not resolve. A head CT without contrast was negative but follow-up brain MRI revealed leptomeningeal enhancement highly suggestive of LC. Cerebrospinal fluid (CSF) cytology results were negative and other CSF studies were inconclusive. Although further studies were planned, the patient continued to deteriorate, and the family elected to withdraw care. He passed away without beginning treatment for the LC. Despite advances in cancer therapies, LC remains difficult to diagnose and treat. Imaging may be suggestive of the condition but the confirmatory tests such as repeated CSF cytology or meningeal biopsy are not only invasive but also usually occur postmortem. Additional methods of CSF testing have been studied to evaluate their role in accurately diagnosing LC but low specificity for LC has somewhat limited their use. Although treatment options are mainly palliative in nature, prompt recognition and early treatment could grant valuable time for patients and families.

Circulating Tumor Cells: Overview and Opportunities in Cytology

Circulating tumor cells (CTCs) have long been assumed to be the substrate of cancer metastasis. However, only in recent years have we begun to leverage the potential of CTCs found in minimally invasive peripheral blood specimens to improve care for cancer patients. Currently, CTC enumeration is an accepted prognostic indicator for breast, prostate, and colorectal cancer; however, CTC enumeration remains largely a research tool. More recently, the focus has shifted to CTC characterization and isolation which holds great promise for predictive testing. This review summarizes the relevant clinical, biological, and technical background necessary for pathologists and cytopathologists to appreciate the potential of CTC techniques. A summary of relevant systematic reviews of CTCs for specific cancers is then presented, as well as potential applications to precision medicine. Finally, we suggest future applications of CTC technologies that can be easily incorporated in the pathology laboratory, with the recommendation that pathologists and particularly cytopathologists apply these technologies to small specimens in the era of "doing more with less."

Circulating Tumor Cells: Applications in Cytopathology

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

Clinicopathological and Treatment-Associated Prognostic Factors in Patients with Breast Cancer Leptomeningeal Metastases in Relation to Tumor Biology

BACKGROUND

Breast cancer (BC) is one of the solid tumors most commonly associated with leptomeningeal disease (LMD). LMD carries a devastating prognosis; however, disease presentation and prognostic factors are uncertain.

SUBJECTS, MATERIALS, AND METHODS

In order to describe patient characteristics, treatment patterns, and factors associated with survival in a contemporary multicentric cohort, 153 consecutive BC patients diagnosed with LMD at two European institutions (2002-2017) were included. Time to LMD and overall survival (OS) after LMD diagnosis were evaluated using the Kaplan-Meier method and Cox proportional hazards models.

RESULTS

Median age at LMD diagnosis was 58 years (25-84). Tumor phenotype distribution was as follows: hormone receptor (HR) positive (HR+)/human epidermal growth receptor 2 (HER2) negative 51.0%, triple-negative 15.0%, HR+/HER2 positive (HER2+) 13.1% and HR negative/HER2+ 7.2%. Most patients received active anticancer treatments (radiation therapy [RT] n = 42, systemic therapy n = 110, intrathecal treatment n = 103).Median OS was 3.9 months (95% confidence interval [CI] 2.4-5.5). Eastern Cooperative Oncology Group performance status (ECOG PS) >2, high white blood cells count, low glucose, and high protein in cerebrospinal fluid (CSF) were poor prognostic factors. Having received RT or systemic treatment was associated with better prognosis. In multivariate analysis, ECOG PS (hazard ratio 2.22, 95% CI 1.25-3.94), CSF glucose levels (hazard ratio 1.74, 95% CI 1.05-2.88), and having received systemic treatment (hazard ratio 0.17, 95% CI 0.09-0.32) were confirmed as independent prognostic factors. In HER2+ BC patients, having received systemic HER2-targeted therapy was the only factor maintaining independent prognostication (hazard ratio 0.12, 95% CI 0.02-0.67) in multivariate analysis.

CONCLUSION

Despite being limited by their retrospective nature, these results highlight the need for clinical trials in BC LMD, stratified on tumor biology.

IMPLICATIONS FOR PRACTICE

Leptomeningeal disease (LMD) is a devastating complication of breast cancer (BC), and its optimal therapy is still not defined. Here, patient characteristics, treatment patterns, and prognostic factors from a contemporary cohort of 153 BC-related LMD patients are reported. In multivariate analysis, Eastern Cooperative Oncology Group performance status, cerebrospinal fluid glucose levels, and having received systemic treatment were confirmed as independent prognostic factors in the overall population, whereas in human epidermal growth receptor 2 (HER2) positive BC patients, having received systemic HER2-targeted therapy was the only factor maintaining independent prognostication in multivariate analysis. These results highlight the need to consider stratification on tumor biology in the treatment of BC LMD.

Leptomeningeal metastasis from solid tumors: clinical features and its diagnostic implication

In this study, we examined the characteristics and aimed to increase the knowledge of clinical features of leptomeningeal metastasis (LM). The clinical data, including initial diagnosis and treatment of primary tumor, clinical manifestations, neuroimaging findings, cerebrospinal fluid (CSF) examination, were analyzed. For the patients with adenocarcinoma/breast cancer, the incidence of cranial lesions and cranial nerve paralysis was obviously higher than patients with small cell lung cancer. Whereas, the incidence of involvement of intravertebral canal was obviously lower than that of small cell lung cancer. Patients with adenocarcinoma/breast cancer showed more incidence of leptomeningeal enhancement compared to those with small cell lung cancer. Persistent severe headache was noticed in those with squamous carcinoma, and usually showed absence of abnormally LM-related neuroimaging and CSF cytological findings, which resulted in a challenge in the diagnosis of LM from squamous carcinoma. Patients with different primary tumors showed differential clinical features. Significant differences were observed in clinical features between patients with adenocarcinoma/breast cancer and small cell lung cancer. Our study contributes to the understanding of clinical characteristics of LM, and contributes to improvement of LM diagnosis in clinical practice.

Management of leptomeningeal metastasis in breast cancer

Leptomeningeal metastasis (LM), which occurs when malignant cells spread to the central nervous system, is becoming an increasingly common complication in patients with breast cancer. Diagnosis and treatment of LM is challenging. Moreover, prognosis of patients with LM is poor, with a median survival of 6 months after diagnosis. This review highlights the strengths and limitations of currently available diagnostic tools and therapies for LM. The current treatments for LM, including radiotherapy, systemic therapy, and intrathecal treatment, aim to maintain the quality of life of patients by correcting neurological deficits and arresting neurological degeneration. However, there is no standardized therapy for LM because of a lack of randomized trials on this condition.

[The liquid biopsies: What is their contribution to the management of cancer?]

The « liquid biopsies » are samples of liquids such as blood, urine, spinal fluid that can contain tumor material. Clinical assays have been mainly focused on the peripheral blood containing circulating tumor cells and circulating tumor DNA. The circulating tumor cells are cancer cells released from the primary tumor or recurrences or metastases. They enter into the bloodstream after passing through the vessel wall. It is possible to analyze the circulating tumor cells by means of all cytologic and biomolecular techniques. The free circulating tumor DNA is made of fragments of DNA released by living or necrotic tumor cells proceeded from any place of the organism. The free circulating tumor DNA and DNA from circulating tumor cells show structural rearrangements among which some are therapeutic targets. Many studies showed that circulating tumor cells and circulating tumor DNA analyses are useful in revealing recurrences and tracking therapeutic targets.

Metastatic Complications of Cancer Involving the Central and Peripheral Nervous Systems

Neurologic complications of cancer may involve both the central nervous system and peripheral nervous system manifesting as brain, leptomeningeal, intramedullary, intradural, epidural, plexus, and skull base metastases. Excluding brain involvement, neurologic complications affecting these other sites are relatively infrequent, but collectively they affect more than 25% of patients with metastatic cancer causing significant morbidity and mortality. Early diagnosis and intervention optimize quality of life and improve survival.

The Utility of Liquid Biopsy in Central Nervous System Malignancies

PURPOSE OF REVIEW

Liquid biopsy is a sampling of tumor cells or tumor nucleotides from biofluids. This review explores the roles of liquid biopsy for evaluation and management of patients with primary and metastatic CNS malignancies.

RECENT FINDINGS

Circulating tumor cell (CTC) detection has emerged as a relatively sensitive and specific tool for diagnosing leptomeningeal metastases. Circulating tumor DNA (ctDNA) detection can effectively demonstrate genetic markup of CNS tumors in the cerebrospinal fluid, though its role in managing CNS malignancies is less well-defined. The value of micro RNA (miRNA) detection in CNS malignancies is unclear at this time. Current standard clinical tools for the diagnosis and monitoring of CNS malignancies have limitations, and liquid biopsy may help address clinical practice and knowledge gaps. Liquid biopsy offers exciting potential for the diagnosis, prognosis, and treatment of CNS malignancies, but each modality needs to be studied in large prospective trials to better define their use.

Mechanisms and Therapy for Cancer Metastasis to the Brain

Advances in chemotherapy and targeted therapies have improved survival in cancer patients with an increase of the incidence of newly diagnosed brain metastases (BMs). Intracranial metastases are symptomatic in 60–70% of patients. Magnetic resonance imaging (MRI) with gadolinium is more sensitive than computed tomography and advanced neuroimaging techniques have been increasingly used in the detection, treatment planning, and follow-up of BM. Apart from the morphological analysis, the most effective tool for characterizing BM is immunohistochemistry. Molecular alterations not always reflect those of the primary tumor. More sophisticated methods of tumor analysis detecting circulating biomarkers in fluids (liquid biopsy), including circulating DNA, circulating tumor cells, and extracellular vesicles, containing tumor DNA and macromolecules (microRNA), have shown promise regarding tumor treatment response and progression. The choice of therapeutic approaches is guided by prognostic scores (Recursive Partitioning Analysis and diagnostic-specific Graded Prognostic Assessment-DS-GPA). The survival benefit of surgical resection seems limited to the subgroup of patients with controlled systemic disease and good performance status. Leptomeningeal disease (LMD) can be a complication, especially in posterior fossa metastases undergoing a “piecemeal” resection. Radiosurgery of the resection cavity may offer comparable survival and local control as postoperative whole-brain radiotherapy (WBRT). WBRT alone is now the treatment of choice only for patients with single or multiple BMs not amenable to surgery or radiosurgery, or with poor prognostic factors. To reduce the neurocognitive sequelae of WBRT intensity modulated radiotherapy with hippocampal sparing, and pharmacological approaches (memantine and donepezil) have been investigated. In the last decade, a multitude of molecular abnormalities have been discovered. Approximately 33% of patients with non-small cell lung cancer (NSCLC) tumors and epidermal growth factor receptor mutations develop BMs, which are targetable with different generations of tyrosine kinase inhibitors (TKIs: gefitinib, erlotinib, afatinib, icotinib, and osimertinib). Other “druggable” alterations seen in up to 5% of NSCLC patients are the rearrangements of the “anaplastic lymphoma kinase” gene TKI (crizotinib, ceritinib, alectinib, brigatinib, and lorlatinib). In human epidermal growth factor receptor 2-positive, breast cancer targeted therapies have been widely used (trastuzumab, trastuzumab-emtansine, lapatinib-capecitabine, and neratinib). Novel targeted and immunotherapeutic agents have also revolutionized the systemic management of melanoma (ipilimumab, nivolumab, pembrolizumab, and BRAF inhibitors dabrafenib and vemurafenib).

Neoplastic meningitis in solid tumors: from diagnosis to personalized treatments

Neoplastic meningitis (NM) is a devastating complication of solid tumors with poor outcome. Some randomized clinical trials have been conducted with heterogeneous inclusion criteria, diagnostic parameters, response evaluation and primary endpoints. Recently, the Leptomeningeal Assessment in Neuro-Oncology (LANO) Group and the European Society for Medical Oncology/European Association for Neuro-Oncology have proposed some recommendations in order to provide diagnostic criteria and response evaluation scores for NM. The aim of these guidelines is to integrate the neurological examination with magnetic resonance imaging and cerebrospinal fluid findings as well as to provide a framework for use in clinical trials. However, this composite assessment needs further validation. Since intrathecal therapy represents a treatment with limited efficacy in NM, many studies have been conducted on systemic therapies, including target therapies, with some encouraging results in terms of disease control. In this review, we have analyzed the clinical aspects and the most recent diagnostic tools and therapeutic options in NM.