Tysabri, a disease-modifying medication indicated for the use of treating numerous autoimmune diseases including multiple sclerosis, is a lab-produced monoclonal antibody. This basically means the drug works to prevent an autoimmune attack where immune cells (for reasons unknown) fight their own body tissues. In the case of multiple sclerosis, this involves the immune system attacking the coverings of the nerves located in the brain and the spinal cord (the central nervous system.)
Tysabri, or its chemical name “natalizumab”, is indicated for use in MS patients who have not tolerated or had favorable results with the disease-modifying injectable drugs– Avonex, Betaseron, Copaxone, or Rebif— or for serious initial multiple sclerosis attacks where a stronger medication is desirable. Tysabri is believed to be about 70 – 75% effective in slowing multiple sclerosis attacks and resulting disability (the injectable drugs have a varying effectiveness of up to roughly 40%.)
Tysabri patients may develop side-effects from use of the drug, including body aches, fatigue, stomach pains, headaches, lowered immunity to certain infections, an allergic reaction upon administration, and other complications. A more serious side effect is the possible development of PML, or progressive multifocal leukoencephalopathy, a neurological virus that can be fatal. Because of this very serious risk, Tysabri has a structured system for intravenous administration throughout the United States, called the “Touch” prescribing program. It is given by infusion about once a month.
There have been three reported deaths from PML after the use of Tysabri. Two were reported during Phase III clinical trials (2005) where the two patients were taking other immunomodulating medications with the Tysabri. A recent death has been reported in the United States, after several cases of PML were acknowledged this year. Because of these deaths, Tysabri is considered a controversial medication, although thousands of patients worldwide have stabilized and even improved from its use.
****For more information about Tysabri (and its administration), see The National Multiple Sclerosis Society (US), Multiple Sclerosis Trust (UK), The Boston Business Journal (a financial perspective), and The Irish Examiner (Elan, the pharmaceutical company who co-owns the Tysabri patent with American company Biogen, is based in Ireland.)
