Natalizumab treatment for multiple sclerosis: updated recommendations for patient selection and monitoring

Infiltration by monocytes of the central nervous system and its role in multiple sclerosis: reflections on therapeutic strategies

Mononuclear macrophage infiltration in the central nervous system is a prominent feature of neuroinflammation. Recent studies on the pathogenesis and progression of multiple sclerosis have highlighted the multiple roles of mononuclear macrophages in the neuroinflammatory process. Monocytes play a significant role in neuroinflammation, and managing neuroinflammation by manipulating peripheral monocytes stands out as an effective strategy for the treatment of multiple sclerosis, leading to improved patient outcomes. This review outlines the steps involved in the entry of myeloid monocytes into the central nervous system that are targets for effective intervention: the activation of bone marrow hematopoiesis, migration of monocytes in the blood, and penetration of the blood-brain barrier by monocytes. Finally, we summarize the different monocyte subpopulations and their effects on the central nervous system based on phenotypic differences. As activated microglia resemble monocyte-derived macrophages, it is important to accurately identify the role of monocyte-derived macrophages in disease. Depending on the roles played by monocyte-derived macrophages at different stages of the disease, several of these processes can be interrupted to limit neuroinflammation and improve patient prognosis. Here, we discuss possible strategies to target monocytes in neurological diseases, focusing on three key aspects of monocyte infiltration into the central nervous system, to provide new ideas for the treatment of neurodegenerative diseases.

Cladribine tablets after treatment with natalizumab (CLADRINA) - rationale and design

Background

Individual disease modifying therapies approved for multiple sclerosis (MS) have limited effectiveness and potentially serious side effects, especially when administered over long periods. Sequential combination therapy is a plausible alternative approach. Natalizumab is a monoclonal therapeutic antibody that reduces leukocyte access to the central nervous system that is associated with an increased risk of progressive multifocal leukoencephalopathy and disease reactivation after its discontinuation. Cladribine tablets act as a synthetic adenosine analog, disrupting DNA synthesis and repair, thereby reducing the number of lymphocytes. The generation of prospective, rigorous safety, and efficacy data in transitioning from natalizumab to cladribine is an unmet clinical need.

Objectives

To test the feasibility of transitioning patients with relapsing forms of MS natalizumab to cladribine tablets.

Design

Cladribine tablets after treatment with natalizumab (CLADRINA) is an open-label, single-arm, multicenter, collaborative phase IV, research study that will generate hypothesis regarding the safety, efficacy, and immunological impact of transition from natalizumab to cladribine tablets in patients with relapsing forms of MS.

Methods and analysis

Participants will be recruited from three different sites. The primary endpoint is the absolute and percent change from baseline of lymphocytes and myeloid cell subsets, as well as blood neurofilament light levels. The secondary endpoint is the annualized relapse rate over the 12- and 24-month trial periods. Exploratory endpoints include the expanded disability status scale, and magnetic resonance imaging outcomes.

Discussion

The CLADRINA trial will generate data regarding the safety, efficacy, and immunological impact of the transition from natalizumab to cladribine. As the pace of immunological knowledge of MS continues, insight into disease modifying therapy transition strategies is needed.

Inflammatory bowel disease is associated with an increase in the incidence of multiple sclerosis: a retrospective cohort study of 24,934 patients

BACKGROUND

Recent data suggest a potential pathophysiological link between inflammatory bowel disease (IBD) and multiple sclerosis (MS), two immune-mediated diseases both of which can have a significant impact on patients' quality of life. In the present manuscript, we investigate the association between IBD and MS in a German cohort of general practice patients. These results may have important implications for the screening and management of patients with IBD, as well as for further research into the pathophysiological mechanisms underlying both disorders.

METHODS

4,934 individuals with IBD (11,140 with Crohn's disease (CD) and 13,794 with ulcerative colitis (UC)) as well as 24,934 propensity score matched individuals without IBD were identified from the Disease Analyzer database (IQVIA). A subsequent diagnosis of MS was analyzed as a function of IBD using Cox regression models.

RESULTS

After 10 years of follow-up, 0.9% and 0.7% of CD and UC patients but only 0.5% and 0.3% of matched non-IBD pairs were diagnosed with MS, respectively (pCD = 0.002 and pUC < 0.001). Both CD (HR: 2.09; 95% CI 1.28-3.39) and UC (HR: 2.35; 95% CI 1.47-3.78) were significantly associated with a subsequent MS diagnosis. Subgroup analysis revealed that the association between both CD and UC and MS was more pronounced among male patients.

CONCLUSION

The results of our analysis suggest a notable association between IBD and a subsequent MS diagnosis. These findings warrant further pathophysiological investigation and may have clinical implications for the screening of IBD patients in the future.

Targeting T-cell integrins in autoimmune and inflammatory diseases

The recruitment of T cells to tissues and their retention there are essential processes in the pathogenesis of many autoimmune and inflammatory diseases. The mechanisms regulating these processes have become better understood over the past three decades and are now recognized to involve temporally and spatially specific interactions between cell-adhesion molecules. These include integrins, which are heterodimeric molecules that mediate in-to-out and out-to-in signalling in T cells, other leukocytes, and most other cells of the body. Integrin signalling contributes to T-cell circulation through peripheral lymph nodes, immunological synapse stability and function, extravasation at the sites of inflammation, and T-cell retention at these sites. Greater understanding of the contribution of integrin signalling to the role of T cells in autoimmune and inflammatory diseases has focused much attention on the development of therapeutics that target T-cell integrins. This literature review describes the structure, activation, and function of integrins with respect to T cells, then discusses the use of integrin-targeting therapeutics in inflammatory bowel disease, multiple sclerosis, and psoriasis. Efficacy and safety data from clinical trials and post-marketing surveillance are presented for currently approved therapeutics, therapeutics that have been withdrawn from the market, and novel therapeutics currently in clinical trials. This literature review will inform the reader of the current means of targeting T-cell integrins in autoimmune and inflammatory diseases, as well as recent developments in the field.

Reconsidering the route of drug delivery in refractory multiple sclerosis: Toward a more effective drug accumulation in the central nervous system

Multiple sclerosis is a chronic demyelinating disease with different disease phenotypes. The current FDA-approved disease-modifying therapeutics (DMTs) cannot cure the disease, but only alleviate the disease progression. While the majority of patients respond well to treatment, some of them are suffering from rapid progression. Current drug delivery strategies include the oral, intravenous, subdermal, and intramuscular routes, so these drugs are delivered systemically, which is appropriate when the therapeutic targets are peripheral. However, the potential benefits may be diminished when these targets sequester behind the barriers of the central nervous system. Moreover, systemic drug administration is plagued with adverse effects, sometimes severe. In this context, it is prudent to consider other drug delivery strategies improving their accumulation in the brain, thus providing better prospects for patients with rapidly progressing disease course. These targeted drug delivery strategies may also reduce the severity of systemic adverse effects. Here, we discuss the possibilities and indications for reconsideration of drug delivery routes (especially for those "non-responding" patients) and the search for alternative drug delivery strategies. More targeted drug delivery strategies sometimes require quite invasive procedures, but the potential therapeutic benefits and reduction of adverse effects could outweigh the risks. We characterized the major FDA-approved DMTs focusing on their therapeutic mechanism and the potential benefits of improving the accumulation of these drugs in the brain.

The novel HS-mimetic, Tet-29, regulates immune cell trafficking across barriers of the CNS during inflammation

BACKGROUND

Disruption of the extracellular matrix at the blood-brain barrier (BBB) underpins neuroinflammation in multiple sclerosis (MS). The degradation of extracellular matrix components, such as heparan sulfate (HS) proteoglycans, can be prevented by treatment with HS-mimetics through their ability to inhibit the enzyme heparanase. The heparanase-inhibiting ability of our small dendrimer HS-mimetics has been investigated in various cancers but their efficacy in neuroinflammatory models has not been evaluated. This study investigates the use of a novel HS-mimetic, Tet-29, in an animal model of MS.

METHODS

Neuroinflammation was induced in mice by experimental autoimmune encephalomyelitis, a murine model of MS. In addition, the BBB and choroid plexus were modelled in vitro using transmigration assays, and migration of immune cells in vivo and in vitro was quantified by flow cytometry.

RESULTS

We found that Tet-29 significantly reduced lymphocyte accumulation in the central nervous system which, in turn, decreased disease severity in experimental autoimmune encephalomyelitis. The disease-modifying effect of Tet-29 was associated with a rescue of BBB integrity, as well as inhibition of activated lymphocyte migration across the BBB and choroid plexus in transwell models. In contrast, Tet-29 did not significantly impair in vivo or in vitro steady state-trafficking under homeostatic conditions.

CONCLUSIONS

Together these results suggest that Tet-29 modulates, rather than abolishes, trafficking across central nervous system barriers.

Comparison Between Dimethyl Fumarate, Fingolimod, and Ocrelizumab After Natalizumab Cessation

Importance

Natalizumab cessation is associated with a risk of rebound disease activity. It is important to identify the optimal switch disease-modifying therapy strategy after natalizumab to limit the risk of severe relapses.

Objectives

To compare the effectiveness and persistence of dimethyl fumarate, fingolimod, and ocrelizumab among patients with relapsing-remitting multiple sclerosis (RRMS) who discontinued natalizumab.

Design, Setting, and Participants

In this observational cohort study, patient data were collected from the MSBase registry between June 15, 2010, and July 6, 2021. The median follow-up was 2.7 years. This was a multicenter study that included patients with RRMS who had used natalizumab for 6 months or longer and then were switched to dimethyl fumarate, fingolimod, or ocrelizumab within 3 months after natalizumab discontinuation. Patients without baseline data were excluded from the analysis. Data were analyzed from May 24, 2022, to January 9, 2023.

Exposures

Dimethyl fumarate, fingolimod, and ocrelizumab.

Main Outcomes and Measures

Primary outcomes were annualized relapse rate (ARR) and time to first relapse. Secondary outcomes were confirmed disability accumulation, disability improvement, and subsequent treatment discontinuation, with the comparisons for the first 2 limited to fingolimod and ocrelizumab due to the small number of patients taking dimethyl fumarate. The associations were analyzed after balancing covariates using an inverse probability of treatment weighting method.

Results

Among 66 840 patients with RRMS, 1744 had used natalizumab for 6 months or longer and were switched to dimethyl fumarate, fingolimod, or ocrelizumab within 3 months of natalizumab discontinuation. After excluding 358 patients without baseline data, a total of 1386 patients (mean [SD] age, 41.3 [10.6] years; 990 female [71%]) switched to dimethyl fumarate (138 [9.9%]), fingolimod (823 [59.4%]), or ocrelizumab (425 [30.7%]) after natalizumab. The ARR for each medication was as follows: ocrelizumab, 0.06 (95% CI, 0.04-0.08); fingolimod, 0.26 (95% CI, 0.12-0.48); and dimethyl fumarate, 0.27 (95% CI, 0.12-0.56). The ARR ratio of fingolimod to ocrelizumab was 4.33 (95% CI, 3.12-6.01) and of dimethyl fumarate to ocrelizumab was 4.50 (95% CI, 2.89-7.03). Compared with ocrelizumab, the hazard ratio (HR) of time to first relapse was 4.02 (95% CI, 2.83-5.70) for fingolimod and 3.70 (95% CI, 2.35-5.84) for dimethyl fumarate. The HR of treatment discontinuation was 2.57 (95% CI, 1.74-3.80) for fingolimod and 4.26 (95% CI, 2.65-6.84) for dimethyl fumarate. Fingolimod use was associated with a 49% higher risk for disability accumulation compared with ocrelizumab. There was no significant difference in disability improvement rates between fingolimod and ocrelizumab.

Conclusion and Relevance

Study results show that among patients with RRMS who switched from natalizumab to dimethyl fumarate, fingolimod, or ocrelizumab, ocrelizumab use was associated with the lowest ARR and discontinuation rates, and the longest time to first relapse.

Natalizumab continuation versus switching to ocrelizumab after PML risk stratification in RRMS patients: a natural experiment

BACKGROUND

Natalizumab (NTZ) and ocrelizumab (OCR) can be used for the treatment of relapsing-remitting multiple sclerosis (RRMS). In patients treated with NTZ, screening for JC virus (JCV) is mandatory, and a positive serology usually requires a change in treatment after 2 years. In this study, JCV serology was used as a natural experiment to pseudo-randomize patients into NTZ continuation or OCR.

METHODS

An observational analysis of patients who had received NTZ for at least 2 years and were either changed to OCR or maintained on NTZ, depending on JCV serology status, was performed. A stratification moment (STRm) was established when patients were pseudo-randomized to either arm (NTZ continuation if JCV negativity, or change to OCR if JCV positivity). Primary endpoints include time to first relapse and presence of relapses after STRm and OCR initiation. Secondary endpoints include clinical and radiological outcomes after 1 year.

RESULTS

Of the 67 patients included, 40 continued on NTZ (60%) and 27 were changed to OCR (40%). Baseline characteristics were similar. Time to first relapse was not significantly different. Ten patients in the JCV + OCR arm presented a relapse after STRm (37%), four during the washout period, and 13 patients in the JCV-NTZ arm (32.5%, p = 0.701). No differences in secondary endpoints were detected in the first year after STRm.

CONCLUSIONS

The JCV status can be used as a natural experiment to compare treatment arms with a low selection bias. In our study, switching to OCR versus NTZ continuation led to similar disease activity outcomes.

Switch to ocrelizumab in MS patients treated with natalizumab in extended interval dosing at high risk of PML: A 96-week follow-up pilot study

We aimed to assess the long-term safety and effectiveness of ocrelizumab in a cohort of patients with multiple sclerosis (MS) at high risk of progressive multifocal leukoencephalopathy (PML), previously treated with natalizumab in extending interval dosing (EID), who switched to ocrelizumab and to compare them with patients who continued EID-natalizumab. Thirty MS patients previously treated with natalizumab in EID (every 8 weeks) were included in this observational retrospective cohort study. Among them, 17 patients were switched to ocrelizumab and 13 continued with EID-natalizumab. Except for the John Cunningham virus (JCV) index, no significant differences were detected between both groups. Main outcome measures included: annualized relapse rate (ARR), radiological activity, disability progression, and the NEDA-3 index. Patients were followed for 96 weeks. The median washout period in ocrelizumab-switchers was 6 weeks. Among them, AAR and radiological activity during follow-up were 0.03, without significant differences in comparison with the previous period on natalizumab-EID. The comparison between ocrelizumab-switchers and patients continuing on EID-natalizumab showed no significant differences in AAR, radiological activity, or disability progression. However, the proportion of patients maintaining a NEDA-3 status in week 96 was slightly superior among ocrelizumab-switchers (94 vs 69%). No serious adverse events were observed in any group. In conclusion, switching from EID-natalizumab to ocrelizumab can be considered as a therapeutic option, particularly in patients with MS at high risk of PML, to mitigate the risks of both PML and disease reactivation.

[A case of multiple sclerosis with a tumefactive lesion during long-term treatment with fingolimod, leading to decompressive craniotomy]

We report a 57-year-old man with multiple sclerosis since his 30s who was treated with fingolimod for 9 years. He developed left hemiparesis and consciousness disturbance. Brain MRI revealed a mass lesion in the right frontal lobe with gadolinium enhancement. Cerebrospinal fluid examination showed no pleocytosis. The lesion continued to expand after admission, and on the 9th day after admission, decompressive craniectomy and brain biopsy were performed. Brain pathology revealed demyelination in the lesion, leading to the diagnosis of a tumefactive demyelinating lesion. Corticosteroid therapy ameliorated the brain lesion, and we inducted natalizumab. Tumefactive demyelinating lesions requiring decompressive craniotomy are rare, and we report this case for the further accumulation of similar cases.

Targeting integrin pathways: mechanisms and advances in therapy

Integrins are considered the main cell-adhesion transmembrane receptors that play multifaceted roles as extracellular matrix (ECM)-cytoskeletal linkers and transducers in biochemical and mechanical signals between cells and their environment in a wide range of states in health and diseases. Integrin functions are dependable on a delicate balance between active and inactive status via multiple mechanisms, including protein-protein interactions, conformational changes, and trafficking. Due to their exposure on the cell surface and sensitivity to the molecular blockade, integrins have been investigated as pharmacological targets for nearly 40 years, but given the complexity of integrins and sometimes opposite characteristics, targeting integrin therapeutics has been a challenge. To date, only seven drugs targeting integrins have been successfully marketed, including abciximab, eptifibatide, tirofiban, natalizumab, vedolizumab, lifitegrast, and carotegrast. Currently, there are approximately 90 kinds of integrin-based therapeutic drugs or imaging agents in clinical studies, including small molecules, antibodies, synthetic mimic peptides, antibody-drug conjugates (ADCs), chimeric antigen receptor (CAR) T-cell therapy, imaging agents, etc. A serious lesson from past integrin drug discovery and research efforts is that successes rely on both a deep understanding of integrin-regulatory mechanisms and unmet clinical needs. Herein, we provide a systematic and complete review of all integrin family members and integrin-mediated downstream signal transduction to highlight ongoing efforts to develop new therapies/diagnoses from bench to clinic. In addition, we further discuss the trend of drug development, how to improve the success rate of clinical trials targeting integrin therapies, and the key points for clinical research, basic research, and translational research.

Innovative therapeutic concepts of progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is an opportunistic viral disease of the brain-caused by human polyomavirus 2. It affects patients whose immune system is compromised by a corresponding underlying disease or by drugs. Patients with an underlying lymphoproliferative disease have the worst prognosis with a mortality rate of up to 90%. Several therapeutic strategies have been proposed but failed to show any benefit so far. Therefore, the primary therapeutic strategy aims to reconstitute the impaired immune system to generate an effective endogenous antiviral response. Recently, anti-PD-1 antibodies and application of allogeneic virus-specific T cells demonstrated promising effects on the outcome in individual PML patients. This article aims to provide a detailed overview of the literature with a focus on these two treatment approaches.

Real-World Effectiveness of Natalizumab in Korean Patients With Multiple Sclerosis

Background and Purpose: Natalizumab is a highly efficacious disease-modifying therapy for relapsing-remitting multiple sclerosis (MS). Data on the efficacy and safety profile of natalizumab in Asian patients with MS are limited. This study assessed the efficacy and safety of natalizumab in Korean patients with MS in a real-world setting.

Methods: This study enrolled consecutive Korean patients with active relapsing-remitting MS who were treated with natalizumab for at least 6 months between 2015 and 2021. To evaluate the therapeutic outcome of natalizumab, we used the Expanded Disability Status Scale (EDSS) scores and brain magnetic resonance imaging; adverse events were assessed at regular intervals. No evidence of disease activity (NEDA) was defined as no clinical relapse, no worsening of EDSS score, and no radiological activities.

Results: Fourteen subjects with MS were included in the study. The mean age at initiation of natalizumab therapy was 32 years. All patients were positive for anti-John Cunningham virus antibodies before natalizumab administration. The mean annual relapse rate was markedly reduced from 2.7 ± 3.2 before natalizumab therapy to 0.1 ± 0.4 during natalizumab therapy (p = 0.001). Disability was either improved or stabilized after natalizumab treatment in 13 patients (93%). During the 1st year and 2 years after initiating natalizumab, NEDA-3 was achieved in 11/12 (92%) and 9/11 (82%) patients, respectively. No progressive multifocal leukoencephalopathy or other serious adverse events leading to the discontinuation of natalizumab were observed.

Conclusions: Natalizumab therapy showed high efficacy in treating Korean patients with active MS, without unexpected safety problems.

Altered expression of microRNAs and B lymphocytes during Natalizumab therapy in multiple sclerosis

MicroRNAs (miRNAs) are a family of non-translated small ribonucleic acids (RNAs) measuring 21–25 nucleotides in length that play various roles in multiple sclerosis (MS). By regulating gene expression via either mediating translational repression or cleavage of the target RNA, miRNAs can alter the expression of transcripts in different cells, such as B lymphocytes, also known as B cells. They are crucial in the pathogenesis of MS; however, they have not been extensively studied during the treatment of some drugs such as natalizumab (NTZ). NTZ is a humanized immunoglobulin G4 antibody antagonist for integrin alpha 4 (α4) used in the treatment of MS. The drug reduces the homing of lymphocytes to inflammation sites. Integrin α4 expression on the cell surface of B cells is related to MS severity, indicating a critical component in the pathogenesis of the disease. NTZ plays an important role in modifying the gene expression in B cells and the levels of miRNAs in the treatment of MS. In this review, we have described changes in gene expression in B cells and the levels of miRNAs during NTZ therapy in MS and its relapse. Studies using the experimental autoimmune encephalomyelitis (EAE) model and those involving patients with MS have described changes in the levels of microRNAs in the regulation of proteins affected by specific miRNAs, gene expression in B cells, and certain functions of B cells as well as their subpopulations. Therefore, there is a possibility that some miRNAs could be studied at different stages of MS during NTZ treatment, and these specific miRNAs can be tested as markers of therapeutic response to this drug in future studies. Physiopathology, gene expression in B cells and their subpopulations can help understand this complex puzzle involving miRNAs and the therapeutic response of patients with MS.

Serum Neurofilament Levels and PML Risk in Patients With Multiple Sclerosis Treated With Natalizumab

Objectives

The study aimed to assess the potential for serum neurofilament light chain (NFL) levels to predict the risk of progressive multifocal leukoencephalopathy (PML) in natalizumab (NTZ)-treated patients with multiple sclerosis (MS) and to discriminate PML from MS relapses.

Methods

NFL levels were measured with single molecule array (Simoa) in 4 cohorts: (1) a prospective cohort of patients with MS who developed PML under NTZ therapy (pre-PML) and non-PML NTZ-treated patients (NTZ-ctr); (2) a cohort of patients whose blood was collected during PML; (3) an independent cohort of non-PML NTZ-treated patients with serum NFL determinations at 2 years (replication cohort); and (4) a cohort of patients whose blood was collected during exacerbations.

Results

Serum NFL levels were significantly increased after 2 years of NTZ treatment in pre-PML patients compared with NTZ-ctr. The prognostic performance of serum NFL levels to predict PML development at 2 years was similar in the NTZ-ctr group and replication cohort. Serum NFL levels also distinguished PML from MS relapses and were 8-fold higher during PML compared with relapses.

Conclusions

These results support the use of serum NFL levels in clinical practice to identify patients with relapsing-remitting MS at higher PML risk and to differentiate PML from clinical relapses in NTZ-treated patients.

Classification of Evidence

This study provides Class I evidence that serum NFL levels can identify NTZ-treated patients with MS who will develop PML with a sensitivity of 67% and specificity of 80%.

Does Extended Interval Dosing Natalizumab Preserve Effectiveness in Multiple Sclerosis? A 7 Year-Retrospective Observational Study

The extended interval dosing (EID) of natalizumab has been suggested to be associated with a reduced risk of progressive multifocal leukoencephalopathy (PML) and short-term preservation of efficacy but its long-term effectiveness remain unknown. We aimed to determine the long-term effectiveness and safety of natalizumab in an EID setting in a cohort of patients with multiple sclerosis (MS) treated for more than 7 years. We conducted an observational retrospective cohort study, including 39 (34 female, 5 male) patients with clinically definite relapsing-MS, initially treated with standard interval dosing (SID) of natalizumab (mean time 54 months [SD29]) who were then switched to EID, every 8 weeks (mean time 76 months [SD13]). The main outcome measures included the following: i) annualized relapse rate (ARR), ii) radiological activity, iii) disability progression, and iv) NEDA-3 no evidence of disease activity index. EID preserved ARR, radiological activity, and prevented disability worsening during follow-up. The proportion of patients maintaining their NEDA-3 status after 24, 48, and 72 months of natalizumab administration in EID was 94%, 73%, and 70%, respectively. Stratified analysis according to history of drug therapy showed that the EID of natalizumab was slightly more effective in naïve patients than in those previously treated with other immunosuppressive drugs. No cases of PML or other severe adverse reactions were reported. In conclusion, long-term therapy with natalizumab in an EID setting following an SID regimen maintained its disease-modifying activity, and was safe and well tolerated for over 7 years. These encouraging observational results need to be confirmed in controlled clinical trials.

JCPyV miR-J1-5p in Urine of Natalizumab-Treated Multiple Sclerosis Patients

The use of Natalizumab in Multiple Sclerosis (MS) can cause the reactivation of the polyomavirus JC (JCPyV); this may result in the development of progressive multifocal leukoencephalopathy (PML), a rare and usually lethal disease. JCPyV infection is highly prevalent in worldwide population, but the detection of anti-JCPyV antibodies is not sufficient to identify JCPyV infection, as PML can develop even in patients with negative JCPyV serology. Better comprehension of the JCPyV biology could allow a better understanding of JCPyV infection and reactivation, possibly reducing the risk of developing PML. Here, we investigated whether JCPyV miR-J1-5p—a miRNA that down-regulates the early phase viral protein T-antigen and promotes viral latency—could be detected and quantified by digital droplet PCR (ddPCR) in urine of 25 Natalizumab-treated MS patients. A 24-month study was designed: baseline, before the first dose of Natalizumab, and after 1 (T1), 12 (T12) and 24 months (T24) of therapy. miR-J1-5p was detected in urine of 7/25 MS patients (28%); detection was possible in three cases at T24, in two cases at T12, in one case at T1 and T12, and in the last case at baseline and T1. Two of these patients were seronegative for JCPyV Ab, and viral DNA was never found in either urine or blood. To note, only in one case miR-J1-5p was detected before initiation of Natalizumab. These results suggest that the measurement of miR-J1-5p in urine, could be a biomarker to monitor JCPyV infection and to better identify the possible risk of developing PML in Natalizumab-treated MS patients.

Reduction of the risk of PML in natalizumab treated MS patients in Sweden: An effect of improved PML risk surveillance

BACKGROUND

Natalizumab (NTZ) treatment of multiple sclerosis (MS) has been associated with increased risk of progressive multifocal leukoencephalopathy (PML). The aim of the present study was to evaluate the impact of PML risk assessment on PML incidence in NTZ treated MS patients.

METHODS

By using information from the population-based Swedish MS registry a retrospective cohort was established of patients treated with NTZ between 2006-2018. The effect on PML incidence before and after utilizing a risk management plan, including JC virus (JCV) serology, was analyzed.

RESULTS

In December 2018, 804 PML cases associated with NTZ therapy of MS had been reported globally, including 9 cases from Sweden. The estimated PML incidence 2018 in Sweden and globally was 0.7 (0.3-1.4) and 4.15 (3.9-4.4) per 1,000 person years, respectively. In Sweden, JCV serology was introduced 2012 for PML risk assessment and the cumulative risk of PML was significantly lower 2012-2018 compared to the period 2006-2011 (p=0.042). The mean NTZ exposure time was 60.1 months (SD 37.2) in the first period (2006-2011) and 32.6 months (SD 22.0) in the second period (2012-2018). The number of patients treated with NTZ decreased, and the number of patients at increased risk of PML was 1.9 % at the end of the study period.

CONCLUSION

Since 2006 the incidence of PML associated with NTZ treatment of MS has decreased in Sweden. Our findings suggest that this reduction is due to an effective adoptation and adherence to the established risk management plan that implies switching patients at increased PML risk from NTZ to other highly efficacious therapies. A less pronounced decline in PML incidence has recently been observed in France, but not globally.

Strategies to prevent hemorrhagic transformation after reperfusion therapies for acute ischemic stroke: A literature review

BACKGROUND

Reperfusion therapies by tissue plasminogen activator (tPA) and mechanical thrombectomy (MT) have ushered in a new era in the treatment of acute ischemic stroke (AIS). However, reperfusion therapy-related HT remains an enigma.

AIM

To provide a comprehensive review focused on emerging concepts of stroke and therapeutic strategies, including the use of protective agents to prevent HT after reperfusion therapies for AIS.

METHODS

A literature review was performed using PubMed and the ClinicalTrials.gov database.

RESULTS

Risk of HT increases with delayed initiation of tPA treatment, higher baseline glucose level, age, stroke severity, episode of transient ischemic attack within 7 days of stroke onset, and hypertension. At a molecular level, HT that develops after thrombolysis is thought to be caused by reactive oxygen species, inflammation, remodeling factor-mediated effects, and tPA toxicity. Modulation of these pathophysiological mechanisms could be a therapeutic strategy to prevent HT after tPA treatment. Clinical mechanisms underlying HT after MT are thought to involve smoking, a low Alberta Stroke Program Early CT Score, use of general anesthesia, unfavorable collaterals, and thromboembolic migration. However, the molecular mechanisms are yet to be fully investigated. Clinical trials with MT and protective agents have also been planned and good outcomes are expected.

CONCLUSION

To fully utilize the easily accessible drug-tPA-and the high recanalization rate of MT, it is important to reduce bleeding complications after recanalization. A future study direction could be to investigate the recovery of neurological function by combining reperfusion therapies with cell therapies and/or use of pleiotropic protective agents.

Qualitative factors shaping MS patients' experiences of infusible disease-modifying drugs: a critical incident technique analysis

OBJECTIVE

To explore factors shaping the experiences of patients with relapsing-remitting multiple sclerosis with infusible disease-modifying drugs in a hospital setting.

DESIGN AND SETTINGS

The critical incident technique served as a framework for collecting and analysing patients' qualitative account practices involving infusible disease-modifying drugs. Data were collected through semistructured interviews and one single-case study. Participants were recruited from all five regions in Denmark. Inductive thematic analysis was used to identify and interpret factors shaping patients' infusion journey over time.

PARTICIPANTS

Twenty-two patients with relapsing-remitting multiple sclerosis receiving infusion with disease-modifying drugs (natalizumab, alemtuzumab and ocrelizumab).

RESULTS

Four time scenarios-preinfusion, day of infusion, long-term infusion and switch of infusion-associated with the infusion of disease-modifying drugs were analysed to reveal how different factors could both positively and negatively affect patient experience. Time taken to make the treatment decision was affected by participants' subjective perceptions of their disease activity; this may have set off a treatment dilemma in the event of a pressing need for treatment. Planning and routine made infusion practices manageable, but external and internal surroundings, including infusion room ambience and the quality of relationships with healthcare professionals and fellow patients, affected patients' cognitive state and well-being irrespective of the infusion regimen. Switching the infusion regimen can reactivate worries akin to the preinfusion scenario.

CONCLUSION

This study provides novel insight into the positive and negative factors that shape patients' experience of infusion care practices. From a patient's perspective, an infusion practice is not a solitary event in time but includes planning and routine which become an integral part of their multiple sclerosis management. The quality of space and the ambience of the infusion room, combined with the relationship with healthcare professionals and fellow patients, can be a significant source of knowledge and support people with relapsing-remitting multiple sclerosis in their experience of agency in life.

Diagnosis and management of multiple sclerosis: MRI in clinical practice

Background

Recent changes in the understanding and management of multiple sclerosis (MS) have increased the role of MRI in supporting diagnosis and disease monitoring. However, published guidelines on the use of MRI in MS do not translate easily into different clinical settings and considerable variation in practice remains. Here, informed by published guidelines for the use of MRI in MS, we identified a clinically informative MRI protocol applicable in a variety of clinical settings, from district general hospitals to tertiary centres.

Methods

MS specialists geographically representing the UK National Health Service and with expertise in MRI examined existing guidelines on the use of MRI in MS and identification of challenges in their applications in various clinical settings informed the formulation of a feasible MRI protocol.

Results

We identified a minimum set of MRI information, based on clinical relevance, as well as on applicability to various clinical settings. This informed the selection of MRI acquisitions for scanning protocols, differentiated on the basis of their purpose and stage of the disease, and indication of timing for scans. Advice on standardisation of MRI requests and reporting, and proposed timing and frequency of MRI scans were generated.

Conclusions

The proposed MRI protocol can adapt to a range of clinical settings, aiding the impetus towards standardisation of practice and offering an example of research-informed service improvement to support optimisation of resources. Other neurological conditions, where a gap still exists between published guidelines and their clinical implementation, may benefit from this same approach.

Extending the Interval of Natalizumab Dosing: Is Efficacy Preserved?

Extending the natalizumab interval after the 24th administration could reduce the risk of progressive multifocal leukoencephalopathy (PML). The objective is to evaluate the noninferiority of the efficacy of an extended interval dosing (EID) compared with the standard interval dosing (SID) of natalizumab. It is an observational, multicenter (14 Italian centers), retrospective cohort study, starting from the 24th natalizumab infusion to the loss of follow-up or 2 years after baseline. Patients were grouped in 2 categories according to the mean number of weeks between doses: < 5 weeks, SID; ≥ 5 weeks, EID. Three hundred and sixty patients were enrolled. Median dose interval (MDI) following 24th infusion was 4.7 weeks, with a bimodal distribution (modes at 4 and 6 weeks). Two hundred and sixteen patients were in the SID group (MDI = 4.3 weeks) and 144 in the EID group (MDI 6.2 weeks). Annualized relapse rate was 0.060 (95% CI = 0.033-0.087) in the SID group and 0.039 (95% CI = 0.017-0.063) in the EID group. The non-inferiority of EID versus SID was satisfied. In conclusion, there is no evidence of a reduced efficacy of natalizumab in an EID setting. This observation confirms previous results and together with the emerging evidence of a reduced risk of PML associated to an EID, supports the need of a randomized study to assess the need to change the standard of the natalizumab dosing schedule.

Risk factors for reactivation of clinical disease activity in multiple sclerosis after natalizumab cessation

BACKGROUND

Natalizumab (NTZ) is widely used for highly active relapsing-remitting multiple sclerosis (MS). Inflammatory disease activity often returns after NTZ treatment discontinuation. We aimed to identify predictive factors for such reactivation in a real-life setting.

METHODS

We conducted a retrospective survey in four Finnish hospitals. A computer-based search was used to identify all patients who had received NTZ for multiple sclerosis. Patients were included if they had received at least six NTZ infusions, had discontinued treatment for at least three months, and follow-up data was available for at least 12 months after discontinuation. Altogether 89 patients were analyzed with Cox regression model to identify risk factors for reactivation, defined as having a corticosteroid-treated relapse.

RESULTS

At 6 and 12 months after discontinuation of NTZ, a relapse was documented in 27.0% and 35.6% of patients, whereas corticosteroid-treated relapses were documented in 20.2% and 30.3% of patients, respectively. A higher number of relapses during the year prior to the introduction of NTZ was associated with a significantly higher risk for reactivation at 6 months (Hazard Ratio [HR] 1.65, p < 0.001) and at 12 months (HR 1.53, p < 0.001). Expanded Disability Status Scale (EDSS) of 5.5 or higher before NTZ initiation was associated with a higher reactivation risk at 6 months (HR 3.70, p = 0.020). Subsequent disease-modifying drugs (DMDs) failed to prevent reactivation of MS in this cohort. However, when subsequent DMDs were used, a washout time longer than 3 months was associated with a higher reactivation risk at 6 months regardless of whether patients were switched to first-line (HR 7.69, p = 0.019) or second-line therapies (HR 3.94, p = 0.035). Gender, age, time since diagnosis, and the number of NTZ infusions were not associated with an increased risk for reactivation.

CONCLUSION

High disease activity and a high level of disability prior to NTZ treatment seem to predict disease reactivation after treatment cessation. When switching to subsequent DMDs, the washout time should not exceed 3 months. However, subsequent DMDs failed to prevent the reactivation of MS in this cohort.

Mechanism-Based Treatment Strategies for IBD: Cytokines, Cell Adhesion Molecules, JAK Inhibitors, Gut Flora, and More

Background

Although TNF inhibitors revolutionized the therapy of inflammatory bowel disease (IBD), we have been reaching a point where other therapies with different mechanisms of action are necessary. A rising number of elderly IBD patients with contraindications to established therapies and a growing group of patients losing response to anti-TNF therapy compel us to find safer, better-tolerated, and, ideally, personalized treatment options. However, in order to choose the right drug to fit a patient, it is indispensable to understand the pathomechanism involved in IBD.

Summary

The aim of this review is to explain the inflammatory signaling pathways in IBD and how to inhibit them with current and future therapeutic approaches. Next to biologic agents targeting inflammatory cytokines (anti-TNF agents, anti-IL-12/-23 agents, and specific inhibitors of IL-23), biologics blocking leukocyte trafficking to the gut (anti-integrin antibodies) are available nowadays. More recently, small molecules inhibiting the JAK-STAT pathway (JAK inhibitors) or preventing lymphocyte trafficking (sphingosine-1-phosphate modulators) have been approved or are under investigation. Furthermore, modifying the microbiota has potential therapeutic effects on IBD, and autologous hematopoietic or mesenchymal stem cell transplantation may be considered for a highly selected group of IBD patients.

Key Message

Physicians should understand the different mechanisms of action of the potential therapies for IBD to select the right drug for the right patient.

Should frequent MRI monitoring be performed in natalizumab-treated MS patients? A contribution to a recent debate

BACKGROUND

Brain magnetic resonance imaging (MRI) is the most effective surveillance tool for the detection of asymptomatic progressive multifocal leukoencephalopathy (PML). However, the optimal frequency for routine MRI surveillance is under-investigated.

OBJECTIVE

To understand whether, upon their first MRI appearance, PML lesions present a difference in volume when comparing patients who frequently underwent MRI surveillance (3/4 months) with those who were assessed at longer intervals (6/12 months) and to understand the impact of the volume of lesions on clinical outcome.

METHODS

The data of patients included in the Italian PML cohort were retrospectively analysed. Patients who had all the pre-diagnostic MRI scans available (n = 37) were included. The volume of PML lesion was calculated by manually outlining the PML lesion.

RESULTS

Compared with patients who underwent MRI examination at least every 4 months, patients who were assessed less frequently had a lesion of significantly higher volume (median: 2567 (883-3583) vs. 664 mm³ (392-963) p = 0.006) and suffered a higher rate of disability (median: 2.25 expanded disability status scale points (-2.5 to 8) vs. 0.5 (-1 to 2.5) p = 0.004).

CONCLUSION

The positive clinical outcome of patients undergoing frequent MRI surveillance and the small volume of the PML lesion upon first appearance justify a frequent surveillance using MRI in patients at high risk of PML.

What is the Relevance of the Systematic Use of Gadolinium During the MRI Follow-Up of Multiple Sclerosis Patients Under Natalizumab?

BACKGROUND

Multiple sclerosis (MS) patients represent a population potentially affected by the intracerebral accumulation of gadolinium-based contrast agents (GBCA) due to repeated magnetic resonance imaging (MRI) performed during their lifetime; however, MRI is still the best tool to monitor MS inflammatory activity.

OBJECTIVE

This study aimed to evaluate the relevance of GBCA injections during the MRI follow-up of MS patients under natalizumab (Tysabri) treatment.

METHODS

The MRI data results were retrospectively reviewed in a monocentric study (University Hospital of Toulouse, France) from all consecutive patients treated with natalizumab from January 2014 to January 2017. For each examination during the whole MRI follow-up, new lesions (enhancing and non-enhancing) were analyzed.

RESULTS

A total of 129 patients were included in this study (65% female, mean age = 41 years, mean treatment duration 6.5 years, 50% positive for John Cunningham virus) and benefited from 735 MRIs with GBCA. Only 3 MRIs showed a new enhancing lesion, systematically encountered after treatment discontinuation.

CONCLUSION

According to this study based on the clinical and radiological practice, the systematic use of GBCA seems of limited relevance in the MRI follow-up of asymptomatic patients treated continuously with natalizumab.

Use of big data in drug development for precision medicine: an update

INTRODUCTION

Big-data-driven drug development resources and methodologies have been evolving with ever-expanding data from large-scale biological experiments, clinical trials, and medical records from participants in data collection initiatives. The enrichment of biological- and clinical-context-specific large-scale data has enabled computational inference more relevant to real-world biomedical research, particularly identification of therapeutic targets and drugs for specific diseases and clinical scenarios.

AREAS COVERED

Here we overview recent progresses made in the fields: new big-data-driven approach to therapeutic target discovery, candidate drug prioritization, inference of clinical toxicity, and machine-learning methods in drug discovery.

EXPERT OPINION

In the near future, much larger volumes and complex datasets for precision medicine will be generated, e.g., individual and longitudinal multi-omic, and direct-to-consumer datasets. Closer collaborations between experts with different backgrounds would also be required to better translate analytic results into prognosis and treatment in the clinical practice. Meanwhile, cloud computing with protected patient privacy would become more routine analytic practice to fill the gaps within data integration along with the advent of big-data. To conclude, integration of multitudes of data generated for each individual along with techniques tailored for big-data analytics may eventually enable us to achieve precision medicine.

The Cerebrospinal Fluid in Multiple Sclerosis

Investigation of cerebrospinal fluid (CSF) in the diagnostic work-up in suspected multiple sclerosis (MS) patients has regained attention in the latest version of the diagnostic criteria due to its good diagnostic accuracy and increasing issues with misdiagnosis of MS based on over interpretation of neuroimaging results. The hallmark of MS-specific changes in CSF is the detection of oligoclonal bands (OCB) which occur in the vast majority of MS patients. Lack of OCB has a very high negative predictive value indicating a red flag during the diagnostic work-up, and alternative diagnoses should be considered in such patients. Additional molecules of CSF can help to support the diagnosis of MS, improve the differential diagnosis of MS subtypes and predict the course of the disease, thus selecting the optimal therapy for each patient.

Serum neurofilaments increase at progressive multifocal leukoencephalopathy onset in natalizumab-treated multiple sclerosis patients

This study analyzed serum neurofilament light chains (NfL) in 2 European cohorts of 312 multiple sclerosis (MS) patients to investigate whether NfL are biomarkers of progressive multifocal leukoencephalopathy (PML) during natalizumab treatment. The cohort comprised 25 PML, 136 natalizumab-treated, and 151 untreated MS patients. Patients subsequently developing PML had similar NfL to other natalizumab-treated MS patients. At PML onset, NfL were 10-fold higher than in the pre-PML condition and in natalizumab-treated or untreated MS patients, and NfL continued to increase until onset of immune reconstitution inflammatory syndrome. The results suggest that in natalizumab-treated patients, NfL may represent an early and accessible marker of PML. Ann Neurol 2019;85:606-610.

Efficacy and safety of rituximab for relapsing-remitting multiple sclerosis: A systematic review and meta-analysis

OBJECTIVE

To evaluate the efficacy and safety of rituximab for relapsing-remitting multiple sclerosis.

RESULTS

Fifteen studies that collectively included 946 patients were selected for the meta-analysis. Rituximab therapy was associated with the mean annualized relapse rates decreasing by 0.80 (95% confidence interval, 0.45-1.15) and the mean Expanded Disability Status Scale score decreasing by 0.46 (95% confidence interval, 0.05-0.87). The likelihood of patients experiencing a relapse after starting rituximab therapy was only 15% (95% confidence interval, 7%-26%). Although mild-to-moderate adverse events occurred in 29.6% of the patients, there were no severe adverse events.

CONCLUSIONS AND RELEVANCE

This systematic review and meta-analysis shows that rituximab is associated with reduced annualized relapse rates and disability levels in patients with relapsing-remitting multiple sclerosis. It is also well tolerated and is not associated with serious adverse events.

The Future of Immunotherapy: A 20-Year Perspective

Immunotherapy is the field of immunology that aims to identify treatments for diseases through induction, enhancement or suppression of an immune response. Immunotherapies designed to instigate or enhance an immune response are considered “activating immunotherapies” while those designed to repress an immune response are “suppressive immunotherapies.” This perspective will focus on two areas of immunotherapy, activating immunotherapies for cancer and suppressive immunotherapies for autoimmunity both of which have seen a resurgence in interest in recent years and are likely to transform the treatment of many human diseases in the next 20 years. Effective immunotherapies for cancer, where the aim is to activate tumor-specific immune responses, will be totally different from those designed to suppress the immune response to self-antigens in autoimmune disease. Furthermore, the reader will appreciate that the degree to which side effects of immunotherapies are acceptable will differ drastically between life-threatening cancers and chronic, debilitating but not necessarily life-threatening autoimmune conditions.

Multidisciplinary Rehabilitation is Efficacious and Induces Neural Plasticity in Multiple Sclerosis even when Complicated by Progressive Multifocal Leukoencephalopathy

A 48-year-old woman with multiple sclerosis (MS), treated with natalizumab for more than one year without clinical and magnetic resonance imaging (MRI) signs of disease activity, was diagnosed with definite progressive multifocal leukoencephalopathy (PML). She presented with subacute motor deficit of the right upper limb (UL), followed by involvement of the homolateral leg and urinary urgency. The patient was treated with steroids and plasma exchange. On follow-up MRI scans, the PML lesion remained stable and no MS rebounds were observed, but the patient complained of a progressive worsening of the right UL motor impairment, becoming dependent in most activities of daily living. A cycle of multidisciplinary rehabilitation (MDR) was then started, including daily sessions of UL robot therapy and occupational therapy. Functional MRI (fMRI) was acquired before and at the end of the MDR cycle using a motor task which consisted of 2 runs: in one run the patient was asked to observe while the second one consisted of hand grasping movements. At the end of the rehabilitation period, both the velocity and the smoothness of arm trajectories during robot-based reaching movements were significantly improved. After MDR, compared with baseline, fMRI showed significantly increased functional activation within the sensory-motor network in the active, motor task, while no significant differences were found in the observational task. MDR in MS, including robot-assisted UL training, seems to be clinically efficacious and to have a significant impact on brain functional reorganization on a short-term, even in the presence of superimposed tissue damage provoked by PML.

Matrix metalloproteinase 9 is decreased in natalizumab-treated multiple sclerosis patients at risk for progressive multifocal leukoencephalopathy

OBJECTIVE

To identify biomarkers associated with the development of progressive multifocal leukoencephalopathy (PML) in multiple sclerosis (MS) patients treated with natalizumab (NTZ).

METHODS

Relapsing-remitting MS patients who developed PML under NTZ therapy (pre-PML) and non-PML NTZ-treated patients (NTZ-ctr) were included in the study. Cryopreserved peripheral blood mononuclear cells and serum samples collected at baseline, at 1- and 2-year treated time points, and during PML were analyzed for gene expression by RNA sequencing and for serum protein levels by Luminex and enzyme-linked immunosorbent assays, respectively.

RESULTS

Among top differentially expressed genes in the RNA sequencing between pre-PML and NTZ-ctr patients, pathway analysis revealed a high representation of genes belonging to the following categories: proangiogenic factors (MMP9, VEGFA), chemokines (CXCL1, CXCL5, IL8, CCL2), cytokines (IL1B, IFNG), and plasminogen- and coagulation-related molecules (SERPINB2, PLAU, PLAUR, TFPI, THBD). Serum protein levels for these candidates were measured in a 2-step manner in a screening cohort and a validation cohort of pre-PML and NTZ-ctr patients. Only matrix metalloproteinase 9 (MMP9) was validated; in pre-PML patients, MMP9 protein levels were significantly reduced at baseline compared with NTZ-ctr patients, and levels remained lower at later time points during NTZ treatment.

INTERPRETATION

The results from this study suggest that the proangiogenic factor MMP9 may play a role as a biomarker associated with the development of PML in MS patients treated with NTZ. Ann Neurol 2017;82:186-195.

Polyomaviruses

Over the last 10 years, the number of identified polyomaviruses has grown to more than 35 subtypes, including 13 in humans. The polyomaviruses have similar genetic makeup, including genes that encode viral capsid proteins VP1, 2, and 3 and large and small T region proteins. The T proteins play a role in viral replication and have been implicated in viral chromosomal integration and possible dysregulation of growth factor genes. In humans, the Merkel cell polyomavirus has been shown to be highly associated with integration and the development of Merkel cell cancers. The first two human polyomaviruses discovered, BKPyV and JCPyV, are the causative agents for transplant-related kidney disease, BK commonly and JC rarely. JC has also been strongly associated with the development of progressive multifocal leukoencephalopathy (PML), a rare but serious infection in untreated HIV-1-infected individuals and in other immunosuppressed patients including those treated with monoclonal antibody therapies for autoimmune diseases systemic lupus erythematosus, rheumatoid arthritis, or multiple sclerosis. The trichodysplasia spinulosa-associated polyomavirus (TSAPyV) may be the causative agent of the rare skin disease trichodysplasia spinulosa. The remaining nine polyomaviruses have not been strongly associated with clinical disease to date. Antiviral therapies for these infections are under development. Antibodies specific for each of the 13 human polyomaviruses have been identified in a high percentage of normal individuals, indicating a high rate of exposure to each of the polyomaviruses in the human population. PCR methods are now available for detection of these viruses in a variety of clinical samples.

[Immune reconstitution inflammatory syndrome and rebound syndrome in multiple sclerosis patients who stopped disease modification therapy: current understanding and a case report]

More and more multiple sclerosis patients have been receiving treatment with new immunomodulatory drugs. Its discontinuation because of side-effects, lack of efficacy or pregnancy has been increasing as well. This paper reviews such severe complications of natalizumab and fingolimod cessation as immune reconstitution inflammatory syndrome (IRIS) and rebound. The short history, immunopathogenesis and diagnostic criteria of IRIS in individuals with human immunodeficiency virus infection are covered. Clinical and radiological presentations as well as possible pathogenic mechanisms of IRIS in patients treated with natalizumab and fingolimod are discussed. The authors also report the case of a woman with multiple sclerosis treated with fingolimod, who experienced a severe relapse when she stopped treatment. Diagnostic criteria and prognostic factors for IRIS and rebound are needed in patients with multiple sclerosis who discontinue the new disease modification therapy.

Expanding Role of T Cells in Human Autoimmune Diseases of the Central Nervous System

It is being increasingly recognized that a dysregulation of the immune system plays a vital role in neurological disorders and shapes the treatment of the disease. Aberrant T cell responses, in particular, are key in driving autoimmunity and have been traditionally associated with multiple sclerosis. Yet, it is evident that there are other neurological diseases in which autoreactive T cells have an active role in pathogenesis. In this review, we report on the recent progress in profiling and assessing the functionality of autoreactive T cells in central nervous system (CNS) autoimmune disorders that are currently postulated to be primarily T cell driven. We also explore the autoreactive T cell response in a recently emerging group of syndromes characterized by autoantibodies against neuronal cell-surface proteins. Common methodology implemented in T cell biology is further considered as it is an important determinant in their detection and characterization. An improved understanding of the contribution of autoreactive T cells expands our knowledge of the autoimmune response in CNS disorders and can offer novel methods of therapeutic intervention.

Monoclonal Antibodies for Relapsing Multiple Sclerosis: A Review of Recently Marketed and Late-Stage Agents

Treatment of multiple sclerosis (MS) has improved considerably over the last decade because of new insights into MS pathology and biotechnological advances. This has led to the development of new potent pharmaceutical compounds targeting different processes in the complex autoimmune pathology leading to chronic central nervous system (CNS) demyelination, neural loss, and, finally, neurological disability. Although a number of disease-modifying treatments are available for the treatment of the inflammatory phase of MS, there is still a need for highly efficacious therapies with an acceptable safety profile in order to gain therapeutic control early in the disease course. Monoclonal antibodies have proven to be some of the most efficacious disease-modifying therapies in the field of MS, and recent developments in clinical research hold promise for new compounds fulfilling the need for improved safety and high efficacy. We review recent developments in the field of therapeutic monoclonal antibodies used for the treatment of MS and current information on the mode of action, efficacy, and safety of existing and emerging therapeutic monoclonal antibodies as well as their place within the context of different treatment strategies. Finally, we consider the most important future developments.

Differences in T cell cytotoxicity and cell death mechanisms between progressive multifocal leukoencephalopathy, herpes simplex virus encephalitis and cytomegalovirus encephalitis

During the appearance of human immunodeficiency virus infection in the 1980 and the 1990s, progressive multifocal leukoencephalopathy (PML), a viral encephalitis induced by the JC virus, was the leading opportunistic brain infection. As a result of the use of modern immunomodulatory compounds such as Natalizumab and Rituximab, the number of patients with PML is once again increasing. Despite the presence of PML over decades, little is known regarding the mechanisms leading to death of infected cells and the role the immune system plays in this process. Here we compared the presence of inflammatory T cells and the targeting of infected cells by cytotoxic T cells in PML, herpes simplex virus encephalitis (HSVE) and cytomegalovirus encephalitis (CMVE). In addition, we analyzed cell death mechanisms in infected cells in these encephalitides. Our results show that large numbers of inflammatory cytotoxic T cells are present in PML lesions. Whereas in HSVE and CMVE, single or multiple appositions of CD8⁺ or granzyme-B⁺ T cells to infected cells are found, in PML such appositions are significantly less apparent. Analysis of apoptotic pathways by markers such as activated caspase-3, caspase-6, poly(ADP-ribose) polymerase-1 (PARP-1) and apoptosis-inducing factor (AIF) showed upregulation of caspase-3 and loss of caspase-6 from mitochondria in CMVE and HSVE infected cells. Infected oligodendrocytes in PML did not upregulate activated caspase-3 but instead showed translocation of PARP-1 from nucleus to cytoplasm and AIF from mitochondria to nucleus. These findings suggest that in HSVE and CMVE, cells die by caspase-mediated apoptosis induced by cytotoxic T cells. In PML, on the other hand, infected cells are not eliminated by the immune system but seem to die by virus-induced PARP and AIF translocation in a type of cell death defined as parthanatos.