Paraneoplastic Diseases of the Central Nervous System

Multi-omics profiling reveals dysregulated ribosome biogenesis and impaired cell proliferation following knockout of CDR2L

BACKGROUND

Cerebellar degeneration-related (CDR) proteins are associated with paraneoplastic cerebellar degeneration (PCD) - a rare, neurodegenerative disease caused by tumour-induced autoimmunity against neural antigens resulting in degeneration of Purkinje neurons in the cerebellum. The pathogenesis of PCD is unknown, in large part due to our limited understanding of the functions of CDR proteins. To this end, we performed an extensive, multi-omics analysis of CDR-knockout cells focusing on the CDR2L protein, to gain a deeper understanding of the properties of the CDR proteins in ovarian cancer.

METHODS

Ovarian cancer cell lines lacking either CDR1, CDR2, or CDR2L were analysed using RNA sequencing and mass spectrometry-based proteomics to assess changes to the transcriptome, proteome and secretome in the absence of these proteins.

RESULTS

For each knockout cell line, we identified sets of differentially expressed genes and proteins. CDR2L-knockout cells displayed a distinct expression profile compared to CDR1- and CDR2-knockout cells. Knockout of CDR2L caused dysregulation of genes involved in ribosome biogenesis, protein translation, and cell cycle progression, ultimately causing impaired cell proliferation in vitro. Several of these genes showed a concurrent upregulation at the transcript level and downregulation at the protein level.

CONCLUSIONS

Our study provides the first integrative multi-omics analysis of the impact of knockout of the CDR genes, providing both new insights into the biological properties of the CDR proteins in ovarian cancer, and a valuable resource for future investigations into the CDR proteins.

The association between paraneoplastic neurological syndromes (PNS) and urothelial carcinoma - A review of the literature

Paraneoplastic neurological syndromes (PNS) are rare neurological disorders arising from malignancy-triggered autoimmunity, yet their association with urothelial carcinoma remains unclear. This systematic review intends to explore any connection, alongside patient/clinical features and management. A literature search identified 25 cases of bladder and upper tract carcinoma linked to PNS. Overall, while infrequent, a meaningful association between PNS and urothelial carcinoma was found in that 84% of cases met a 'possible'-or-'higher-likelihood' PNS diagnosis. Most cases presented with high-risk PNS phenotypes, predominantly cerebellar syndromes and encephalomyelitis/sensory neuronopathy, ∼17 months within cancer diagnosis/recurrence. Review findings suggest a female preponderance in suspected PNS despite higher male incidence of urothelial cancer. Main treatments consisted of surgery alongside chemotherapy or immunotherapeutics (IVIG and/or corticosteroids), which improved symptoms for a slight majority (60%). Ultimately, while common PNS-associated neoplasms should always first be excluded in suspected PNS, in the absence of alternative causes, urothelial carcinomas do merit clinical consideration.

Immune-Mediated Myelopathies

OBJECTIVE

Immune-mediated myelopathies are conditions in which the immune system attacks the spinal cord. This article describes the distinguishing characteristics of immune-mediated myelopathies and treatment strategies for patients affected by these disorders.

LATEST DEVELOPMENTS

New biomarkers, such as aquaporin 4 and myelin oligodendrocyte glycoprotein antibodies, in the blood and spinal fluid have led to the identification of antigen-specific immune-mediated myelopathies and approved therapies to prevent disease progression.

ESSENTIAL POINTS

The first step in the diagnosis of an immune-mediated myelopathy is confirming that the immune system is the cause of the attack by excluding non-immune-mediated causes. The second step is to narrow the differential diagnosis based on objective biomarkers such as serology and MRI patterns. The third step is to treat the specific immune-mediated myelopathy by using evidence-based medicine.

Paraneoplastic Neurological Syndromes as Initial Presentation of Tumors: An Eight-Year Single-Center Experience

BACKGROUND

Paraneoplastic Neurological Syndromes (PNS) comprise a diverse group of disorders propagated by immune-mediated effects of malignant tumors on neural tissue.

METHODS

A single-center longitudinal study was performed including consecutive adult patients treated at a tertiary academic hospital between 2015 and 2023 and diagnosed with PNS. PNS were ascertained using the 2004 and the revised 2021 PNS-Care diagnostic criteria.

RESULTS

Thirteen patients who fulfilled the 2004 definite PNS criteria were included. PNS comprise diverse neurological syndromes, with neuromuscular junction disorders (54%) and limbic encephalitis (31%) being predominant. PNS-related antibodies were detected in 85% of cases, including anti-AChR (n = 4), anti-P/Q-VGCC (n = 3), anti-Hu (n = 3), anti-Yo (n = 1), anti-Ma (n = 1), anti-titin (n = 1), anti-IgLON5 (n = 1), and anti-GAD65 (n = 1). Thymoma (31%), small-cell lung cancer (23%), and papillary thyroid carcinoma (18%) were the most frequent tumors. Imaging abnormalities were evident in 33% of cases. Early immunotherapy within 4-weeks from symptom onset was associated with favorable outcomes. At a mean follow-up of 2 ± 1 years, two patients with anti-Hu and anti-Yo antibodies died (18%). Four and three patients fulfilled the 2021 PNS-Care diagnostic criteria for definite and probable PNS, respectively.

CONCLUSIONS

This study highlights the clinical heterogeneity of PNS, emphasizing the need for early suspicion and prompt treatment initiation for optimal outcomes.

Imaging of central nervous system emergencies in oncology

Central nervous system (CNS) may be predisposed to devastating complications in cancer patients which may add to morbidity and mortality in this group. Majority of the complications are vascular in nature due to the altered coagulation profile and pro-inflammatory state in these patients. However, there are a host of other conditions which may affect the clinical course of these patients including metabolic and toxic encephalopathies, infections, and paraneoplastic syndromes. Moreover, multimodality management of these patients, which is often used in majority of the cancers, exposes them to treatment related complications. This pictorial review aims to enlighten the reader regarding the various complications affecting the CNS as seen at our tertiary cancer care institute. We aim to highlight the emergent nature of these complications and the need to identify them quickly and accurately on imaging which helps to institute early appropriate management and prevents further morbidity and mortality.

Paraneoplastic neurological syndromes of the central nervous system: a single institution 7-year case series

BACKGROUND

Paraneoplastic neurological syndromes (PNSs) are nonmetastatic complications of malignancy, defined by the presence of onconeural antibodies (ONAs). ONAs may be found in 60% of patients with central nervous system (CNS) involvement, and they are directed against intraneuronal antigens or channels, receptors or associated proteins located at the synaptic or extra-synaptic neuronal cell membrane. Given its rare incidence, there are few epidemiological case series on CNS-PNS. We aim to discuss the variability of CNS-PNSs etiology, clinical features, management and outcome, highlighting the importance of early recognition and appropriate treatment, leading to significant reduction of mortality and morbidity.

METHODS

We retrospectively reviewed our 7-years single-center experience, and specifically discussed the underlying etiology, parenchymal CNS involvement, and the acute treatment response. Only cases fulfilling PNS Euronetwork criteria for definitive PNS were included.

RESULTS

A total of 26 probable PNSs cases involving CNS were identified. We reported medical records of eleven (42.3%) illustrative cases, meeting the criteria of definite PNS and presenting variable clinical spectrum and different radiological appearances. Our series has a relative paucity of the most common syndromes and larger portion of clinical diagnosis with ONAs. Well-characterized ONAs had been detected in CSF of six patients.

CONCLUSIONS

Our case series supports the utmost importance of early recognition of CNS-PNSs. Screening for occult malignancies should not be limited to patients with classical CNS syndrome. Empiric immunomodulatory therapy may be considered before the diagnostic evaluation is completed, in order to prevent unfavorable outcome. Late presentations should not discourage initiation of treatment.

Paraneoplastic Syndromes from Head to Toe: Pathophysiology, Imaging Features, and Workup

Patients often have symptoms due to the mass effect of a neoplasm on surrounding tissues or the development of distant metastases. However, some patients may present with clinical symptoms that are not attributable to direct tumor invasion. In particular, certain tumors may release substances such as hormones or cytokines or trigger an immune cross-reactivity between malignant and normal body cells, resulting in characteristic clinical features that are broadly referred to as paraneoplastic syndromes (PNSs). Recent advances in medicine have improved the understanding of the pathogenesis of PNSs and enhanced their diagnosis and treatment. It is estimated that 8% of patients with cancer develop a PNS. Diverse organ systems may be involved, most notably the neurologic, musculoskeletal, endocrinologic, dermatologic, gastrointestinal, and cardiovascular systems. Knowledge of various PNSs is necessary, as these syndromes may precede tumor development, complicate the patient's clinical presentation, indicate tumor prognosis, or be mistaken for metastatic spread. Radiologists should be familiar with the clinical presentations of common PNSs and the selection of appropriate imaging examinations. Many of these PNSs have imaging features that can assist with arriving at the correct diagnosis. Therefore, the key radiographic findings associated with these PNSs and the diagnostic pitfalls that can be encountered during imaging are important, as their detection can facilitate early identification of the underlying tumor, reveal early recurrence, and enable monitoring of the patient's response to therapy. ^© RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Progressive Global Ataxia With Sensory Changes as a Paraneoplastic Syndrome in a Patient With Chromophobe Renal Cell Carcinoma

Paraneoplastic syndromes (PNS) are rare and can be challenging to diagnose and treat. The uniqueness of PNS lies in the complexity of presentation, the importance of early diagnosis, and the role of multidisciplinary care in managing those patients to mitigate long-term neurologic complications. We describe a patient with metastatic renal cell carcinoma who presented with a complex constellation of neurological symptoms (progressive global ataxia and sensory changes) that did not resolve following nephrectomy. While complete resolution of symptoms was not achieved, he did have stabilization of his neurologic decline with the initiation of cancer-directed therapies.

Identification of Anti-Collapsin Response Mediator Protein 2 Antibodies in Patients With Encephalitis or Encephalomyelitis

Background and Purpose

An increasing number of autoimmune encephalitis (AE)-associated autoantibodies have been successfully characterized. However, many cases of AE remain unexplained on account of unknown antibodies. The aim of the present study was to identify a novel antibody against collapsin response mediator protein 2 (CRMP2) in suspected AE patients.

Methods

A patient’s serum and cerebrospinal fluid samples tested negative for known AE antibodies; however, strong immunolabel signals were observed in the neuronal cytoplasm of the cortex, hippocampus, and Purkinje cells on rat brain sections. Immunoprecipitation from the rat brain protein lysate, followed by mass spectrometry analysis, was used to identify the targeting antigen. Western blotting and cell-based assay with antigen-overexpressing HEK293T cells were used for antibody specificity, epitope, IgG subtype determination, and retrospective study.

Results

An antibody against CRMP2, a synaptic protein involved in axon guidance, was identified. The immunostains of the patient’s samples on rat brain sections were eliminated by pre-absorption with HEK293T cells overexpressing CRMP2. The samples specifically immunoreacted with CRMP2, but not with CRMP1, CRMP3, CRMP4, and CRMP5. The C-terminus of CRMP2 with 536 amino acids contained the epitope for antibody binding. The subtype analysis showed that the anti-CRMP2 antibody was IgG4. Furthermore, a screening of 46 patients with neurological disoders and neuro-cytoplasm immunostainings on rat brain sections resulted in the identification of anti-CRMP2 antibodies in a case of encephalomyelitis. The two patients responded well to immunotherapies.

Conclusions

This study discovered that a novel anti-CRMP2 antibody was associated with suspected AE and thus should be included in the testing list for AE.

A scoping review on paraneoplastic autoimmune limbic encephalitis (PALE) psychiatric manifestations

The term limbic encephalitis has been used with an oncological precedent for over 50 years and, since then, has been applied in relation to multiple antibodies found in its etiological process. Over the last decade, the psychiatric community has brought paraneoplastic autoimmune limbic encephalitis (PALE) to a new light, scattering the once known relationships between said screened antibodies responsible for causing limbic encephalitis. Due to the fact that some individuals with this condition have a psychiatric syndrome as an initial manifestation, the aim of this updated scoping review is to reestablish a causal relationship between the onconeuronal autoantibodies, both intracellular and extracellular, possible underlying malignancies and subsequent neuropsychiatric syndrome. In pair with it, there is the idea of sketching a cleaner thorough picture of what poses as psychiatric symptoms as well as possible therapeutics. Even though the always evolving epistemology of the neurosciences achieved a significant unveiling of what includes PALE in its relevant pathological subgroups, the amount of gray literature still is much superior, appealing to a further research with more randomized controlled trials, with larger populations, so that the results corroborate the small amount of data that already exist and posteriorly be applied in the general population.

Additional Value of [18F]FDG PET/CT in Detection of Suspected Malignancy in Patients with Paraneoplastic Neurological Syndromes Having Negative Results of Conventional Radiological Imaging

Background: Paraneoplastic neurological syndromes (PNS) affecting the CNS (central nervous system) are rare, presenting in less than 1% of all those with cancer. The pathogenesis of paraneoplastic neurological syndromes is not fully understood, but it is presumed to result from an immune attack on the underlying malignancy. The presence of different types of onconeural antibodies may occur in different tumors and can lead to different clinical manifestations, making the early detection of cancers challenging. Aim: An evaluation of [18F]FDG PET/CT in neoplastic tumor detection in patients with paraneoplastic neurological syndromes having negative or unremarkable results of conventional radiological imaging. Methods: Among all patients diagnosed with paraneoplastic neurological syndromes in the Neurology Department in 2016–2020, 15 patients with unremarkable conventional radiological findings who underwent [18F]FDG PET/CT were included in the study. Results: [18F]FDG PET/CT enabled localization of suspected malignancy in 53% (8 of 15) of PNS cases with previous unremarkable conventional radiological findings. Conclusion: [18F]FDG PET/CT may be considered as a useful tool for neoplastic tumor detection in patients with paraneoplastic neurological syndromes, accelerating the diagnostic process and enabling faster initiation of appropriate treatment.

Update in Autoimmune Movement Disorders: Newly Described Antigen Targets in Autoimmune and Paraneoplastic Cerebellar Ataxia

Movement disorders are a common feature of many antibody-associated neurological disorders. In fact, cerebellar ataxia is one of the most common manifestations of autoimmune neurological diseases. Some of the first autoantibodies identified against antigen targets include anti-neuronal nuclear antibody type 1 (ANNA-1 or anti-Hu) and Purkinje cell cytoplasmic antibody (PCA-1) also known as anti-Yo have been identified in paraneoplastic cerebellar degeneration. Historically these antibodies have been associated with an underlying malignancy; however, recently discovered antibodies can occur in the absence of cancer as well, resulting in the clinical syndrome of autoimmune cerebellar ataxia. The pace of discovery of new antibodies associated with autoimmune or paraneoplastic cerebellar ataxia has increased rapidly over the last few years, and pathogenesis and potential treatment options remains to be explored. Here we will review the literature on recently discovered antibodies associated with autoimmune and paraneoplastic cerebellar ataxia including adaptor protein-3B2 (AP3B2); inositol 1,4,5-trisphophate receptor type 1 (ITPR1); tripartite motif-containing (TRIM) proteins 9, 67, and 46; neurochondrin; neuronal intermediate filament light chain (NIF); septin 5; metabotropic glutamate receptor 2 (mGluR2); seizure-related 6 homolog like 2 (SEZ6L2) and homer-3 antibodies. We will review their clinical characteristics, imaging and CSF findings and treatment response. In addition, we will discuss two clinical case examples of autoimmune cerebellar ataxia.

Cancer and Peripheral Nerve Disease

Patients with cancer may experience neuropathy at any stage of malignancy, ranging from symptoms that are the earliest signs of cancer to side effects of treatment. Peripheral nerves are affected most commonly in a symmetric, stocking-glove pattern. Sensory neuronopathies, plexopathies, and radiculopathies may also be seen. The most common type of neuropathy in patients with cancer is related to chemotherapy, and recently peripheral nerve complications have been described as an effect of immune checkpoint inhibitors too. Other causes include paraneoplastic syndromes, direct tumor infiltration, and radiation. Treatment focuses on addressing the underlying cancer and management of neuropathic pain.

A Rare Case of Sensory Neuropathy Associated with Transitional Cell Carcinoma of the Bladder

Malignancies can trigger an autoimmune response against the nervous system and manifest as paraneoplastic neurological syndromes (PNS). Initial symptoms of PNS may develop up to 5 years prior to the diagnosis of the underlying malignancy. We report a rare case of PNS associated with transitional cell carcinoma of the bladder in a 70-year-old male with a 6-month history of rapidly progressive symmetric sensory neuropathy. Peripheral neuropathy serological workup was unremarkable. A paraneoplastic neuropathy panel revealed anti-Hu autoantibodies. Further evaluation with a whole-body PET scan could not identify the primary malignancy, but it showed hypermetabolic hilar lymph nodes. An endobronchial ultrasound biopsy of the hilar lymph nodes was negative for cancer. The patient developed painless hematuria 2.5 years after the onset of the sensory neuropathy. Cystoscopy with biopsy revealed non-muscle-invasive transitional cell carcinoma of the bladder. Progression of the sensory neuropathy stopped after tumor resection. This case highlights the importance of a diligent and systematic approach to diagnose PNS. A relentless search is often required to detect PNS-associated occult malignancies.

Immunological Bases of Paraneoplastic Cerebellar Degeneration and Therapeutic Implications

Paraneoplastic cerebellar degeneration (PCD) is a rare immune-mediated disease that develops mostly in the setting of neoplasia and offers a unique prospect to explore the interplay between tumor immunity and autoimmunity. In PCD, the deleterious adaptive immune response targets self-antigens aberrantly expressed by tumor cells, mostly gynecological cancers, and physiologically expressed by the Purkinje neurons of the cerebellum. Highly specific anti-neuronal antibodies in the serum and cerebrospinal fluid represent key diagnostic biomarkers of PCD. Some anti-neuronal antibodies such as anti-Yo autoantibodies (recognizing the CDR2/CDR2L proteins) are only associated with PCD. Other anti-neuronal antibodies, such as anti-Hu, anti-Ri, and anti-Ma2, are detected in patients with PCD or other types of paraneoplastic neurological manifestations. Importantly, these autoantibodies cannot transfer disease and evidence for a pathogenic role of autoreactive T cells is accumulating. However, the precise mechanisms responsible for disruption of self-tolerance to neuronal self-antigens in the cancer setting and the pathways involved in pathogenesis within the cerebellum remain to be fully deciphered. Although the occurrence of PCD is rare, the risk for such severe complication may increase with wider use of cancer immunotherapy, notably immune checkpoint blockade. Here, we review recent literature pertaining to the pathophysiology of PCD and propose an immune scheme underlying this disabling disease. Additionally, based on observations from patients' samples and on the pre-clinical model we recently developed, we discuss potential therapeutic strategies that could blunt this cerebellum-specific autoimmune disease.