Interferon beta-1a in MS: results following development of neutralizing antibodies in PRISMS.

BACKGROUND: Debate continues concerning the relevance of neutralizing antibody (NAb) development on the efficacy of interferon (IFN) therapy in patients with multiple sclerosis (MS). The PRISMS (Prevention of Relapses and Disability by Interferon beta-1a Subcutaneously in Multiple Sclerosis) Study of subcutaneous IFNbeta-1a showed significant benefit on all efficacy outcomes with no significant impact from NAb development on relapses at 2 years. The 2-year extension permitted longer observation following NAb development. METHODS: Exploratory post-hoc analyses of pharmacodynamic response and clinical and MRI outcomes were performed on data from 368 patients with relapsing MS treated with IFN from study start, based on NAb status. RESULTS: Persistent NAbs, above 20 NU/mL, were present in 14% of the 44-microg three times weekly (TIW) and 24% of the 22-microg TIW group over 4 years. NAb development was associated with reduced pharmacodynamic marker induction at 1 year. Over the entire 4 years of study, relapse and disability measures were similar between NAb+ and NAb- patients. However, once NAbs developed, significant differences were noted between NAb+ and NAb- groups, particularly on MRI and relapse measures. The presence of binding antibodies alone did not affect outcome. CONCLUSION: Neutralizing antibody development in interferon-treated patients is correlated with reduced efficacy and is a potential cause for renewed disease activity.

Anti-alpha4 integrin therapy for multiple sclerosis: mechanisms and rationale.

The symptoms, severity, and course of multiple sclerosis (MS) vary among patients, leading to complex treatment issues. In recent years, research has focused on specific adhesion molecules that participate in the activation and function of lymphocytes, especially the migration of these cells to sites of inflammation. In particular, the integrin, very late activation antigen (VLA)-4, has been implicated in mediating adhesion and migration of immune cells through interaction with its ligand, vascular cell adhesion molecule (VCAM)-1. VLA-4 is comprised of alpha4/beta1 and is critical in mediating Th-1 cell migration in the animal model of MS, experimental autoimmune encephalomyelitis, and has been the target of several recent clinical trials in MS. The humanized monoclonal antibody to alpha4 integrin, natalizumab (Tysabri, Biogen Idec/Elan), was recently approved in the United States for the treatment of relapsing MS. The authors discuss the mechanisms by which alpha4 integrins alter lymphocyte function as a rationale for anti-alpha4 integrin use in MS.

Significant linkage to migraine with aura on chromosome 11q24.

Migraine with aura (MA) is a prevalent neurological condition with strong evidence for a genetic basis. Familial hemiplegic migraine, a rare Mendelian form of MA, can be caused by mutations in the calcium channel gene, CACNA1A or in the ATP1A2 gene, a Na+/K+ pump. Susceptibility genes for the more prevalent forms of migraine have yet to be identified despite several reports of linkage including loci on 4q24, 1q31, 19p13 and Xq24-28. We have undertaken a genome-wide screen of 43 Canadian families, segregating MA with families chosen for an apparent autosomal dominant pattern of transmission. Diagnosis was based upon International Headache Society Criteria. Parametric linkage analysis revealed a novel locus on 11q24 with a two-point LOD score of 4.2 and a multi-point parametric LOD score of 5.6. We did not find any support for linkage at previously reported loci. The lack of consensus amongst linkage studies, including this study, is probably an indication of the heterogeneity that is inherent for MA. Nevertheless, the finding of a highly significant locus with a LOD score of 5.6 is powerful evidence that a gene increasing susceptibility to MA resides on 11q24. Several candidate genes map to this region of the genome including a number of ion channel genes such as GRIK4, SCNB2, KCNJ5 and KCNJ1.

Interferons in relapsing remitting multiple sclerosis: a systematic review.

BACKGROUND: Recombinant interferons have been approved by many national regulatory agencies for treatment of relapsing remitting multiple sclerosis, but widespread discussion continues about their true effectiveness, benefits, side-effects, and costs. METHODS: With the Cochrane Collaboration methodology, we reviewed all published, randomised, placebo-controlled trials of recombinant interferons undertaken in patients with relapsing remitting multiple sclerosis between 1993 and 2002. Our primary aim was to find out whether recombinant interferons reduced the number of patients who had clinical exacerbations and disease progression, compared with placebo. FINDINGS: The seven trials that met our criteria included 1215 randomised patients: data from 667 (55%) were available for analysis at 1 year's and from 919 (76%) at 2 years' follow-up. Interferon seemed to reduce the number of patients who had exacerbations during the first year of treatment (relative risk 0.73, 95% CI 0.54-0.99), but results at 2 years' follow-up were not robust and were difficult to interpret because of the many dropouts. Although the number of patients who had exacerbations (0.81, 0.74-0.89) or progressed (0.70, 0.55-0.88) during the first 2 years fell significantly in the protocol analysis, results were inconclusive after sensitivity analyses for exacerbations (1.11, 0.73-1.68) and disease progression (1.31, 0.60-2.89). Data were insufficient to establish whether steroid use and admissions to hospital were reduced in the interferon group. Similarly, MRI outcome data could not be analysed quantitatively. Side-effects were common, and acute toxic effects adversely affected quality of life. INTERPRETATION: Recombinant interferons slightly reduce the number of patients who have exacerbations during first year of treatment. Their clinical effect beyond 1 year is uncertain and new trials are needed to assess their long-term effectiveness and side-effects.

A controlled trial of natalizumab for relapsing multiple sclerosis.

BACKGROUND: In patients with multiple sclerosis, inflammatory brain lesions appear to arise from autoimmune responses involving activated lymphocytes and monocytes. The glycoprotein alpha4 integrin is expressed on the surface of these cells and plays a critical part in their adhesion to the vascular endothelium and migration into the parenchyma. Natalizumab is an alpha4 integrin antagonist that reduced the development of brain lesions in experimental models and in a preliminary study of patients with multiple sclerosis. METHODS: In a randomized, double-blind trial, we randomly assigned a total of 213 patients with relapsing-remitting or relapsing secondary progressive multiple sclerosis to receive 3 mg of intravenous natalizumab per kilogram of body weight (68 patients), 6 mg per kilogram (74 patients), or placebo (71 patients) every 28 days for 6 months. The primary end point was the number of new brain lesions on monthly gadolinium-enhanced magnetic resonance imaging during the six-month treatment period. Clinical outcomes included relapses and self-reported well-being. RESULTS: There were marked reductions in the mean number of new lesions in both natalizumab groups: 9.6 per patient in the placebo group, as compared with 0.7 in the group given 3 mg of natalizumab per kilogram (P<0.001) and 1.1 in the group given 6 mg of natalizumab per kilogram (P<0.001). Twenty-seven patients in the placebo group had relapses, as compared with 13 in the group given 3 mg of natalizumab per kilogram (P=0.02) and 14 in the group given 6 mg of natalizumab per kilogram (P=0.02). The placebo group reported a slight worsening in well-being (a mean decrease of 1.38 mm on a 100-mm visual-analogue scale), whereas the natalizumab groups reported an improvement (mean increase of 9.49 mm in the group given 3 mg of natalizumab per kilogram and 6.21 mm in the group given 6 mg of natalizumab per kilogram). CONCLUSIONS: In a placebo-controlled trial, treatment with natalizumab led to fewer inflammatory brain lesions and fewer relapses over a six-month period in patients with relapsing multiple sclerosis.