Natalizumab therapy of multiple sclerosis: recommendations of the Multiple Sclerosis Study Group--Italian Neurological Society.

Three years after the introduction of natalizumab (NA) therapy for the second line treatment of relapsing-remitting multiple sclerosis (MS), Italian MS centers critically reviewed the scientific literature and their own clinical experience. Natalizumab was shown to be highly efficacious in the treatment of MS. However, the risk of progressive multifocal leukoencephalopathy was confirmed and defined better. This article summarizes the MS-SIN Study Group recommendations on the use of NA in MS, with particular reference to the appropriate selection and monitoring of patients as well as to the management of adverse events.

Neutralizing antibodies in multiple sclerosis patients treated with 375 micrograms interferon-beta-1b.

BACKGROUND: Neutralizing antibodies (NAbs) to IFN-beta may have a detrimental effect on treatment response, but increasing IFN-beta dose could reduce their occurrence. The OPTimization of Interferon for MS (OPTIMS) study was a multicenter trial investigating clinical and MRI outcomes with the approved IFN-beta-1b dose (250 microg) and a higher dose (375 microg), s.c. every other day. OBJECTIVE: To analyze the occurrence of NAbs and their effect on clinical and MRI response over a long-term (4-year) follow-up using cross-sectional and longitudinal statistical analysis. METHODS: Relapses or disease progression was assessed open-label and MRI scans were performed serially during the first year of the study. Neutralizing antibodies were measured using the MxA protein production neutralization assay. RESULTS: A total of 145 patients with relapsing-remitting multiple sclerosis from 14 centers participated in the study. Neutralizing antibody frequency was negatively associated with MRI treatment response, but no detrimental effect of NAbs on the clinical response was observed. Results obtained using cross-sectional or longitudinal statistical approaches were similar. Over the 4-year period, NAb-positive patients treated with 375 microg had a significantly greater probability of NAb disappearance (hazard ratio: 3.41; 95% confidence interval: 1.78 - 6.43; p < 0.01). CONCLUSION: Use of an IFN-beta-1b dose higher than the currently approved 250-microg dose is associated with an increased probability of NAb disappearance. The OPTIMS study was registered at ClinicalTrials.gov: NCT00473213.

Recombinant interferon beta or glatiramer acetate for delaying conversion of the first demyelinating event to multiple sclerosis.

BACKGROUND: Immunomodulatory drugs have been shown to be only modestly effective in clinically definite relapsing remitting multiple sclerosis (RRMS). It has been hypothesized that their efficacy could be higher if used at the first appearance of symptoms, that is in the clinically isolated syndromes (CIS) suggestive of demyelinating events, a pathology which carries a high risk to convert to clinically definite MS (CDMS). OBJECTIVES: The objective of this review was to assess the effects of immunomodulatory drugs compared to placebo in adults in preventing conversion from CIS to CDMS which means the prevention of a second attack. SEARCH STRATEGY: We searched the Cochrane MS Group Trials Register (June 2007), Cochrane Central Register of Controlled Trials (CENTRAL)The Cochrane Library Issue 3, 2007, MEDLINE (January 1966 to June 2007), EMBASE (January 1974 to June 2007) and reference lists of articles. We also contacted manufacturers and researchers in the field. SELECTION CRITERIA: The trials selected were double-blind, placebo-controlled, randomised trials of CIS patients treated with immunomodulatory drugs. DATA COLLECTION AND ANALYSIS: Study selection have been independently done by two reviewers. Two further reviewers independently assessed trial quality and extracted and analysed data. Study authors were contacted for additional informations. Adverse effects information was collected from the trials. MAIN RESULTS: Only three trials tested the efficacy of interferon (IFN) beta including a total of 1160 participants (639 treatment, 521 placebo); no trial tested the efficacy of glatiramer acetate (GA). The metanalyses showed that the proportion of patients converting to CDMS was significantly lower in IFN beta-treated than in placebo-treated patients both after one year (pooled OR 0.53; 95% CI, 0.40 to 0.71; p <0.0001) as well as after two years of follow-up (pooled OR 0.52; 95% CI, 0.38 to 0.70; p <0.0001). Early treatment with IFN beta was associated with the side effect profile reported by the randomised controlled trials with this drug. Since side effects were reported with some heterogeneity in the three studies the metanalysis was possible only for the frequency of serious adverse events, not significantly different in IFN beta-treated or placebo-treated patients. AUTHORS' CONCLUSIONS: The efficacy of IFN beta treatment on preventing the conversion from CIS to CDMS was confirmed over two years of follow-up. Since patients had some clinical heterogeneity (length of follow-up, clinical findings of initial attack), it could be useful for the clinical practice to further analyse the efficacy of IFN beta treatment in different patient subgroups.

MRI activity and neutralising antibody as predictors of response to interferon beta treatment in multiple sclerosis.

OBJECTIVE: To prospectively validate MRI activity and neutralising anti-interferon antibody (NAb) during the first 6 months of interferon beta treatment as response indicators in multiple sclerosis (MS). METHODS: Patients with relapsing-remitting MS were followed during the first 2 years of treatment. Neurological assessments were performed every 3 months or when a relapse was suspected. MRI scans performed at baseline and at 3, 4, 5 and 6 months after the start of treatment were assessed centrally for disease activity: new T2 or gadolinium enhancing T1 lesions. NAb were assessed using the MxA protein assay; positivity was defined as two consecutive titres >or=20 NU/ml. We evaluated the predictivity of an active scan, NAb positivity, or both, during the first 6 months of treatment, on the occurrence of clinical disease activity in the following 18 months. RESULTS: 147 patients were assessed at 16 centres. Predictivity parameters (with confidence intervals) were as follows: active scan, sensitivity (SN) 52% (34-69%), specificity (SP) 80% (65-91%), negative predictive value (NPV) 73% (58-77%), positive predictive value (PPV) 62% (42-79%), p = 0.002; NAb positivity, SN 71% (45-88%), SP 66% (55-76%), NPV 92% (82-97%), PPV 29% (16-45%), p = 0.01; active scan and NAb positivity, SN 71% (38-91%), SP 86% (73-94%), NPV 94% (86-98%), PPV 50% (29-70%), p = 0.0003. CONCLUSIONS: MRI activity and NAb occurrence during the first 6 months of interferon beta treatment were reliable predictors of long term clinical response, particularly when combined. Patients with negative predictors showed a less than 10% risk of developing clinical activity. Patients with positive predictors showed a 50% risk of further clinical activity. These patients need to be followed carefully with further MRI and NAb tests.

Every-other-day interferon beta-1b versus once-weekly interferon beta-1a for multiple sclerosis (INCOMIN Trial) II: analysis of MRI responses to treatment and correlation with Nab.

BACKGROUND: In RRMS, clinical exacerbations are usually associated with different types of active lesions at MRI, including: hyperintense lesions on T1-weighted post-gadolinium sequences; new hyperintense lesions or enlarging old lesions on PD/T2-weighted scans; or new hypointense lesions on T1-weighted pre-Gd sequences. OBJECTIVE/METHODS: Primary outcome was the occurrence of patients with at least one active MRI lesion of the different types indicated above during treatment with 250 microg every other day (EOD) interferon beta (IFNbeta)-1b or 30 microg once weekly (OW) IFNbeta-1a in outpatients with RRMS (INCOMIN Trial). RESULTS: The number of patients with at least one 'active' lesion, evaluated over the two-year follow-up, was significantly (P = 0.014) lower in the EOD IFNbeta-1 b arm (1 3/76, 17%) then in the OW IFNbeta-1a arm (25/73, 34%). NAb frequency over two-year follow-up was 22/65 (33.8%) in the EOD IFNbeta-1b arm and 4/62 (6.5%) in the OW IFNbeta-1a arm, significantly greater in the EOD IFNbeta-1b arm. CONCLUSIONS: The development of MRI active lesions is strongly reduced by EOD-IFNbeta-1b compared with OW-IFNbeta-1a, indicating that EOD-IFNbeta-1b is more effective than OW-IFNbeta-1a in reducing ongoing inflammation and demyelination in MS. Logistic regression showed that NAb status did not affect the risk of MRI activity.

Thalidomide neuropathy: clinical, electrophysiological and neuroradiological features.

OBJECTIVE: Thalidomide is a promising therapy for multiple myeloma. Sensory neuropathy is a side effect of thalidomide and resulted to be partially reversible in 50% of cases, suggesting a sensory ganglionopathy. Spinal cord magnetic resonance imaging (MRI) was found to be useful in the diagnosis of sensory ganglionopathies and we use it to determine if thalidomide neuropathy has features of a ganglionopathy. MATERIAL AND METHODS: Six patients with multiple myeloma developed thalidomide-induced polyneuropathy. Nerve conduction studies, somatosensory-evoked potentials (SEPs) and cervical and dorsal spinal cord MRI were obtained in all. RESULTS: All patients had a sensory neuropathy, with clinical or electrophysiological abnormalities involving all four limbs. Spinal cord MRI showed high signal intensity in the posterior columns in only one patient, with abnormal central conduction time at SEPs. CONCLUSION: Our results suggest that thalidomide can induce either an axonal length-dependent neuropathy or, less frequently, a ganglionopathy.

Immunoglobulin treatment of multiple sclerosis: future prospects.

In one of the most frequent MS demyelination patterns, IgG and complement are demonstrable on myelin surface. It is, probably, an antibody-mediated pattern of myelin damage, usually associated with acute MS, but, at times, observed even in chronic cases. This pattern of myelin damage is extremely similar to that observed in acute demyelinating inflammatory polineuropathies, such as Guillain-Barré syndrome, and in acute disseminated encephalomyelitis (ADEM), a rare demyelinating disease usually occurring after a viral infection or vaccination. These pathologies response well to IgG treatment. Although hyperacute severe cases of MS seem to respond well to IgG treatment, this does not seem the case for other cases of relapses in relapsing-remitting MS. Several trials failed to provide clear evidence of clinical and MRI efficacy of high-dose IgG parenteral treatment in relapsing-remitting multiple sclerosis (MS). The study of Confavreux and the PRIMS study showed that the relapse rate decreases significantly during pregnancy in MS patients, while increases after delivery. IgG is not a cytostatic drug and therefore it has been tested to see whether it reduces relapse occurrence after delivery. In pregnant MS patients treated with high dose, Haas' study and our experience noted a slight increase relapse rate during the six month after delivery but lower than that showed in Confavreux and PRIMS studies in untreated pregnant MS women.

Different clinical, electrophysiological and immunological features of CIDP associated with paraproteinaemia.

Chronic inflammatory demyelinating polyneuropathy (CIDP) is frequently associated with monoclonal gammopathies of undetermined significance (MGUS), Waldenström disease and osteosclerotic myeloma. There are still controversies about the role of these paraproteinaemias in determining the clinical features and the response to treatment of CIDP. We review the clinical, electrophysiological and immunological features and the response to treatment of patients with CIDP associated with paraproteinaemias. The available literature suggest some conclusions: presence of antimyelin-associated glycoprotein (MAG) antibody (Ab) identifies patients with mainly sensory CIDP and low response to treatment; CIDP associated with IgM-paraproteinaemia without anti-MAG Ab probably are similar to CIDP not associated with paraproteinaemia as well as CIDP with IgG- or IgA-MGUS; however, some patients with IgA-MGUS can show features similar to CIDP with IgM paraproteinaemia and anti-MAG Ab. Low response to immunomodulating treatment in patients with mainly motor CIDP should prompt a careful research of an underlying osteosclerotic myeloma.

Hypothalamic-pituitary-adrenal axis function and cytokine production in multiple sclerosis with or without interferon-beta treatment.

OBJECTIVES: Pro-inflammatory cytokines mediate brain damage in multiple sclerosis (MS); they can also influence the hypothalamic-pituitary-adrenal (HPA) axis function. We evaluated the possible abnormalities of HPA axis function in relapsing-remitting MS (RR-MS). MATERIAL AND METHODS: IFN-gamma, TNF-alpha and IL-6 production by ex-vivo lymphocytes from 10 normal volunteers and 10 RR-MS patients before and during IFN-beta therapy was assessed; pituitary-adrenal function was evaluated by means of CRH and ACTH stimulation tests. RESULTS: In untreated patients the production of IFN-gamma, TNF-alpha, IL-6 was increased, and was significantly decreased by IFN-beta. Neither basal, nor stimulated ACTH, cortisol, DHEA, DHEAs, 17-alpha-OH-progesterone levels differed between controls and RR-MS patients, both before and during treatment. Moreover, no correlation was found between endocrine and immune parameters. CONCLUSION: In MS the HPA axis function seems normal and not influenced by IFN-beta treatment. This result is discussed in relation to the increased production of pro-inflammatory cytokines found in this disease.

High-dose intravenous immunoglobulin G treatment of myasthenia gravis.

IVIg is a safe and effective adjunctive treatment for myasthenia gravis, but there are no well established guidelines for the use of IVIg in this disease, lacking controlled randomized trials to assess its efficacy in homogeneous group of patients. The main advantages of IVIg are the rapid onset of the effect, the lack of long-term toxicity, and the possibility to reduce the required doses of immunosuppressive drugs. IVIg appears to have a role as an acute treatment in rapidly progressive myasthenia gravis weakness, particularly in situations when therapeutic apheresis is not feasible. In addition, IVIg is safer than plasma exchange (PE) in patients with hypotension or autonomic instability, in children, in patients of older age (>65 years), and in those suffering from sepsis. For these reasons, at present, IVIg are recommended during crises of myasthenia gravis in older patients when PE is contraindicated or not feasible IVIg can be also used as a chronic maintenance therapy when other immunosuppressive treatments have failed or cannot be used. Periodic administration of IVIg on a bimonthly or monthly basis may be able to stabilize chronic, nonresponding patients.

High-dose intravenous immunoglobulin treatment of multiple sclerosis.

A review of the pathological basis of multiple sclerosis is presented to see whether the many immunological effects if IVIg may exert some benefit and at what level. This is probably due to the wide spectrum of interactions between IVIg and the immune system, which are analyzed in this review. Macrophage Fc receptor saturation and block, anti-idiotypic effect, reduction of endothelial cell activation and superantigen-neutralizing antibodies are probably involved in the action of IVIg in dysimmune demyelinating diseases. Furthermore, IVIg promote remyelination in virus-induced experimental encephalomyelitis. Trials on IVIg in MS demonstrated a reduction of relapse rate (RR) and appearance of gadolinium-enhancing lesions on magnetic resonance imaging. Furthermore IvIg are regarded as a promising treatment to reduce RR in post-partum period. However, studies on secondary-progressive MS failed to demonstrate an IVIg effect on disability and IVIg failed to improve stabilized visual and motor deficits in two large trials.

Effects of high doses of corticosteroids on bone metabolism.

The effects of a chronic treatment with corticosteroids on bone are well known, but few data are available regarding the acute effect of these drugs on bone turnover. This study was aimed at evaluating the effects of high doses of corticosteroids administered for a short period on bone metabolism. We assessed 23 subjects (15 women and 8 men) suffering from multiple sclerosis and treated with methylprednisolone (1 g i.v. for 10 days) followed by oral prednisone for 9 days; patients affected by diseases involving bone or treated during the previous 6 months with drugs influencing bone metabolism were excluded. We observed a significant decrease of ALP and bone glia protein (BGP), in these subjects, and a significant sudden increase of urinary calcium/creatinine and urinary cross-laps after 3 days of treatment. All of these parameters, except urinary calcium/creatinine, returned to basal levels after 30 days from the beginning of treatment (11 days after the interruption of corticosteroids administration). Serum phosphorus showed a significant decrease after 3 days of treatment, but returned to basal levels after 10 days. These data suggest that high doses of corticosteroids administered for a short period are able to induce an increase of bone resorption and a decrease of bone formation; moreover, bone turnover returns to basal levels when the treatment is stopped.

Autoantibodies in multiple sclerosis patients before and during IFN-beta 1b treatment: are they correlated with the occurrence of autoimmune diseases?

Autoimmune side effects, namely autoantibody (autoAb) occurrence and thyroid function alteration, have been described during interferon-beta (IFN-beta) treatment for multiple sclerosis (MS). AutoAb occurrence and autoimmune thyroid diseases are also frequently detected in MS patients free of any treatment. The aim of this study was to evaluate the relationship between IFN-beta 1b treatment, autoAb occurrence, and autoimmune diseases in MS. Thyroid and liver function and serum autoAb (antithyroid, antinuclear, anti-liver, anti-kidney microsomes, anti-smooth muscle and parietal cell antigens) occurrence were evaluated in 156 relapsing-remitting MS (RRMS) patients before and every 3 months after starting IFN-beta 1b treatment (8 MIU subcutaneously [s.c.] on alternate days). The probability of having liver or thyroid function alteration or autoAb occurrence was analyzed longitudinally with the generalized estimating equations (GEE) approach. At baseline, 16.1% of patients had autoAb. During treatment, autoAb occurred de novo in 7.2% of patients. GEE analysis showed that the probability of having autoAb at any time during IFN-beta 1b treatment did not change significantly compared with baseline. AutoAb occurring de novo rarely persisted during treatment and significantly less than those already present at baseline. Positivity for autoAb at baseline or during treatment was not correlated with the development of thyroid or liver function alteration during IFN-beta 1b treatment. Our study indicates that IFN-beta treatment is a safe treatment for MS patients, free of risk of autoimmunity and of associated liver or thyroid function alteration.

Thyroid function and anti-thyroid antibodies in MS patients screened for interferon treatment. A multicenter study.

Interferon beta (IFNB) treatment for multiple sclerosis (MS) has been associated with thyroid disorders (TD), in particular in patients with subclinical TD or anti-thyroid (AT) autoantibodies (autoAb) before starting treatment. TD and AT autoAb frequency was reported increased in MS. To determine whether MS patients have subclinical thyroid function abnormalities or anti-thyroid autoimmunity predisposing to develop TD, we performed a prospective multicenter screening of thyroid function and autoimmunity in 152 relapsing-remitting (RR) MS patients selected to receive IFNB treatment and in 437 healthy normothyroidal controls. Thyroid-related hormones and anti-thyroid microsomal antigen (anti-TMA) autoAb were tested with sensitive immunoradiometric or chromatographic assays. Cases were stratified for different progressively decreasing or increasing cutoff values of thyroid-stimulating hormone (TSH) (0.3, 0.2, 0.1, 3 and 5 mIU/l), and odds ratios (OR) with 95% confidence intervals (CI) calculated using logistic regression adjusted for gender, age, and anti-TMA autoAb positivity. The frequency of cases below or above the TSH cutoff values was not significantly different in MS patients and controls, and the risk to have an abnormal TSH level was not significantly increased in MS patients (OR ranging 0.37-0.84; CI, 0.05-3.01), even if anti-TMA autoAb positive (OR ranging 0.35-0.85; CI, 0.04-3.00). Frequencies of subclinical hypothyroidism and of anti-TMA autoAb positivity were, however, trending higher in MS men (ranging 5-7%) than in controls (3%). MS patients do not have an increased risk of subtle thyroid function abnormalities, subclinical TD, or anti-TMA autoAb positivity that may predispose to develop thyroid dysfunction during IFNB treatment. The positive trend for subclinical hypothyroidism and anti-TMA autoAb positivity, however, advises a longitudinal study of thyroid function and autoimmunity during IFNB treatment to see whether patients with baseline subclinical thyroid dysfunction develop clinically significant alteration during treatment.

Liver and thyroid function and autoimmunity during interferon-beta 1b treatment for MS.

BACKGROUND: The occurrence or recurrence of autoimmune diseases or of autoantibodies (autoAb) has been reported during type I interferon (IFN) treatment. OBJECTIVE: To define the frequency of thyroid and liver dysfunction and of autoimmunity during IFN-beta 1b (IFNB) treatment of MS. METHODS: Prospective 1-year multicenter follow-up of 156 patients with MS recruited by 18 centers was conducted. Thyroid-stimulating hormone and anti-thyroid autoAb were measured by an immunoradiometric method, thyroid hormones by chromatographic assay, and non-organ-specific autoAb by indirect immunofluorescence. Tests were repeated every 3 months. The probability of having liver, thyroid, or autoAb alterations was analyzed longitudinally with the generalized estimating equations (GEE) method. RESULTS: Thyroid dysfunction was observed in 5.3% of cases at baseline and 8.3% de novo during IFNB treatment. GEE analysis showed that the probability of having thyroid alteration did not change significantly during treatment compared with baseline. Liver alteration was observed in 4.6% of cases at baseline and 37.5% de novo during IFNB treatment (p < 0.0001). GEE analysis showed that the probability of having liver alteration was higher (p < 0.002) at months 3 and 6 compared with baseline, returning to values similar to baseline by month 9. AutoAb were detected in 16.1% of patients at baseline and in 20% during IFNB. GEE analysis showed that the probability of having autoAb did not change significantly during treatment compared with baseline. Thyroid or liver alteration or autoAb occurring de novo during IFNB were usually transient. CONCLUSIONS: Differently from the frequency of liver function alteration (which significantly increased during the first months of IFNB treatment, suggesting a probable causal relationship with IFNB), the frequency of thyroid dysfunction or of autoimmunity showed random and insignificant changes over time, probably not related to IFNB treatment.

Interferon-beta dose and efficacy: the OPTIMS study.

Interferon beta (IFN-beta) reduces exacerbation rates in patients with relapsing-remitting multiple sclerosis (MS), but some patients do not respond to treatment. Recent studies have shown a clear dose-response effect on the reduction of exacerbation rates, and on burden of disease accumulation and active lesion frequency seen on MRI. During treatment with 8 MIU IFN-beta we noticed a 30% rate of treatment failure. We then treated non-responders with 12 MIU IFN-beta and observed significant improvement in the clinical signs of disease activity. In order to compare the efficacy of two different doses of IFN-beta-1b, a multicenter study for the optimization of interferon for MS (OPTIMS) has been organized. The design of the study is presented here.

Terminal latency index in polyneuropathy with IgM paraproteinemia and anti-MAG antibody.

Criteria for the diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP) are met by the polyneuropathy associated with immunoglobulin M (IgM) paraproteinemia and anti-myelin-associated glycoprotein (MAG) antibody (MAG-CIDP). However, MAG-CIDP differs from other types of CIDP, mainly in its poorer response to treatment. The utility of terminal latency index (TLI) as an electrophysiological marker for MAG-CIDP has been debated. In this study we confirmed its diagnostic usefulness and evaluated TLI threshold values for motor nerves investigated in routine nerve conduction studies. Median, ulnar, peroneal, and tibial TLIs of 11 subjects with MAG-CIDP, 18 with CIDP, and 76 healthy controls were compared, and threshold values for MAG-CIDP evaluated as the lowest value with a likelihood ratio higher than 10. Mean TLI values and TLIs of all but the peroneal nerve were significantly lower in MAG-CIDP. Median nerve TLI of 0.26 and ulnar nerve TLI of 0.33 were identified as the threshold TLI values for MAG-CIDP.

Thyroid function and autoimmunity during interferon beta-1b treatment: a multicenter prospective study.

Thyroid dysfunction and autoimmunity have been reported during type I interferon therapy, namely interferon-alpha for chronic hepatitis or interferon-beta for multiple sclerosis. To define the frequency of thyroid dysfunction and autoimmunity during interferon-beta treatment, 156 multiple sclerosis patients were prospectively followed up by 18 centers for 1 yr after starting interferon-beta-1b treatment. Serial clinical assessments and tests of thyroid and liver function and antithyroid autoantibodies (all performed by the same centralized laboratory) were conducted every 3 months. TSH and antithyroid autoantibodies against human TG or thyroid microsomal antigens were measured by immunoradiometric methods; free T3 and T4 were measured by chromatographic assays. Longitudinal occurrence of thyroid or liver alterations or of autoantibodies was analyzed with the generalized estimating equations method, correcting for the correlation of repeated measurements of the same subject over time. Pretreatment comparison with a control group of 437 healthy blood donors did not show significant differences in the frequency of thyroid dysfunction or antithyroid autoantibody positivity. During interferon-beta treatment, the de novo frequency of thyroid alteration was 8.3%, that of liver alteration was 37.5%, and that of antithyroid autoantibody was 4.5%. Generalized estimating equations analysis demonstrated that the frequency of liver alteration significantly increased during treatment compared with the baseline value (odds ratio, 7.03; confidence interval, 2.49-19.9), whereas that of thyroid alteration or of antithyroid autoantibodies did not. The frequency of thyroid dysfunction during interferon-beta treatment showed random, nonsignificant changes over time and, in addition, was not correlated to antithyroid autoantibody positivity.

Effect of early interferon treatment on conversion to definite multiple sclerosis: a randomised study.

BACKGROUND: Interferon beta reduces activity in multiple sclerosis as measured clinically and by magnetic resonance imaging (MRI). We assessed the effect of interferon beta-1a on the occurrence of relapses in patients after first presentation with neurological events, who are at high risk of conversion to clinically definite multiple sclerosis. METHODS: Eligible patients had had a first episode of neurological dysfunction suggesting multiple sclerosis within the previous 3 months and had strongly suggestive brain MRI findings. Patients were randomly assigned interferon beta-1a 22 microg or placebo subcutaneously once weekly for 2 years. Neurological and clinical assessments were done every 6 months and brain MRI every 12 months. Analyses excluded one patient assigned placebo who received no study injections. FINDINGS: 241 (78%) of 308 randomised patients received study treatment for 2 years; 278 (90%) remained in the study until termination. 57 (85%) of 67 who stopped therapy did so after conversion to clinically definite multiple sclerosis. Fewer patients developed clinically definite multiple sclerosis in the interferon group than in the placebo group (52/154 [34%] vs 69/154 [45%]; p=0.047). The time at which 30% of patients had converted to clinically definite multiple sclerosis was 569 days in the interferon group and 252 in the placebo group (p=0.034). The annual relapse rates were 0.33 and 0.43 (p=0.045). The number of new T2-weighted MRI lesions and the increase in lesion burden were significantly lower with active treatment. INTERPRETATION: Interferon beta-1a treatment at an early stage of multiple sclerosis had significant positive effects on clinical and MRI outcomes.