Soon after The Medical Letter first reviewed use of natalizumab (Tysabri – Biogen Idec and Elan) for treatment of relapsing forms of multiple sclerosis (MS) (Med Lett Drugs Ther 2005; 47:13), the drug was withdrawn from the market. The unpublished clinical trials that led to its approval by the FDA have since been published, and now the drug has been returned to the market with prescribing restrictions.Natalizumab decreases the number of relapses and new brain lesions in patients with MS. It was withdrawn because progressive multifocal leukoencephalopathy (PML) occurred in 3 (of about 3000)...

The February 14th issue of The Medical Letter reviewed natalizumab (Tysabri - Biogen Idec), a new monoclonal antibody that was granted accelerated approval because it decreased the number of relapses in patients with multiple sclerosis. On February 28th, the FDA issued a Public Health Advisory announcing that marketing of the drug had been suspended because 2 patients who had been treated with natalizumab for more than 2 years had developed progressive multifocal leukoencephalopathy, a rare, often fatal disease...

Natalizumab (Tysabri - Elan and Biogen) is a monoclonal antibody approved for induction and maintenance treatment of moderate to severe Crohn's disease (CD) refractory to conventional therapies and inhibitors of tumor necrosis factor (TNF). Initially approved in 2004 for the treatment of multiple sclerosis (MS), natalizumab was temporarily withdrawn from the market after 3 patients developed progressive multifocal leukoencephalopathy (PML). It is now available for treatment of both MS and CD through a restricted distribution program.

The May 5, 2008 article (Med Lett Drugs Ther 2008; 50:34) on the approval of natalizumab (Tysabri) for treatment of Crohn's disease in the "Adverse Effects" section on page 35 included the statement: "post-marketing hepatotoxicity, sometimes fatal or requiring liver transplantation, has occurred." Actually, no fatal hepatotoxicity or liver transplantation has been reported to date. The FDA warning about post-marketing hepatotoxicity with Tysabri that was the basis for our statement said: "The combination of transaminase elevations and elevated bilirubin without evidence of obstruction is...

Natalizumab, a recombinant humanized monoclonal antibody, has received accelerated approval from the FDA for intravenous treatment of relapsing forms of multiple sclerosis (MS). The beta interferons and glatiramer acetate are widely used for treatment of MS; they generally reduce the number of relapses by about 30% compared to placebo, and have been shown to be safe and effective for periods ranging from 4 to 10 years.

The FDA has approved the use of dalfampridine (4-aminopyridine; Ampyra – Acorda), a potassium channel blocker, to improve walking speed in patients with multiple sclerosis (MS). Walking speed is considered a reliable clinical measure of impairment in patients with MS.

The FDA has approved vedolizumab (Entyvio - Takeda), an intravenous integrin receptor antagonist, for treatment of moderate to severe ulcerative colitis or Crohn's disease in adults who have not responded to, lost response to, or cannot tolerate standard treatment. Natalizumab (Tysabri), another integrin receptor antagonist, has been available for several years for treatment of Crohn's disease and multiple sclerosis.

The FDA has approved a new interferon beta-1b product (Extavia – Novartis) for treatment of relapsing forms of multiple sclerosis (MS). Extavia is identical to Betaseron (Bayer); both are produced in the same factory and packaged separately.

In recent years, several new drugs have been approved by the FDA for use in multiple sclerosis (MS), and many others are in the pipeline. Most recently, teriflunomide (Aubagio – Genzyme) became the second oral drug to be approved by the FDA for treatment of relapsing forms of MS.

The FDA has approved a pegylated form of interferon beta-1a (Plegridy – Biogen) for biweekly treatment of patients with relapsing multiple sclerosis (MS).