SOX1 antibodies in sera from patients with paraneoplastic neurological syndromes

Objectives – SOX1 antibodies have been described in patients with Lambert–Eaton myasthenic syndrome (LEMS) in association with voltage‐gated calcium channel antibodies as serological markers of small cell lung cancer (SCLC). This study was aimed to screen for additional SOX1 autoimmunity in onconeural antibody‐positive sera from patients with paraneoplastic neurological syndromes (PNS) other than LEMS and to identify the clinical–immunological profile and associated tumours of patients with coexisting SOX1 antibodies. Methods– We retrospectively analysed sera from 55 patients with different PNS positive for well‐characterized antineuronal antibodies for the presence of SOX1 antibodies by recombinant ELISA and immunoblot. Results– Eight (14.5%) patients showed additional SOX1 antibodies in the ELISA and the recombinant immunoblot. Five patients had coexisting Hu antibodies, while the other three showed coexisting CV2/CRMP5, amphiphysin, and coexisting CV2/CRMP5 and Hu antibodies, respectively. PNS included (partially overlapping) subacute sensory neuropathy, subacute sensorimotor neuropathy, cerebellar degeneration, brainstem encephalitis, encephalomyelitis and limbic encephalitis. No tumour was detected in two patients, while the others had lung cancer (four SCLC and two non‐SCLC). One patient showed SOX1‐specific intrathecal antibody synthesis. Conclusions– We describe SOX1 reactivity for the first time overlapping with CV2/CRMP5 and amphiphysin antibodies. SOX1 reactivity is predominantly associated with Hu antibodies and SCLC, but can occur also in other types of lung cancer. Neurological manifestations present in patients with coexisting SOX1 antibodies and well‐characterized antineuronal antibodies do not differ from those previously described in patients positive for antineuronal antibodies but no SOX1‐specific anti‐glial antibodies.     

神经系统副肿瘤综合征与神经副肿瘤抗体分析

目的探讨神经系统副肿瘤综合征(PNS)临床表现及神经副肿瘤抗体的特征。方法分析2009年1月至2019年9月北京大学第一医院神经内科确诊的110例PNS患者的临床特征及神经副肿瘤抗体类型。结果110例患者出现17种临床综合征,其中43例(39.1%)为经典临床综合征,最常见的为亚急性小脑变性14例(12.7%)和边缘性脑炎11例(10.0%);62例(56.4%)为非经典临床综合征,最常见的为感觉运动周围神经病19例(17.3%)和重症肌无力10例(9.1%)。69例(62.7%)患者发现恶性肿瘤,肺癌20例(18.2%)及血液系统肿瘤12例(10.9%)为最常见的肿瘤。71例(64.5%)患者在血液中检测到特征性副肿瘤抗体,最常见的为抗Amphiphysin抗体26例(23.6%)和抗Yo抗体24例(21.8%)。结论临床表现为非经典副肿瘤综合征的患者,亦应积极进行特征性副肿瘤抗体的检测,并根据抗体结果对特定肿瘤进行重点筛查。     

Paraneoplastic peripheral neuropathies

The PNS Euronet group criteria have classified paraneoplastic peripheral neuropathies as definite or possible according as to whether the neuropathy is a classical paraneoplastic disorder, the presence of onconeural antibodies, the delay between tumor and neuropathy, and improvement of the neuropathy with tumor treatment. Denny Brown's subacute sensory neuronopathy and neuropathies with anti-Hu or anti-CV2 antibodies are definite paraneoplastic disorders. Possible paraneoplastic neuropathies are heterogeneous. This classification is useful for the diagnostic of these disorders and the selection of patients in whom a search for cancer is warranted.     

Paraneoplastic anti-CV2 antibodies react with peripheral nerve and are associated with a mixed axonal and demyelinating peripheral neuropathy

Subacute sensory neuronopathy with anti-Hu antibodies is the best-characterized paraneoplastic peripheral neuropathy associated with carcinoma. Anti-CV2 antibodies, another group of paraneoplastic antibodies, react with a 66-kd brain protein belonging to the family of Ulip/CRMP proteins. The manifestations associated with anti-CV2 antibodies include cerebellar degeneration, uveitis, and peripheral neuropathy. Some of these patients also have anti-Hu antibodies. We have compared the clinical, electrophysiological, and pathological characteristics of the peripheral neuropathy in 9 patients with anti-CV2 antibodies (3 of whom also had anti-Hu antibodies) and 12 patients with only anti-Hu antibodies. Data for patients with anti-Hu antibodies alone indicated subacute sensory neuronopathy. Patients with anti-CV2 antibodies had a mixed axonal and demyelinating sensory motor neuropathy that was sometimes superimposed on subacute sensory neuronopathy when both anti-CV2 and anti-Hu antibodies were present. Unlike anti-Hu antibodies, anti-CV2 antibodies reacted with peripheral nerve antigens, as shown by their ability to bind to a 66-kd protein in human and rat nerve on Western blot analysis and to immunolabel peripheral nerve axons and sensory neurons on immunohistochemical study.     

Antibodies and neuronal autoimmune disorders of the CNS

We review the neuronal antibodies described in CNS disorders in order to clarify their diagnostic value, emphasize potentials pitfalls and limitations in the diagnosis of paraneoplastic neurological syndromes (PNS), and examine the current evidence for a possible pathogenic role. We propose to classify the neuronal antibodies associated with syndromes resulting from CNS neuronal dysfunction into two groups according to the location of the antigen: inside the neuron or in the cell membrane. Group I includes antibodies which target intracellular antigens and probably are not pathogenic. They are further subdivided into three groups. Group Ia comprises well-characterized onconeural antibodies (Hu (ANNA1), Yo (PCA1), Ri (ANNA2), CV2 (CRMP5), amphiphysin, Ma2) that are useful for the diagnosis of PNS. Group Ib antibodies (SOX and ZIC) are cancer-specific but there is no evidence that the immune response is in any way pathogenically related to the PNS. Antibodies in group Ic (glutamic acid decarboxylase (GAD), adenylate kinase 5 and Homer 3) identify non-PNS: stiff-person syndrome (SPS), cerebellar ataxia, and limbic encephalitis (LE). Group II antibodies recognize neuronal surface antigens. Antibodies in group IIa associate with characteristic CNS syndromes but their detection does not indicate that the disorder is paraneoplastic. Antibodies to potassium channels, AMPA and GABA_B receptors are associated with LE, NMDA receptor antibodies identify a well-defined encephalitis, and antibodies against glycine receptors associate with SPS with encephalitis. A pathogenic role of the antibodies is suggested by the response of symptoms to immunotherapy and the correlation between antibody titers and neurological outcome. Lastly, Group IIb includes antibodies that are found in patients with paraneoplastic cerebellar ataxia associated with lung cancer (P/Q type calcium channels antibodies) or Hodgkin disease (metabotropic glutamate receptor type 1 antibodies).     

Retrospective study of paraneoplastic neurological syndromes in a Chinese Han population from Shandong,East China

Objective: To analyze the clinical features, diagnostic strategies and therapeutic methods associated with paraneoplastic neurological syndromes.

Methods: A retrospective study of paraneoplastic neurological syndromes was performed at a single center in Shandong, East China. The medical records and follow-up data of 28 patients were intensively reviewed between February 2011 and December 2014.

Results: Twenty-four (85.7%) patients experienced subacute or chronic onset of disease, and the most common symptoms reported were mild myasthenia and paresthesias. Twenty-five (89.3%) patients presented nervous system lesions prior to occult tumors, and the median time frame between paraneoplastic neurological syndromes onset and the diagnosis of a tumor was 15 weeks. Sensorimotor neuropathy, Lambert-Eaton myasthenic syndrome and limbic encephalitis were the three most common neurological syndromes reported. Elevated serum tumor markers were observed in 44.0% of patients, while 40.7% of patients were positive for onconeural antibodies. Tumors were detected in 21 (75.0%) patients after repeated whole-body screening, and lung carcinomas were the most common primary tumor detected. Seventeen patients received anti-tumor or immunological therapy, and clinical symptoms were relieved in 13 (76.5%) of these patients.

Conclusions: In the majority of paraneoplastic neurological syndromes patients, the onset of disease is subacute or chronic with mild clinical symptoms. Nervous system lesions usually occur prior to occult tumors with complicated and various clinical manifestations. Neither tumor markers nor onconeural antibodies exhibit a high rate of occurrence, while repeated whole-body screening is helpful in identifying occult tumors. Early diagnosis and treatment are crucial to these patients.     

BR serine/threonine kinase 2: a new autoantigen in paraneoplastic limbic encephalitis

We describe a new antigen, BR serine/threonine kinase 2 (BRSK2), identified by an antibody present in the serum of a patient with limbic encephalitis and small-cell lung cancer (SCLC). Patient's serum immunolabeled the neuronal cytoplasm and, less intense, the neuropil of rat brain but did not immunoreact with other rat tissues with the exception of testis. Immunoblots of rat brain homogenate identified several immunoreactive bands in the range of 88-82 kDa and a weaker broad band of 47-43 kDa. Probing a rat hippocampus expression library with the patient's serum resulted in the isolation of BR serine/threonine kinase 2 (BRSK2), a protein (also know as SAD1B kinase) preferentially expressed in the brain and testis and implicated in neuronal polarization as well as synaptic development. Eluted IgG from the BRSK2 clone gave a similar immunolabeling than the patient's serum by immunohistochemistry and immunoblot of rat brain and testis. BRSK2 antibodies reacted with two SCLC from patients without paraneoplastic neurological syndromes. No anti-BRSK2 antibodies were found in the serum of 50 patients with SCLC without PNS, 19 with limbic encephalitis without onconeural antibodies, 50 with anti-Hu antibodies and several paraneoplastic neurological syndromes, including 14 with limbic encephalitis, and 160 with a variety of non-paraneoplastic neurological syndromes. Our study suggests BRSK2 may be an autoantigen involved in the pathogenesis of SCLC-associated limbic encephalitis.     

Rapidly progressive neurological deterioration in anti-AMPA receptor encephalitis with additional CRMP5 antibodies

Anti-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) encephalitis positive for additional onconeural antibodies is rarely reported. Here we report the clinical features of a patient who developed limbic encephalitis with both glutamate receptor 2 (GluR2) and collapsin response mediator protein 5 (CRMP5) antibodies. Brain magnetic resonance imaging revealed multifocal encephalopathy. Chest computed tomography showed a highly suspicious malignant thymoma. He experienced rapid neurological deterioration during hospitalization. This report indicates that the clinical diversity of anti-AMPAR encephalitis and the presence of onconeural antibodies may lead to poor prognosis.     

Antibodies to a subpopulation of glial cells and a 66 kDa developmental protein in patients with paraneoplastic neurological syndromes.

BACKGROUND: Paraneoplastic neurological syndromes (PNS) are inflammatory disorders that probably depend on autoimmune processes. Several autoantibodies (anti-Hu, anti-Ri, and anti-Yo) have been characterised in PNS and proved to be helpful in the diagnosis. However, these do not account for all the cases and the possibility that other types of antibodies could be detected was investigated. METHODS AND RESULTS: Of 45 patients with PNS whose serum was probed on paraformaldehyde fixed rat brain sections, 11 patients were identified whose serum samples recognised a cytoplasmic antigen in a subpopulation of glial cells in the white matter of adult rat brainstem, cerebellum, and spinal cord that were double labelled with a monoclonal antibody specific for oligodendrocytes. All serum samples reacted with a 66 kDa protein of newborn rat brain on western blot analysis. These antibodies were designated as anti-CV2 antibodies. Only one of the 11 patients had one of the well characterised autoantibodies (anti-Hu). Five patients had cerebellar degeneration, three had limbic encephalitis, two had encephalomyelitis, and one had Lambert-Eaton myasthenic syndrome. The tumours were small cell lung cancer or undifferentiated mediastinal cancer in seven patients, uterine sarcoma in two, and malignant thymoma in two. Among 1061 control serum samples, only two patients had anti-CV2 antibodies. One had small cell lung cancer and the other malignant thymoma. CONCLUSIONS: The detection of anti-CV2 antibodies in patients with neurological disorders should be considered as an indication of the presence of an occult cancer.     

Paraneoplastic neurological syndromes in patients with carcinoid

Background: Paraneoplastic neurological syndromes (PNS) are mainly associated with small‐cell lung cancer, gynaecological tumours and lymphomas. Few studies report the association of neurological syndromes with a carcinoid, the majority being a serotonin‐related myopathy. We report four patients with a PNS associated with carcinoid. Patients and results: The clinical syndromes were sensory neuropathy, limbic encephalitis, myelopathy and brain stem encephalitis. Two patients had antineuronal autoantibodies (one anti‐Hu, one anti‐Yo), one patient had antinuclear antibodies, and one patient had no autoantibodies. For two of the carcinoids, expression of HuD in the tumour could be demonstrated. Conclusion: This study demonstrates that carcinoids can also be associated with classical antineuronal antibody‐associated PNS.     

Peripheral neuropathies associated with antibodies directed to intracellular neural antigens

Antibodies directed to intracellular neural antigens have been mainly described in paraneoplastic peripheral neuropathies and mostly includes anti-Hu and anti-CV2/CRMP5 antibodies. These antibodies occur with different patterns of neuropathy. With anti-Hu antibody, the most frequent manifestation is sensory neuronopathy with frequent autonomic involvement. With anti-CV2/CRMP5 the neuropathy is more frequently sensory and motor with an axonal or mixed demyelinating and axonal electrophysiological pattern. The clinical pattern of these neuropathies is in keeping with the cellular distribution of HuD and CRMP5 in the peripheral nervous system. Although present in high titer, these antibodies are probably not directly responsible for the neuropathy. Pathological and experimental studies indicate that cytotoxic T-cells are probably the main effectors of the immune response. These disorders contrast with those in which antibodies recognize a cell surface antigen and are probably responsible for the disease. The neuronal cell death and axonal degeneration which result from T-cell mediated immunity explains why treating these disorders remains challenging.     

Onconeural antibodies: improved detection and clinical correlations

Onconeural antibodies are found in many patients with paraneoplastic neurological syndromes (PNS) and define the disease as paraneoplastic. The study describes the presence of onconeural antibodies and PNS in 555 patients with neurological symptoms and confirmed cancer within five years, and compares the diagnostic accuracy of different antibody assays (immunoprecipitation, immunofluorescence and immunoblot). Onconeural antibodies were found in 11.9% of the patients by immunoprecipitation, in 7.0% by immunofluorescence and in 6.3% by immunoblot. PNS were present in 81.8% of the cancer patients that were seropositive by immunoprecipitation. Immunofluorescence and immunoblot failed to detect onconeural antibodies in almost one third of the PNS cases.     

Limbic encephalitis: a probably under-recognized syndrome

Limbic encephalitis was identified as a clinicopathological entity in 1968. Up to a few years ago, 200 cases were described, most associated with lung cancer and more infrequently with other tumors. The recent identification of patients with this syndrome, idiopathic limbic encephalitis, who never develop cancer and have high titers of antibodies to voltage-gated potassium channels (VGKC) and an excellent response to immunosuppressive therapy, has extended the etiological spectrum and suggests that the syndrome may be under-recognized. The disorder, which develops in a few days or weeks, is characterized by the development of short-term memory loss, seizures, confusion and psychiatric features. The presence of symptoms beyond the limbic system is highly suggestive of a paraneoplastic origin. When limbic encephalitis is suspected, the following tests should be performed in order to demonstrate: a) involvement of the temporal lobes (EEG and brain MRI); b) presence of inflammatory abnormalities in the CSF, and c) the presence of onconeural antibodies or anti-VGKC. Once the diagnosis is confirmed by the clinical picture and MRI findings, treatment must be initiated without waiting for the antibody results because its negativity does not exclude the diagnosis. Detection of an onconeural antibody will confirm that the limbic syndrome is paraneoplastic and will help us to search for an underlying tumor and to predict possible response to the treatment. The recommended treatment is cycles of methylprednisolone (1 g/day for 3 to 5 days). Therapeutic response in the idiopathic limbic encephalitis is excellent and may be good in limbic encephalitis with anti-Ma2 or without onconeural antibodies. On the contrary, immunosuppressant treatment is not usually effective in limbic encephalitis associated to anti-Hu antibodies.     

Therapeutic approaches in antibody-associated central nervous system pathologies

Initially, antibodies targeting intracellular compounds were described in patients with paraneoplastic neurological syndromes (PNS) such as anti-Hu, anti-Yo, anti-Ri or anti-CV2/CRMP5 antibodies. As more than 90% of patients with these antibodies suffer from an associated cancer, these antibodies were used as biomarkers of an underlying tumour. Recently, autoantibodies targeting cell-surface synaptic antigens have been described in patients with neurological symptoms suggesting PNS. These autoantibodies being less frequently associated with a tumour, they completely changed the concept of PNS. They lead to a new classification, not based on clinical symptoms or oncological status but on the location of the targeted antigens. Three groups of autoantibodies can be delineated according to the neuronal localization of the targeted antigen: Group 1: cytoplasmic neuronal antigens (CNA) (anti-Hu, Yo, CV2/CRMP5, Ri, Ma1/2, Sox, Zic4). Group 2: cell-surface neuronal antigens (CSNA) (anti-NMDAR, Lgi1, CASPR2, VGCC, AMPAr, GlyR, DNER, GABABR, GABAAR, IgLONS, mGluR1 and mGluR5). Group 3: intracellular synaptic antigens (ISA) (anti-GAD65 and anti-amphiphysin). More than being solely a classification of patients, these three groups are related to profound differences in the pathophysiology and in the pathogenic role of the associated autoantibody. According to the type of associated autoantibody, the age and sex of patients, physicians are now able to predict the presence or absence of tumour, the clinical evolution and prognostic and also the response to immunomodulator treatments that differ fundamentally from one group to the others.     

Screening for well-characterized paraneoplastic antineuronal antibodies in multiple sclerosis

Some epidemiological surveys have shown an increased incidence of malignancies in patients with multiple Sclerosis (MS). Furthermore, in rare cases central demyelinating disorders like optic neuritis, encephalomyelitis, and myelitis could be of paraneoplastic origin. Antineuronal antibodies are frequently associated with paraneoplastic neurological syndromes (PNS) but are also described in cancer patients without neurological symptoms. In this study, we retrospectively analyzed sera from 247 patients with MS and clinically isolated syndrome (CIS) for the presence of anti-HuD, Yo, Ri, CV2/CRMP5, Ma2, and amphiphysin antibodies using ELISA employing recombinant onconeural antigens. None of the sera revealed high titers of antineuronal antibodies and only two sera from MS patients show weak reactivity, representing in all probability background activity. Furthermore, cancer incidence in our study is low (0.8%). Our analysis does not support an association between MS and well-characterized paraneoplastic antineuronal antibodies, suggestive of a secondary humoral autoimmune response, underlying latent malignancy, or paraneoplastic origin in our cohort. In reverse, negative screening results in samples of MS patients confirm the high specificity of these antibodies for PNS.     

Management of paraneoplastic neurological syndromes: report of an EFNS Task Force

Paraneoplastic neurological syndromes (PNS) are remote effects of cancer on the nervous system. An overview of the management of classical PNS, i.e. paraneoplastic limbic encephalitis, subacute sensory neuronopathy, paraneoplastic cerebellar degeneration, paraneoplastic opsoclonus-myoclonus, Lambert–Eaton myasthenic syndrome and paraneoplastic peripheral nerve hyperexcitability is given. Myasthenia gravis and paraproteinemic neuropathies are not included in this report. No evidence-based recommendations were possible, but good practice points were agreed by consensus. Urgent investigation is indicated, especially in central nervous system (CNS) syndromes, to allow tumour therapy to be started early and prevent progressive neuronal death and irreversible disability. Onconeural antibodies are of great importance in the investigation of PNS and can be used to focus tumour search. PDG-PET is useful if the initial radiological tumour screen is negative. Early detection and treatment of the tumour is the approach that seems to offer the greatest chance for PNS stabilization. Immune therapy usually has no or modest effect on the CNS syndromes, whereas such therapy is beneficial for PNS affecting the neuromuscular junction. Symptomatic therapy should be offered to all patients with PNS.     

Onconeural antibodies are essential to diagnose paraneoplastic neurological syndromes

Paraneoplastic neurological syndromes (PNS) can be defined as remote effects of cancer that are not caused by the tumor and its metastasis or by infection, ischemia or metabolic disruptions. In most patients, the neurological disorder develops before the cancer becomes clinically overt and the patient is referred to the neurologist who has the charge of identifying a neurological disorder as paraneoplastic. They are usually severely disabling. PNS are rare and are seen in less than 1% of patients with cancer. PNS depend on an autoimmune process triggered by cancer and directed to antigens common to both the cancer and the nervous system designated as onconeural antigens. Because of their high specificity (>90%), the best way to diagnose neurological disorders as paraneoplastic is to identify one of the well-characterized onconeural antibodies in the patient's serum. In addition, as these antibodies are associated with a restricted range of cancer, they permit orientating the search of the underlying tumor at a stage where it is frequently not clinically overt. This is a critical point, as today the best way to stabilize PNS is probably to treat the cancer as soon as possible. Unfortunately, about one-third of the patients do not have detectable antibodies and 5–10% have an atypical antibody that is not well characterized.     

Neuro-ophthalmology and paraneoplastic syndromes

PURPOSE OF REVIEW: To describe the neuro-ophthalmological manifestations of paraneoplastic syndromes and their immunological associations. RECENT FINDINGS: Neuro-ophthalmological signs and symptoms are usually present in paraneoplastic syndromes of the central nervous system. Unlike opsoclonus, less characteristic eye movement abnormalities are difficult to recognize as presenting symptoms of paraneoplastic syndromes. In this setting, the detection of several antibodies, including anti-Hu, Yo, Ma2, Ri, Tr, CV2/CRMP5 or voltage-gated calcium channel antibodies may help to establish that the neuro-ophthalmological disorder is paraneoplastic. Among the recently characterized antibodies, those against the Ma proteins often associate with brainstem encephalitis and vertical gaze paralysis. A small subset of patients with opsoclonus and ataxia harbor anti-Ri antibodies. In other patients, there is preliminary evidence that the autoantigens of opsoclonus reside in the postsynaptic density, but no dominant antibody marker has been identified. Uveitis and optic neuritis are rare accompaniments of paraneoplastic encephalomyelitis; some of these patients harbor anti-CV2/CRMP5 in association with other antibodies. Studies on paraneoplastic retinopathy indicate that immunity to retinal proteins other than recoverin can result in a similar syndrome to that associated with recoverin antibodies, and that melanoma-associated retinopathy may associate with several retinal antibodies. SUMMARY: There is increasing recognition of an extensive variety of neuro-ophthalmological abnormalities as manifestations of paraneoplastic syndromes and of several antineuronal antibodies as clinical markers of these disorders. Basic immunological studies support the pathogenic role of some of these antibodies, and are elucidating the pathogenic mechanisms that underlie these and other antibody-associated paraneoplastic syndromes.     

Paraneoplastic epilepsy

Epilepsy can be a manifestation of paraneoplastic syndromes which are the consequence of an immune reaction to neuronal elements driven by an underlying malignancy affecting other organs and tissues. The antibodies commonly found in paraneoplastic encephalitis can be divided into two main groups depending on the target antigen: 1) antibodies against neuronal cell surface antigens, such as against neurotransmitter (N-methyl-d-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), gamma-aminobutyric acid (GABA)) receptors, ion channels (voltage-gated potassium channel (VGKC)), and channel-complex proteins (leucine rich, glioma inactivated-1 glycoprotein (LGI1) and contactin-associated protein-2 (CASPR2)) and 2) antibodies against intracellular neuronal antigens (Hu/antineuronal nuclear antibody-1 (ANNA-1), Ma2/Ta, glutamate decarboxylase 65 (GAD65), less frequently to CV2/collapsin response mediator protein 5 (CRMP5)). In this review, we provide a comprehensive survey of the current literature on paraneoplastic epilepsy indexed by the associated onconeuronal antibodies. While a range of seizure types can be seen with paraneoplastic syndromes, temporal lobe epilepsy is the most common because of the association with limbic encephalitis. Early treatment of the paraneoplastic syndrome with immune modulation/suppression may prevent the more serious potential consequences of paraneoplastic epilepsy.