Biogen Idec and Elan Pharmaceuticals, Inc.
- Administered via intravenous infusion every four
weeks. Dose is 300 mg.
- Approved for all individuals with relapsing types
of MS. This drug is generally recommended for
patients who have not responded adequately to,
or who cannot tolerate, another treatment for MS.
- This laboratory-produced monoclonal antibody
acts against a molecule involved in the activation
and function of lymphocytes (immune-system
cells produced to fight infection and disease)
and their migration into the central nervous
system (CNS). Recent data suggest that it may
also enhance remyelination and stabilize
damage to the myelin sheath (the protective
covering of the nerves). Preliminary results
suggest that the drug may actually produce an
improvement in function.
- At 18 months and up to 24 months of treatment
with Tysabri, 87 percent of RRMS patients
previously treated with other disease-modifying
therapies showed stable or improved MRI scans.
In this same group, disability scores as measured
by the EDSS were stable or improved in 59
percent of patients.
Progressive Multifocal Leukoencephalopathy
- The Phase III SURPASS trial continues to
evaluate 1,800 individuals with RRMS who have
been treated earlier with either Rebif or
Copaxone, and are then switched to Tysabri
after continuing to experience relapses. The
study began in February 2010 and is scheduled
for completion in May 2013. The primary
- outcome measure is the annualized relapse rate.
A small Phase II clinical trial, Natalizumab
Treatment of Progressive Multiple Sclerosis
(NAPMS), is continuing at Copenhagen
University Hospital to study the safety and
efficacy of Tysabri treatment of PPMS and
secondary-progressive MS (SPMS). It enrolled
24 patients and is scheduled for completion in
- A small study of 20 individuals with RRMS is
evaluating the role of Tysabri on cognition and
neurodegeneration (the breakdown or cell
death of nerve cells). Its objective is to further
establish the role of Tysabri in preventing
neurodegeneration in MS and to establish new
markers for such damage.
- A small Phase IV study of 20 individuals who
have been treated with Tysabri for 12 months,
is gradually switching Tysabri treatment to
Betaseron and comparing it to continuing
treatment with Tysabri. The primary outcome
measure is the time to a first relapse during the
study; other measures include clinical and MRI
findings, as well as patient-reported outcomes
on quality of life and fatigue. Safety will be
assessed by reports of adverse events.
- Other studies are exploring the effects of Tysabri
on ambulation (walking and mobility), cognition,
fatigue, depression, bladder function, sexual
function, disability, and health-related quality of
life. One study indicated that Tysabri-treated
patients had fewer MS-related hospitalizations
and emergency-room visits over one year of
treatment, suggesting that it may reduce the
economic burden of MS.
- Following a suspension of the drug in 2005 after
two patients developed Progressive Multifocal
Leukoencephalopathy (PML), an often-fatal viral
infection of the brain, Tysabri was re-released in
2006.While often fatal, when discovered early in
patients taking Tysabri, new treatments have
helped many to survive this infection by removing
Tysabri from the blood system. Severe disability is
still a major concern. All patients now receive the
drug through safety monitoring programs.
- As of September 2011, there were 150 reported
cases of PML with Tysabri, and its labeling has been
updated to further quantify the risk. The new
labeling also notes the increased risk from
previous use of immunosuppressive medications.
- The three major risk factors for developing PML
are: being on the drug for more than two years;
prior immunosuppressant therapy; and positive
blood tests for previous infection with the JC
virus, which causes PML.
- It is presumed that patients with no antibodies
to the JC virus will be at a much-reduced risk of
developing PML. A new assay (a test used for
analysis) has been developed to identify
antibody-negative patients. This JC virus
antibody blood test is now commercially
available and is under review by the FDA.
- The JCV Antibody Program (STRATIFY-2)
began April 2010 and is scheduled to end
December 2012. It will enroll 8,000
participants. This program will define the
prevalence of the JCV antibody in the MS
population, and potentially stratify patients into
lower or higher risk for developing PML based
on antibody status.