Cerebrospinal fluid tumor markers for the diagnosis and management of leptomeningeal metastases

Leptomeningeal Metastasis from Non-Small Cell Lung Cancer and Current Landscape of Treatments

Leptomeningeal metastasis (LM), also known as leptomeningeal carcinomatosis (LC), is a devastating complication of metastatic cancer that occurs when neoplastic cells invade the meningeal space. Diagnosis of LM remains challenging given the heterogeneous signs and symptoms at presentation and requires thorough neurological examination, cerebrospinal fluid (CSF) analysis, and MRI of the brain and spine with gadolinium. Detecting neoplastic cells in the CSF is the gold standard for diagnosing leptomeningeal metastases; however, it has low sensitivity and may require multiple CSF samples. New emerging technologies, such as liquid biopsy of CSF, have increased sensitivity and specificity for detecting circulating tumor cells in CSF. The management of LM in patients with NSCLC requires an individualized multidisciplinary approach. Treatment options include surgery for ventricular shunt placement, radiation therapy to bulky or symptomatic disease sites, systemic or intrathecal chemotherapy, molecularly targeted agents, and, more recently, immunotherapy. Targeting actionable mutations in LM from NSCLC, such as EGFR tyrosine kinase inhibitors or anaplastic lymphoma kinase gene rearrangement inhibitors, has shown encouraging results in terms of disease control and survival. Although there are limited data regarding the use of immunotherapy in LM, immunotherapy has produced promising results in several case reports. In this review, we focused on the epidemiology, pathophysiology, clinical presentation, diagnosis, and current treatment strategies, with a special emphasis on novel agents, including targeted therapies and immunotherapy of LM in patients with NSCLC.

Novel Therapeutic Approaches in Neoplastic Meningitis

Central nervous system (CNS) metastasis from systemic cancers can involve the brain parenchyma, leptomeninges, or the dura. Neoplastic meningitis (NM), also known by different terms, including leptomeningeal carcinomatosis and carcinomatous meningitis, occurs due to solid tumors and hematologic malignancies and is associated with a poor prognosis. The current management paradigm entails a multimodal approach focused on palliation with surgery, radiation, and chemotherapy, which may be administered systemically or directly into the cerebrospinal fluid (CSF). This review focuses on novel therapeutic approaches, including targeted and immunotherapeutic agents under investigation, that have shown promise in NM arising from solid tumors.

Treatment Options for Leptomeningeal Metastases of Solid Cancers: Literature Review and Personal Experience

Leptomeningeal metastases (LM) may complicate the clinical course of any solid cancer or hematological malignancy. Diagnosis of such cases requires a multifaceted approach, including careful evaluation of the clinical history, detailed neurological examination, advanced imaging studies, and related laboratory data analysis. Therapeutic options for management of LM have not been standardized yet. Conventional intrathecal chemotherapy with or without involved-field fractionated radiotherapy has only modest efficacy, and the prognosis of most patients remains grim. Therefore, development of new, more aggressive multimodal treatment strategies is definitely needed. Immune checkpoint inhibitors-in particular, molecular targeted therapy-have demonstrated promising results in selected groups of patients. There may be an important role for stereotactic radiosurgery as well. Because organization of prospective randomized multi-institutional trials on treatment of LM of solid cancers may be problematic, practical guidelines for optimal therapeutic strategies in such cases should be established on the basis of integrated results of small-scale prospective and retrospective studies.

Leptomeningeal Metastasis: Challenges in Diagnosis and Treatment

As therapeutic options and supportive care for the treatment of neoplastic disease have improved, there has been an associated increase in the incidence of leptomeningeal disease. In this review, the clinical presentation, natural history, diagnostic evaluation, and treatment options for this often devastating sequela of solid tumors, lymphoma, and leukemia will be summarized. The therapeutic efficacy of ionizing radiation, systemic agents, and intrathecal drugs will be examined from the existing literature. Additionally the pathophysiology, which in part defines the therapeutic limitations in approaching this patient population, will be discussed in order to assist in individualized clinical decision making.

Proteomic analysis of cerebrospinal fluid discriminates malignant and nonmalignant disease of the central nervous system and identifies specific protein markers

CNS diseases are often accompanied by changes in the protein composition of cerebrospinal fluid (CSF). SELDI-TOF-MS provides an approach for identifying specific protein markers of disease in biological fluids. We compared the CSF proteomes from patients with neoplastic and reactive/inflammatory CNS diseases to identify potential biomarkers. SELDI-TOF-MS was performed on CSF derived from lumbar puncture of 32 patients, including 10 with CNS malignancies, 12 with inflammatory or reactive conditions, and 10 with unknown CNS disease. Using the SAX-2 (strong anionic exchange) chip, we uncovered three conserved protein peak ranges within each disease category. For neoplastic diseases, we identified conserved peaks at 7.5-8.0 kDa (9/10 samples), 15.1-15.9 kDa (8/10 samples), and 30.0-32.0 kDa (5/10 samples). In reactive/inflammatory diseases, conserved peaks were found at 6.7-7.1 kDa (10/12 samples), 11.5-11.9 kDa (12/12 samples), and 13.3-13.7 kDa (9/12 samples). A protein from the 30.0 to 32.0 kDa peak range found in neoplastic CSF was identified by MALDI analysis as carbonic anhydrase, a protein overexpressed in many malignancies including high-grade gliomas. Similarly, cystatin C was identified in the 13.3-13.7 kDa peak range in non-neoplastic CSF and was most prominent in inflammatory conditions. Our approach provides a rational basis for identifying biomarkers that could be used for detection, diagnosis, and monitoring of CNS diseases.

Neoplastic meningitis

Neoplastic meningitis is recognized clinically in 4% to 7% of patients with extraneural cancer, but it remains dramatically under-diagnosed. The frequency of neoplastic meningitis is increasing because of heightened clinical suspicion, improved neuroimaging techniques, and longer survival in patients with extraneural cancer Longer survival allows residual tumor cells within central nervous system sanctuary sites time to become symptomatic. Affected patients may present with cerebral, cranial nerve, or spinal signs and symptoms, depending on the specific sites of central nervous system (CNS) involvement. Magnetic Resonance Imaging (MRI) seems to be sensitive for detecting metastatic deposits along the neuraxis. However, metastases at a microscopic level are below the resolution of MRI scanning. As a result, the standard diagnostic test for neoplastic meningitis remains the cytologic identification of malignant cells in cerebrospinal fluid (CSF). Although CSF cytology is useful, malignant cells are not detected in as many as one third of patients who have compelling clinical or radiographic evidence of neoplastic meningitis. Novel assays are being tested that may enhance the early identification of malignant cells in CSF. Currently, the diagnosis occurs generally after the onset of neurologic manifestations and heralds a rapidly fatal course for most patients. By the time symptoms appear, most tumors have disseminated widely within the CNS, due to cortical irritation, compression of nervous system structures, or obstruction of CSF flow. At this stage surgery, cranial irradiation, and chemotherapy are rarely, if ever, curative. The goals of treatment are to improve or to stabilize the neurologic status of patients and to prolong survival. A major problem in treating neoplastic meningitis is that the entire neuraxis must be treated. If only symptomatic areas are treated, reseeding of the neuraxis with tumor cells will occur. Therefore, intrathecal chemotherapy remains a mainstay of therapy. Currently, four therapeutic agents are available for intrathecal treatment: methotrexate, ara-C, sustained-release ara-C (DepoCyt; Chiron Therapeutics, San Francisco, CA), and thiotepa. Unfortunately, intrathecal chemotherapy does not treat bulky disease in the subarachnoid space, and often is slow to stabilize progressive neurologic deficits. For these reasons, radiation therapy to sites of symptomatic disease and sites of bulky disease on imaging studies is recommended. High dose intravenous methotrexate may be as effective as intrathecal methotrexate. Alternative approaches (which offer less toxicity, enhanced therapeutic effect, and prolonged survival) are being investigated.

Lipid-associated sialoprotein in the cerebrospinal fluid: association with brain malignancies

BACKGROUND

Changes in the glycosylation process by tumor cells result in larger amounts of sialoproteins on their surface compared with normal cells. Sialoproteins then are released into the surrounding environment primarily by shedding or cell lysis. In the current study, the authors attempted to evaluate whether lipid-associated sialoprotein (LSP) in the cerebrospinal fluid (CSF) can distinguish patients with primary and metastatic brain tumors from those without brain tumors as well as determine response to treatment.

METHODS

CSF samples were obtained from a tissue bank. The concentration of LSP was determined after chloroform:methanol extraction followed by protein precipitation. One-way analysis of variance and Scheffe pairwise comparisons were used for statistical analysis.

RESULTS

The CSF of neurologically normal controls, patients with a normal leukocyte count (< or = 5/microl), and patients with various neurologic disorders or systemic tumors without central nervous system (CNS) malignancies contained similar levels of LSP. The CSF from patients with a normal leukocyte count and newly diagnosed primary or metastatic brain tumors contained on average 3.7-fold higher levels of LSP compared with CSF from patients without CNS tumors (P = 0.0001). The CSF from patients with brain tumors with progressive disease not responding to treatment contained high levels of LSP comparable to the levels found in newly diagnosed patients. The CSF from treatment-responsive patients contained decreased levels of LSP similar to that found in control patients.

CONCLUSIONS

The LSP in CSF may be a useful marker with which to determine the presence of intracranial malignancies and assess response to treatment.

Meningeal metastases: clinical aspects and diagnosis

The authors review the clinical and diagnostic aspects involved in leptomeningeal disease due to solid tumours, leukaemias and lymphomas. The importance of the combination of clinical findings with cerebral spinal fluid (CSF) examination and imaging studies in making an early diagnosis is underlined. The raising prevalence of this complication of systemic cancer deserves specific attention on the part of neurologists involved in consultation liason with general medicine and oncology.

Humoral CSF parameters in the differential diagnosis of hematologic CNS neoplasia

Cerebrospinal fluid (CSF) and serum samples of 20 patients with central nervous system manifestations of hematological malignancies including primary cerebral lymphoma (n = 5) and disseminated non-Hodgkin lymphoma (n = 7) were examined for albumin, IgG, IgM, fibronectin, beta 2-microglobulin, interleukin-6, soluble interleukin-2 receptor, tumor necrosis factor alpha, and oligoclonal immunoglobulin bands. Although a broad range of abnormalities were detected, no reliable CSF parameter for the diagnosis of leptomeningeal spread from hematological neoplasias could be identified. An analysis of 61 repeat lumbar punctures added little to the findings of the first CSF examinations. Currently, immunochemical studies of CSF cell surface markers and early biopsy have probably more clinical value than the determination of the humoral CSF parameters included in this study. However, analysis of cytokine synthesis by single CSF cells using molecular biology techniques may improve the differential diagnosis of hematological neoplasia of the brain and spinal cord in the future.

Cerebrospinal fluid B2-microglobulin levels in meningeal involvement by malignancy

Cerebrospinal fluid (CSF) and serum B2-microglobulin (B2m) levels were measured prospectively in 63 patients with hematological malignancies and 14 patients with solid tumours to evaluate the correlation between elevated levels and malignant infiltration of meninges. Serial CSF B2-m levels were also measured in 18 patients who received prophylactic intrathecal cytotoxic treatment. CSF B2-m levels were significantly higher in patients with central nervous system (CNS) involvement than in those without (p less than 0.001). A CSF B2-m level greater than 1.80 mg/L was closely associated with CNS disease (specificity 96%, sensitivity 76%) and CNS infiltration was also likely when the CSF B2-m level exceeded a simultaneously drawn serum level (specificity 98%, sensitivity 46%). Intrathecal methotrexate prophylaxis resulted in a consistent and significant rise in CSF B2-m levels with an average increase of 96% during a course of intrathecal injections. These results suggest that CSF B2-m levels may not be helpful for predicting early CNS relapse in these patients. However the CSF B2-m level and the corresponding serum B2-m level is a useful adjunct to the cytological diagnosis of CNS involvement by malignancy at presentation. Its value in predicting early CNS relapse and documenting response to CNS treatment requires further clarification.

Leukemic relapse presenting as sciatic nerve involvement by chloroma (granulocytic sarcoma)

A relapse of acute nonlymphocytic leukemia in a child presented as subacute mononeuropathy involving the sciatic nerve. Surgical exploration showed a chloroma (granulocytic sarcoma) of the distal sciatic nerve, but resection and irradiation did not lead to recovery of nerve function or complete resolution of the patient's symptomatic neuropathic pain. This case represents a rare neurologic complication of what is currently an uncommon presentation for leukemic relapse, and may be the only reported case of chloromatous involvement of the peripheral nervous system (PNS) without coexisting epidural or leptomeningeal leukemia.

Routine investigations of the CSF with special reference to meningeal malignancy and infectious meningitis

Usefulness of cell count and concentrations of glucose and total protein in CSF are analysed with regard to the diagnosis of leptomeningeal metastasis from solid and hematological malignancy. A group of patients with pleiocytosis in CSF of non-neoplastic origin served as a reference group. It is concluded that these routine tests have limited value for the determination of the viral, bacterial or neoplastic etiology of meningeal disorders. The most important value of these tests appears to be the discriminating capacity of the finding of an increased number of polymorphonuclear leucocytes, regularly found in patients with acute bacterial meningitis.