Development Of Progressive Multifocal Leukoencephalopathy Research Articles

A second-generation ELISA (STRATIFY JCV™ DxSelect™) for detection of JC virus antibodies in human serum and plasma to support progressive multifocal leukoencephalopathy risk stratification

BackgroundJC virus (JCV) infection is a prerequisite for development of progressive multifocal leukoencephalopathy (PML). The development and validation of a two-step enzyme-linked immunosorbent assay (ELISA) that detects JCV antibodies in human serum or plasma and its clinical utility for stratification of PML risk have been described. ObjectiveTo develop a second-generation JCV antibody ELISA kit with improved assay performance characteristics. Study designThe assay design was optimized by pre-coating the JC virus-like particles (VLP) on microtiter plates. Assay cut-points were statistically established using sera from >1300 multiple sclerosis patients from natalizumab clinical studies. The assay was analytically validated and then used to determine the presence of JCV antibodies in both treatment-naïve and natalizumab-treated MS patients, as well as in natalizumab-treated PML patients. ResultsAn improved assay for detection of JCV antibodies in human serum and plasma was developed. Key enhancements included improved delineation and reproducibility of low JCV antibody responses and assay ease of use. The assay was validated, demonstrating good agreement with the original two-step JCV antibody ELISA, and similar seroprevalence of 50%–60%. Samples from 63 natalizumab-treated PML patients collected 6–180 months prior to PML diagnosis tested JCV antibody positive. One patient tested JCV antibody negative 15 months prior to PML diagnosis but JCV antibody positive 2 months prior to PML diagnosis. ConclusionsThe validated second-generation JCV antibody ELISA offers improved assay design as a kit and enhanced performance characteristics that advance routine clinical use of the assay as a PML risk stratification tool.

A case of natalizumab-associated progressive multifocal leukoencephalopathy with repeated negative CSF JCV testing

The development of progressive multifocal leukoencephalopathy (PML) in patients treated with natalizumab is a well-known potential risk. Diagnosis of PML can be confounded in patients with multiple sclerosis (MS) if new demyelinating lesions develop, and the sensitivity of existing diagnostic tests is less than ideal. In the case presented here, four samples of cerebrospinal fluid tested negative for John Cunningham virus (JCV) DNA by polymerase chain reaction, yet brain biopsy eventually proved positive by immunohistochemistry. A review of the limitations of existing clinical diagnostic tests is addressed, and we review the most recent literature on the proper management of natalizumab-treated MS patients.

Polyomavirus JC in the Context of Immunosuppression: A Series of Adaptive, DNA Replication-Driven Recombination Events in the Development of Progressive Multifocal Leukoencephalopathy

Polyomavirus JC (JCV) is the etiological agent of progressive multifocal leukoencephalopathy (PML), a demyelinating infection of oligodendrocytes in the brain. PML, a frequently fatal opportunistic infection in AIDS, has also emerged as a consequence of treatment with several new immunosuppressive therapeutic agents. Although nearly 80% of adults are seropositive, JCV attains an ability to infect glial cells in only a minority of people. Data suggest that JCV undergoes sequence alterations that accompany this ability, and these changes can be derived from an archetype strain by mutation, deletion, and duplication. While the introductory source and primary tissue reservoir of JCV remain unknown, lymphoid cells have been identified as potential intermediaries in progression of JCV to the brain. This review is focused on sequence changes in the noncoding control region (NCCR) of the virus. We propose an adaptive mechanism that involves a sequential series of DNA replication-driven NCCR recombination events involving stalled DNA replication forks at NCCR palindromic secondary structures. We shall describe how the NCCR sequence changes point to a model in which viral DNA replication drives NCCR recombination, allowing JCV adaptation to different cell types in its progression to neurovirulence.

JC Polyomavirus (JCV) and Monoclonal Antibodies: Friends or Potential Foes?

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system (CNS), observed in immunodeficient patients and caused by JC virus ((JCV), also called JC polyomavirus (JCPyV)). After the HIV pandemic and the introduction of immunomodulatory therapy, the PML incidence significantly increased. The correlation between the use of natalizumab, a drug used in multiple sclerosis (MS), and the PML development of particular relevance. The high incidence of PML in natalizumab-treated patients has highlighted the importance of two factors: the need of PML risk stratification among natalizumab-treated patients and the need of effective therapeutic options. In this review, we discuss these two needs under the light of the major viral models of PML etiopathogenesis.

Natalizumab Use in Patients With Crohnʼs Disease (CD) and Relapsing Multiple Sclerosis (MS): Updated Utilization and Safety Results

Natalizumab was approved by the FDA in 2008 for adult patients with moderately to severely active CD with evidence of inflammation who have had an inadequate response to, or are unable to tolerate, conventional CD therapies and inhibitors of TNF-α. The TYSABRI Outreach: Unified Commitment to Health (TOUCH®) Prescribing Program, Crohn's Disease: Investigating Natalizumab through Further Observational Research & Monitoring (CD INFORM), TYSABRI Global Observation Program In Safety (TYGRIS), and TYSABRI® Pregnancy Exposure Registry (TPER) are ongoing risk management activities designed to further evaluate the safety of natalizumab. This report summarizes recent data on natalizumab utilization and safety in patients with Crohn's disease (CD) and relapsing multiple sclerosis (MS). TOUCH® is a mandatory prescribing program for all patients, prescribers, pharmacies and infusion centers in the US using natalizumab. TOUCH® is designed to inform about the risk of progressive multifocal leukoencephalopathy (PML); warn against concurrent use with antineoplastic, immunosuppressant, or immunomodulating agents, and in patients who are immunocompromised; and promote early diagnosis of PML and timely discontinuation of natalizumab in the event of suspected PML. CD INFORM, a post-marketing commitment, collects patient history, efficacy as assessed by the Harvey Bradshaw Index (HBI), Health Related Quality of Life outcomes, and serious adverse events (SAE) in CD patients on natalizumab therapy. TYGRIS, also a post-marketing commitment, is evaluating the long-term safety of natalizumab in MS. Post-marketing surveillance data are also collected. TPER evaluates the outcomes of pregnancy in women with CD and MS exposed to natalizumab. As of 30 June 2012, ˜104,300 patients have been exposed to natalizumab in the post-marketing setting (103,259 MS; 1,041 CD),. As of 01 August 2012, 271 cases of PML have been confirmed (270 MS, 1 CD). Of the 271 natalizumabtreated patients who developed PML, 212 (78%) had survived, exhibiting varying levels of disability and there were 59 (22%) deaths. Presence of anti-JCV antibodies, prior treatment with immunosuppressants and longer treatment duration with natalizumab, especially beyond 2 years, are identified risk factors for potential development of PML. As of 07 August 2012, 163 patients were enrolled in CD INFORM with the number of natalizumab infusions ranging from 1-56, with a mean and median of 14.6 and 10, respectively. The average HBI at time of entry for these patients was 8.2 (range 0 to 28). Of the 99 CD patients with an HBI assessment after receiving 6 months of natalizumab therapy, the average total score was 4.8, a mean decrease of 2.8 points from baseline. Cumulatively, as of 07 August 2012, there were 93 SAEs occurring in 51 patients reported in CD INFORM, 4 patients experienced 8 SAEs that were considered treatment related. As of 23 May 2012, 375 women (7 with CD) were prospectively enrolled in the TPER with372 outcomes reported, including 8 twin pregnancies resulting in 2 outcomes for each pregnancy. Current exposure and safety data from patients receiving natalizumab in both indications will be presented. Cumulative data from both indications suggest a safety profile consistent with natalizumab product labeling.

Reactivation of JC Virus in 171 Allografted Patients: Incidence and Clinical Significance

AbstractAbstract 4148 Background:Recent studies demonstrated an increased incidence of JC virus (JCV)-related progressive multifocal leukoencephalopathy (PML) in immunocompromised patients. Expanding application of allogeneic stem cell transplantation (alloSCT) nowadays, reflecting growing availability of matched unrelated donors, is expected to increase the frequency of this complication. Therapeutic options in PML are extremely limited and patients eventually die. However, immune restoration, whenever possible, is claimed to be potentially effective. Aims:The current study was aimed to determine the incidence, clinical course and risk factors for JCV reactivation in patients undergoing alloSCT, and explore the possibility for preemptive detection of JCV reactivation prior to PML development. Methods:This retrospective study was approved by the Rambam IRB (approval # RMB 0097-12). All consecutive patients, treated with an alloSCT for various hematological malignancies at Rambam between January 2009 and December 2011 were included in the analysis. Frozen DNA samples, originally assessed for CMV-PCR, drawn monthly, starting at transplantation date up to the cessation of immunosuppression (as part of a pre-emptive CMV detection), were thawed and evaluated for JCV reactivation using a quantitative JCV-PCR analysis. In case of sample positivity, additional weekly drawn DNA samples were thawed and analyzed. JCV was detected by quantitative RT0-PCR of whole blood. The institutional electronic database was searched, focusing on hematological diagnosis, disease course prior to transplantation, transplant conditioning regimen, post-transplant complications, particularity graft- versus-host disease (GvHD), immunosuppressive therapy and neurological symptoms. Incidence and clinical significance of JCV reactivation were evaluated. Results:631 DNA samples, obtained from 171 consecutive allografted patients, were analyzed. Eighteen patients had a single positive blood test, 6 had repeated positive results (accounting for 100 positive samples), and 147 had consecutive negative tests. Patient characteristics are presented in Table 1. The maximal JCV load in patients anecdotally exhibiting JCV reactivation, was always lower than 500 copies/ml (130–485), whereas in all subjects demonstrating persistent reactivation (initially detected between day 0– 172 post-SCT), levels approached thousands to millions JCV- copies, though tended to correlate directly to steroid dosages applied. Five of the persistently reactivating subjects: 4 with lymphoproliferative disorders and 1 with AML, were heavily pre-treated, failing ≥ 4 prior therapies (3-had rituximab and 4- failed high dose therapy), and all were subjected to continuing immunosuppression due to GvHD. None of the “non-reactivating” and the “anecdotally reactivating” patients developed PML. Two of the 6 “persistently reactivating” subjects showed a gradual increase in JCV levels, preceding the development of clinically proven PML (confirmed by clinical features, typical MRI and JCV in CSF) within 62 and 84 days, respectively. Despite cessation of immunsuppresion, one of these 2 patients died of PML, whereas the other experienced complete durable resolution of neurological symptoms. The remaining 5 patients died within 0.75–3 months since JCV reactivation, due to other causes, in the presence of continuing positive tests for JCV. Conclusions:The findings of the current study suggest that JCV reactivation is relatively uncommon, occurring in 15% of SC allografted patients. Moreover, in most patients reactivation is anecdotal and not clinically significant. However, in some very heavily pretreated patients, persistent reactivation may evolve, eventually resulting in PML development. Cessation of immunosuppression, especially if performed at earlier stages of JCV reactivation/disease may reverse the PML fatal course.Table 1Persistently positive (n=6)Anecdotally Positive (n=18)JCV neg (n=147)46 (31-49)39 (22-63)44 (17-71)Age (yrs)85%67%58%Sex (male%)33%51%<span >75%DiagnosisAcute leukemiaMature Lymphoid66%49%25%66%56%45%Disease status at SCTComplete response2358740204Med time from diagnosis to SCT (days)50%/50%56%/44%64%/36%Donor typeSib/MUD100%61%61%GvHD Disclosures:No relevant conflicts of interest to declare.

Effects of Tat proteins and Tat mutants of different human immunodeficiency virus type 1 clades on glial JC virus early and late gene transcription

Polyomavirus JC (JCV) is the aetiological agent of progressive multifocal leukoencephalopathy (PML), a frequently fatal infection of the brain afflicting nearly 4% of AIDS patients in the USA. Human immunodeficiency virus type 1 (HIV-1) Tat, acting together with cellular proteins at the JCV non-coding control region (NCCR), can stimulate JCV DNA transcription and replication. Tat in the brain is secreted by HIV-1-infected cells and incorporated by oligodendroglia, cells capable of infection by JCV. Thus far the effects of Tat on JCV have been studied primarily with protein encoded by the HIV-1 B clade most common in North America. Here, we determine the abilities of Tat from different HIV-1 clades to alter JCV early and late gene transcription and DNA replication initiated at the JCV origin. Tat from all clades tested stimulates both JCV early and late gene promoters, with clade B Tat being significantly most effective. Tat proteins from the HIV-1 clades display parallel patterns of differences in their effects on HIV-1 and JCV transcription, suggesting that Tat effects in both cases are mediated by the same cellular proteins. Clade B Tat is most effective at directing Smad mediators of tumour growth factor beta and cellular partner Purα to the NCCR. Tat proteins from all non-B clades inhibit initiation of JCV DNA replication. The effectiveness of HIV-1 clade B Tat at promoting JCV transcriptional and replicative processes highlights a need for further investigation to determine which molecular aspects of Tat from distinct HIV-1 substrains can contribute to the course of PML development in neuroAIDS.

Changes in JC Virus-Specific T Cell Responses during Natalizumab Treatment and in Natalizumab-Associated Progressive Multifocal Leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) induced by JC virus (JCV) is a risk for natalizumab-treated multiple sclerosis (MS) patients. Here we characterize the JCV-specific T cell responses in healthy donors and natalizumab-treated MS patients to reveal functional differences that may account for the development of natalizumab-associated PML. CD4 and CD8 T cell responses specific for all JCV proteins were readily identified in MS patients and healthy volunteers. The magnitude and quality of responses to JCV and cytomegalovirus (CMV) did not change from baseline through several months of natalizumab therapy. However, the frequency of T cells producing IL-10 upon mitogenic stimulation transiently increased after the first dose. In addition, MS patients with natalizumab-associated PML were distinguished from all other subjects in that they either had no detectable JCV-specific T cell response or had JCV-specific CD4 T cell responses uniquely dominated by IL-10 production. Additionally, IL-10 levels were higher in the CSF of individuals with recently diagnosed PML. Thus, natalizumab-treated MS patients with PML have absent or aberrant JCV-specific T cell responses compared with non-PML patients, and changes in T cell-mediated control of JCV replication may be a risk factor for developing PML. Our data suggest further approaches to improved monitoring, treatment and prevention of PML in natalizumab-treated patients.

CLASSIFICATION OF JC VIRUS SEROSTATUS DEPENDS UPON ASSAY SELECTION: A COMPARISON OF BIOGEN AND HPA ASSAYS

IntroductionJC virus (JCV) seroposivity is a risk factor for the future development of progressive multifocal leukoencephalopathy in people with multiple sclerosis (MS) about to start natalizumab. In the UK, two...

The Long and Evolving Relationship between Viruses and Multiple Sclerosis

Multiple sclerosis (MS) is a demyelinating disorder of unknown etiology, possibly caused by a virus or is virus-triggered. Several viruses, including herpesviruses, were suggested as etiologic agents or risk factors for exacerbation in the course of illness but none have been shown to be irrefutably linked. Recently the interest of researchers and clinicians in the association between viruses and MS was reawakened by the development of progressive multifocal leukoencephalopathy, a demyelinating and fatal disease caused by JC polyomavirus replication, in natalizumab-treated MS patients. In this review, we will illustrate the evidence underlying the viral hypothesis for MS pathogenesis and will review the main features of the potential viral candidates. We will also describe the risks associated with newer MS therapies and with viral/bacterial vaccinations.

Treatment-related progressive multifocal leukoencephalopathy: current understanding and future steps.

Progressive multifocal leukoencephalopathy (PML) is a rare demyelinating disorder of the brain caused by a ubiquitous polyomavirus, JC virus. PML is almost always associated with some underlying immunosuppression and acquired immune deficiency syndrome has been the most common predisposing disorder. Recently, different pharmacological agents have been demonstrated to increase the risk of PML. Therapies that predispose people to PML can be classified into three categories: therapies that uniquely increase the risk for the disorder, such as the monoclonal antibodies natalizumab and efalizumab; therapies that appear to increase the risk in individuals already at risk of PML due to pre-existing conditions, such as rituximab and mycophenolate mofetil; and therapies with a mechanism of action that might suggest a potential for increased PML risk and/or with which rare cases of PML have been observed. Unlike the latter two classes, therapeutic agents uniquely increasing the risk of PML are associated with a much greater prevalence of the disorder and a latent interval from the time of drug initiation to the development of PML. PML development with pharmacological agents has provided new insight into the pathogenesis of this devastating disorder. This review focuses on the risks of PML with multiple pharmacological agents, the proposed pathogenesis with these agents, and potential risk mitigation strategies.

Update on PML and PML-IRIS Occurring in Multiple Sclerosis Patients Treated With Natalizumab

The use of natalizumab to treat multiple sclerosis (MS) has been associated with the development of progressive multifocal leukoencephalopathy (PML), with 242 PML cases reported as of May 3, 2012. Fortunately, rapid withdrawal of the drug and administration of plasma exchange has allowed survival in many of these patients, but a new problem, immune reconstitution inflammatory syndrome (IRIS), has emerged after drug withdrawal. This report provides an update on PML in natalizumab-treated patients and reviews what is currently known about PML-IRIS in this setting; autopsy findings from a well-studied patient are illustrated. This patient with relapsing-remitting MS had been treated for 4 years with natalizumab, with discontinuation of drug after diagnosis of PML by cerebrospinal fluid polymerase chain reaction testing. Disease was manifested by severe paraparesis and expressive aphasia, which progressed before and after the diagnosis of PML. Immune reconstitution inflammatory syndrome was diagnosed, comfort care was instituted, but demise did not occur until 9 months later. Autopsy showed ongoing severe PML-IRIS, with massive cavitary brain lesions containing abundant perivascular and parenchymal CD8-positive T-cell infiltrates. Bone marrow and spleen, but not brain, contained monoclonal T-cell populations by polymerase chain reaction-based gene rearrangement studies, indicating overstimulation of peripheral T cells; T-cell lymphoma was not identified by morphological or immunohistochemical criteria.

Progressive Multifocal Leukoencephalopathy in a Patient with Polymyositis: Case Report and Literature Review

To the Editor: We describe a fatal case of progressive multifocal leukoencephalopathy (PML) in a patient with polymyositis (PM) and antisynthetase syndrome treated with conventional immunosuppressive drugs. PML is a rare and fatal demyelinating disease caused by the ubiquitous John Cunningham virus (JCV)1,2. JCV infection is usually an asymptomatic event in childhood and about 60%–80% of the normal adult population are seropositive for antibodies against JCV3,4. After primary infection, the virus remains in a latent form in the bone marrow, lymphoid organs, and kidney and some studies have demonstrated that it also can establish latency in healthy brain tissue although this is a matter of debate5,6. The virus may later reactivate, undergoing genomic rearrangement in the non-coding regulatory region, and migrate to the brain, where it infects glial cells and causes a lytic infection known as PML7,8. Reactivation usually occurs during conditions of immunosuppression but there are also reports of PML development in immunocompetent individuals9. The mechanisms behind the pathway leading to viral reactivation remain insufficiently defined. The risk of PML in autoimmune diseases has recently been highlighted because of an increasing number of PML cases occurring during treatment with new biological immunosuppressive agents including natalizumab (for multiple sclerosis, MS), rituximab (RTX; for rheumatic diseases), and efalizumab (for psoriasis) and also with the newer immunosuppressant agent mycophenolate mofetil (MMF)10. In the more rare autoimmune diseases polymyositis/dermatomyositis (PM/DM) there are a few reports of PML developing in patients treated with conventional disease-modifying antirheumatic drugs9,11,12,13,14,15,16, but also in patients during off-label treatment with RTX17. The increased risk for PML associated with the new biologics has raised … Address correspondence to Dr. E. Iacobaeus; E-mail: ellen.iacobaeus{at}karolinska.se

Urinary JCV-DNA Testing during Natalizumab Treatment May Increase Accuracy of PML Risk Stratification

The risk of progressive multifocal leukoencephalopathy (PML) in patients treated with natalizumab for multiple sclerosis (MS) is a serious concern. The presence of anti-JC virus antibodies is a risk factor for PML development, but 2.5 % of the patients result falsely-negative, while the prognostic relevance of testing JCV-DNA in biological fluids of treated patients is debated. Aim of this work was to evaluate the utility of testing JCV-DNA, together with anti-JCV antibodies, in biological samples of treated patients as a tool for PML risk stratification. 126 subjects from 5 MS Centers in Italy were included in the study. We performed a cross-sectional study in 63 patients testing JCV-DNA in blood, peripheral blood cells and urine. We longitudinally assessed the presence of JCV-DNA in a cohort of 33 subjects, one of which developed PML. We could test retrospectively serum samples from another PML case occurred during natalizumab therapy. Anti-JCV antibodies and urinary JCV-DNA were both tested in 73 patients. No changes in JCV-DNA status occurred during natalizumab treatment. The subject who developed PML in the longitudinal cohort had detectable JCV-DNA in urine at all time-points while serum or blood from both PML patients were always negative before the onset of disease and, in one case, after. Four subjects with JCV-DNA in urine and undetectable anti-JCV antibodies were retested for anti-JCV antibodies and three out of four resulted positive. In conclusion, testing JCV-DNA in urine is complementary to testing anti-JCV antibodies in identifying patients at risk of PML.

Anti-JCV Antibody Prevalence in Patients with Relapsing Multiple Sclerosis Receiving or Considering Treatment with Natalizumab: Baseline Results of STRATIFY-2 (S41.002)

Objective: Determine the prevalence of anti-JC (JCV) antibodies in patients with relapsing multiple sclerosis (MS) using a 2-step anti-JCV antibody assay. Background JCV infection is a prerequisite for development of progressive multifocal leukoencephalopathy (PML). Assessing anti-JCV antibody status represents a means to determine JCV exposure and stratify PML risk in MS patients. Design/Methods: STRATIFY-2 is an ongoing, longitudinal, observational US study that is currently enrolling relapsing MS patients being treated or considering treatment with natalizumab. Serum is collected at baseline and annually thereafter for 2 years and tested for anti-JCV antibodies using a 2-step anti-JCV antibody assay. This interim analysis represents baseline data collected as of May 13, 2011. Results: At baseline (n=19,537), overall anti-JCV antibody prevalence was 54.7% (95% confidence interval [CI]: 54.0%–55.4%). Prevalence was lower in females (52.5% [95% CI: 51.7%–53.3%]) than in males (60.8% [95% CI: 59.4%−62.1%]) and increased with age ( Conclusions: STRATIFY-2 represents the largest data set to date to analyze anti-JCV antibody prevalence. Baseline results are consistent with other, smaller studies using this assay, which report anti-JCV antibody prevalence of 50%–60%. While anti-JCV antibody status was influenced by age and gender, natalizumab exposure use did not affect serostatus. Final study results will be used to assess PML incidence in anti-JCV antibody positive and negative MS patients. Supported by: Biogen Idec Inc. and Elan Pharmaceuticals, Inc. Disclosure: Dr. Bozic has received personal compensation for activities with Biogen Idec. Dr. Bozic holds stock and/or stock options in Biogen Idec, which sponsored research in which Dr. Bozic was involved as an investigator. Dr. Bozic holds stock and/or stock options in Biogen Idec. Dr. Richman has received personal compensation for activities with Biogen Idec as employees.Dr. Richman holds stock and/or options in Biogen Idec, which sponsored research in which Dr. Richman was involved as an investigator. Dr. Plavina has received personal compensation for activities with Biogen Idec as an employee.Dr. Plavina holds stock and/or stock options in Biogen Idec which sponsored research in which Dr. Plavina was involved as an investigator. Dr. Natarajan has received personal compensation for activities with Biogen Idec as an employee. Dr. Scanlon has received personal compensation for activities with Biogen Idec as an employee. Dr. Subramanyam has received personal compensation for activities with Biogen Idec as an employee. Dr. Subramanyam holds stock and/or stock options in Biogen Idec. Dr. Sandrock has received personal compensation for activities with Biogen Idec as an employee. Dr. Sandrock holds stock and/or stock options in Biogen Idec. Dr. Bloomgren has received personal compensation for activities with Biogen Idec as an employee.

Subtle Lesion Appearance on MRI May Precede Development of Progressive Multifocal Leukoencephalopathy in Multiple Sclerosis Patients Treated with Natalizumab (P07.059)

Objective: To report MRI features of 3 cases with confirmed progressive multifocal leukoencephalopathy (PML) in multiple sclerosis (MS) patients treated with natalizumab that presented with subtle new lesions on MRI several months prior to diagnosis. Background Clinical vigilance and early recognition of specific MRI changes are considered caveats for early diagnoses of PML in natalizumab treated patients. Design/Methods: Retrospective clinical and MRI evaluation of 3 patients with confirmed PML (by detection of JC virus in cerebrospinal fluid), who had several serial scans prior to the PML diagnosis. Results: Case 1: 41 year old man who received 29 monthly natalizumab infusions. A small new T2 hyperintense/T1 enhancing lesion in the subcortical white matter of the left frontal lobe was detected. No clinical symptoms were associated and he tested negative for prior JC virus exposure 6 months previous. Seven months later, a large T2 hyperintense/T1 enhancing lesion, indicative of PML was detected in the same location. He tested positive for JC virus exposure on repeat analysis, one month prior to diagnosis. Case 2: 47 year old woman on natalizumab for 31 months complained of new onset double vision. A small T2 hyperintense, T1 non-enhancing lesion was detected in pons. Two months later, a large T2 hyperintense lesion consistent with PML was detected in the same location, in addition to multiple other lesions. Case 3: 54 year old woman on natalizumab for 61 months presented with mild vertigo. A small new T2 hyperintense lesion in pons was seen retrospectively. Four months later a large T2 hyperintense lesion consistent with PML was detected in the same location, in addition to multiple other lesions. Conclusions: The appearance of subtle new T2 hyperintense lesions may suggest PML in patients treated with natalizumab for more than two years. Disclosure: Dr. Hojnacki has received personal compensation for activities with Biogen Idec, Serono, Inc., Pfizer Inc, and Teva Neuroscience as a speaker and/or participant on scientific advisory boards. Dr. Zivadinov has received personal compensation for activities with Teva Neuroscience, Biogen Idec, EMD Serono, and Questcor Pharmaceuticals as a speaker and/or consultant. Dr. Zivadinov has received research support from Biogen Idec, Teva Neuroscience, Genzyme Corporation, Bracco, Questcor Pharmaceuticals and EMD Serono. Dr. Weinstock-Guttman has received personal compensation for activities with Acorda Therapeutics, Biogen Idec, Serono, Inc., Novartis, Pfizer Inc, Teva Neuroscience as a speaker and/or participant on an advisory board. Dr. Weinstock-Guttman has received research support from Acorda Therapeutics, Biogen Idec, Serono Inc., Novartis, Pfizer Inc, Teva Neuroscience, National Multiple Sclerosis Society, the National Institutes of Health, ITN, Teva Neuroscience, Aspreva-Roche, Acorda Therapeutics and Shire Pharmaceuticals.

Antibody to α4 integrin suppresses natural killer cells infiltration in central nervous system in experimental autoimmune encephalomyelitis

Natalizumab inhibits the influx of leukocytes into the central nervous system (CNS) via blockade of alpha-4 subunit of very late activation antigen (VLA)-4. The association of natalizumab therapy with progressive multifocal leukoencephalopathy (PML) suggests a disturbance of CNS immune surveillance in a small percentage of Multiple Sclerosis (MS) patients exposed to the medication. Natural killer (NK) cells are known to play an important role in modulating the evolution of different phases of this lymphocyte mediated disease, and we investigated the effects of natalizumab on the NK cell phenotype and infiltration in the CNS in experimental autoimmune encephalomyelitis (EAE), a murine model of MS. Our data show that both resting (from naïve mice) and activated (from EAE mice) NK cells express high levels of VLA-4, and anti-VLA-4 antibody treatment significantly decreases NK cells frequency in the CNS of EAE mice. Moreover, we find that anti-VLA-4 possibly impairs NK cells migratory potential, since unblocked VLA-4 expression levels were downregulated on those NK cells that penetrate the CNS. These data suggest that treatment with antibody to VLA-4 may alter immune surveillance of the CNS by impacting NK cell functions and might contribute to the understanding of the mechanisms leading to the development of PML in some MS patients.

Progressive Multifocal Leukoencephalopathy in a Patient Treated With Etanercept

Recently, increased attention has been paid to the association of progressive multifocal leukoencephalopathy (PML) with the use of immunomodulatory medications for autoimmune diseases. A 23-year-old Native American woman with a history of systemic lupus erythematosus and erosive polyarthritis treated with prednisone and etanercept presented with focal weakness, hemiataxia, diplopia, and dysarthria. Brain magnetic resonance imaging demonstrated progressive, T2 signal hyperintensities within the brainstem and cerebellar white matter without mass effect or gadolinium enhancement. Cerebrospinal fluid showed elevated protein and JC virus polymerase chain reaction positive with 28,600 copies/ml diagnostic of PML. The development of PML in this patient treated with etanercept and prednisone highlights the increased risk for opportunistic infection with JC virus in patients with autoimmune diseases on immunosuppressive therapies.

Risk stratification for progressive multifocal leukoencephalopathy in patients treated with natalizumab

Natalizumab is a highly effective immunomodulator in the treatment of multiple sclerosis (MS). Treatment with natalizumab has been associated with progressive multifocal leukoencephalopathy (PML), an infection of the central nervous system (CNS) caused by a pathogenic form of the normally benign JC virus (JCV). We searched PubMed and used current data from the natalizumab global safety database to assess risk factors and quantify the risk of PML. Natalizumab treatment duration and prior use of immunosuppressive therapies are established risk factors for development of PML in natalizumab-treated patients. With the development of a reliable and validated assay for detection of antibodies in patients with MS directed against JCV, it is now possible to identify persons who are carriers of JCV. The availability of this assay provides an additional option for risk stratification of PML in patients using or considering natalizumab therapy. Recommendations for clinical management of patients with MS and use of natalizumab are provided based on the presence of these three risk factors. The identification of risk factors that increase the likelihood of PML in natalizumab-treated patients can facilitate benefit–risk discussions between health care professionals and patients. Continued research and data collection will further develop our understanding of PML and the mechanisms by which these risk factors contribute to its development.

Risk stratification and patient counseling for natalizumab in multiple sclerosis

Natalizumab has demonstrated efficacy in multiple sclerosis (MS), but is associated with increased risk of progressive multifocal leukoencephalopathy (PML), a potentially fatal brain infection caused by the JC virus. At the time of natalizumab's reapproval in 2006, the estimated risk of PML was 1:1,000 (95% confidence interval 0.2–2.80) over 17.9 months of treatment.1 Since then, 3 risk factors for natalizumab-related PML have emerged2: 1) cumulative exposure to natalizumab, with risk increasing up to 3 years, after which risk appears to plateau; 2) previous treatment with cytotoxic or immunosuppressive (IS) drugs3; and 3) prior history of JCV infection, as indicated by the presence of JCV antibodies. Using a 2-step ELISA assay for anti-JCV antibodies, Gorelik et al.4 reported a 53.6% incidence of anti-JCV antibodies in patients with MS; the false-negative rate was 2.5%. To date, 28 natalizumab-related PML cases had blood specimens available 1 year or more prior to the development of PML. Using this assay, all 28 patients were seropositive, which is highly statistically significant ( p = 3.21 × 10−8).5 This assay is now clinically available in the United States …