Phase ll trial suggests Rituximab may
reduce
MS Disease Activity
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Medical Update Memo
February 19, 2008
Summary
A small preliminary trial suggests that two
infusions of the cancer drug Rituxan reduced
inflammatory brain lesions and clinical relapses
for 48 weeks, as compared to placebo, in a
group of relapsing remitting MS patients.
Details
Researchers report that one course of the
IV drug rituximab (Rituxan®, Genentech and
Biogen Idec) reduced disease activity seen
in enhancing brain lesions and relapses for
48 weeks in people with relapsing-remitting
(RR) MS*. Rituximab depletes immune B cells,
which may play a role in the immune attack
on brain and spinal cord tissues in MS.
Dr. Stephen Hauser (University of California
at San Francisco) and colleagues report these
results in the February 14, 2008 issue of The
New England Journal of Medicine. The clinical
trial was supported by Biogen Idec and Genentech.
Larger and longer-term studies are needed to
confirm the drug’s safety and effectiveness.
These positive findings point to a potential
new therapeutic strategy for MS. It is generally
accepted that “T cells” – a
type of immune cell - play a pivotal role in
the development and course of MS. This study
suggests that another type of immune cell,
known as 'B" cells are also involved.
The phase 2 trial was conducted at 32 centers
in the U.S. and Canada. Two infusions of rituximab
were administered two weeks apart to 69 people,
and inactive placebo to 35 people. The primary
goal of the study was to determine the drug’s
effect on “enhancing” brain lesions
(areas of tissue damage that glow with a contrast
agent to signal active inflammation) at weeks
12, 16, 20 and 24. Other study goals included
the proportion of patients who experienced
relapses. The number of active lesions at 24
weeks was reduced by 91% in the group taking
rituximab versus those on placebo, and 58%
fewer people in the treatment group had relapses
(14.5% vs. 34.3%). More infusion-related reactions
occurred in the group taking rituximab. Of
the 104 patients, 79 completed 48 weeks. The
original results the reduction in number of
active lesions and in the proportion of people
having relapses compared with the placebo group
were maintained at 48 weeks.
In an accompanying editorial, MS expert Henry
F. McFarland, MD (NINDS, Bethesda, MD) suggests
that these findings may shed light on the immunologic
mechanisms leading to the disease. Rituximab
treatment showed benefit as early as four weeks.
This suggests that the clinical benefit of
depleting B cells may not be be from curbing
their production of immune system antibodies,
as it has been believed. For decades, immune
T cells have been thought to be the main culprits
in MS, and the rituximab study raises the possibility
that interactions between B cells and T cells
may be key to the destructive action of the
immune system in MS. Dr. McFarland cautions,
however, that some antibodies produced by B
cells have been found to induce tissue repair,
so investigators conducting phase 3 trials
should conduct long-term, careful monitoring
of participants.
Rituximab is approved for use with certain
types of lymphoma and a form of arthritis.
The drug has been associated with severe adverse
effects including fatal infusion reactions
and progressive multifocal leukoencephalopathy,
but these have not occurred in the MS studies.
While promising, more clinical trials are needed
to assess long-term safety and efficacy before
being used as a treatment for MS.
Adapted from the National MS Society website
ASK Information System Code: 1.4.1.12.2.c
Disponible en français.
Disclaimer
The Multiple Sclerosis Society of Canada is an independent, voluntary health
agency and does not approve, endorse or recommend any specific product or
therapy, but provides information to assist individuals in making their own
decisions.
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