Rituximab is a man made antibody most frequently used in the treatment of autoimmune Rheumatoid Arthritis and B cell non-Hodgkins Lymphoma - a type of cancer. Rituximab is a type of chemotherapy agent. In 2008 it was the world's best selling cancer drug.
was published in the journal Arthritis Rheum Jan, 2010 that discussed
its use in patients with primary Sjogren's Syndrome - an autoimmune
disease that primarily affects the moisture producing (exocrine) glands.
any autoimmune disease, the body mistakenly begins to attack its own
cells (self). The immune system is multi-faceted and works much like an
army. Autoimmunity is largely a mystery, but what is known is the system
somehow (there can be multiple mechanisms) 'forgets' which cells are
foreign and which cells are self. The body targets self, and healthy
cells are destroyed by friendly fire.
Rituximab is an injectible
chimeric antibody. (A chimera is a mythical creature with body parts
from different animals) In this case, Rituximab is part human and part
mouse. Because it is prepared using the cells/proteins of living
creatures it is called a biologic. Because it depletes the immune system it is also called a DMARD - Disease Modifying Anti-Rheumatic Drug.
is used mixed with other fluids and given via IV once weekly. Each
infusion may take 3-4 or more hours. It works as an autoimmune treatment
by depleting the number of B cells - one of the many types of
specialized cells in the immune system that play a part in inflammation.
Normally, inflammation is a necessary and normal immune response. In
autoimmune primary Sjogren's Syndrome, the inflammatory response is out
Rituximab is not a first line drug. It is used only
when other biologic medications have failed. Rituximab is an antibody
that is specific for a molecule called CD20 that is normally present on
the surface of B cells. The cells are targeted and lysed (destruction
via explosion) by the Rituximab antibodies.
There can be significant side effects,
especially during or shortly after the first or second doses. One of
those side effects is called serum sickness. In serum sickness, the body
reacts negatively to the introduction of a foreign protein (the
Rituximab) into the system. Reactions can range from mild to life
threatening. It is interesting to note that serum sickness was noted in 3
of 8 patients in an earlier study
in which low or no corticosteroids were used, but in only one diabetic
patient in the second study of 30 patients in which higher doses of
steroids were used.
It is unknown if the use of steroids in the
second study helped to increase the positive outcome for Rituximab and
placebo patients (slight improvement at 5 weeks) in that study, but it
seems suggestive that it may have helped to prevent serum sickness in
the Rituximab patients.
In the respective studies, improvement
was seen in these areas: secretion of saliva as well as inflammatory
activity within the saliva, improved lab values (ESR, IgG, FACS analysis
on B and T cells), fatigue, parotid (salivary gland) biopsies, and there
were fewer extraglandular symptoms (joint pain, kidney involvement,
etc). There was no increase seen in tear production. The most
significant point in time at which improvement was noticed in the second
study was between 12 - 36 weeks of treatment.
patients are at increased risk for B cell Lymphoma (a type of cancer
treatable by this medication) and Rituximab depletes B cells, the
studies suggest that treatment with Rituximab may also help those
patients lower their risk for this disease complication.
conclusion, the second study's research team stated: "This study
indicates that rituximab could be an effective and safe treatment...for
patients with primary Sjogren's syndrome."
I speculate that it may be important to some patients that the addition
of mouse DNA to Rituximab may create problems for those allergic to
mice. Please check with your doctor if you are concerned about this type
of reaction. A quick allergy test to see if you are sensitive may be a
I would also like to add that, when we
transfuse equine (horse) foals with antibodies (a fairly frequent
occurrence), serum sickness also frequently develops. Slowing down the
infusion (sometimes greatly) and allowing the foals to move around, eat
etc, helps to prevent/lessen stress and this reaction. I don't know if
this would be helpful for their human counterparts or not, but might be
worth mentioning to your physicians in case you'd like to ask to try it.
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