Management and outcome of CSF-JC virus PCR-negative PML in a natalizumab-treated patient with MS

JC polyomavirus: a short review of its biology, its association with progressive multifocal leukoencephalopathy, and the diagnostic value of different methods to manifest its activity or presence

INTRODUCTION

JC polyomavirus is the causative agent of progressive multifocal leukoencephalopathy (PML), a demyelinating disease resulting from the lytic infection of oligodendrocytes that may develop in immunosuppressed individuals: HIV1 infected or individuals under immunosuppressive therapies. Understanding the biology of JCPyV is necessary for a proper patient management, the development of diagnostic tests, and risk stratification.

AREAS COVERED

The review covers different areas of expertise including the genomic characterization of JCPyV strains detected in different body compartments (urine, plasma, and cerebrospinal fluid) of PML patients, viral mutations, molecular diagnostics, viral miRNAs, and disease.

EXPERT OPINION

The implementation of molecular biology techniques improved our understanding of JCPyV biology. Deep sequencing analysis of viral genomes revealed the presence of viral quasispecies in the cerebrospinal fluid of PML patients characterized by noncoding control region rearrangements and VP1 mutations. These neurotropic JCPyV variants present enhanced replication and an altered cell tropism that contribute to PML development. Monitoring these variants may be relevant for the identification of patients at risk of PML. Multiplex realtime PCR targeting both the LTAg and the archetype NCCR could be used to identify them. Failure to amplify NCCR should indicate the presence of a JCPyV prototype speeding up the diagnostic process.

Neurofilament light level correlates with brain atrophy, and cognitive and motor performance

Background

The usefulness of neurofilament light (NfL) as a biomarker for small vessel disease has not been established. We examined the relationship between NfL, neuroimaging changes, and clinical findings in subjects with varying degrees of white matter hyperintensity (WMH).

Methods

A subgroup of participants (n = 35) in the Helsinki Small Vessel Disease Study underwent an analysis of NfL in cerebrospinal fluid (CSF) as well as brain magnetic resonance imaging (MRI) and neuropsychological and motor performance assessments. WMH and structural brain volumes were obtained with automatic segmentation.

Results

CSF NfL did not correlate significantly with total WMH volume (r = 0.278, p = 0.105). However, strong correlations were observed between CSF NfL and volumes of cerebral grey matter (r = -0.569, p < 0.001), cerebral cortex (r = -0.563, p < 0.001), and hippocampi (r = -0.492, p = 0.003). CSF NfL also correlated with composite measures of global cognition (r = -0.403, p = 0.016), executive functions (r = -0.402, p = 0.017), memory (r = -0.463, p = 0.005), and processing speed (r = -0.386, p = 0.022). Regarding motor performance, CSF NfL was correlated with Timed Up and Go (TUG) test (r = 0.531, p = 0.001), and gait speed (r = -0.450, p = 0.007), but not with single-leg stance. After adjusting for age, associations with volumes in MRI, functional mobility (TUG), and gait speed remained significant, whereas associations with cognitive performance attenuated below the significance level despite medium to large effect sizes.

Conclusion

NfL was strongly related to global gray matter and hippocampal atrophy, but not to WMH severity. NfL was also associated with motor performance. Our results suggest that NfL is independently associated with brain atrophy and functional mobility, but is not a reliable marker for cerebral small vessel disease.

Flaccid Brachial Monoplegia As Initial Presentation in a Patient With Progressive Multifocal Leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease caused by activation of John Cunningham virus (JCV) replication in the setting of impaired cellular immunity. A positive polymerase chain reaction (PCR) assay for JCV DNA in the cerebrospinal fluid (CSF) in conjunction with clinical findings and neuroimaging are diagnostic of PML. A false negative JCV PCR in the CSF may occur, necessitating PML confirmation by brain biopsy. We describe the unique clinical profile of a patient with no prior history of immunocompromise, referred to us for electrodiagnostic evaluation, who initially presented with rapidly progressive weakness of the right upper extremity. The unusual pattern of motor weakness suggested a conduction block or disconnection at the subcortical level. The patient was later diagnosed with atypical small cell lymphocytic lymphoma although not treated with monoclonal antibodies or other forms of chemotherapy. The CSF was negative for JCV, and PML was subsequently confirmed by brain biopsy. This case illustrates an uncommon presentation of PML and highlights the need for a high index of suspicion to diagnose PML.

The risk of infections for multiple sclerosis and neuromyelitis optica spectrum disorder disease-modifying treatments: Eighth European Committee for Treatment and Research in Multiple Sclerosis Focused Workshop Review. April 2021

Over the recent years, the treatment of multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) has evolved very rapidly and a large number of disease-modifying treatments (DMTs) are now available. However, most DMTs are associated with adverse events, the most frequent of which being infections. Consideration of all DMT-associated risks facilitates development of risk mitigation strategies. An international focused workshop with expert-led discussions was sponsored by the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) and was held in April 2021 to review our current knowledge about the risk of infections associated with the use of DMTs for people with MS and NMOSD and corresponding risk mitigation strategies. The workshop addressed DMT-associated infections in specific populations, such as children and pregnant women with MS, or people with MS who have other comorbidities or live in regions with an exceptionally high infection burden. Finally, we reviewed the topic of DMT-associated infectious risks in the context of the current SARS-CoV-2 pandemic. Herein, we summarize available evidence and identify gaps in knowledge which justify further research.

JC polyomavirus DNA detection in clinical practice

BACKGROUND

There are limited data about the use and clinical value of JC polyomavirus (JCPyV) DNA detection in various clinical indications.

METHODS

We reviewed the clinical records of 410 patients from whom cerebrospinal fluid (CSF), plasma, urine, or tissue samples had been collected for JCPyV DNA polymerase chain reaction (PCR) between 2012 and 2018.

RESULTS

JCPyV DNA was analyzed in 224 plasma, 190 CSF-, 32 urine and 10 tissue samples. 240 patients had a history of hematopoietic stem cell or solid organ transplantation, 159 had nephrological disease, 90 had hematologic malignancies, 58 had neurological disease, 37 had infectious disease and 23 had AIDS/HIV as underlying disease. Six patients had no underlying disease. The main reasons to take CSF or plasma samples were neurological symptoms of unknown etiology. Most urine samples were taken to monitor kidney transplantation patients. JCPyV DNA PCR contributed to the diagnosis of progressive multifocal leukoencephalopathy in eight patients (2.0%), of which seven had hematologic malignancy as an underlying disease.

CONCLUSIONS

JCPyV PCR is most informative among immunosuppressed patients with neurologic symptoms. CSF and brain biopsy are useful when there is clinical suspicion of PML, whereas plasma samples are not useful. The value of plasma samples is a matter of dispute in the screening of JCPyV-associated nephropathy, as BK polyomavirus is the causative agent in most polyomavirus-associated nephropathy cases. JCPyV detection is valuable in case the patient has past, current or planned treatment with immunosuppressive drugs.

Progressive multifocal leukoencephalopathy successfully treated with mefloquine and literature review

Progressive multifocal leukoencephalopathy (PML) is an opportunistic infection due to reactivation of John Cunningham virus (JCV). The diagnosis depends on evidence from clinical, imaging, and virologic studies. When the cerebrospinal fluid shows a negative polymerase chain reaction result, brain biopsy is required to confirm the diagnosis. PML has no standard treatment except for immune reconstitution. The anti-JCV effect of mefloquine, however, is supported by some studies, and if brain biopsy is difficult, a mefloquine trial can be considered. We describe a case of possible PML successfully treated with mefloquine.

Advances in Treatment of Progressive Multifocal Leukoencephalopathy

Progressive multifocal encephalopathy (PML) is a severe demyelinating disease of the central nervous system (CNS) caused by JC virus (JCV), which occurs in immunocompromised individuals. Management of PML relies on restoration of immunity within the CNS. However, when this restoration cannot be readily achieved, PML has a grim prognosis. Innovative strategies have shown promise in promoting anti‐JCV immune responses, and include T‐cell adoptive transfer or immune checkpoint inhibitor therapies. Conversely, management of immune reconstitution inflammatory syndrome, particularly in iatrogenic PML, remains a major challenge. In this paper, we review recent development in the treatment of PML. ANN NEUROL 2021;90:865–873

Pharmacovigilance during treatment of multiple sclerosis: early recognition of CNS complications

An increasing number of highly effective disease-modifying therapies for people with multiple sclerosis (MS) have recently gained marketing approval. While the beneficial effects of these drugs in terms of clinical and imaging outcome measures is welcomed, these therapeutics are associated with substance-specific or group-specific adverse events that include severe and fatal complications. These adverse events comprise both infectious and non-infectious complications that can occur within, or outside of the central nervous system (CNS). Awareness and risk assessment strategies thus require interdisciplinary management, and robust clinical and paraclinical surveillance strategies. In this review, we discuss the current role of MRI in safety monitoring during pharmacovigilance of patients treated with (selective) immune suppressive therapies for MS. MRI, particularly brain MRI, has a pivotal role in the early diagnosis of CNS complications that potentially are severely debilitating and may even be lethal. Early recognition of such CNS complications may improve functional outcome and survival, and thus knowledge on MRI features of treatment-associated complications is of paramount importance to MS clinicians, but also of relevance to general neurologists and radiologists.

Neuroimaging Insights Into Early Stages of HIV-Progressive Multifocal Leukoencephalopathy: A Case Report

This report aims to enhance the understanding of early longitudinal neuroimaging features of progressive multifocal leukoencephalopathy (PML) in human immunodeficiency virus (HIV). Neuroimaging has become crucial in the diagnosis and early recognition of PML. Recognition of magnetic resonance imaging (MRI) features in the early stages of PML is paramount to avoid misdiagnosis and facilitate the delivery of treatments aimed at reducing disease progression. A 49-year-old white man with HIV presented with 4-month progressive left-sided weakness. Neurological examination revealed mild cognitive impairment, left-sided hemiparesis, and somatosense impairment to all modalities. Brain MRI revealed a punctate pattern with innumerable T2-FLAIR (fluid attenuated inversion recovery) hyperintensities in the cortex, brainstem, cerebellum, subcortical, and periventricular areas. Susceptibility-weighted imaging (SWI) revealed hypointensities involving subcortical U-fibers and cortical architecture. A comprehensive diagnostic evaluation was inconclusive. John Cunningham virus (JCV) PCR in cerebrospinal fluid (CSF) was indeterminate. He was started on antiretroviral therapy. Repeat brain MRI performed 1.5 months later, in the setting of further neurological decline, demonstrated progression of the T2-hyperintensities into a large confluent white matter lesion in the right frontoparietal lobe. Despite an indeterminate JCV PCR, the appearance and characteristic progression of the lesions in successive imaging in the setting of severe immunosuppression, with extensive negative infectious workup, was indicative of PML. This clinical experience illustrates unique neuroimaging features of HIV-PML in early stages and its progression over time. It especially highlights the relevance of the SWI sequence in the diagnosis and features observed with disease evolution. Short-term imaging follow-up may assist with the recognition of MRI features consistent with the biology of the infection.

Specific antibodies reacting to JC polyomavirus capsid protein mimotopes in sera from multiple sclerosis and other neurological diseases-affected patients

Published data support the hypothesis that viruses could be trigger agents of multiple sclerosis onset. This link is based on evidence of early exposure to viral agents in patients affected by this neurologic disease. JC (JC polyomavirus [JCPyV]), BK (BKPyV), and simian virus 40 (SV40) neurotropic polyomavirus footprints have been detected in brain tissue specimens and samples from patients affected by different neurological diseases. In this investigation, serum samples from patients affected by multiple sclerosis and other inflammatory and noninflammatory neurologic diseases, as well as healthy subjects representing the control, were investigated for immunoglobulin G (IgG) antibodies against JCPyV. To this end, an immunologic approach was employed, which consists of employing indirect enzyme-linked immunosorbent assay testing with synthetic peptides mimicking viral capsid protein 1 antigens. A significantly lower prevalence of IgG antibodies against JCPyV VP1 epitopes, with a low titer, was detected in serum samples from patients with multiple sclerosis (MS) and other neurologic diseases than in healthy subjects. Our study indicates that the prevalence of JCPyV antibodies from patients with multiple sclerosis is 50% lower than in healthy subjects, suggesting specific immune impairments. These results indicate that patients affected by neurological diseases, including MS, respond poorly to JCPyV VP1 antigens, suggesting specific immunologic dysfunctions.

Improving detection of JC virus by ultrafiltration of cerebrospinal fluid before polymerase chain reaction for the diagnosis of progressive multifocal leukoencephalopathy

Background

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disorder caused by JC virus (JCV). Although detecting JCV DNA in the cerebrospinal fluid (CSF) by real-time polymerase chain reaction (PCR) is useful, diagnosis is difficult when JCV concentrations are low. We therefore aimed to lower the detection limit of real-time PCR testing by enriching JCV in the CSF via ultrafiltration.

Methods

Virus suspensions and CSF specimens from 20 untreated patients with suspected PML were collected and total DNAs were extracted. The JCV large T gene was detected by quantitative real-time PCR under condition with and without prior centrifugal ultrafiltration.

Results

The JCV DNA was reliably detected to a lower limit of 10 copies/mL of virus suspension by real-time PCR with ultrafiltration. When using this method, the quantity of JCV DNA per PCR reaction increased 3.2- to 8.7-fold compared with the standard procedure. Seven patients were positive for JCV when using the standard procedure, and an additional patient was positive when using ultrafiltration. All JCV-positive patients had neurological features and magnetic resonance imaging findings compatible with PML.

Conclusions

The detection limit of JCV DNA by real-time PCR can be lowered by viral enrichment using ultrafiltration. Our simple protocol offers a valuable tool for PML diagnosis when extremely low copy numbers of JCV are released into the CSF or when brain biopsy is not feasible.

Association of Progressive Multifocal Leukoencephalopathy Lesion Volume With JC Virus Polymerase Chain Reaction Results in Cerebrospinal Fluid of Natalizumab-Treated Patients With Multiple Sclerosis

Importance

The JC virus (JCV) was named after the first patient to be described with progressive multifocal leukoencephalopathy (PML), John Cunningham. Detection of JC virus DNA in cerebrospinal fluid (CSF) by polymerase chain reaction (PCR), and of specific lesions by brain magnetic resonance imaging (MRI), are both considered essential for the diagnosis of natalizumab-associated PML (NTZ-PML) in patients with multiple sclerosis. However, strict pharmacovigilance by MRI can result in detection of patients with small lesions and undetectable JCV DNA in CSF.

Objective

To investigate the association of PML lesion characteristics on MRI with both qualitative and quantitative JCV PCR results in CSF of patients with NTZ-PML.

Design, Setting and Participants

This was a retrospective, cross-sectional study conducted from January 2007 to December 2014 in patients considered to have NTZ-PML based on a set of predefined criteria. Follow-up was at least 6 months. Data of patients from the Dutch-Belgian NTZ-PML cohort and patients treated at multiple medical centers in Belgium and the Netherlands and selected for research purposes were included as a convenience sample.

Main Outcomes and Measures

Brain MRI scans were analyzed for PML lesion volume, location, dissemination, and signs of inflammation. Associations of the qualitative and quantitative CSF JCV PCR results with PML MRI characteristics were calculated.

Results

Of the 73 patients screened, 56 were included (37 were women). At inclusion, 9 patients (16.1%) had undetectable JCV DNA in CSF. Patients with a positive PCR had larger total PML lesion volumes than those with undetectable JCV DNA (median volume, 22.9 mL; interquartile range, 9.2-60.4 mL vs median volume, 6.7 mL; interquartile range, 4.9-14.7 mL; P = .008), and logistic regression showed that a lower PML lesion volume significantly increased the probability for undetectable JCV DNA. There was a positive correlation between PML lesion volume and JCV copy numbers (Spearman ρ, 0.32; P = .03). Progressive multifocal leukoencephalopathy lesion volume was higher in patients with PML symptoms and in patients with more widespread lesion dissemination. No association was found between PCR results and PML lesion dissemination, signs of inflammation, or PML symptoms.

Conclusions and Relevance

Smaller NTZ-PML lesions are associated with a higher likelihood of undetectable JCV DNA in CSF. This may preclude a formal diagnosis of PML and can complicate patient treatment in patients with small MRI lesions highly suggestive of PML detected early through pharmacovigilance.

Progressive Multifocal Leukoencephalopathy Diagnosed by Brain Biopsy, not by the DNA Test for JC Virus

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system caused by a lytic infection of oligodendrocytes due to the presence of JC polyomavirus (JCV). The disease occurs mostly in immunocompromised patients and is associated with a high mortality rate. The diagnosis of PML is based on a polymerase chain reaction (PCR) assay for JC viral DNA in cerebrospinal fluid (CSF). However, case reports of the diagnosis of PML established with brain biopsy despite negative JCV CSF PCR analysis when clinical and neuroimaging features are suggestive of PML have been published. A 44-year-old male with a 6-year history of acquired immunodeficiency syndrome developed mental confusion and memory impairment despite 3 months of highly active antiretroviral therapy. Magnetic resonance imaging revealed multiple subcortical white matter lesions in bilateral hemispheres and subcortical nuclei including the thalamus and basal ganglia. JCV DNA was not detected in CSF study, but a brain biopsy showed a high JCV DNA titer. The diagnosis of PML was established with brain biopsy. An early brain biopsy may be important in the diagnosis of PML in patients with clinical manifestations and neuroimaging findings if JCV DNA is undetectable in the CSF PCR.

Progressive Multifocal Leukoencephalopathy in the Absence of Typical Radiological Changes: Can We Make a Diagnosis?

Patient: Female, 32

Final Diagnosis: Progressive multifocal leukoencephalopathy

Symptoms: Progressive behavioral changes • seizures

Medication: —

Clinical Procedure: Management

Specialty: Neurology

Performance of PML diagnostic criteria in natalizumab-associated PML: data from the Dutch-Belgian cohort

OBJECTIVE

To test the current progressive multifocal leukoencephalopathy (PML) diagnostic criteria by applying them to patients previously diagnosed with natalizumab (NTZ)-associated PML in a real-world clinical setting.

METHODS

Patients from the Dutch-Belgian NTZ-PML cohort (n=28) were reviewed at the time of first diagnostic work-up and during follow-up, using the PML diagnostic criteria as proposed in a consensus statement from the American Academy of Neurology.

RESULTS

At first diagnostic work-up, 18 patients (64.3%) met the criteria for high diagnostic certainty for PML ('definite PML' or 'probable PML'). During follow-up, this increased to 20 patients (71.4%) as JC virus DNA was detected in cerebrospinal fluid of two additional patients. Nonetheless, 28.6% of patients were still classified as 'possible PML' or 'not PML' (6 (21.5%) and 2 (7.1%) patients, respectively) despite a very high suspicion for PML based on lesion evolution and signs of PML-immune reconstitution inflammatory syndrome on MRI, and development of compatible symptoms.

CONCLUSIONS

The current case definition of PML has low sensitivity for diagnosis of NTZ-PML in a real-world clinical setting in which MRI is frequently used for PML screening. This may delay diagnosis and appropriate management of PML, and may complicate a valid estimation of PML incidence during NTZ therapy.

Anaplastic astrocytoma mimicking progressive multifocal leucoencephalopathy: a case report and review of the overlapping syndromes

Background

Co-occurrence of multiple sclerosis (MS) and glial tumours (GT) is uncommon although occasionally reported in medical literature. Interpreting the overlapping radiologic and clinical characteristics of glial tumours, MS lesions, and progressive multifocal leukoencephalopathy (PML) can be a significant diagnostic challenge.

Case presentation

We report a case of anaplastic astrocytoma mimicking PML in a 27-year-old patient with a 15-year history of MS. She was treated with interferon, natalizumab and finally fingolimod due to active MS. Follow-up MRI, blood and cerebrospinal fluid examinations, and biopsy were conducted, but only the latter was able to reveal the cause of progressive worsening of patient’s disease.

Conclusions

Anaplastic astrocytoma misdiagnosed as PML has not yet been described. We suppose that the astrocytoma could have evolved from a low grade glioma to anaplastic astrocytoma over time, as the tumour developed adjacent to typical MS plaques. The role of the immunomodulatory treatment as well as other immunological factors in the malignant transformation can only be hypothesised. We discuss clinical, laboratory and diagnostic aspects of a malignant GT, MS lesions and PML. The diagnosis of malignant GT must be kept in mind when an atypical lesion develops in a patient with MS.

Brain Biopsy Is More Reliable than the DNA test for JC Virus in Cerebrospinal Fluid for the Diagnosis of Progressive Multifocal Leukoencephalopathy

The current standard diagnostic approach for progressive multifocal leukoencephalopathy (PML) is to perform a DNA test to identify the presence of the JC virus in cerebrospinal fluid (CSF). A 32-year-old woman with a 5-year history of systemic lupus erythematosus developed right hemiplegia and motor aphasia. MRI revealed a large white matter lesion in the left frontal lobe. JC virus DNA was undetectable in the CSF, but a brain biopsy showed typical histopathology and a high DNA load of the JC virus. The patient was treated with mefloquine and mirtazapine, and is currently alive at 24 months after onset. An early brain biopsy may therefore be important for making a timely diagnosis of PML.

Progressive Multifocal Leukoencephalopathy in a Multiple Sclerosis Patient Diagnosed after Switching from Natalizumab to Fingolimod

Background. Natalizumab- (NTZ-) associated progressive multifocal leukoencephalopathy (PML) is a severe and often disabling infectious central nervous system disease that can become evident in multiple sclerosis (MS) patients after NTZ discontinuation. Recently, novel diagnostic biomarkers for the assessment of PML risk in NTZ treated MS patients such as the anti-JC virus antibody index have been reported, and the clinical relevance of milky-way lesions detectable by MRI has been discussed. Case Presentation and Conclusion. We report a MS patient in whom PML was highly suspected solely based on MRI findings after switching from NTZ to fingolimod despite repeatedly negative (ultrasensitive) polymerase chain reaction (PCR) testing for JC virus DNA in cerebrospinal fluid. The PML diagnosis was histopathologically confirmed by brain biopsy. The occurrence of an immune reconstitution inflammatory syndrome (IRIS) during fingolimod therapy, elevated measures of JCV antibody indices, and the relevance of milky-way-like lesions detectable by (7 T) MRI are discussed.

[Progressive multifocal leukoencephalopathy]

Progressive multifocal leukoencephalopathy (PML) is a disease of immunosuppressed patients caused by the JC polyomavirus (JCPyV). Due to the elevated risk in patients treated with natalizumab for multiple sclerosis (MS) and also treatment with other biologicals for different indications, the relevance of PML has increased in recent years. This article summarizes the published knowledge on the biology and pathogenesis of PML with a focus on the role of cerebrospinal fluid diagnostics in the work-up for PML and the current PML case definition. Current recommendations regarding risk management are discussed, as are possible therapies and prevention.

Drug-associated progressive multifocal leukoencephalopathy: a clinical, radiological, and cerebrospinal fluid analysis of 326 cases

The implementation of a variety of immunosuppressive therapies has made drug-associated progressive multifocal leukoencephalopathy (PML) an increasingly prevalent clinical entity. The purpose of this study was to investigate its diagnostic characteristics and to determine whether differences herein exist between the multiple sclerosis (MS), neoplasm, post-transplantation, and autoimmune disease subgroups. Reports of possible, probable, and definite PML according to the current diagnostic criteria were obtained by a systematic search of PubMed and the Dutch pharmacovigilance database. Demographic, epidemiologic, clinical, radiological, cerebrospinal fluid (CSF), and histopathological features were extracted from each report and differences were compared between the disease categories. In the 326 identified reports, PML onset occurred on average 29.5 months after drug introduction, varying from 14.2 to 37.8 months in the neoplasm and MS subgroups, respectively. The most common overall symptoms were motor weakness (48.6 %), cognitive deficits (43.2 %), dysarthria (26.3 %), and ataxia (24.1 %). The former two also constituted the most prevalent manifestations in each subgroup. Lesions were more often localized supratentorially (87.7 %) than infratentorially (27.4 %), especially in the frontal (64.1 %) and parietal lobes (46.6 %), and revealed enhancement in 27.6 % of cases, particularly in the MS (42.9 %) subgroup. Positive JC virus results in the first CSF sample were obtained in 63.5 %, while conversion after one or more negative outcomes occurred in 13.7 % of cases. 52.2 % of patients died, ranging from 12.0 to 83.3 % in the MS and neoplasm subgroups, respectively. In conclusion, despite the heterogeneous nature of the underlying diseases, motor weakness and cognitive changes were the two most common manifestations of drug-associated PML in all subgroups. The frontal and parietal lobes invariably constituted the predilection sites of drug-related PML lesions.

Progressive multifocal leukoencephalopathy with bilateral middle cerebellar peduncle lesions confirmed by repeated CSF-JC virus tests and coexistence of JC virus granule cell neuronopathy. Report of a case

A 65 year-old woman with small lymphocytic leukemia presented with subacute cerebellar ataxia. Six months after rituximab chemotherapy, a cranial MRI revealed lesions in the bilateral middle cerebellar peduncles. Both cerebrospinal fluid (CSF) JC virus (JCV)-DNA PCR test on three occasions and brain biopsy were negative. CSF tests were repeated. The fourth test performed 6 months after the onset showed positive JCV-DNA, and a definite diagnosis of progressive multifocal leukoencephalopathy (PML) was made. Neuroimaging of cerebellar atrophy was considered to be coexistence of granule cell neuronopathy. Medication with mirtazapine and mefloquine was temporarily effective for several months. Little are known solitary bilateral MRI lesions of the middle cerebellar peduncle in PML. JCV-PCR test of CSF may be negative at an earlier stage of PML. Repeated CSF tests should be essential to confirming the diagnosis in such cases.

Switching patients at high risk of PML from natalizumab to another disease-modifying therapy

There are several options for switching people with multiple sclerosis (MS) who are at high risk of developing progressive multifocal leukoencephalopathy (PML) from natalizumab to alemtuzumab. However, some of these have risks that need to be managed, for example, the risks of carrying over asymptomatic PML from natalizumab on to the new therapy, and the risk of rebound disease activity associated with a prolonged washout after starting natalizumab. We propose a pragmatic bridging strategy, using another disease-modifying therapy (DMT), to reduce the risk of switching from natalizumab to alemtuzumab. We also discuss the caveats and subtleties associated with sequencing DMTs in MS and the complex decision making involved.

Stratification and monitoring of natalizumab-associated progressive multifocal leukoencephalopathy risk: recommendations from an expert group

The use of natalizumab for highly active relapsing-remitting multiple sclerosis (MS) is influenced by the occurrence of progressive multifocal leukoencephalopathy (PML). Through measurement of the anti-JCV antibody index, and in combination with the presence or absence of other known risk factors, it may be possible to stratify patients with MS according to their risk of developing PML during treatment with natalizumab and detect early suspected PML using MRI including a diffusion-weighted imaging sequence. This paper describes a practical consensus guideline for treating neurologists, based on current evidence, for the introduction into routine clinical practice of anti-JCV antibody index testing of immunosuppressant-naïve patients with MS, either currently being treated with, or initiating, natalizumab, based on their anti-JCV antibody status. Recommendations for the frequency and type of MRI screening in patients with varying index-associated PML risks are also discussed. This consensus paper presents a simple and pragmatic algorithm to support the introduction of anti-JCV antibody index testing and MRI monitoring into standard PML safety protocols, in order to allow some JCV positive patients who wish to begin or continue natalizumab treatment to be managed with a more individualised analysis of their PML risk.

Diagnostic assays for polyomavirus JC and progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a devastating and often fatal demyelinating disease of the central nervous system for which effective therapies are lacking. It is caused by the replication of polyomavirus JC (JCV) in the oligodendrocytes and astrocytes leading to their cytolytic death and loss of myelin from the subcortical white matter. While the virus is very common in human populations worldwide, the incidence of the disease is very low and confined almost exclusively to individuals with some form of immunological dysfunction. However, the number of people who constitute the at-risk population is growing larger and includes individuals with HIV-1/AIDS and patients receiving immunomodulatory therapies such as multiple sclerosis patients treated with natalizumab. Further adding to the public health significance of this disease are the difficulties encountered in the diagnosis of PML and the lack of useful biomarkers for PML progression. In this review, we examine the diagnostic assays that are available for different aspects of the JCV life cycle, their usefulness and drawbacks, and the prospects for improvements.

7T MRI in natalizumab-associated PML and ongoing MS disease activity: A case study

Objective:

To assess the ability of ultra-high-field MRI to distinguish early progressive multifocal leukoencephalopathy (PML) from multiple sclerosis (MS) lesions in a rare case of simultaneous presentation of natalizumab–associated PML and ongoing MS activity.

Methods:

Advanced neuroimaging including 1.5T, 3T, and 7T MRI with a spatial resolution of up to 0.08 mm³ was performed.

Results:

7T MRI differentiated between PML-related and MS-related brain damage in vivo. Ring-enhancing MS plaques displayed a central vein, whereas confluent PML lesions were preceded by punctate or milky way–like T2 lesions.

Conclusions:

Given the importance of early diagnosis of treatment-associated PML, future systematic studies are warranted to assess the value of highly resolving MRI in differentiating between early PML- and MS-induced brain parenchymal lesions.

Broadly neutralizing human monoclonal JC polyomavirus VP1-specific antibodies as candidate therapeutics for progressive multifocal leukoencephalopathy

In immunocompromised individuals, JC polyomavirus (JCPyV) may mutate and gain access to the central nervous system resulting in progressive multifocal leukoencephalopathy (PML), an often fatal opportunistic infection for which no treatments are currently available. Despite recent progress, the contribution of JCPyV-specific humoral immunity to controlling asymptomatic infection throughout life and to eliminating JCPyV from the brain is poorly understood. We examined antibody responses against JCPyV major capsid protein VP1 (viral protein 1) variants in the serum and cerebrospinal fluid (CSF) of healthy donors (HDs), JCPyV-positive multiple sclerosis patients treated with the anti-VLA-4 monoclonal antibody natalizumab (NAT), and patients with NAT-associated PML. Before and during PML, CSF antibody responses against JCPyV VP1 variants show "recognition holes"; however, upon immune reconstitution, CSF antibody titers rise, then recognize PML-associated JCPyV VP1 variants, and may be involved in elimination of the virus. We therefore reasoned that the memory B cell repertoire of individuals who recovered from PML could be a source for the molecular cloning of broadly neutralizing antibodies for passive immunization. We generated a series of memory B cell-derived JCPyV VP1-specific human monoclonal antibodies from HDs and a patient with NAT-associated PML-immune reconstitution inflammatory syndrome (IRIS). These antibodies exhibited diverse binding affinity, cross-reactivity with the closely related BK polyomavirus, recognition of PML-causing VP1 variants, and JCPyV neutralization. Almost all antibodies with exquisite specificity for JCPyV, neutralizing activity, recognition of all tested JCPyV PML variants, and high affinity were derived from one patient who had recovered from PML. These antibodies are promising drug candidates for the development of a treatment of PML.

Neuroimaging of Natalizumab Complications in Multiple Sclerosis: PML and Other Associated Entities

Natalizumab (Tysabri) is a monoclonal antibody (α4 integrin antagonist) approved for treatment of multiple sclerosis, both for patients who fail therapy with other disease modifying agents and for patients with aggressive disease. Natalizumab is highly effective, resulting in significant decreases in rates of both relapse and disability accumulation, as well as marked decrease in MRI evidence of disease activity. As such, utilization of natalizumab is increasing, and the presentation of its associated complications is increasing accordingly. This review focuses on the clinical and neuroimaging features of the major complications associated with natalizumab therapy, focusing on the rare but devastating progressive multifocal leukoencephalopathy (PML). Associated entities including PML associated immune reconstitution inflammatory syndrome (PML-IRIS) and the emerging phenomenon of rebound of MS disease activity after natalizumab discontinuation are also discussed. Early recognition of neuroimaging features associated with these processes is critical in order to facilitate prompt diagnosis, treatment, and/or modification of therapies to improve patient outcomes.

Progressive neurologic dysfunction in a psoriasis patient treated with dimethyl fumarate

Progressive multifocal leukoencephalopathy (PML) has recently been described in psoriasis or multiple sclerosis patients treated with fumaric acid esters (fumarates), who had developed severe and long-standing lymphocytopenia (<500/mm(3) ). We report a psoriasis patient who presented with progressive neurologic dysfunction and seizures after 2.5 years of fumarate therapy. Despite absolute lymphocyte counts remaining between 500-1000/mm(3) , his CD4(+) and CD8(+) T-cell counts were markedly low. MRI showed right hemispheric and brainstem lesions and JC virus DNA was undetectable in his cerebrospinal fluid. Brain biopsy revealed typical features of PML as well as JC virus-infected neurons. Clinicians should consider PML in the differential diagnosis of fumarate-treated patients presenting with brain lesions or seizures even in the absence of severe lymphocytopenia.

Optimizing JC and BK polyomavirus IgG testing for seroepidemiology and patient counseling

BACKGROUND

Polyomavirus JC (JCPyV) and BK (BKPyV) can cause significant diseases in immunocompromised patients including nephropathy, hemorrhagic cystitis, and leukoencephalopathy. Recently, JCPyV and BKPyV IgG have been explored as risk predictors in multiple sclerosis and transplant patients, but sensitivity, specificity and quantification issues limit current performance.

OBJECTIVE

To improve JCPyV and BKPyV-specific antibody testing.

STUDY DESIGN

Healthy blood donor sera (N=400) were tested at dilutions 1:100, 1:200, and 1:400 for JCPyV- and BKPyV-specific IgG using VP1 virus-like particle (VLP)-based ELISAs normalized to a laboratory reference serum. Normalized optical density 492nm greater or equal 0.1 in all 3 dilutions was regarded as reactive. Sera with discordant reactivity in at least one dilution were retested after VLP preadsorption.

RESULTS

At dilutions 1:100, 1:200, and 1:400, IgG reactivity was 74%, 60% and 53% for JCPyV, and 93%, 86% and 74% for BKPyV, respectively. At these dilutions, JCPyV-VLP preadsorption identified 56, 4 and 0 false-positives and 0, 4 and 27 false-negatives, respectively. Dilution-dependent sensitivity was 100%, 98%, and 89%, and specificity 65, 98%, and 100%, respectively. For sera diluted 100-, 200-, and 400-fold, BKPyV-VLP preadsorption identified 28, 1 and 0 false-positives, and 0, 0 and 46 false-negatives, and sensitivity was 100%, 100%, 86%, and specificity 50%, 98%, 100%, respectively.

CONCLUSION

For seroepidemiology studies, normalized JCPyV and BKPyV IgG ELISA at 1:200 serum dilution provides optimal sensitivity and specificity with the lowest false-positive and false-negative rate. For individual risk assessment, dilutions of 100, 200, and 400 combined with preadsorption for low-reactive sera may be most appropriate.

Treatment of progressive multifocal leukoencephalopathy-immune reconstitution inflammatory syndrome with intravenous immunoglobulin in a patient with multiple sclerosis treated with fingolimod after discontinuation of natalizumab

We report a case of progressive multifocal leukoencephalopathy-immune reconstitution inflammatory syndrome in a multiple sclerosis (MS) patient 3.5 months after fingolimod commencement and 4.5 months after natalizumab (NTZ) cessation. Three cerebrospinal fluid analyses were required before a definitive diagnosis of progressive multifocal leukoencephalopathy was reached. Intravenous immunoglobulin (IVIG) was subsequently given as the sole MS treatment along with mirtazapine and mefloquine. There has been improvement and subsequent clinical stabilization. The notable features are the difficult timing of fingolimod commencement in the context of previous NTZ therapy, the role of repeated cerebrospinal fluid John Cunningham virus analyses in progressive multifocal leukoencephalopathy diagnosis, and the role of IVIG.

Cerebrospinal fluid JC virus antibody index for diagnosis of natalizumab-associated progressive multifocal leukoencephalopathy

OBJECTIVE

Progressive multifocal leukoencephalopathy (PML), caused by JC virus (JCV), can occur in patients receiving natalizumab for multiple sclerosis (MS). JCV detection by quantitative polymerase chain reaction (qPCR) in cerebrospinal fluid (CSF), or brain biopsy, is required for probable or definite diagnosis of PML. However, in some patients only low levels of JCV DNA (<100 copies/ml) are present in CSF, making the diagnosis challenging. Our objective was to assess the complementary value of a CSF JCV antibody index (AIJCV ) in the diagnosis of natalizumab-associated PML.

METHODS

AIJCV was assessed in 37 cases of natalizumab-associated PML and 89 MS-patients treated with natalizumab without PML. Sera and CSF were tested in a capture enzyme-linked immunosorbent assay, using JCV-VP1 fused to glutathione S-transferase as antigen. Albumin levels and total immunoglobulin G concentration were determined by immunonephelometry, and the AIJCV was calculated as published.

RESULTS

Twenty-six of 37 (70%) patients with natalizumab-associated PML exhibited an AIJCV > 1.5, whereas this was seen in none of the controls (p < 0.0001). At time of the first positive qPCR for JCV DNA, 11 of 20 (55%) patients with natalizumab-associated PML had an AIJCV > 1.5. JCV DNA levels of <100 copies/ml were seen in 14 (70%) of these 20 patients, of whom 8 (57%) demonstrated an AIJCV > 1.5.

INTERPRETATION

Determination of the AIJCV could be an added tool in the diagnostic workup for PML and should be included in the case definition of natalizumab-associated PML.

Management of disease-modifying treatments in neurological autoimmune diseases of the central nervous system

The therapeutic armamentarium for autoimmune diseases of the central nervous system, specifically multiple sclerosis and neuromyelitis optica, is steadily increasing, with a large spectrum of immunomodulatory and immunosuppressive agents targeting different mechanisms of the immune system. However, increasingly efficacious treatment options also entail higher potential for severe adverse drug reactions. Especially in cases failing first-line treatment, thorough evaluation of the risk-benefit profile of treatment alternatives is necessary. This argues for the need of algorithms to identify patients more likely to benefit from a specific treatment. Moreover, paradigms to stratify the risk for severe adverse drug reactions need to be established. In addition to clinical/paraclinical measures, biomarkers may aid in individualized risk-benefit assessment. A recent example is the routine testing for anti-John Cunningham virus antibodies in natalizumab-treated multiple sclerosis patients to assess the risk for the development of progressive multi-focal leucoencephalopathy. Refined algorithms for individualized risk assessment may also facilitate early initiation of induction treatment schemes in patient groups with high disease activity rather than classical escalation concepts. In this review, we will discuss approaches for individiualized risk-benefit assessment both for newly introduced agents as well as medications with established side-effect profiles. In addition to clinical parameters, we will also focus on biomarkers that may assist in patient selection.

Efficacy and side effects of natalizumab therapy in patients with multiple sclerosis

Natalizumab (Nat) is a humanized monoclonal antibody used for the treatment of relapsing multiple sclerosis (MS). Nat inhibits lymphocyte migration via the blood brain barrier (BBB) by blockage of an integrin adhesion molecule, very late antigen 4. During the phase III clinical trials, it was shown that Nat reduces disease activity and prevents disability progression. In addition, several smaller studies indicate a positive influence of Nat on cognition, depression, fatigue, and quality of life (Qol). Therapeutic efficacy has to be weighed against the risk of developing potentially fatal progressive multifocal leukoencephalopathy (PML), an opportunistic infection by JC-virus (JCV) with an incidence of 3.4/1000 (95% CI 3.08–3.74) in Nat treated MS patients. In this review article, we will review data on the presumed mechanism of Nat action, clinical and paraclinical efficacy parameters, and adverse drug reactions with a special focus on PML.

Natalizumab-associated progressive multifocal leukoencephalopathy in a patient with multiple sclerosis: a postmortem study

Natalizumab, a monoclonal antibody directed against α4 integrins, has, to date, been associated with 399 cases of progressive multifocal leukoencephalopathy (PML) worldwide in patients receiving treatment for multiple sclerosis (MS). Because of the limited number of histologic studies, the possible interplay between MS and PML lesions has not been investigated. We report the clinical, radiologic, and histologic findings of an MS patient who developed PML after 32 months of natalizumab monotherapy. After withdrawal of natalizumab, she received plasma exchange, mefloquine, and mirtazapine but died soon thereafter. Postmortem examination was restricted to examination of the brain and spinal cord. Extensive PML lesions, characterized by the presence of JC virus DNA were found in the cerebral white matter and neocortex. Sharply demarcated areas of active PML lesions contained prominent inflammatory infiltrates composed of approximately equal numbers of CD4-positive and CD8-positive T cells, consistent with an immune reconstitution inflammatory syndrome. Conversely, all MS lesions identified were hypocellular, long-standing inactive plaques characterized by myelin loss, relative axonal preservation, and gliosis and, importantly, were devoid of JC virus DNA and active inflammation. Chronic inactive MS lesions were separate and distinct from nearby PML lesions. This case demonstrates the coexistence and apparent lack of interplay between chronic inactive MS and PML lesions, and that immune reconstitution inflammatory syndrome seems to affect the shape and appearance of PML but not MS lesions.

The chameleon of neuroinflammation: magnetic resonance imaging characteristics of natalizumab-associated progressive multifocal leukoencephalopathy

Natalizumab is a monoclonal antibody against α4-integrin approved for the treatment of multiple sclerosis (MS) due to a positive effect on clinical and magnetic resonance imaging (MRI) outcome measures. However, one relatively rare but serious side effect of this drug is a higher risk of developing progressive multifocal leukoencephalopathy (PML). Since the FDA approval, more than 300 natalizumab-associated PML cases have been documented among more than 100,000 treated MS patients. MRI is a crucial tool in the surveillance of patients treated with natalizumab in order to detect possible signs of PML in the asymptomatic stage. Although classical imaging characteristics of PML are well established, MRI findings in natalizumab-associated PML, particularly in early disease stages, show rather new and heterogeneous imaging findings including different patterns of inflammation with contrast enhancement. This review provides a comprehensive overview of the heterogeneous imaging findings in natalizumab-associated PML in the context of the underlying pathophysiology, histopathology, and the diagnostic procedure. We describe the MRI patterns of PML lesion evolution and complications including immune reconstitution inflammatory syndrome (IRIS). Finally, we present guidelines to differentiate MRI findings in PML from inflammatory demyelinating lesions, to facilitate the early diagnosis of PML in patients treated with natalizumab.