Stability and predictive value of anti-JCV antibody index in multiple sclerosis: A 6-year longitudinal study

Anti-JCV antibody index seroconversion in Turkish multiple sclerosis patients treated with natalizumab

BACKGROUND

The anti-JCV antibody index is widely used to monitor multiple sclerosis (MS) patients receiving natalizumab, as seroconversion is linked to an increased risk of progressive multifocal leukoencephalopathy. This study aimed to evaluate the prevalence and risk factors of anti-JCV antibody seroconversion in patients treated with natalizumab.

METHODS

We included MS patients exposed to natalizumab treatment for at least one year, with a negative anti-JCV antibody index at baseline, and a minimum of two anti-JCV antibody assessments more than six months apart. We employed Kaplan-Meier survival analysis to assess the median time to seroconversion and the annual seroconversion rate, and univariate and multivariate Cox regression models to evaluate the covariates.

RESULTS

Among 96 patients followed for a median of 99 months, 29 (30.2%) patients had seroconversion. The median time to seroconversion was 8.3 years, with an annual rate of 6.1%. Seroconversion rates were higher in smokers (p = 0.02) and patients with a body mass index (BMI) over 25 kg/m2 (p = 0.006). Patients who started natalizumab at age 35 or older had a shorter median time to seroconversion (p = 0.003), and most seroconversions occurred within the first three years. No significant associations were found with gender, prior immunosuppressive treatment, MS subtype, or MS age of onset.

CONCLUSION

Anti-JCV seroconversion is more likely in patients who smoke, have a higher BMI, start natalizumab therapy after age 35, and within the first three years of treatment. For these high-risk patients, vigilant monitoring of anti-JCV antibodies is required.

The impact of social distancing measures on anti-JC virus serostatus changes before and during the COVID-19 pandemic in US patients with multiple sclerosis

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic offered an epidemiological opportunity to evaluate if isolation and masking affected John Cunningham (JC) virus transmission.

OBJECTIVE

This study aimed to assess the proportion of natalizumab-treated patients who converted to a positive anti-JCV antibody serostatus before and during the pandemic.

METHODS

Data from TYSABRI Outreach: Unified Commitment to Health (TOUCH) for 22,375 US patients treated with natalizumab with anti-JCV antibody records were assessed in epochs annually from 2017 to 2022.

RESULTS

Pre-pandemic anti-JCV antibody serostatus change was observed for 7.4%-7.7%. During the first and second years of the pandemic, 7.3% and 7.2% of patients' serostatus changed, respectively.

CONCLUSION

The proportion of patients with anti-JCV antibody serostatus change did not significantly differ during the first 2 years of the pandemic compared with prior years. In contrast to seasonal influenza, masking and social distancing had no discernable effect on JCV serostatus change.

Longitudinal stability of JCV antibody index in Natalizumab treated people with multiple sclerosis

OBJECTIVE

The aim of this study was to evaluate the evolution of JCV index over time in Natalizumab treated people with multiple sclerosis.

MATERIALS AND METHODS

We retrospectively reviewed antibody index values from pwMS who were treated with Natalizumab for greater than six months and had at least two antibody results available between 2011 and 2019. Survival analysis was performed on those who were JCV index value negative at baseline to evaluate time to seroconversion. In pwMS who had index values available at 48 and/or 96 months post Natalizumab initiation, t-tests were performed to evaluate change in index over time.

RESULTS

1144 JCV antibody index results were available for 132 pwMS. Median time to seroconversion based on survival analysis was 103 months. Annualised seroconversion rate was 5.8%. Initial antibody index and rate of seroconversion did not differ with regards to age or gender. Antibody index increased significantly over time on treatment for the cohort as a whole, initial antibody index (0.27) to final antibody testing (0.86), t(131)=6.45, p<.0005. There was a significant increase in those with initial positive index value, between first (0.95) and final index (2.14), t(33) = 4.85, p<.0005 over a median of 77 months.

CONCLUSIONS

In those who were seronegative at baseline there is a long median duration of treatment with Natalizumab prior to seroconversion. In individuals with positive JCV antibody index at treatment initiation, antibody index increases over time.

Immune cell subset profiling in multiple sclerosis after fingolimod initiation and continued treatment: The FLUENT study

Background

Fingolimod is a sphingosine 1-phosphate receptor modulator approved for relapsing MS. Long-term effects on the immunological profile are not fully understood.

Objective

Investigate fingolimod's temporal effects on immune cell subsets, and safety outcomes.

Methods

In FLUENT, a 12-month, prospective, non-randomized, open-label, phase IV study, adult participants received fingolimod 0.5 mg/day. Changes in immune cell subsets, anti-John Cunningham virus (JCV) antibody index, and serum neurofilament levels were assessed.

Results

165 fingolimod-naive and 217 participants treated for 2–12 years in routine clinical practice were enrolled. Levels of all monitored peripheral lymphocyte subsets were reduced from month 3 in fingolimod-naive participants. Greatest reductions occurred in naive and central memory CD4+ and CD8+ T cells, and in naive and memory B cells. Most lymphocyte subset levels remained stable in the continuous fingolimod group. Components of the innate immune system remained within reference ranges. No increase in JCV seropositivity was observed. No single cellular subset correlated with anti-JCV antibody index at any time point. Neurofilament levels remained within healthy adult reference limits throughout. No opportunistic infections were reported; no new or unexpected safety signals were observed.

Conclusion

FLUENT provides insights into the utility of immunological profiling to evaluate therapy response and potential infection risk.

JC Virus Seroprevalence and JCVAb Index in Polish Multiple Sclerosis Patients Treated with Immunomodulating or Immunosuppressive Therapies

The use of a highly-effective treatment for multiple sclerosis (MS) is associated with a severe risk of developing complications, such as progressive multifocal leukoencephalopathy (PML) caused by the John Cunningham virus (JCV). The aim of this study was to evaluate the correlation between anti-JCV Ab seroprevalence, anti-JCV AI, demographic and clinical factors as well as the type of therapy used in the Polish MS population. This is a multicentre, prospective and cross-sectional study involving 1405 MS patients. The seroprevalence of anti-JCV Ab and anti-JCV AI levels as well as AI categories were analysed with the use of a second-generation two-step ELISA test (STRATIFY JCV DxSelect). The overall prevalence of anti-JCV Ab was 65.8%. It was shown that seroprevalence increases with the patient's age. The seroprevalence was significantly associated with the treatment type, and the highest values (76%) were obtained from immunosuppressant-treated patients. Overall, 63.3% of seropositive patients had an antibody index (AI) level of >1.5. In the seropositive patient group, the mean AI level amounted to 2.09. Similarly to the seroprevalence, AI levels correlated with the patient's age; AI level for patients above 40 years old and from subsequent age quintiles plateaued, amounting to at least 1.55. Patients treated with immunosuppressants and immunomodulatory drugs obtained the highest (1.67) and lowest (1.35) AI levels, respectively. Of the immunosuppressants used, the highest mean AI levels were observed in mitoxantrone and cladribine groups, amounting to 1.75 and 1.69, respectively. In patients treated with immunomodulatory drugs, the lowest AI levels were observed in the dimethyl fumarate (DMF) group (1.11). The seroprevalence rate in the Polish MS population is one of the highest in Europe. The majority of seropositive patients had an anti-JCV Ab level qualifying them for a high-risk category. The highest mean AI levels are observed in patients receiving immunosuppressants, especially mitoxantrone and cladribine. Patients receiving immunomodulatory drugs have lower AI levels compared to treatment-naïve subjects, especially when treated with DMF. Further studies, especially longitudinal studies, are required to determine the impact of MS drugs on the seroprevalence of anti-JCV Ab and AI levels.

High rates of JCV seroconversion in a large international cohort of natalizumab-treated patients

Aims:

To retrospectively assess factors associated with John Cunningham virus (JCV) seroconversion in natalizumab-treated patients.

Background:

Natalizumab is highly effective for the treatment of relapsing–remitting multiple sclerosis (RRMS), but its use is complicated by opportunistic JCV infection. This virus can result in progressive multifocal leukoencephalopathy (PML). Serial assessment of JCV serostatus is mandated during natalizumab treatment.

Methods:

Patients treated with natalizumab for RRMS at six tertiary hospitals in Melbourne, Australia (n = 865) and 11 MS treatment centres in Brazil (n = 136) were assessed for change in JCV serostatus, duration of exposure to natalizumab and prior immunosuppression. Sensitivity analyses examined whether sex, age, tertiary centre, prior immunosuppression or number of JCV tests affected time to seroconversion.

Results:

From a cohort of 1001 natalizumab-treated patients, durable positive seroconversion was observed in 83 of 345 initially JCV negative patients (24.1%; 7.3% per year). Conversely, 16 of 165 initially JCV positive patients experienced durable negative seroconversion (9.7%; 3.8% per year). Forty patients (3.9%) had fluctuating serostatus. Time-to-event analysis did not identify a relationship between JCV seroconversion and duration of natalizumab exposure. Prior exposure to immunosuppression was not associated with an increased hazard of positive JCV seroconversion. Male sex was associated with increased JCV seroconversion risk [adjusted hazard ratio 2.09 (95% confidence interval 1.17–3.71) p = 0.012].

Conclusion:

In this large international cohort of natalizumab-treated patients we observed an annual durable positive seroconversion rate of 7.3%. This rate exceeds that noted in registration and post-marketing studies for natalizumab. This rate also greatly exceeds that predicted by epidemiological studies of JCV seroconversion in healthy populations. Taken together, our findings support emerging evidence that natalizumab causes off-target immune changes that may be trophic for JCV seroconversion. In addition, male sex may be associated with increased positive JCV seroconversion.

JC Virus Seroprevalence and JCVAb Index in Polish Multiple Sclerosis Treatment-Naïve Patients

Multiple sclerosis (MS) treatment with new agents is associated with the risk of the development of progressive multifocal leukoencephalopathy (PML). The seropositivity and a high index of anti-John Cunningham virus (JCV) antibodies are some of the risk factors for PML development. The aim of this study was to assess the seroprevalence of anti-JCVAb and JCVAb index (AI), as well as its correlations with demographic and clinical characteristics in treatment-naïve Polish MS patients. This is a multicenter, prospective, and cross-sectional study involving 665 MS patients. The overall prevalence of anti-JCVAb was 65.3%, while 63.1% of seropositive patients had an index level of >1.5. The seroprevalence was shown to increase along with the patient's age. Except for age, the prevalence of anti-JCVAb was not associated with demographic or clinical data. No correlations between the index levels and the demographic or clinical data were observed. In Poland, the seroprevalence of anti-JCVAb in treatment-naïve MS patients is one of the highest in Europe. The majority of seropositive patients had an anti-JCV antibody level denoting a high-risk category. This means that we need further studies to be conducted on the individualization of MS treatment in order to provide patients with an appropriate therapeutic safety level.

The impact of lymphocytosis and CD4/CD8 ratio on the anti-JCV antibody index and clinical data in patients treated with natalizumab

BACKGROUND

Natalizumab is an effective therapy in the treatment of relapsing-remitting multiple sclerosis; it induces lymphocytosis (NIL, natalizumab-induced lymphocytosis) and changes the peripheral lymphocyte pattern.

METHODS

This study aims to evaluate NIL, peripheral blood lymphocyte subsets, CD4/CD8 ratio, and their impacts on JCV index and clinical data-No Evidence of Disease Activity (NEDA-3) and annualized relapse rate (ARR) in patients treated with natalizumab.

RESULTS

Forty-one patients (33 women) were included in the study. The mean duration of follow-up on natalizumab treatment was 6.7 ± 3.2 years. Significant increases in relative lymphocytosis after 1 month, with a median of 40.4% (- 34.1 to + 145.5%) (p < 0.001), and after 1 year (49.0% (- 9.3 to + 127.6%)) (p < 0.001) were found. Significant differences were found after 1 month when comparing NIL between patients JCV-seroconverting (20.6% (- 17.7 to 72.7%)) and stable JCV-seronegative ones (43.5% (- 6.3 to +96.3%)) (p = 0.04). No significant difference NIL level was found between the patients exhibiting NEDA-3 status and those without it. ARR on natalizumab treatment correlated with CD4/CD8 ratio (r = 0.356; p = 0.021); patients who maintained NEDA-3 status over the whole treatment period exhibited a lower CD4/CD8 ratio (1.89 ± 1.08 vs. 2.5 ± 0.73; p < 0.04).

CONCLUSION

This contribution reports the CD4/CD8 ratio as a possible biomarker for better clinical efficacy of natalizumab in patients exhibiting a lower CD4/CD8 ratio. NIL did not correlate with long-term therapeutic efficacy in patients treated with natalizumab, but was demonstrated as lower in patients JCV-seroconverting in the course of follow-up.

Prevalence of Anti-JC Virus Antibody Seropositivity in Patients with Multiple Sclerosis: A Systematic Review and Meta-Analysis

BACKGROUND

The John Cunningham virus (JCV) is the causative agent of progressive multifocal leukoencephalopathy. Anti-JCV antibody seropositivity is an important consideration in patients with multiple sclerosis (MS). The reported prevalence of JCV in MS patients has been conflicting.

OBJECTIVE

We aimed to conduct a systematic review and meta-analysis to estimate the pooled prevalence of anti-JCV antibody seropositivity in cases with MS.

METHODS

We searched PubMed, Scopus, EMBASE, CINAHL, Web of Science, Ovid, ProQuest, Google Scholar, and gray literature including reference of included studies, and conference abstracts which were published up to April 2019. Two independent researchers independently assessed the articles.

RESULTS

The literature search found 181 articles. After eliminating duplicates, reviews, case reports, and trials, 15 articles remained. Finally, 8 articles were included for the final analysis (from Asia, Europe, the USA, and Canada). In total, 16,041 MS cases were analyzed. The prevalence of anti-JCV antibody seropositivity varied between 40 and 80%, and the pooled estimate was calculated as 60% (95% CI: 56-64%), though with significant heterogeneity (I2 = 95%, p = 0.01).

CONCLUSION

The prevalence of anti-JCV antibody seropositivity is variable among MS patients in different countries, and the pooled estimate showed that this is 60% overall.

Conversion and reversion of anti-John Cunningham virus antibody serostatus: A prospective study

INTRODUCTION

Determination of antibodies against the John Cunningham virus (JCV) is an important tool for risk stratification in Natalizumab-treated multiple sclerosis (MS) patients. Six-monthly testing has been suggested for anti-JCV antibody negative patients and patients with low antibody index in order to detect changes of serostatus. We conducted a prospective study with predefined testing intervals in order to investigate the predictability of anti-JCV antibody status and the intervals for repetitive testing.

METHODS

Our study included 109 patients at the MS Clinic of the Departments of Neurology, Medical Universities of Innsbruck and Salzburg. Blood withdrawals were performed at five time points: baseline, month 1, 3, 6, and 12. Patients' sera were sent to Unilabs, Copenhagen, Denmark, where anti-JCV antibodies were tested by a two-step enzyme-linked immunosorbent assay. Qualitative (negative/positive) and quantitative results (anti-JCV antibody index) were used for statistical analyses.

RESULTS

In our cohort, 52.3% of the patients were positive for anti-JCV antibodies at baseline, with a significant correlation with age, but no association with sex or prior disease-modifying therapy. Seven patients converted and reverted from negative to positive status and vice versa around the cut-off index of 0.4, but no patient showed a permanent seroconversion from negative to highly positive anti-JCV antibody status.

CONCLUSION

Long-term anti-JCV antibody status, including seroconverters/-reverters around the cut-off index, is highly predictable by testing three times within short intervals, however, we cannot suggest clearly defined intervals for repetitive testing. The rate of real seroconverters, i.e., new infections with JCV, per year seems lower than previously described.

Serological profile of John Cunningham virus (JCV) in patients with multiple sclerosis

Treatment options for multiple sclerosis (MS) have changed over the last few years, bringing about a new category of drugs with more efficient profiles. However, these drugs have come with a whole new profile of potential adverse events that neurologists have to learn well and quickly. One of the most feared complications of these MS treatments is progressive multifocal leukoencephalopathy caused by the reactivation of the John Cunningham virus (JCV).

OBJECTIVE

To identify the serologic profile of JCV in patients with MS.

METHODS

Data on serum antibodies for JCV were obtained using the enzyme-linked immunosorbent assay provided by the STRATIFY-JCV program.

RESULTS

A total of 1,501 blood tests were obtained from 1,102 patients with MS. There were 633 patients (57.1%) who were positive for antibodies for JCV and 469 patients who were negative (42.9%). Twenty-three patients became positive after initially having negative JCV antibody status. The rate of seroconversion was 18.5% over 22 months.

CONCLUSION

The JCV serologic profile and seroconversion in Brazilian patients were similar to those described in other countries.

Post-natalizumab disease reactivation in multiple sclerosis: systematic review and meta-analysis

Background

Natalizumab (NTZ) is sometimes discontinued in patients with multiple sclerosis, mainly due to concerns about the risk of progressive multifocal leukoencephalopathy. However, NTZ interruption may result in recrudescence of disease activity.

Objective

The objective of this study was to summarize the available evidence about NTZ discontinuation and to identify which patients will experience post-NTZ disease reactivation through meta-analysis of existing literature data.

Methods

PubMed was searched for articles reporting the effects of NTZ withdrawal in adult patients (⩾18 years) with relapsing-remitting multiple sclerosis (RRMS). Definition of disease activity following NTZ discontinuation, proportion of patients who experienced post-NTZ disease reactivation, and timing to NTZ discontinuation to disease reactivation were systematically reviewed. A generic inverse variance with random effect was used to calculate the weighted effect of patients' clinical characteristics on the risk of post-NTZ disease reactivation, defined as the occurrence of at least one relapse.

Results

The original search identified 205 publications. Thirty-five articles were included in the systematic review. We found a high level of heterogeneity across studies in terms of sample size (10 to 1866 patients), baseline patient characteristics, follow up (1-24 months), outcome measures (clinical and/or radiological), and definition of post-NTZ disease reactivation or rebound. Clinical relapses were observed in 9-80% of patients and peaked at 4-7 months, whereas radiological disease activity was observed in 7-87% of patients starting at 6 weeks following NTZ discontinuation. The meta-analysis of six articles, yielding a total of 1183 patients, revealed that younger age, higher number of relapses and gadolinium-enhanced lesions before treatment start, and fewer NTZ infusions were associated with increased risk for post-NTZ disease reactivation (p ⩽ 0.05).

Conclusions

Results from the present review and meta-analysis can help to profile patients who are at greater risk of post-NTZ disease reactivation. However, potential reporting bias and variability in selected studies should be taken into account when interpreting our data.

Post-natalizumab disease reactivation in multiple sclerosis: systematic review and meta-analysis

Background:

Natalizumab (NTZ) is sometimes discontinued in patients with multiple sclerosis, mainly due to concerns about the risk of progressive multifocal leukoencephalopathy. However, NTZ interruption may result in recrudescence of disease activity.

Objective:

The objective of this study was to summarize the available evidence about NTZ discontinuation and to identify which patients will experience post-NTZ disease reactivation through meta-analysis of existing literature data.

Methods:

PubMed was searched for articles reporting the effects of NTZ withdrawal in adult patients (⩾18 years) with relapsing–remitting multiple sclerosis (RRMS). Definition of disease activity following NTZ discontinuation, proportion of patients who experienced post-NTZ disease reactivation, and timing to NTZ discontinuation to disease reactivation were systematically reviewed. A generic inverse variance with random effect was used to calculate the weighted effect of patients’ clinical characteristics on the risk of post-NTZ disease reactivation, defined as the occurrence of at least one relapse.

Results:

The original search identified 205 publications. Thirty-five articles were included in the systematic review. We found a high level of heterogeneity across studies in terms of sample size (10 to 1866 patients), baseline patient characteristics, follow up (1–24 months), outcome measures (clinical and/or radiological), and definition of post-NTZ disease reactivation or rebound. Clinical relapses were observed in 9–80% of patients and peaked at 4–7 months, whereas radiological disease activity was observed in 7–87% of patients starting at 6 weeks following NTZ discontinuation. The meta-analysis of six articles, yielding a total of 1183 patients, revealed that younger age, higher number of relapses and gadolinium-enhanced lesions before treatment start, and fewer NTZ infusions were associated with increased risk for post-NTZ disease reactivation (p ⩽ 0.05).

Conclusions:

Results from the present review and meta-analysis can help to profile patients who are at greater risk of post-NTZ disease reactivation. However, potential reporting bias and variability in selected studies should be taken into account when interpreting our data.

Effect of dosage reduction on peripheral blood lymphocyte count in patients with multiple sclerosis receiving long-term fingolimod therapy

Of the 19 cases of fingolimod-associated progressive multifocal leukoencephalopathy (PML) reported worldwide by the end of 2017, 4 cases were from Japan. This may indicate that fingolimod sensitivity is higher in the Japanese population than in the western population because the fingolimod dosage used for the prevention of multiple sclerosis (MS) is the same in both populations. Therefore, the laboratory data of nine patients with MS receiving fingolimod treatment for more than 2 years were retrospectively collected. Moreover, the effect of drug holiday was compared between five patients who underwent at least 3 months of dosage reduction via drug holiday after receiving fingolimod for more than 2 years and three patients who underwent drug holiday after receiving fingolimod for less than 2 years. The total, CD3(+), CD4(+), C19(+) lymphocyte counts, the CD4(+)/CD8(+) cell ratio, and the serum IgG concentrations were similar between Japanese patients with MS receiving fingolimod for more than 2 years and Western patients from the previous reports. Recovery of lymphocyte counts in the peripheral blood after fingolimod dosage reduction was worse in some MS patients who received long-term fingolimod treatment than in MS patients who received short-term fingolimod treatment. My findings indicate that the currently used fingolimod dosage may be too high for some Japanese MS patients receiving long-term fingolimod treatment.

High Seroprevalence and Index of Anti-John-Cunningham Virus Antibodies in Korean Patients with Multiple Sclerosis

Background and Purpose

The anti-John-Cunningham virus (JCV)-antibody serostatus and index are used in the risk stratification of progressive multifocal leukoencephalopathy (PML) in multiple sclerosis (MS) patients treated with natalizumab. However, little information on these parameters is available for Asian countries. The purpose of this study was to determine the rate of seropositivity, index, and longitudinal index evolution in Korean patients with MS.

Methods

The antibody seroprevalence was analyzed in 355 samples from 187 patients with clinically isolated syndrome or MS using a second-generation, two-step, enzyme-linked immunosorbent assay. A 4-year longitudinal evaluation was applied to 66 patients.

Results

The overall antibody seroprevalence was 80% (n=149). Among antibody-positive patients, the index had a median value of 3.27 (interquartile range, 1.52–4.18), with 77% (n=114) and 56% (n=83) of patients having indices >1.5 and >3.0, respectively. The serostatus of 59 (89%) of the 66 patients did not change during the longitudinal analysis, while 3 (6%) of the 53 patients who were initially seropositive reverted to seronegativity, and 2 (15%) of the 13 patients who were initially seronegative converted to seropositivity. All patients with a baseline index >0.9 maintained seropositivity, and 92% of patients with a baseline index >1.5 maintained this index over 4 years. No patients developed PML (median disease duration, 8 years).

Conclusions

The seroprevalence and index of anti-JCV antibodies in Korean patients with MS may be higher than those in Western countries.

Impact of Disease-Modifying Treatments on the Longitudinal Evolution of Anti-JCV Antibody Index in Multiple Sclerosis

Background: Risk of natalizumab-related progressive multifocal leukoencephalopathy is associated with the presence of anti-JC-virus (JCV) antibodies.

Objective: To investigate the impact of disease-modifying treatments (DMT) on the longitudinal evolution of anti-JCV antibody index.

Methods: Patients with multiple sclerosis who had serum sampling at intervals of 6 ± 3 months over up to 6 years and who either started DMT (interferon-β, glatiramer acetate or natalizumab) during the observation period with at least one serum sample available before and after treatment initiation or received no DMT during the observation period were included. Anti-JCV antibody serological status and index were determined by 2-step second-generation anti-JCV antibody assay.

Results: A total of 89 patients were followed for a median time of 55.2 months. Of those, 62 (69.7%) started DMT and 27 (30.3%) were without therapy during the observation period. Variation of longitudinal anti-JCV antibody index ranged from 9 to 15% and was similar in patients with and without DMT. Applying a mixed model considering the combined effects of treatment and time as well as individual heterogeneity did not show a significant change of anti-JCV antibody index by the start of treatment with interferon-β, glatiramer acetate, or natalizumab.

Conclusion: Evaluated DMTs do not impact longitudinal anti-JCV antibody index evolution.

Anti-JC virus antibody sera positivity and index value among patients with multiple sclerosis may be correlated with age, sex, and area of residence

Anti-JC virus (JCV) antibody index is the predictive factor of progressive multifocal leukoencephalopathy (PML) for multiple sclerosis (MS) patients treating with natalizumab. The aim of this study is to evaluate the prevalence of anti-JCV antibody positivity and index among Iranian patients who are the candidate for natalizumab and its correlation with their demographic data and previous therapies. A cross-sectional design was assessed for receiving anti-JCV antibody test results between January 2014 and December 2016. Demographic data and disease characteristics were also obtained. Statistical analysis and logistic regression were done using SPSS. Among 803 MS patients that were observed, the prevalence of anti-JCV antibody positivity was 67.9% (mean of index = 2.23 ± 1.16) and 67.6% of positive patients had an index ≥ 1.5. Males were more antibody positive than females (81.7 and 64% respectively; significance (sig.) < 0.001, OR = 2.51, CI 1.65-3.81). The rate of positivity was lower in patients under the age of 18. Patients who lived in cold regions had significantly more prevalence of positivity (Num. = 403; sig. = 0.043 and OR = 1.86; CI 1.02-3.39) and with higher rate of index ≥ 1.5 (sig. = 0.017; OR = 3.99, CI 1.79-8.88). Disease onset age between 28 and 37 years were more positive compared to 18-27 years (N = 480; sig. = 0.02; OR = 1.85, CI 1.09-3.14). Age, male gender, onset age, and cold area of residency significantly influenced anti-JCV antibody sera positivity. Only age of onset and cold area of residency were related to the index. No significant difference was observed between type, dosage, and duration of previous immunosuppressant drugs and anti-JCV antibody positivity and index value.

JC Virus-DNA Detection Is Associated with CD8 Effector Accumulation in Peripheral Blood of Patients with Multiple Sclerosis under Natalizumab Treatment, Independently from JC Virus Serostatus

Although natalizumab (anti-α4 integrin) represents an effective therapy for relapsing remitting multiple sclerosis (RRMS), it is associated with an increased risk of developing progressive multifocal leukoencephalopathy (PML), caused by the polyomavirus JC (JCV). The aim of this study was to explore natalizumab-induced phenotypic changes in peripheral blood T-lymphocytes and their relationship with JCV reactivation. Forty-four patients affected by RRMS were enrolled. Blood and urine samples were classified according to natalizumab infusion number: 0 (N0), 1–12 (N12), 13–24 (N24), 25–36 (N36), and over 36 (N > 36) infusions. JCV-DNA was detected in plasma and urine. T-lymphocyte phenotype was evaluated with flow cytometry. JCV serostatus was assessed. Ten healthy donors (HD), whose ages and sexes matched with the RRMS patients of the N0 group, were enrolled. CD8 effector (CD8 E) percentages were increased in natalizumab treated patients with detectable JCV-DNA in plasma or urine compared to JCV-DNA negative patients (JCV−) (p < 0.01 and p < 0.001, resp.). Patients with CD8 E percentages above 10.4% tended to show detectable JCV-DNA in plasma and/or urine (ROC curve p = 0.001). The CD8 E was increased when JCV-DNA was detectable in plasma or urine, independently from JCV serology, for N12 and N24 groups (p < 0.01). As long as PML can affect RRMS patients under natalizumab treatment with a negative JCV serology, the assessment of CD8 E could help in the evaluation of JCV reactivation.

Serum IgG antibodies from healthy subjects up to 100 years old react to JC polyomavirus

JC polyomavirus (JCPyV) was identified in 1971 in the brain tissue of a patient (J.C.) affected by the progressive multifocal leukoencephalopathy (PML). JCPyV encodes for the oncoproteins large T antigen (Tag) and small t-antigen (tag). These oncoproteins are responsible of the cell transformation and tumorigenesis in experimental animals. JCPyV is ubiquitous in human populations. After the primary infection, which is usually asymptomatic, JCPyV remains lifelong in the host in a latent phase. Its reactivation may occur in heathy subjects and immunocompromised patients. Upon reactivation, JCPyV could reach (i) the CNS inducing the PML, (ii) the kidney of transplant patients causing the organ rejection. Association between JCPyV, which is a small DNA tumor virus, and gliomas and colorectal carcinomas has been published. In the present investigation, we report on a new indirect ELISA with two specific synthetic peptides mimicking JCPyV VP1 immunogenic epitopes to detect specific serum IgG antibodies against JCPyV. Serum samples of healthy subjects (n = 355) ranging 2-100 years old, were analyzed by this new indirect ELISA. The linear peptides VP1 K and VP1 N resemble the natural JCPyV VP1 capsidic epitopes constituting a docking site for serum antibodies. Data from this innovative immunologic assay indicate that the overall prevalence of JCPyV-VP1 antibodies in healthy subjects is at 39%. The innovative indirect ELISA with JCPyV VP1 mimotopes seems to be a useful method to detect specific IgG antibodies against this virus, without cross-reactivity with the closely related SV40 and BKPyV polyomaviruses.

Biomarkers in the evolution of multiple sclerosis

Nonimaging biomarkers can be applied in differential diagnosis, evaluation of disease progression and therapy monitoring of multiple sclerosis (MS). Presence of oligoclonal IgG bands in cerebrospinal fluid is a diagnostic element and a negative predictor of MS evolution. AQP4 antibodies are pathogenic and diagnostic for neuromyelitis optica spectrum disorder. Antibodies to myelin oligodendrocyte glycoprotein develop in about 50% of predominantly pediatric patients with acute disseminated encephalomyelitis, but their possible role in pathogenesis is unknown. Currently, there are no individualized biomarkers suitable to track disease progression. Neutralizing antibodies against IFN-β, natalizumab and daclizumab arise with variable frequency and reduce treatment efficacy. The anti-John Cunningham virus antibody index has potential as a biomarker for risk of progressive multifocal leukoencephalopathy.

The clinical utility of JC virus antibody index measurements in the context of progressive multifocal leukoencephalopathy

In natalizumab-treated patients without previous immunosuppressive treatment, the JCV antibody index is used to stratify PML risk. A high index value indicates that the risk to develop PML is significantly elevated, although probably about 99% of patients with this index value will not develop PML. This minireview aimed to provide an overview of the basic virology and immunology relevant to understanding JCV infections in MS patients, with a focus on what is presently known about antibodies to JCV and how they could be of use to predict and diagnose PML.

Age as a risk factor for early onset of natalizumab-related progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a rare but potentially fatal opportunistic infection that arises almost exclusively in immunocompromised patients or in those treated with monoclonal antibodies, especially natalizumab. Here, we aimed at exploring if age at treatment start affects the time to onset of natalizumab-related PML. PubMed was searched for the terms "natalizumab and progressive multifocal leukoencephalopathy" in articles published from January 2005 to March 2017. We collected information on each identified PML case, including demographic and clinical variables at natalizumab start and at PML onset. The number of natalizumab infusions until PML onset was investigated in time-to-event analyses. We identified 238 cases who developed PML after a median number of 33 natalizumab infusions (range 6 to 103). Risk factors for an earlier onset of natalizumab-related PML were prior immunosuppressant exposure (hazard ratio [HR] = 1.43, p = 0.017) and older age at treatment start (HR = 1.02, p = 0.016). In particular, patients older than 50 years had a more than doubled-increased risk for an earlier PML onset (HR = 2.11, p = 0.006). Our findings suggest that the age at natalizumab start may represent a risk factor for an earlier PML onset, thus claiming further investigations about the interplay between immunosenescence and MS treatments.

Neurological safety of fingolimod: An updated review

Fingolimod (FTY) is the first oral medication approved for treatment of relapsing–remitting multiple sclerosis (RRMS). Its effectiveness and safety were confirmed in several phase III clinical trials, but proper evaluation of safety in the real patient population requires long‐term post‐marketing monitoring. Since the approval of FTY for RRMS in Japan in 2011, it has been administered to approximately 5000 MS patients, and there have been side‐effect reports from 1750 patients. Major events included infectious diseases, hepatobiliary disorders, nervous system disorders and cardiac disorders. In the present review, we focus especially on central nervous system adverse events. The topics covered are: (i) clinical utility of FTY; (ii) safety profile; (iii) post‐marketing adverse events in Japan; (iv) white matter (tumefactive) lesions; (v) rebound after FTY withdrawal; (vi) relationship between FTY and progressive multifocal leukoencephalopathy; (vii) FTY and progressive multifocal leukoencephalopathy‐related immune reconstitution inflammatory syndrome; and (viii) neuromyelitis optica and leukoencephalopathy.