Efficacy of natalizumab in second line therapy of relapsing-remitting multiple sclerosis: results from a multi-center study in German speaking countries

Natalizumab for relapsing remitting multiple sclerosis

BACKGROUND

Natalizumab (NTZ) (Tysabri(®)) is a monoclonal antibody that inhibits leukocyte migration across the blood-brain barrier, thus reducing inflammation in central nervous system, and has been approved worldwide for the treatment of relapsing-remitting multiple sclerosis (RRMS).

OBJECTIVES

To evaluate the efficacy, tolerability and safety of NTZ in the treatment of patients with RRMS.

SEARCH STRATEGY

We searched the Cochrane Multiple Sclerosis Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, 2010, Issue 1), MEDLINE (PubMed) and EMBASE, all up to 19 February 2010, and bibliographies of papers. Handsearching was carried out. Trialists and pharmaceutical companies were contacted. Furthermore, the websites of US Food and Drug Administration (FDA), the European Medicines Evaluation Agency (EMA) and the National Institute for health and Clinical Excellence (NICE) were also checked.

SELECTION CRITERIA

All double-blind, randomised, controlled trials analysing more than a single infusion of NTZ (dosage > 3 mg/kg intravenous infusion every 4 weeks), also including its use as add-on treatment, versus placebo or other drugs in patients with RRMS. No restrictions on the basis of duration of treatment or length of follow up.

DATA COLLECTION AND ANALYSIS

Three reviewers independently selected articles which met the inclusion criteria. Disagreements were solved by discussion. Two reviewers independently extracted the data and assessed the methodological quality of each trial. Missing data was sought by contacting principal authors and Biogen Idec, through Biogen-Dompé Italia.

MAIN RESULTS

Three studies met the inclusion criteria. These included one placebo-controlled trial (942 patients) and two add-on placebo-controlled trials, i.e. one plus glatiramer acetate (110 patients) and the second plus interferon beta-1a (1171 patients).This review assessed the efficacy, tolerability and safety of NTZ in patients with RRMS. Data was conclusive with respect to efficacy and tolerability, but not safety. As far as efficacy is concerned, the results showed statistically significant evidence in favour of NTZ for all the primary outcomes and for the secondary ones where data was available. NTZ reduced the risk of experiencing at least one new exacerbation at 2 years by about 40% and of experiencing progression at 2 years by about 25% as compared to a control group. MRI parameters showed statistical evidence in favour of participants receiving NTZ. Infusion reactions, anxiety, sinus congestion, lower limb swelling, rigors, vaginitis and menstrual disorders were reported as adverse events (AEs) more frequently after NTZ treatment. In this review NTZ was found to be well tolerated over a follow-up period of two years: the number of patients experiencing at least one AE (including severe and serious AEs) during this period did not differ between NTZ-treated patients and controls. Safety concerns have been raised about Progressive Multifocal Leukoencephalopathy (PML). In the trials included in this review, two cases of PML were encountered: one in a patient who had received 29 doses of NTZ and a second fatal case of PML in another patient after 37 doses of NTZ. Our protocol was insufficient to evaluate PML risk as well as other rare and long-term adverse events such as cancers and other opportunistic infections, which are very important issues in considering the risk/benefit ratio of NTZ.

AUTHORS' CONCLUSIONS

Although one trial did not contribute to efficacy results due to its duration, we found robust evidence in favour of a reduction in relapses and disability at 2 years in RRMS patients treated with NTZ. The drug was well tolerated. There are current significant safety concerns due to reporting of an increasing number of PML cases in patients treated with NTZ. This review was unable to provide an up-to-date systematic assessment of the risk due to the maximum 2 year-duration of the trials included. An independent systematic review of the safety profile of NTZ is warranted. NTZ should be used only by skilled neurologists in MS centres under surveillance programs.All the data in this review came from trials supported by the Pharmaceutical Industry. In agreement with the Cochrane Collaboration policy, this may be considered a potential source of bias.

Accidental natalizumab administration to the third trimester of pregnancy in an adolescent patient with multiple sclerosis

BACKGROUND

Natalizumab is neither licensed for the use in adolescents nor during pregnancy. There are no reports of accidental natalizumab exposure during pregnancy continued as long as to the third trimester of pregnancy.

AIMS

We report the outcome of pregnancy in a 17-year-old adolescent patient with multiple sclerosis (MS) treated with natalizumab from the age of 16, who was diagnosed to be pregnant in the 31st gestational week (gw) of pregnancy. To our knowledge, this report describes the first patient receiving natalizumab to the third trimester of pregnancy.

CASE REPORT

  Because of high relapse activity, natalizumab treatment was administered in an adolescent patient with MS. Pregnancy was diagnosed in the 31st gw after 17 natalizumab infusions, seven of them accidentally during pregnancy.

RESULTS

Pre- and postnatal development of the child was normal.

CONCLUSIONS

The case reported indicates that accidentally continued natalizumab treatment until few weeks before delivery may have no negative impact on the developing foetus.

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

Natalizumab, a highly specific α4-integrin antagonist, is approved for treatment of patients with active relapsing-remitting multiple sclerosis (RRMS). It is generally recommended for individuals who have not responded to a currently available first-line disease-modifying therapy or who have very active disease. The expected benefits of natalizumab treatment have to be weighed against risks, especially the rare but serious adverse event of progressive multifocal leukoencephalopathy. In this Review, we revisit and update previous recommendations on natalizumab for treatment of patients with RRMS, based on additional long-term follow-up of clinical studies and post-marketing observations, including appropriate patient selection and management recommendations.

Principles of a new treatment algorithm in multiple sclerosis

We are entering a new era in the management of patients with multiple sclerosis (MS). The first oral treatment (fingolimod) has now gained US FDA approval, addressing an unmet need for patients with MS who wish to avoid parenteral administration. A second agent (cladribine) is currently being considered for approval. With the arrival of these oral agents, a key question is where they may fit into the existing MS treatment algorithm. This article aims to help answer this question by analyzing the trial data for the new oral therapies, as well as for existing MS treatments, by applying practical clinical experience, and through consideration of our increased understanding of how to define treatment success in MS. This article also provides a speculative look at what the treatment algorithm may look like in 5 years, with the availability of new data, greater experience and, potentially, other novel agents.

Natalizumab in pediatric multiple sclerosis patients

Pediatric multiple sclerosis (MS) comprises 2-5% of all cases of MS. Although first-line disease-modifying therapy (DMT) including interferons and glatiramer acetate appear to be well tolerated in this population, recent work has suggested that a growing number of children suffer from disease which is resistant to treatment with these therapies. Natalizumab is a therapy which, although associated with a 1 : 1000 risk for progressive multifocal leukoencephalopathy (PML), has been shown to be well tolerated in the adult population and may lead to disease remission in adults with highly active disease. Reports of use of this therapy in the pediatric population with highly active disease have been published. This paper reviews current experience with the use of natalizumab in the pediatric MS population, with attention to potential risks and possible long-term outcomes in this population.

Natalizumab induces a rapid improvement of disability status and ambulation after failure of previous therapy in relapsing-remitting multiple sclerosis

BACKGROUND

Natalizumab (Tysabri) is a monoclonal antibody that was recently approved for the treatment of relapsing-remitting multiple sclerosis (RRMS). Our primary objective was to analyse the efficacy of natalizumab on disability status and ambulation after switching patients with RRMS from other disease-modifying treatments (DMTs).

METHODS

A retrospective, observational study was carried out. All patients (n=45) initiated natalizumab after experiencing at least 1 relapse in the previous year under interferon-beta (IFNB) or glatiramer acetate (GA) treatments. The patients also had at least 1 gadolinium-enhancing (Gd+) lesion on their baseline brain MRI. Expanded Disability Status Scale (EDSS) scores, and performance on the Timed 25-Foot Walk Test and on the Timed 100-Metre Walk Test were prospectively collected every 4 weeks during 44 weeks of natalizumab treatment. Brain MRI scans were performed after 20 and 44 weeks of treatment.

RESULTS

Sixty-two per cent of patients showed no clinical and no radiological signs of disease activity, and 29% showed a rapid and confirmed EDSS improvement over 44 weeks of natalizumab therapy. Patients with improvement on the EDSS showed similar levels of baseline EDSS and active T1 lesions, but had a significantly higher number of relapses, and 92% of them had experienced relapse-mediated sustained EDSS worsening in the previous year. A clinically meaningful improvement in ambulation speed was observed in approximately 30% of patients.

CONCLUSIONS

These results indicate that natalizumab silences disease activity and rapidly improves disability status and walking performance, possibly through delayed relapse recovery in patients with RRMS who had shown a high level of disease activity under other DMTs.

Occurrence of antibodies against natalizumab in relapsing multiple sclerosis patients treated with natalizumab

BACKGROUND

In the clinical trials about 9% of natalizumab treated multiple sclerosis (MS) patients generated anti-natalizumab antibodies, of which 6% were persistent and 3% transient. The occurrence of antibodies reduced serum levels of natalizumab, decreased bio-efficacy, and abrogated the therapeutic efficacy.

OBJECTIVE

The objective was to assess the frequency of anti-natalizumab antibodies in an unselected cohort of patients from four different countries.

METHODS

We measured anti-natalizumab antibodies in a large cohort of 4881 unselected patients from four MS centres that systematically measured antibodies in patients treated with natalizumab. We applied the same ELISA assay developed by Biogen Idec and used in the pivotal trials of natalizumab.

RESULTS

Antibodies occurred in 4.5% (95% confidence interval, CI: 4.0-5.1%) of the patients, and were persistent in 3.5% (95% CI: 3.0-4.0%) and transient in 1.0% (95% CI: 0.7-1.3%) of the patients. The frequencies of permanently antibody positive patients did not show statistically significant differences between the four centres, whereas the frequencies of transiently antibody positive patients showed some variations.

CONCLUSION

The frequencies of antibodies appeared to be of the same magnitude in the four centres, but might be less than in the pivotal studies of natalizumab.

Definitions of breakthrough disease and second-line agents

Conventional disease-modifying agents are only moderately effective, so breakthrough disease activity is commonly seen. The evidence from randomized clinical trials and real-world observational data supporting the use of the second-line agents natalizumab, mitoxantrone, and cyclophosphamide are reviewed. Potential future treatment options are also discussed. Management algorithms for breakthrough disease are outlined.

Switching multiple sclerosis patients with breakthrough disease to second-line therapy

Background

Multiple sclerosis (MS) patients with breakthrough disease on immunomodulatory drugs are frequently offered to switch to natalizumab or immunosuppressants. The effect of natalizumab monotherapy in patients with breakthrough disease is unknown.

Methods

This is an open-label retrospective cohort study of 993 patients seen at least four times at the University of California San Francisco MS Center, 95 had breakthrough disease on first-line therapy (60 patients switched to natalizumab, 22 to immunosuppressants and 13 declined the switch [non-switchers]). We used Poisson regression adjusted for potential confounders to compare the relapse rate within and across groups before and after the switch.

Results

In the within-group analyses, the relapse rate decreased by 70% (95% CI 50,82%; p<0.001) in switchers to natalizumab and by 77% (95% CI 59,87%; p<0.001) in switchers to immunosuppressants; relapse rate in non-switchers did not decrease (6%, p = 0.87). Relative to the reduction among non-switchers, the relapse rate was reduced by 68% among natalizumab switchers (95% CI 19,87%; p = 0.017) and by 76% among the immunosuppressant switchers (95% CI 36,91%; p = 0.004).

Conclusions

Switching to natalizumab or immunosuppressants in patients with breakthrough disease is effective in reducing clinical activity of relapsing MS. The magnitude of the effect and the risk-benefit ratio should be evaluated in randomized clinical trials and prospective cohort studies.