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PubMed2006

Natalizumab for induction of remission in Crohn's disease.

BACKGROUND: The pathogenesis of Crohn's disease involves migration of leukocytes into gut tissue and subsequent inflammation. Natalizumab (Tysabri, Elan Pharmaceuticals and Biogen Idec) a recombinant humanized IgG4 monoclonal antibody that blocks adhesion and subsequent migration of leukocytes into the gut by binding the alpha4 integrin is a member of a new class of molecules known as selective adhesion molecule (SAM) inhibitors. The results of animal studies suggest that alpha4 integrin blockade could be a useful therapy for inflammatory bowel disease. The results of randomized controlled trials suggest that natalizumab may be an effective therapy for active Crohn's disease. This systematic review summarizes the current evidence on the use of natalizumab for the induction of remission in Crohn's disease. OBJECTIVES: To determine the efficacy and safety of natalizumab for induction of remission in Crohn's disease. SEARCH STRATEGY: A computer assisted search of the Cochrane Central Register of Controlled Trials, the Cochrane Inflammatory Bowel Disease and Functional Bowel Disorders Review Group Specialized Trials Register, MEDLINE and EMBASE was performed to identify relevant publications between 1966 and June 2005. The medical subject heading (MeSH) terms "Crohn disease" or "inflammatory bowel disease", "Natalizumab" or "Antegren" or "Tysabri" and "Antibodies, Monoclonal" were used to perform key word searches of each database. Manual searches of reference lists from potentially relevant papers were performed in order to identify additional studies that may have been missed using the computer-assisted search strategy. Abstracts from major gastroenterological meetings were searched to identify research submitted in abstract form only. Personal contacts, leaders in the field, and the manufacturers were contacted to identify other studies which may not be published. SELECTION CRITERIA: We included only randomized controlled trials comparing natalizumab to a placebo or control therapy for the induction of remission in Crohn's disease. DATA COLLECTION AND ANALYSIS: Data were analyzed using Review Manager (RevMan 4.2.8). All data were analyzed on an intention-to-treat basis. For pooled data, summary test statistics were derived using the relative risk and 95% confidence intervals. Fixed and random effects models were used where appropriate. The definitions of treatment success, remission and clinical improvement were set by the authors of each paper, and the data were combined for analysis only if these definitions were sufficiently similar. MAIN RESULTS: Pooled data from the three included studies suggest that natalizumab (3 to 4 mg/kg) may be effective for induction of clinical response and remission in patients with moderately to severely active Crohn's disease. This benefit is statistically significant for one, two and three infusion treatments. There was a trend toward increased benefit with additional infusions of natalizumab. Natalizumab appears to provide greater benefit for patient subgroups characterized by objective confirmation of active inflammation or chronically active disease despite conventional therapies. These subgroup analyses demonstrated significantly greater clinical response and remission rates for natalizumab compared with placebo in patients with elevated C-reactive protein levels, active disease despite the use of immunosuppressants, or prior anti-tumor necrosis factor therapy. These benefits were apparent for both short term (one infusion) and longer term treatment (two or three infusions). Natalizumab was generally well tolerated and the safety profile observed in the three included studies was similar. Adverse events occurred infrequently and were experienced by a similar proportion of natalizumab and placebo treated patients. There were no statistically significant differences between natalizumab and placebo treated patients in the proportions of patients who withdrew due to adverse events or those who experienced serious adverse events. The included trials lacked adequate power to detect serious adverse events that occur infrequently. Recently, two patients with multiple sclerosis treated with natalizumab in combination with interferon beta-1a and one patient with Crohn's disease treated with natalizumab in combination with azathioprine developed progressive multifocal leukoencephalopathy (PML) resulting in two patient deaths. As a result all dosing in clinical trials and commercial use of natalizumab has been suspended. A retrospective investigation was conducted to assess the risk of PML in natalizumab treated patients and no new cases were identified. AUTHORS' CONCLUSIONS: Pooled data and the results of an ongoing study suggest that natalizumab may be effective for induction of clinical response and remission in patients with moderately to severely active Crohn's disease. The clinical benefit of induction therapy with natalizumab in Crohn's disease should be weighed against the potential risk of serious adverse events. Currently natalizumab is not available on the market for routine clinical use as a consequence of the unexpected association with PML. However, preliminary data from the retrospective investigation of adverse events associated with natalizumab suggest that it may be possible to identify patients at risk for PML by testing for the appearance of JC virus in plasma.

Antibodies, Monoclonal↗

PubMed2004

Natalizumab: AN 100226, anti-4alpha integrin monoclonal antibody.

Natalizumab [AN 100226, anti-alpha4 integrin monoclonal antibody, Antegren] is a humanised monoclonal antibody that blocks alpha4beta1 integrin-mediated leukocyte migration. Natalizumab is in phase III trials for the treatment of multiple sclerosis in North America and the UK, and for the treatment of Crohn's disease also in the UK. It may have potential in the treatment of other immune-related inflammatory disease. Elan Corporation intends to examine the potential of natalizumab in rheumatoid arthritis and ulcerative colitis. 4beta1 integrin on circulating leukocytes binds to vascular cell adhesion molecule-1, which is expressed at high levels in the blood vessels in the CNS during exacerbations of multiple sclerosis. This allows leukocytes expressing alpha4beta1 integrin (very late antigen-4) to move from the peripheral blood into the CNS. Inflammatory proteins and other factors released from lymphocytes in the brain lead to the progression of symptoms. A limitation of natalizumab is that it must be injected and cannot be administered orally. Scientists have transformed the large anti-alpha4 monoclonal antibody into much smaller, drug-like molecules suitable for oral administration. Protein Design Labs has granted a worldwide nonexclusive licence under its antibody humanisation patents to Elan Pharmaceuticals for natalizumab. Biogen Inc. has entered into an agreement with Elan for a worldwide exclusive collaboration to develop, manufacture and commercialise natalizumab for multiple sclerosis and Crohn's disease and rheumatoid arthritis. Development of natalizumab is also being funded, in part, by Axogen (acquired by Elan in 1999). In November 2003, Biogen and IDEC Pharmaceuticals merged to form Biogen Idec. Elan repurchased royalty rights on a package of products, including natalizumab, from Autoimmune Disease Research Company. Elan and Genzyme Transgenics Corporation signed an agreement to produce natalizumab in GTC's genetically engineered goats, which will express the compound in their milk. Genzyme Transgenics Corporation changed its name to GTC Biotherapeutics in June 2002; it is no longer a subsidiary of Genzyme Corporation. Following discussions with the US FDA, Elan completed enrolment in a second phase III trial, involving approximately 420 patients with Crohn's disease. This Evaluation of Natalizumab as Continuous Therapy-2 (ENACT-2) trial evaluated the effect of natalizumab on duration of response and remission in patients with Crohn's disease. In January 2004, Elan Corporation and Biogen Idec announced that the phase III, ENACT-2 maintenance trial of natalizumab in Crohn's disease met the primary endpoint of maintenance of response. Elan and Biogen Idec will discuss these data with regulatory authorities in both the US and Europe and determine the appropriate path forward for natalizumab in Crohn's disease. An NDA for Antegren in Crohn's disease was expected to be filed at the end of 2003; however, due to failing to meet the primary endpoint in the induction trial, Elan is unable to predict when and if a regulatory filing will be made. Earlier, on 23 January 2001, the Wall Street Journal reported that the Biogen CEO expects Antegren to become a blockbuster drug, with sales of at least $US1 billion. He also predicted that Antegren could be on the market as early as 2003 for the indication of Crohn's disease and in 2004 for multiple sclerosis. The Journal stated that Biogen is under pressure to develop new drugs since its flagship product Avonex will be losing its US Orphan Drug Act protection in 2003. Antegren has a different mechanism to that of Avonex and could be used either alone or as a combination therapy.

Animals↗

PubMed2005

Natalizumab induction and maintenance therapy for Crohn's disease.

BACKGROUND: Natalizumab, a humanized monoclonal antibody against alpha4 integrin, inhibits leukocyte adhesion and migration into inflamed tissue. METHODS: We conducted two controlled trials to evaluate natalizumab as induction and maintenance therapy in patients with active Crohn's disease. In the first trial, 905 patients were randomly assigned to receive 300 mg of natalizumab or placebo at weeks 0, 4, and 8. The primary outcome was response, defined by a decrease in the Crohn's Disease Activity Index (CDAI) score of at least 70 points, at week 10. In the second trial, 339 patients who had a response to natalizumab in the first trial were randomly reassigned to receive 300 mg of natalizumab or placebo every four weeks through week 56. The primary outcome was a sustained response through week 36. A secondary outcome in both trials was disease remission (a CDAI score of less than 150). RESULTS: In the first trial, the natalizumab and placebo groups had similar rates of response (56 percent and 49 percent, respectively; P=0.05) and remission (37 percent and 30 percent, respectively; P=0.12) at 10 weeks. Continuing natalizumab in the second trial resulted in higher rates of sustained response (61 percent vs. 28 percent, P<0.001) and remission (44 percent vs. 26 percent, P=0.003) through week 36 than did switching to placebo. Serious adverse events occurred in 7 percent of each group in the first trial and in 10 percent of the placebo group and 8 percent of the natalizumab group in the second trial. In an open-label extension study, a patient treated with natalizumab died from progressive multifocal leukoencephalopathy, associated with the JC virus, a human polyomavirus. CONCLUSIONS: Induction therapy with natalizumab for Crohn's disease resulted in small, nonsignificant improvements in response and remission rates. Patients who had a response had significantly increased rates of sustained response and remission if natalizumab was continued every four weeks. The benefit of natalizumab will need to be weighed against the risk of serious adverse events, including progressive multifocal leukoencephalopathy. (ClinicalTrials.gov numbers, NCT00032786 and NCT00032799.)

Adult↗

PubMed2003

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.

Adult↗

PubMed2003

Natalizumab for active Crohn's disease.

BACKGROUND: In chronic inflammatory conditions such as Crohn's disease, the migration of leukocytes from the circulation into the parenchyma and their activation within inflammatory sites are mediated in part by alpha4 integrins. METHODS: We conducted a double-blind, placebo-controlled trial of the alpha4 integrin-specific humanized monoclonal antibody natalizumab in 248 patients with moderate-to-severe Crohn's disease. Patients were randomly assigned to receive one of four treatments: two infusions of placebo; one infusion of 3 mg of natalizumab per kilogram of body weight, followed by placebo; two infusions of 3 mg of natalizumab per kilogram; or two infusions of 6 mg of natalizumab per kilogram. Infusions were given four weeks apart. Outcomes included changes in scores for the Crohn's Disease Activity Index (higher scores indicate more severe disease), the health-related quality of life, and C-reactive protein levels. RESULTS: The group given two infusions of 6 mg of natalizumab per kilogram did not have a significantly higher rate of clinical remission (defined by a score of less than 150 on the Crohn's Disease Activity Index) than the placebo group at week 6 (the prospectively defined primary end point in the efficacy analysis). However, both groups that received two infusions of natalizumab had higher remission rates than the placebo group at multiple time points. Natalizumab also produced a significant improvement in response rates (defined by a reduction of at least 70 points in the score on the Crohn's Disease Activity Index). The highest remission rate was 44 percent and the highest response rate was 71 percent (at week 6 in the group given two infusions of 3 mg per kilogram). Overall, the two infusions of 6 mg of natalizumab per kilogram and of 3 mg per kilogram had similar effects. The quality of life improved in all natalizumab groups; C-reactive protein levels improved in groups receiving two infusions of natalizumab. The rates of adverse events were similar in all four groups. CONCLUSIONS: Treatment with the selective adhesion-molecule inhibitor natalizumab increased the rates of clinical remission and response, improved the quality of life and C-reactive protein levels, and was well tolerated in patients with active Crohn's disease.

Adolescent↗

PubMed2006

A randomized, placebo-controlled trial of natalizumab for relapsing multiple sclerosis.

BACKGROUND: Natalizumab is the first alpha4 integrin antagonist in a new class of selective adhesion-molecule inhibitors. We report the results of a two-year phase 3 trial of natalizumab in patients with relapsing multiple sclerosis. METHODS: Of a total of 942 patients, 627 were randomly assigned to receive natalizumab (at a dose of 300 mg) and 315 to receive placebo by intravenous infusion every four weeks for more than two years. The primary end points were the rate of clinical relapse at one year and the rate of sustained progression of disability, as measured by the Expanded Disability Status Scale, at two years. RESULTS: Natalizumab reduced the risk of sustained progression of disability by 42 percent over two years (hazard ratio, 0.58; 95 percent confidence interval, 0.43 to 0.77; P<0.001). The cumulative probability of progression (on the basis of Kaplan-Meier analysis) was 17 percent in the natalizumab group and 29 percent in the placebo group. Natalizumab reduced the rate of clinical relapse at one year by 68 percent (P<0.001) and led to an 83 percent reduction in the accumulation of new or enlarging hyperintense lesions, as detected by T2-weighted magnetic resonance imaging (MRI), over two years (mean numbers of lesions, 1.9 with natalizumab and 11.0 with placebo; P<0.001). There were 92 percent fewer lesions (as detected by gadolinium-enhanced MRI) in the natalizumab group than in the placebo group at both one and two years (P<0.001). The adverse events that were significantly more frequent in the natalizumab group than in the placebo group were fatigue (27 percent vs. 21 percent, P=0.048) and allergic reaction (9 percent vs. 4 percent, P=0.012). Hypersensitivity reactions of any kind occurred in 25 patients receiving natalizumab (4 percent), and serious hypersensitivity reactions occurred in 8 patients (1 percent). CONCLUSIONS: Natalizumab reduced the risk of the sustained progression of disability and the rate of clinical relapse in patients with relapsing multiple sclerosis. Adhesion-molecule inhibitors hold promise as an effective treatment for relapsing multiple sclerosis. (ClinicalTrials.gov number, NCT00027300.).

Adolescent↗

PubMed2006

Altered CD4+/CD8+ T-cell ratios in cerebrospinal fluid of natalizumab-treated patients with multiple sclerosis.

BACKGROUND: Treatment with natalizumab, a monoclonal antibody against the adhesion molecule very late activation antigen 4, an alpha4beta(1) integrin, was recently associated with the development of progressive multifocal leukoencephalopathy, a demyelinating disorder of the central nervous system caused by JC virus infection. OBJECTIVE: To test the effect of natalizumab treatment on the CD4(+)/CD8(+) T-cell ratios in cerebrospinal fluid (CSF) and peripheral blood. DESIGN: Prospective longitudinal study. SETTING: Academic and private multiple sclerosis centers. PATIENTS: Patients with multiple sclerosis (MS) treated with natalizumab, untreated patients with MS, patients with other neurologic diseases, and human immunodeficiency virus-infected patients. MAIN OUTCOME MEASURES: CD4(+) and CD8(+) T cells were enumerated in CSF and peripheral blood. The mean fluorescence intensity of unbound alpha4 integrin on peripheral blood CD4(+) and CD8(+) T cells was analyzed before and after natalizumab therapy. RESULTS: Natalizumab therapy decreased the CSF CD4(+)/CD8(+) ratio of patients with MS to levels similar to those of human immunodeficiency virus-infected patients. CD4(+)/CD8(+) ratios in peripheral blood in patients with MS progressively decreased with the number of natalizumab doses, but they remained within normal limits. Six months after the cessation of natalizumab therapy, CSF CD4(+)/CD8(+) ratios normalized. The expression of unbound alpha4 integrin on peripheral blood T cells decreases with natalizumab therapy and was significantly lower on CD4(+) vs CD8(+) T cells. CONCLUSIONS: Natalizumab treatment alters the CSF CD4(+)/CD8(+) ratio. Lower expression of unbound alpha4 integrin on CD4(+) T cells is one possible mechanism. These results may have implications for the observation that some natalizumab-treated patients with MS developed progressive multifocal leukoencephalopathy.

Adolescent↗

PubMed2007

Safety and tolerability of concurrent natalizumab treatment for patients with Crohn's disease not in remission while receiving infliximab.

BACKGROUND: Natalizumab, a humanized monoclonal IgG(4) antibody to alpha4 integrin, was investigated as a treatment of active Crohn's disease (CD). The safety of natalizumab given in combination with infliximab has not previously been studied. METHODS: Seventy-nine adult patients with active CD (Crohn's Disease Activity Index [CDAI] score > or = 150) despite ongoing infliximab treatment were randomized 2:1 to receive 3 intravenous infusions of natalizumab (300 mg; n = 52) or placebo (n = 27) every 4 weeks. Patients received infliximab (5 mg/kg) every 8 weeks for at least 10 weeks before randomization and throughout the study. The primary objective was to assess the short-term safety and tolerability of natalizumab in patients concurrently receiving infliximab. Secondary and tertiary objectives included measures of efficacy, health-related quality of life (HRQoL), and effects on inflammatory markers. A subset of patients also participated in a pharmacokinetic/pharmacodynamic (PK/PD) analysis of the effects of concurrent treatment. RESULTS: Incidence of adverse events (AEs) was similar in the treatment groups. AEs frequently reported in both groups were headache, CD exacerbation, nausea, and nasopharyngitis. No patient had a hypersensitivity-like reaction to natalizumab, whereas 4 patients (5%) experienced reactions to infliximab. Two patients (4%) developed anti-natalizumab antibodies; 10 patients (14%) developed anti-infliximab antibodies. The mean CDAI score decreased with natalizumab plus infliximab but was unchanged with infliximab alone (-37.7 versus +3.5; P = 0.084). Patients in both groups showed small increases in HRQoL (P = 0.811). No drug-drug interactions were noted. CONCLUSIONS: The combination of natalizumab plus infliximab was well tolerated. Several positive trends suggested that treating patients not in remission with infliximab plus natalizumab had greater efficacy than treatment with infliximab alone.

Adult↗

PubMed2006

Review of progressive multifocal leukoencephalopathy and natalizumab.

BACKGROUND: Progressive multifocal leukoencephalopathy (PML), a destructive demyelinating infection which lytically infects oligodendrocytes, has occurred in patients treated with natalizumab. Magnetic resonance imaging (MRI) scan imaging of the brain gives clues to diagnosis but is nonspecific in distinguishing multiple sclerosis from PML. Spinal fluid detection of JC virus is specific but incompletely sensitive. Associated immunosuppression is typically of the cell-mediated type but can be poorly defined on clinical grounds. REVIEW SUMMARY: It is apparent that natalizumab is a predisposing factor for developing PML from the 3 cases of natalizumab-treated patients. There is no reliable presymptomatic way to detect PML or JC virus infection of the brain by virologic or imaging surveillance techniques. One patient with multiple sclerosis and natalizumab treatment has survived, indicating that withdrawal of antibody, possibly in combination with antiviral therapy, may permit survival. However, immune reconstitution disease is a risk after immune restoration and withdrawal of natalizumab. PML deficits would be expected to be permanent. The estimate of incidence of PML in natalizumab-treated patients is 1 per 1000. The duration of natalizumab treatment may be an independent risk factor for development of PML. CONCLUSION: PML, a usually fatal neurologic infection, should be considered as a risk factor when using natalizumab. The treatment of multiple sclerosis patients with natalizumab is a matter of informed risk, individualized for each multiple sclerosis patient.

Antibodies, Monoclonal↗

PubMed2006

Natalizumab in multiple sclerosis: proceed with caution?

Multiple sclerosis (MS) is an autoimmune inflammatory demyelinating disease of the CNS. In a Phase II clinical trial, natalizumab was shown to reduce the relapses in patients with relapsing MS, without improving the disability score. After 1-year of Phase III clinical trials, natalizumab was approved by the FDA for use in relapsing MS but was withdrawn 3 months later, due to two reported cases of progressive multifocal leukoencephalopathy (PML). The completed clinical trials with natalizumab for relapsing MS have recently been reported. In a trial of 1171 subjects with relapsing MS, natalizumab alone was shown to reduce the relapse rate and lesions, without causing PML. Although natalizumab was also shown to reduce the relapse rates and lesions in patients taking IFN-beta, two cases of PML with natalizumab occurred in these patients. An assessment of patients who had taken natalizumab for 1 - 2 years (approximately 3000), showed the incidence of PML to be 1/1000. A drug that is useful in relapsing MS will be used as a long-term therapy in large numbers of patients. For instance, in the 3 months that natalizumab was registered, 5000 patients commenced taking it. In the author's opinion, large numbers of patients should not be allowed to take natalizumab until its safety has been monitored in the long-term use in a clinical trial environment.

Journal Article↗

PubMed2006

Multiple sclerosis, natalizumab therapy, and progressive multifocal leukoencephalopathy.

PURPOSE OF REVIEW: Multiple sclerosis affects many people, often in early adulthood, and causes significant disability. Natalizumab is a novel agent to be evaluated for multiple sclerosis and Crohn's disease that has demonstrated unique efficacy but has unfortunately been implicated in three cases of progressive multifocal leukoencephalopathy. This review covers the mechanism of action of natalizumab and efficacy for multiple sclerosis, the three cases of natalizumab-associated progressive multifocal leukoencephalopathy, our understanding of progressive multifocal leukoencephalopathy, and the mechanisms that may account for these events. RECENT FINDINGS: Natalizumab, an anti-alpha4-integrin antibody, binds to T-cell surface receptors to prevent migration from the circulation into the brain tissue. Phase II and III trials have been completed and demonstrate previously unseen efficacy in preventing relapses and disease progression. The cases of progressive multifocal leukoencephalopathy, two fatal and one disabling, resulted in the voluntary suspension of natalizumab and bring this entire class of agents into doubt. It is important to determine what led to the development of progressive multifocal leukoencephalopathy in the natalizumab-associated cases and to advance understanding and continue to develop therapies for the treatment of multiple sclerosis. SUMMARY: With ongoing safety evaluations, natalizumab is being reevaluated by the US Food and Drug Administration for possible reapproval and return to the market. If natalizumab is reapproved, challenging questions and issues will remain in treating patients with multiple sclerosis.

Adult↗

PubMed2005

Natalizumab for the treatment of multiple sclerosis and Crohn's disease.

OBJECTIVE: To review the pharmacology, pharmacokinetics, safety, and pivotal clinical trials for natalizumab in the treatment of multiple sclerosis (MS) and inflammatory bowel disease. DATA SOURCES: A PubMed/MEDLINE search was conducted (1966-June 2005), and information was obtained from Iowa Drug Information Services. Additional data sources included meeting abstracts, bibliographies from identified articles, and information from the manufacturer. STUDY SELECTION AND DATA EXTRACTION: Studies and review articles examining natalizumab were evaluated. All published, randomized clinical trials evaluating natalizumab in MS and IBD were included in this review. DATA SYNTHESIS: Natalizumab is the first drug in a new class of agents called selective adhesion molecule inhibitors. It has shown promising results in MS and inflammatory bowel disease and appears superior compared with current therapies in reducing relapse rates. However, 3 recent, confirmed case reports of progressive multifocal leukoencephalopathy (PML) create concern about natalizumab's use in combination with existing therapies or in undefined patient subgroups. Natalizumab was voluntarily withdrawn from the market in March 2005 while the drug's safety is further evaluated. CONCLUSIONS: Although long-term efficacy and safety of natalizumab have not been established, available data indicate that it is a novel drug for patients with MS or inflammatory bowel disease. Analysis of its possible association with PML will determine the risk-benefit evaluation and eventual place in therapy for natalizumab.

Animals↗

PubMed2004

Randomized multicenter trial of natalizumab in acute MS relapses: clinical and MRI effects.

BACKGROUND: Relapses in multiple sclerosis (MS) can cause significant neurologic disability. Natalizumab (Antegren) is a humanized anti-alpha4-integrin antibody that inhibits the trafficking of leukocytes across endothelium by blocking binding of alpha4beta1-integrin to vascular cell adhesion molecule-1. OBJECTIVE: To assess the effects of a single dose of IV natalizumab administered soon after the onset of MS relapses. METHODS: In this randomized, double-blind, multicenter trial, the effects of a single dose of IV natalizumab administered soon after the onset of MS relapses were assessed. MS patients (n = 180) in acute relapse were randomly assigned to receive a single dose of natalizumab 1 or 3 mg/kg or placebo and were followed for 14 weeks. RESULTS: There was no difference in Expanded Disability Status Scale (EDSS) score change over time between treatment and placebo groups. In all three groups, approximately half of patients showed EDSS improvement after 2 weeks, rising to 67% by 8 weeks. EDSS improved by a mean value of 0.8 point at week 1, 1.2 points at week 4, and 1.6 points at week 8 in the natalizumab group compared with EDSS improvement of 1.0 point at week 1, 1.6 points at week 4, and 1.6 points at week 8 in the placebo group. A significant decrease in Gd-enhancing lesion volume was seen in both active treatment groups at weeks 1 and 3 compared with placebo. CONCLUSIONS: A single dose of IV natalizumab did not hasten clinical recovery after relapse, although a significant decrease in Gd-enhancing lesion volume was observed at 1 and 3 weeks after treatment. These MRI findings are consistent with prior studies of natalizumab and support its further investigation as an agent for the treatment of MS.

Acute Disease↗

PubMed2006

Immune surveillance in multiple sclerosis patients treated with natalizumab.

OBJECTIVE: Our objective was to test whether natalizumab, an antibody against very late activating antigen (VLA)-4, interferes with central nervous system immune surveillance as assessed by leukocyte cell numbers and cellular phenotypes in cerebrospinal fluid (CSF) and peripheral blood. METHODS: Cell numbers and cellular phenotypes in CSF and peripheral blood were analyzed in multiple sclerosis (MS) patients treated with natalizumab, untreated MS patients, and patients with other neurological disease (OND). JC virus DNA in the CSF and peripheral blood was quantified by kinetic polymerase chain reaction. RESULTS: CSF leukocyte counts, CD4(+) and CD8(+) T cells, CD19(+) B cells, and CD138(+) plasma cells were significantly lower in natalizumab-treated MS patients compared with OND patients and untreated MS patients. JC virus DNA was not detected in CSF or peripheral blood from natalizumab-treated patients. Six months after cessation of natalizumab therapy, low lymphocyte counts in the CSF persisted. The patient with the highest total leukocyte and CD4(+) and CD8(+)T-cell counts in the CSF experienced a clinical relapse. INTERPRETATION: These data suggest that natalizumab treatment results in a prolonged decrease of lymphocytes in the CSF and are consistent with the hypothesis that natalizumab impairs immune surveillance of the central nervous system.

Adult↗

PubMed2005

[Blocking adhesion molecules with natalizumab in multiple sclerosis].

Natalizumab is a humanized, monoclonal antibody, that inhibits adhesion molecules (alpha(4)-integrins) on the surface of immune cells. These adhesion molecules are important for binding of lymphocytes to endothelial cells of blood vessels and infiltration of inflammatory cells into tissues. Natalizumab is currently being tested in large clinical trials for the treatment of multiple sclerosis (MS) and other autoimmune diseases (inflammatory bowel diseases, rheumatoid arthritis). After demonstrating the safety and potential effectiveness of natalizumab in MS therapy during shorter treatment periods (</=6 months) in clinical phase I and II studies, two ongoing large, double-blinded, placebo-controlled phase III trials (named AFFIRM and SENTINEL) are evaluating its efficacy for patients with relapsing-remitting MS in respect to primary clinical endpoints (relapse rate, disease progression). Based a 1-year interim analysis of these studies, natalizumab was recently authorized by the U.S. Food and Drug Administration for treatment in reducing the frequency of clinical surges in multiple sclerosis, and an application was also made for its use in Europe. After more than 2 years of combined natalizumab (Tysabri) and interferon beta-1a (Avonex) therapy in the so-called Sentinel Study, there was one unexpected death and one appearance of progressive multifocal leukoencephalopathy. As a result, in February 2005 the manufacturers (Biogen/Elan) stopped all running studies of natalizumab and removed the drug from the market. New studies are underway to gain more understanding and especially to determine the risk to patients treated in the Sentinel Study. This article summarizes and updates the results of previous and ongoing natalizumab trials in the context of MS.

Antibodies, Monoclonal↗

PubMed2004

An open-label safety and drug interaction study of natalizumab (Antegren) in combination with interferon-beta (Avonex) in patients with multiple sclerosis.

In this open-label drug-interaction trial, we studied 38 patients with relapsing-remitting multiple sclerosis (MS) who received 3.0 or 6.0 mg/kg of natalizumab as a single intravenous (i.v.) infusion during stable treatment with intramuscular (i.m.) interferon beta-1a 30 microg (IFNbeta-1a; Avonex). To assess the pharmacokinetic (PK) interaction of natalizumab and IFNbeta-1a, serum concentration-time data for both agents were collected and analysed. Biologic response markers of IFNbeta-1a activity, beta2-microglobulin and neopterin, were also assessed to determine effects of natalizumab on IFNbeta-1a pharmacodynamics (PD). Further, safety and immunogenicity were evaluated. The combination of drug therapies was well tolerated. Although natalizumab serum concentrations (and corresponding PK exposure measures) appeared to be somewhat elevated in the presence of IFNbeta-1a, when compared to the same dose (6.0 mg/kg) administered alone in a concurrent comparator study, the differences were generally small and unlikely to be clinically relevant. In general, natalizumab had no apparent clinically relevant effects on the PK or PD properties of IFNbeta-1a. The presence of antibodies to IFNbeta-1a and natalizumab was relatively low. Overall, the study provided safety, immunogenicity, PK and PD data to support a combination strategy for the use of natalizumab and IFNbeta-1a in the treatment of patients with relapsing-remitting MS. A large clinical study is currently in progress to evaluate the efficacy and long-term safety of this combination drug therapy.

Adjuvants, Immunologic↗

PubMed2004

Natalizumab: alpha 4-integrin antagonist selective adhesion molecule inhibitors for MS.

Natalizumab (Antegren, Elan Corp. plc.; Biogen Idec.) is the first alpha4-integrin antagonist in the class of selective adhesion molecule inhibitors and is in Phase III clinical trials for the treatment of multiple sclerosis. After a 300 mg intravenous infusion, natalizumab has an elimination half-life of 6 to 9 days, but alpha4-integrin receptors expressed on the surface of peripheral blood leukocytes are more than 80% saturated approximately 1 month postinfusion. Therefore, natalizumab is given as a 300 mg dose administered monthly. Preliminary efficacy results showed a marked reduction (approximately 90%) in the formation of new gadolinium-enhancing lesions and reduced the number of patients with relapse by 50% in patients with relapsing-remitting or secondary progressive multiple sclerosis receiving natalizumab versus those receiving placebo over a 6-month period. In clinical studies, natalizumab has demonstrated a favorable safety profile. Pivotal Phase III studies of natalizumab as monotherapy and in combination with intramuscular interferon-beta-1a are underway in patients with relapsing-remitting multiple sclerosis. Natalizumab may be an important addition to the therapeutic armamentarium for multiple sclerosis.

Antibodies, Monoclonal↗

PubMed2004

Effect of natalizumab on conversion of gadolinium enhancing lesions to T1 hypointense lesions in relapsing multiple sclerosis.

BACKGROUND: Natalizumab, a humanized monoclonal anti-adhesion molecule antibody, reduces the frequency of new gadolinium (Gd) enhancing lesions and relapses in multiple sclerosis (MS). Its effect on evolution of new Gd enhancing lesions to T1 hypointense lesions is unknown. METHODS: 213 patients were randomized to receive 3 mg/kg or 6 mg/kg natalizumab or placebo monthly for 6 months and then followed for a further 6 months. A subset of patients who had one or more new gadolinium enhancing lesions from Month 0 to Month 6 and available electronic data were analysed. Each new Gd enhancing lesion that developed during treatment (months 1-6) was investigated for conversion to a new T1 hypointense lesion at month 12. Lesions were classified as large or small if their cross-sectional area was greater or less than 20 mm2. Because of the similarity of both doses of natalizumab on the frequency of new Gd enhancing lesions, the two natalizumab arms were combined in all analyses. RESULTS: Compared with the placebo group, the natalizumab group exhibited significant decreases in: (i) the proportion of patients with new Gd enhancing lesions that evolved to T1-hypointense lesions (10/38 [26 %] versus 27/40 [68 %]; p<0.01); (ii) the proportion of patients who developed large T1 hypointense lesions (2/38 [5 %] versus 16/40 [40 %]; p<0.01); (iii) the proportion of new Gd enhancing lesions that became T1 hypointense (11/75 [15 %] versus 118/466 [25 %]; p=0.045); (iv) the mean proportion per patient of new Gd enhancing lesions that converted to T1-hypointense lesions (0.15 versus 0.28; p=0.005), and (v) the odds ratio (OR) of converting from Gd enhancing to T1-hypointense lesions (OR=0.48; 95% CI=0.24, 0.94, p=0.031). CONCLUSION: Natalizumab significantly suppresses the evolution of new Gd enhancing to T1-hypointense lesions. This may reflect several mechanisms including reduced cell migration across the blood brain barrier, reduced T cell activation within lesions, an inhibitory effect on subsequent axonal damage within the new central nervous system lesion, and a reduced likelihood of recurrent lesion inflammation.

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