Joep Killestein

T helper type 1 and 17 cells determine efficacy of interferon-[beta] in multiple sclerosis and experimental encephalomyelitis

Interferon-β (IFN-β) is the major treatment for multiple sclerosis. However, this treatment is not always effective. Here we have found congruence in outcome between responses to IFN-β in experimental autoimmune encephalomyelitis (EAE) and relapsing-remitting multiple sclerosis (RRMS). IFN-β was effective in reducing EAE symptoms induced by T helper type 1 (TH1) cells but exacerbated disease induced by TH17 cells. Effective treatment in TH1-induced EAE correlated with increased interleukin-10 (IL-10) production by splenocytes. In TH17-induced disease, the amount of IL-10 was unaltered by treatment, although, unexpectedly, IFN-β treatment still reduced IL-17 production without benefit. Both inhibition of IL-17 and induction of IL-10 depended on IFN-γ. In the absence of IFN-γ signaling, IFN-β therapy was ineffective in EAE. In RRMS patients, IFN-β nonresponders had higher IL-17F concentrations in serum compared to responders. Nonresponders had worse disease with more steroid usage and more relapses than did responders. Hence, IFN-β is proinflammatory in TH17-induced EAE. Moreover, a high IL-17F concentration in the serum of people with RRMS is associated with nonresponsiveness to therapy with IFN-β.

Recommendations for clinical use of data on neutralising antibodies to interferon-beta therapy in multiple sclerosis

The identification of factors that can affect the efficacy of immunomodulatory drugs in relapsing-remitting multiple sclerosis (MS) is important. For the available interferon-beta products, neutralising antibodies (NAb) have been shown to affect treatment efficacy. In June, 2009, a panel of experts in MS and NAbs to interferon-beta therapy convened in Amsterdam, Netherlands, under the auspices of the Neutralizing Antibodies on Interferon beta in Multiple Sclerosis consortium, a European-based project of the 6th Framework Programme of the European Commission, to review and discuss data on NAbs and their practical consequences for the treatment of patients with MS on interferon beta. The panel believed that information about NAbs and other markers of biological activity of interferons (ie, myxovirus resistance protein A [MxA]) can be integrated with clinical and imaging indicators to guide individual treatment decisions. In cases of sustained high-titre NAb positivity and/or lack of MxA bioactivity, a switch to a non-interferon-beta therapy should be considered. In patients who are doing poorly clinically, therapy should be switched irrespective of NAb or MxA bioactivity.

PML in a patient treated with dimethyl fumarate from a compounding pharmacy.

Two cases of progressive multifocal leukoencephalopathy (PML) are reported in patients with psoriasis who were treated with fumarates, one with Fumaderm and the other with a compound containing dimethyl fumarate. The manufacturer of Fumaderm comments on the reports.

Differential effect of drug interference in immunogenicity assays

The presence of anti-drug antibodies (ADA) in adalimumab-treated patients is associated with reduced serum adalimumab levels and a lower clinical response. Currently, there is no standard for measurement of anti-drug antibodies and many factors influence the results. Consequently, the incidence of ADA as reported in different studies varies considerably. Here we investigated the differential effect of drug interference in two common types of assays used to measure anti-adalimumab: an antigen binding test (ABT) and a more often-used bridging elisa. We measured ADA to adalimumab in a cohort of 216 rheumatoid arthritis patients treated with adalimumab for 28 weeks. Only 15 samples (7%) were positive in the bridging elisa, compared to 29 (13%) in the ABT, despite the fact that the bridging elisa was the most sensitive assay. Furthermore, in an ABT specific for IgG4, 48 samples (22%) were found positive. The bridging elisa was found to detect only the bivalent form of (drug-specific) IgG4, resulting in an underestimation of ADA levels. However, the predominant reason for the different outcomes of these assays was a differential susceptibility to drug interference. In particular, the bridging elisa only detected ADA in the absence of detectable amounts of circulating adalimumab and is therefore not suited for measurement of ADA in complex with the drug. In summary, we showed that a bridging elisa is susceptible to drug interference and typically measures ADA only in absence of detectable drug levels.

Natalizumab Drug Holiday in Multiple Sclerosis: Poorly Tolerated

It has been suggested that natalizumab‐associated progressive multifocal leukoencephalopathy may be prevented by structured interruptions of treatment. Evidence supporting such a drug holiday is not yet available. Here we present initial observations in 10 multiple sclerosis patients who were stringently monitored up to 6 months after discontinuation of the infusions. Cumulatively, a combination of clinical relapse and new and/or enhanced lesions on magnetic resonance imaging had occurred in 7 of 10 patients. Although numbers are small, our data suggest that in patients who were switched to natalizumab because of disease activity despite first‐line treatment, a natalizumab drug holiday without reinstatement of alternate disease‐modifying therapy is poorly tolerated. Ann Neurol 2010

Pharmacogenomics of Interferon-ß Therapy in Multiple Sclerosis: Baseline IFN Signature Determines Pharmacological Differences between Patients

Background Multiple sclerosis (MS) is a heterogeneous disease. In order to understand the partial responsiveness to IFNß in Relapsing Remitting MS (RRMS) we studied the pharmacological effects of IFNß therapy. Methodology Large scale gene expression profiling was performed on peripheral blood of 16 RRMS patients at baseline and one month after the start of IFNß therapy. Differential gene expression was analyzed by Significance Analysis of Microarrays. Subsequent expression analyses on specific genes were performed after three and six months of treatment. Peripheral blood mononuclear cells (PBMC) were isolated and stimulated in vitro with IFNß. Genes of interest were measured and validated by quantitative realtime PCR. An independent group of 30 RRMS patients was used for validation. Principal Findings Pharmacogenomics revealed a marked variation in the pharmacological response to IFNß between patients. A total of 126 genes were upregulated in a subset of patients whereas in other patients these genes were downregulated or unchanged after one month of IFNß therapy. Most interestingly, we observed that the extent of the pharmacological response correlates negatively with the baseline expression of a specific set of 15 IFN response genes (R = −0.7208; p = 0.0016). The negative correlation was maintained after three (R = −0.7363; p = 0.0027) and six (R = −0.8154; p = 0.0004) months of treatment, as determined by gene expression levels of the most significant correlating gene. Similar results were obtained in an independent group of patients (n = 30; R = −0.4719; p = 0.0085). Moreover, the ex vivo results could be confirmed by in vitro stimulation of purified PBMCs at baseline with IFNß indicating that differential responsiveness to IFNß is an intrinsic feature of peripheral blood cells at baseline. Conclusion These data imply that the expression levels of IFN response genes in the peripheral blood of MS patients prior to treatment could serve a role as biomarker for the differential clinical response to IFNß.

Efficacy of vitamin D3 as add-on therapy in patients with relapsing–remitting multiple sclerosis receiving subcutaneous interferon beta-1a: A Phase II, multicenter, double-blind, randomized, placebo-controlled trial

Recent studies have demonstrated the immunomodulatory properties of vitamin D, and vitamin D deficiency may be a risk factor for the development of MS. The risk of developing MS has, in fact, been associated with rising latitudes, past exposure to sun and serum vitamin D status. Serum 25-hydroxyvitamin D [25(OH)D] levels have also been associated with relapses and disability progression. The identification of risk factors, such as vitamin D deficiency, in MS may provide an opportunity to improve current treatment strategies, through combination therapy with established MS treatments. Accordingly, vitamin D may play a role in MS therapy. Small clinical studies of vitamin D supplementation in patients with MS have reported positive immunomodulatory effects, reduced relapse rates and a reduction in the number of gadolinium-enhancing lesions. However, large randomized clinical trials of vitamin D supplementation in patients with MS are lacking. SOLAR (Supplementation of VigantOL(®) oil versus placebo as Add-on in patients with relapsing-remitting multiple sclerosis receiving Rebif(®) treatment) is a 96-week, three-arm, multicenter, double-blind, randomized, placebo-controlled, Phase II trial (NCT01285401). SOLAR will evaluate the efficacy of vitamin D(3) as add-on therapy to subcutaneous interferon beta-1a in patients with RRMS. Recruitment began in February 2011 and is aimed to take place over 1 calendar year due to the potential influence of seasonal differences in 25(OH)D levels.

IL-7 promotes T(H)1 development and serum IL-7 predicts clinical response to interferon-beta in multiple sclerosis

High serum IL-7 predicts responsiveness of multiple sclerosis patients to IFN-β therapy and indicates a TH1 cell–driven disease. An Expanding View of IL-7 in Multiple Sclerosis Multiple sclerosis (MS) is an autoimmune disease characterized by loss of the myelin sheath protecting nerves, resulting in a variety of neurological symptoms including paralysis. Several genome-wide association studies have identified a variation (single-nucleotide polymorphism) in the gene encoding interleukin-7 receptor α (IL-7Rα), suggesting that this receptor may be associated with susceptibility to developing MS. Signaling via the IL-7R is necessary for the proliferation and survival of T lymphocytes. Now, Lee et al. investigate the role of IL-7 and its receptor on different T cell populations in MS. They show that IL-7 promotes the differentiation of human and mouse naïve T cells into T helper type 1 (TH1) cells but not TH17 cells. Both of these T helper cell populations are involved in the inflammatory response in MS. When the authors administered IL-7 to mice with experimental autoimmune encephalomyelitis (a mouse model of MS), disease symptoms were exacerbated. However, when they administered antibodies that blocked signaling via the IL-7Rα receptor, there was amelioration of disease symptoms even when antibodies were given after the onset of paralysis. The authors propose that blocking IL-7 or IL-7Rα may be a potential therapeutic strategy for treating MS driven by TH1 cells. Next, the authors wondered whether the IL-7 concentration in the serum of MS patients might be a useful indicator of whether the patients had MS driven by TH1 or TH17 cells. The authors demonstrate that high serum IL-7 concentrations correlate with MS driven by TH1 cells. To be able to identify MS patients with a TH1 or TH17 form of the disease is important because interferon-β (IFN-β) therapy given to patients with a TH1 form of MS improves symptoms, whereas IFN-β therapy given to patients with a TH17 form of the disease exacerbates symptoms. The authors go on to show that high IL-7 serum concentrations in MS patients indeed do correlate with a good clinical response of those MS patients to IFN-β therapy. Together, these data confirm the importance of IL-7 in TH1-driven MS and suggest that high serum concentrations of IL-7 could be used as a marker to identify MS patients with TH1-driven MS, who would benefit from IFN-β therapy. The interleukin-7 receptor α chain (IL-7Rα) gene was identified as a top non–major histocompatibility complex–linked risk locus for multiple sclerosis (MS). Recently, we showed that a T helper 1 (TH1)–driven, but not a TH17-driven, form of MS exhibited a good clinical response to interferon-β (IFN-β) therapy. We now demonstrate that high serum levels of IL-7, particularly when paired with low levels of IL-17F, predict responsiveness to IFN-β and hence a TH1-driven subtype of MS. We also show that although IL-7 signaling is neither necessary nor sufficient for the induction or expansion of TH17 cells, IL-7 can greatly enhance both human and mouse TH1 cell differentiation. IL-7 alone is sufficient to induce human TH1 differentiation in the absence of IL-12 or other cytokines. Furthermore, targeting IL-7/IL-7Rα is beneficial in experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. Mice treated with IL-7Rα–blocking antibodies before or after onset of paralysis exhibited reduced clinical signs of EAE, with reduction in peripheral naïve and activated T cells, whereas central memory T, regulatory T, B, and natural killer cell populations were largely spared. IL-7Rα antibody treatment markedly reduced lymphocyte infiltration into the central nervous system in mice with EAE. Thus, a serum profile of high IL-7 may signify a TH1-driven form of MS and may predict outcome in MS patients undergoing IFN-β therapy. Blockade of IL-7 and the IL-7Rα pathway may have therapeutic potential in MS and other autoimmune diseases.

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

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

Clinical relevance of serum natalizumab concentration and anti-natalizumab antibodies in multiple sclerosis.

Background: Antibodies against natalizumab have been found in 4.5–14.1% of natalizumab-treated multiple sclerosis (MS) patients. If antibodies persist, they are associated with an adverse effect on treatment response. However, it has proved to be difficult to standardize anti-drug antibody measurements. Objectives: The purpose of this study was to evaluate the clinical and radiological impact of serum natalizumab concentrations and their relation with anti-natalizumab antibodies in MS patients. Methods: In this prospective observational cohort study of 73 consecutive patients treated with natalizumab, we measured serum natalizumab levels and antibody titers before the start of natalizumab treatment, at weeks 12 and 24 and annually after natalizumab initiation. Antibodies against natalizumab were measured by radioimmunoassay and serum natalizumab concentrations using a newly developed enzyme linked immunosorbent assay (ELISA). Magnetic resonance imaging (MRI) scan and clinical evaluation were performed before the start of natalizumab treatment and subsequently every year. Results: Antibodies were detected in 58% of the natalizumab-treated patients. All patients developed their antibodies before week 24. The large majority of these patients reverted to neutralizing antibody (NAb) negative status during follow-up. The presence of antibodies was inversely correlated with serum natalizumab concentration (p<0.001). Only high antibody titers are associated with very low or undetectable serum natalizumab concentration. Both high antibody titers and low serum natalizumab concentrations are associated with relapses and gadolinium-enhancing lesions on MRI. Conclusions: Our data show that both low natalizumab serum concentration and high antibody titers are associated with a lack of efficacy of natalizumab. Measuring serum natalizumab, using a highly specific assay, might lead to more enhanced precision using natalizumab in individual patients.