Liquid biopsy in brain tumors: moving on, slowly.

PURPOSE OF REVIEW: Due to limited access to the tumor, there is an obvious clinical potential for liquid biopsy in patients with primary brain tumors. Here, we review current approaches, present limitations to be dealt with, and new promising data that may impact the field. RECENT FINDINGS: The value of circulating tumor cell-free DNA (ctDNA) in the cerebrospinal fluid (CSF) for the noninvasive diagnosis of primary brain tumors has been confirmed in several reports. The detection of ctDNA in the peripheral blood is desirable for patient follow-up but requires ultrasensitive methods to identify low mutant allelic frequencies. Digital PCR approaches and targeted gene panels have been used to identify recurrent hotspot mutations and copy number variations (CNVs) from CSF or plasma. Tumor classification from circulating methylomes in plasma has been actively pursued, although the need of advanced bioinformatics currently hampers clinical application. The use of focused ultrasounds to open the blood-brain barrier may represent a way to enrich of ctDNA the peripheral blood and enhance plasma-based liquid biopsy. SUMMARY: Monitoring CNVs and hotspot mutations by liquid biopsy is a promising tool to detect minimal residual disease and strengthen response assessment in patients with primary brain tumors. Novel methods to increase the relative and/or absolute amount of ctDNA can improve the clinical potential of plasma-based liquid biopsies.

Hypersomnia in anti-glutamic acid decarboxylase 65 (GAD65) associated neurological syndromes: A pilot study.

BACKGROUND AND PURPOSE: Despite their detrimental impact on the quality of life in autoimmune encephalitis, sleep disorders have not been investigated in anti-glutamic acid decarboxylase (GAD65) associated neurological syndromes. METHODS: Six consecutive adult patients diagnosed with anti-GAD65-associated neurological syndromes (four with limbic encephalitis and two with stiff-person syndrome) and 12 healthy controls were enrolled. Participants underwent sleep interviews and sleep studies including night-time video-polysomnography, followed by five daytime multiple sleep latency tests (MSLTs, to assess propensity to fall asleep) and an 18 h bed rest polysomnography (to assess excessive sleep need). RESULTS: Patients reported the need for daily naps and that their cognition and quality of life were altered by sleepiness, but they had normal scores on the Epworth sleepiness scale. Compared with controls, sleep latencies during the MSLT were shorter in the patient group (median 5.8 min, interquartile range [IQR] 4.5, 6.0 vs. 17.7 min, IQR 16.3, 19.7, p = 0.001), and the arousal index was reduced (2.5/h, IQR 2.3, 3.0 vs. 22.3/h, IQR 13.8, 30.0, p = 0.002), although total sleep time was similar between groups (621 min, IQR 464, 651 vs. 542.5 min, IQR 499, 582, p = 0.51). Remarkably, all six patients had MSLT latencies ≤8 min, indicating severe sleepiness. No parasomnia or sleep-disordered breathing was detected. CONCLUSION: Central hypersomnia is a relevant characteristic of anti-GAD65-associated neurological syndromes.

The coming of age of liquid biopsy in neuro-oncology.

The clinical role of liquid biopsy in oncology is growing significantly. In gliomas and other brain tumours, targeted sequencing of cell-free DNA (cfDNA) from CSF may help differential diagnosis when surgery is not recommended and be more representative of tumour heterogeneity than surgical specimens, unveiling targetable genetic alterations. Given the invasive nature of lumbar puncture to obtain CSF, the quantitative analysis of cfDNA in plasma is a lively option for patient follow-up. Confounding factors may be represented by cfDNA variations due to concomitant pathologies (inflammatory diseases, seizures) or clonal haematopoiesis. Pilot studies suggest that methylome analysis of cfDNA from plasma and temporary opening of the blood-brain barrier by ultrasound have the potential to overcome some of these limitations. Together with this, an increased understanding of mechanisms modulating the shedding of cfDNA by the tumour may help to decrypt the meaning of cfDNA kinetics in blood or CSF.

CSF-based liquid biopsy pointing to a diagnosis of diffuse glioma in a patient with supposed neurodegenerative disorder.

INTRODUCTION: The differential diagnosis of brain diseases becomes challenging in cases where imaging is not sufficiently informative, and surgical biopsy is impossible or unacceptable to the patient. METHODS: An elderly patient with progressive short-term memory loss and cognitive impairment presented with a normal brain CT scan, a brain FDG-PET that indicated symmetrical deterioration of the white matter in the frontal lobes, and inconclusive results of a molecular marker analysis of suspected dementia in cerebrospinal fluid (CSF). Brain MRI suggested the diagnosis of lower grade glioma. The patient refused surgical biopsy. In order to investigate whether somatic mutations associated with gliomas existed, we performed a "liquid biopsy" by the targeted sequencing of cell-free DNA (cfDNA) from his CSF. RESULTS: Deep sequencing of the cfDNA from CSF revealed somatic mutations characteristically found in gliomas, including mutations of the TP53 (Arg282Trp), BRAF (Val600Glu), and IDH1 (Arg132His) genes. The patient is currently treated with temozolomide, and his clinical and MRI findings suggest the stabilization of his disease. CONCLUSION: Neurological patients may benefit from liquid biopsy diagnostic work-up as it can reveal therapeutically targetable mutations.

Adoptive Transfer of JC Virus-Specific T Lymphocytes for the Treatment of Progressive Multifocal Leukoencephalopathy.

OBJECTIVE: Progressive multifocal leukoencephalopathy (PML) is still burdened by high mortality in a subset of patients, such as those affected by hematological malignancies. The aim of this study was to analyze the safety and carry out preliminary evaluation of the efficacy of polyomavirus JC (JCPyV)-specific T cell therapy in a cohort of hematological patients with PML. METHODS: Between 2014 and 2019, 9 patients with a diagnosis of "definite PML" according to the 2013 consensus who were showing progressive clinical deterioration received JCPyV-specific T cells. Cell lines were expanded from autologous or allogenic peripheral blood mononuclear cells by stimulation with JCPyV antigen-derived peptides. RESULTS: None of the patients experienced treatment-related adverse events. In the evaluable patients, an increase in the frequency of circulating JCPyV-specific lymphocytes was observed, with a decrease or clearance of JCPyV viral load in cerebrospinal fluid. In responsive patients, transient appearance of punctate areas of contrast enhancement within, or close to, PML lesions was observed, which was interpreted as a sign of immune control and which regressed spontaneously without the need for steroid treatment. Six of 9 patients achieved PML control, with 5 alive and in good clinical condition at their last follow-up. INTERPRETATION: Among other novel treatments, T cell therapy is emerging as a viable treatment option in patients with PML, particularly for those not amenable to restoration of specific immunity. Neurologists should be encouraged to refer PML patients to specialized centers to allow access to this treatment strategy. ANN NEUROL 2021;89:769-779.

Peripheral neuropathies after BRAF and/or MEK inhibitor treatment: A pharmacovigilance study.

Reports suggested the potential occurrence of peripheral neuropathies (PN) in patients treated with BRAF (BRAFi) and/or MEK inhibitors (MEKi) for BRAF-activated tumours. We aimed to better characterize these PN. We queried the French pharmacovigilance database for all cases of PN attributed to BRAFi and/or MEKi. Fifteen patients were identified. Two main clinical PN phenotypes were seen. Six patients presented a length-dependent, axonal polyneuropathy: symptoms were mostly sensory and affecting the lower limbs; management and outcome were variable. Nine patients developed a demyelinating polyradiculoneuropathy: symptoms affected the four limbs and included hypoesthesia, weakness and ataxia; cranial nerves were involved in four cases; most patients received intravenous immunoglobulins or glucocorticoids, with variable outcome; one patient was rechallenged with a different BRAFi/MEKi combination with a rapid relapse in symptoms. In conclusion, patients under BRAFi/MEKi therapy may develop treatment-induced PN. Two main phenotypes can occur: a symmetric, axonal, length-dependent polyneuropathy and a demyelinating polyradiculoneuropathy.

MINCR: A long non-coding RNA shared between cancer and neurodegeneration.

The multitasking nature of lncRNAs allows them to play a central role in both physiological and pathological conditions. Often the same lncRNA can participate in different diseases. Specifically, the MYC-induced Long non-Coding RNA MINCR is upregulated in various cancer types, while downregulated in Amyotrophic Lateral Sclerosis patients. Therefore, this work aims to investigate MINCR potential mechanisms of action and its implications in cancer and neurodegeneration in relation to its expression levels in SH-SY5Y cells through RNA-sequencing approach. Our results show that MINCR overexpression causes massive alterations in cancer-related genes, leading to disruption in many fundamental processes, such as cell cycle and growth factor signaling. On the contrary, MINCR downregulation influences a small number of genes involved in different neurodegenerative disorders, mostly concerning RNA metabolism and inflammation. Thus, understanding the cause and functional consequences of MINCR deregulation gives important insights on potential pathogenetic mechanisms both in cancer and in neurodegeneration.

Leukoencephalopathy with transient splenial lesions related to 5-fluorouracil or capecitabine.

BACKGROUND: 5-Fluorouracil (5-FU) and its oral prodrug capecitabine have been rarely but consistently associated with acute central nervous system toxicity, including transient leukoencephalopathies involving the splenium of the corpus callosum. METHODS: We performed a retrospective search in the French Pharmacovigilance database (FPDB) (January 1985-July 2020) for adult patients affected by solid cancers who developed acute toxic leukoencephalopathies with splenial lesions following treatment with 5-FU or capecitabine. A comprehensive review of the literature helped to circumstantiate our findings. RESULTS: Our research in the FPDB identified six patients who, within 3 days from their first cycle of 5-FU or capecitabine, developed acute neurological symptoms, including gait ataxia (n = 4), dysarthria (n = 3), dysmetria (n = 2), headache (n = 2), and confusion (n = 2). Brain magnetic resonance imaging (MRI) showed T2/FLAIR (fluid-attenuated inversion recovery) hyperintensities in the corpus callosum, with diffusion restriction and no contrast enhancement, generally accompanied by additional alterations in the bilateral supratentorial white matter (n = 5). All patients discontinued the agent supposedly responsible for the toxicity and experienced full recovery after a median of 8.5 days from symptom onset. Control MRI showed a progressive normalization of acute MRI abnormalities. Literature review identified 26 cases with similar clinical and paraclinical characteristics. A single patient from the literature resumed 5-FU at a lower dose, with no recurrent toxicity. CONCLUSIONS: 5-FU and capecitabine might be responsible for acute leukoencephalopathies with transient splenial lesions that are generally reversible upon drug discontinuation. Resuming the agent responsible for toxicity might be feasible in selected cases, after having excluded dihydropyrimidine dehydrogenase deficiency, if expected benefits outweigh the risks.

Adult brainstem glioma: a multicentre retrospective analysis of 47 Italian patients.

BACKGROUND AND PURPOSE: Adult brainstem gliomas are rare primary brain tumours with heterogeneous clinical course. The low frequency of these tumours makes it difficult to achieve high-quality evidence regarding prognostic factors, adequate therapeutic approach and outcome in such patients. METHODS: In this retrospective study, we analysed clinical, radiological, molecular, prognostic and therapeutic factors in a series of 47 histologically proven adult brainstem gliomas recruited over a 20-year period (1998-2018). RESULTS: Twenty-two patients were male, 25 female with median age of 39 years. The tumour involved one brainstem segment in 20 cases and 2 or more segments in 27. Contrast enhancement was reported in 28 cases. Surgical procedures included biopsy in 26 cases and partial/total resection in the remaining 21. Histological diagnosis was of low-grade glioma in 23 patients, high-grade glioma in 22 and non-diagnostic in 2 cases. Data regarding molecular biology were available for 22 patients. Median overall survival was 35 months, in particular 16 months in high-grade glioma and 84 months in low-grade glioma. At univariate analysis, tumour grade was the only factor with a statistically significant impact on survival time (p = 0,003), whereas younger age, better performance status and total/subtotal resection showed a trend to more prolonged survival. This study also confirms safety of biopsy/surgery in adult brainstem glioma patients and shows a clear trend to a more frequent assessment of molecular biology data. CONCLUSIONS: Further prospective multicentre efforts, and hopefully clinical trials, are necessary to improve outcome in this neglected glioma patient population.

Guillain-Barré Syndrome During Platinum-Based Chemotherapy: A Case Series and Review of the Literature.

Platinum-based chemotherapy is commonly associated with toxic sensory neuropathies, but also, although rarely, with Guillain-Barré syndrome (GBS). We describe five patients who developed GBS while receiving platinum-based chemotherapy for a solid tumor and report the five cases published so far. Most patients had received cumulative platinum doses below known neurotoxic levels, and all of them had an optimal outcome after platinum discontinuation, associated in most cases with administration of intravenous immunoglobulin. Clinical presentation, electroneuromyography, and cerebrospinal fluid analysis help clinicians to differentiate GBS from toxic neuropathy. Platinum compounds are the only chemotherapeutic agents used for solid tumors that have been associated to GBS. Thus, we propose that GBS may constitute a non-dose-dependent side effect of platinum drugs and that awareness needs to be raised among oncologists on this rare but potentially life-threatening complication of platinum chemotherapy. IMPLICATIONS FOR PRACTICE: Many patients on platinum-based chemotherapy for solid tumors develop sensory neuropathy, a common dose-dependent side effect. The authors propose that Guillain-Barré syndrome may constitute an immune-mediated, non-dose-related side effect of platinum-based chemotherapy. Prompt diagnosis of Guillain-Barré syndrome and distinction from classical toxic neuropathy are crucial for optimal treatment. Platinum discontinuation, associated if needed to intravenous immunoglobulin administration, radically changes the course of the disease and minimizes neurological sequelae.

Neurological complications of chimeric antigen receptor T cells and immune-checkpoint inhibitors: ongoing challenges in daily practice.

PURPOSE OF REVIEW: The aim of this review is to summarize the most recent advances in the management of neurological toxicities associated with immune-checkpoint inhibitors (ICIs) and chimeric antigen receptor (CAR)-T cells. RECENT FINDINGS: The advent of cancer immunotherapies has dramatically improved the prognosis of several refractory and advanced neoplasms. Owing to their mechanism of action, cancer immunotherapies have been associated with a variety of immune-related adverse events (irAE). Neurological irAE are uncommon compared with other irAE, but they are associated with significant morbidity and mortality. Despite the efforts to draft common protocols and guidelines, the management of neurological irAE remains challenging. Our ability to predict the development of neurotoxicity is still limited, hampering to elaborate prevention strategies. Treatment heavily relies on the administration of high-dose corticosteroids that, however, have the potential to impair oncological efficacy. The experimentation of novel strategies to avoid resorting to corticosteroids is hindered by the lack of an adequate understanding of the pathogenetic mechanisms driving the development of irAE. SUMMARY: In this review, we will discuss the most recent advances on the diagnosis and management of neurological irAE associated with ICIs and CAR-T cells, focusing on the issues that remain most challenging in clinical practice.

Diagnosing acute encephalitis in patients with hematological disorders: caveats and pitfalls.

The aim of this study was to review the quality of the diagnostic work-up for acute encephalitis carried out at our center in a cohort of patients with hematological disorders. Our data showed substantial heterogeneity in investigating patients. Not all patients had their CSF tested for viruses commonly responsible for encephalitis in immunocompetent individuals (e.g., VZV, enterovirus). A blood sample for the calculation of the CSF/blood replication ratio was collected in 74% of cases. CSF cultures and immunophenotyping of CSF cells were performed in 77% and 21% of patients, respectively. A multidisciplinary consensus is needed to improve current guidelines and standardize diagnostic protocols.

Cranial nerve palsies in patients with hematological malignancies: a case series.

Objectives: Cranial neuropathies (CNs) can be due to a wide spectrum of causes, and the differential diagnosis is particularly challenging in patients with positive history of hematological malignancies, when neoplastic meningitis (NM) must be excluded.Patients and Methods: We retrospectively selected a series of twelve haematological patients with isolated cranial neuropathies (ICNs) or multiple cranial neuropathies (MCNs). among 71 patients that developed neurologic symptoms during different stages of the cancer, between 1 January, 2010 and 31 December, 2017. Brain and cauda equina magnetic resonance imaging (MRI) with gadolinium, cerebrospinal fluid (CSF) analysis, including flow cytometry for cell immunophenotyping and microbiological exams were performed in all patients.Results: Patients developed signs and symptoms of involvement of isolated (n = 11) or multiple (n = 1) cranial nerves, at different stages of the primary disease, and, in 5 of these cases in complete remission after hematopoietic stem cell transplantation. Among the 5 cases that eventually were diagnosed as having NM, cerebrospinal fluid was positive for neoplastic cells in 3, and MRI gadolinium-enhancement was present in 3. The other episodes were attributed to heterogeneous pathologies that were unrelated to meningeal infiltration by neoplastic cells.Conclusions: Our observations confirm that NM in haematological malignancies can yield insidious isolated signs of cranial nerves. Only a multidisciplinary approach allows prompt recognition of these conditions through a challenging process of differential diagnosis, and proper therapies.

Neurological Syndromes Associated with Anti-GAD Antibodies.

Glutamic acid decarboxylase (GAD) is an intracellular enzyme whose physiologic function is the decarboxylation of glutamate to gamma-aminobutyric acid (GABA), the main inhibitory neurotransmitter within the central nervous system. GAD antibodies (Ab) have been associated with multiple neurological syndromes, including stiff-person syndrome, cerebellar ataxia, and limbic encephalitis, which are all considered to result from reduced GABAergic transmission. The pathogenic role of GAD Ab is still debated, and some evidence suggests that GAD autoimmunity might primarily be cell-mediated. Diagnosis relies on the detection of high titers of GAD Ab in serum and/or in the detection of GAD Ab in the cerebrospinal fluid. Due to the relative rarity of these syndromes, treatment schemes and predictors of response are poorly defined, highlighting the unmet need for multicentric prospective trials in this population. Here, we reviewed the main clinical characteristics of neurological syndromes associated with GAD Ab, focusing on pathophysiologic mechanisms.

Transcriptomic immune profiling of ovarian cancers in paraneoplastic cerebellar degeneration associated with anti-Yo antibodies.

BACKGROUND: Paraneoplastic neurological syndromes are rare conditions where an autoimmune reaction against the nervous system appears in patients suffering from a tumour, but not linked to the spreading of the tumour. A break in the immune tolerance is thought to be the trigger. METHODS: The transcriptomic profile of 12 ovarian tumours (OT) from patients suffering from paraneoplastic cerebellar degeneration (PCD) linked to anti-Yo antibodies (anti-Yo PCD OT) was compared with 733 ovarian tumours (OT control) from different public databases using linear model analysis. RESULTS: A prominent significant transcriptomic over-representation of CD8+ and Treg cells was found in anti-Yo PCD OT, as compared to the OT control. However, the overall degree of immune cell infiltration was similar, according to the ESTIMATE immune score. We also found an under-representation of M2 macrophages in anti-Yo PCD OT. Furthermore, the differentially expressed genes were enriched for AIRE-related genes, a well-known transcription factor associated with a broad range of autoimmune diseases. Finally, we found that the differentially expressed genes were correlated to the transcriptomic profiling of the cerebellar structures. CONCLUSIONS: Our data pinpointed the enrichment of acquired immune response, particularly high density of CD8+ lymphocytes, and high-level expression of CDR-related antigens in anti-Yo PCD OT.

Neurological paraneoplastic syndromes: an update.

PURPOSE OF REVIEW: To describe recent advances in the diagnosis and treatment of paraneoplastic neurological syndromes (PNS). RECENT FINDINGS: PNS are rare complications of cancer caused by an immune cross-reaction between antigens expressed by tumor cells and neurons. The target of the immune attack can be an intracellular antigen or a cell-surface antigen. Although both types of autoimmunity are 'paraneoplastic', as indirectly triggered by the presence of a tumor, they profoundly differ in terms of clinical profile, pathogenesis and outcome. PNS associated with antibodies to intracellular antigens (icPNS) are characterized by relentless progression and poor response to treatment, because of rapid and permanent neuronal loss. PNS associated with antibodies to cell-surface antigens (csPNS) generally show favorable response to immune therapy and good functional outcome, as they result from reversible neuronal dysfunction. SUMMARY: The spectrum of paraneoplastic autoimmunity has dramatically expanded following the discovery of cell-surface antibodies. Novel antibodies are incessantly discovered, some of which have a solid association with cancer. As csPNS usually respond to immune therapy, the optimization of current treatment strategies should have high priority to improve therapeutic results and prevent relapses.

Diffuse gliomas classified by 1p/19q co-deletion, TERT promoter and IDH mutation status are associated with specific genetic risk loci.

Recent genome-wide association studies of glioma have led to the discovery of single nucleotide polymorphisms (SNPs) at 25 loci influencing risk. Gliomas are heterogeneous, hence to investigate the relationship between risk SNPs and glioma subtype we analysed 1659 tumours profiled for IDH mutation, TERT promoter mutation and 1p/19q co-deletion. These data allowed definition of five molecular subgroups of glioma: triple-positive (IDH mutated, 1p/19q co-deletion, TERT promoter mutated); TERT-IDH (IDH mutated, TERT promoter mutated, 1p/19q-wild-type); IDH-only (IDH mutated, 1p/19q wild-type, TERT promoter wild-type); triple-negative (IDH wild-type, 1p/19q wild-type, TERT promoter wild-type) and TERT-only (TERT promoter mutated, IDH wild-type, 1p/19q wild-type). Most glioma risk loci showed subtype specificity: (1) the 8q24.21 SNP for triple-positive glioma; (2) 5p15.33, 9p21.3, 17p13.1 and 20q13.33 SNPs for TERT-only glioma; (3) 1q44, 2q33.3, 3p14.1, 11q21, 11q23.3, 14q12, and 15q24.2 SNPs for IDH mutated glioma. To link risk SNPs to target candidate genes we analysed Hi-C and gene expression data, highlighting the potential role of IDH1 at 2q33.3, MYC at 8q24.21 and STMN3 at 20q13.33. Our observations provide further insight into the nature of susceptibility to glioma.

Herpes simplex encephalitis in glioma patients: a challenging diagnosis.

OBJECTIVES: In recent years, herpes simplex encephalitis (HSE) has been reported with increasing frequency in settings of immunosuppression, such as acquired immunodeficiency, transplantation and cancer. As observed, in immunocompromised individuals HSE presents peculiar clinical and paraclinical features, and poorer prognosis. METHODS: Here we describe a retrospective series of seven cases of HSE in patients with high-grade glioma (HGG), collected among three institutions in a 5-year period (during this time, a total of 1750 patients with HGG were treated). RESULTS: Diagnosis of the condition was particularly challenging due to the confounding clinical presentation and the atypical biological findings. As a result, antiviral treatment was started with a sharp delay compared with immunocompetent hosts. Prognosis was poor, with high short-term mortality and severe residual disability in survivors. CONCLUSIONS: The substantial incidence of HSE observed in our centres together with the difficulty in diagnosing the condition suggest that the incidence of this complication may be highly underestimated. The aim of our report is to strengthen the observation of HSE in patients with HGG and outline the key elements that may allow its diagnosis.