Rituximab is a laboratory manufactured antibody that targets the cells in our bodies that produce antibodies. This was genetically engineered and is the first monoclonal antibody to be approved by the FDA for the treatment of cancer. The current indication for its use is in the treatment of non-Hodgkin’s lymphoma. It has become an important tool for patients with that disease.
What does it do?
Rituximab is a monoclonal antibody that targets CD20+ B-cells. The CD-20 molecule is present on B-cells as they mature. However, since they are not present on stem cells, stem cells are not affected. It bind to the CD-20 molecule on the cell surface of the intermediate B-cells and kills them.
How do I take Rituximab?
Consult your doctor. Rituximab is given by IV infusion – once a week for 4 weeks taking about 3 to 4 hours. If there are initial problems, the infusion can last much longer. The dose is usually about 500-700 mg. The removal from the blood can be followed by using an instrument called a flow cytometry. How often do I have to take Rituximab?
As stem cells are not killed, the CD20 positive B-cells begin to repopulate within about 6 to 12 months. Rituximab is expensive, but less expensive than IVIg. Total drug cost is about $10,000 for one 4 week treatment.
PV is not the only autoimmune disease for which this drug is being explored. There is evidence it is helpful in other autoimmune diseases, such as ITP (idiopathic thrombocytopenic purpura) and other diseases including Rheumatoid arthritis. The drug is often used in combination with other standard immunosuppressive drugs.
Experience in PV is limited. To date, there are no formal trials going on at present for Rituximab. However, there are some impressive case reports. At present it is used more frequently in patients with paraneoplastic pemphigus than in pemphigus vulgaris or foliaceus. Some problems with infection after treatment with Rituxan have been reported. Rituximab eventually could be come a good tool for treatment of PV. Our biggest problem with this class of drugs is to know how to most effectively use these expensive drugs, define which patients will benefit the most, and who will respond the best.
Milo C. is a PV patient using Rituximab. He has added this information from his own research and experience.
What are the side effects?
Most of the problematic side effects occur while treatment is given. These include reactions similar to allergic reactions and can be very serious or even lethal (just as a bee sting can be for some people). However, to reduce the risk of side effects during administration of Rituxan patients are given Benadril and Tylenol, and in some cases cortisone. In addition, the rate of infusion seems to be related directly to problems, so slowing the infusion rate typically alleviates any problems.
The biggest problem is one seen by all immunosupressive drugs – immune suppression. Since the many of the body’s B-cells are destroyed, after a few months your supply of antibodies will “dry up” and you will be more vulnerable to infection. Unlike typical chem. meds, Rituxan leave your T-cells and the rest of your immune system in tact, so you are still fairly protected. The problem is that if you become infected with something more severe, like the flu, your body will have a very difficult time mounting a defense against it.
Will I loose my hair and be nauseated like Cytoxan?
Cytoxan, and many of the cytotoxic chemotherapy medications work by killing rapidly reproducing cells. This affects the cells of the gut and hair follicles which rapidly reproduce and can cause hair loss and nausea in some people. Rituximab does not work in this way, and therefore should not cause hair loss or nausea. Nausea might appear as a result after infusions or during, but should pass and should not be persistent.