The Scoop on Tysabri

Tysabri was approved by the FDA in 2004 for relapsing forms of MS, but was then withdrawn from the market by the manufacturer (Biogen Idec) because of safety concerns. It was approved to return to the market in 2006 with a special restricted distribution program. Tysabri is the newest of the immunomodulating drugs and is not approved for people with primary progressive or secondary progressive MS.

Tysabri is administered every four weeks by intravenous infusion. It works by preventing damaging immune cells from crossing the blood-brain barrier and entering the CNS. It is usually used in cases where other MS medications have not worked. Tysabri has been proven to decrease the number of exacerbations, slow down the progression of disabling effects from MS, and reduce the number of lesions seen on MRI scans. To date, there has been no study directly comparing Tysabri to existing treatments to prove whether or not it is superior to those treatments.

While Tysabri is considered to be a very effective therapy, it is balanced by risk. In clinical trials of Tysabri, three people involved in the studies developed a rare disorder of the nervous system called progressive multifocal leukoencephalopathy (PML). PML primarily affects individuals with suppressed immune systems and is caused by a virus called the JC virus. This virus lies dormant in the immune system of most people, but in individuals who have a suppressed immune system (such as people with AIDS or those who are being treated with chemotherapy), the virus can become active and cause progressive neurological symptoms. PML is usually fatal. Two of the three people who had PML during the clinical trials of Tysabri died. One of them had been diagnosed with MS (the other had been in the trial for Crohn's disease). The FDA approved Tsyabri's re-entry into the market in 2006 after there were no additional cases of PML reported.


The people in the MS clinical trial who developed PML were taking Tysabri in combination with Avonex, and because of this, the FDA has indicated Tsyabri's use as a monotherapy, meaning it cannot be used in combination with other disease-modifying drugs for MS.

The manufacturer, Biogen Idec, has developed a risk management plan called the TOUCH (Tysabri Outreach: Unified Commitment to Health) Prescribing Program to ensure safe use of the product. Here are the details of the plan:

  • Only patients who are enrolled in the mandatory TOUCH program will be able to receive Tysabri.

  • Heath care providers and their staff, infusion centers, and pharmacies must all be registered with the TOUCH program and complete an education program about the risks of Tysabri treatment.

  • Before each infusion, a checklist must be completed by the patient and nurse to help track any new signs or symptoms that may require an evaluation by a physician. This ensures careful monitoring of the drug.

  • Patients will be evaluated three and six months after starting Tysabri and then every six months thereafter.

  • Patients with a compromised immune system or those who are taking other disease-modifying drugs for MS are not eligible for the treatment.

Based on current information, the FDA puts the risk of developing PML at 1 in 1,000. If you are considering Tysabri, it is important to balance the risks with the benefits. Keep in mind that Tysabri is indicated for people with relapsing forms of MS, meaning that some people with progressive forms of MS who still experience relapses may be candidates for Tysabri.

Common side effects of Tysabri include infusion reactions, fatigue, headaches, and joint pain. Less common (4 percent of patients) are severe allergic reactions to the drug that may cause hives/itching, chills, dizziness, chest pain, flushing, trouble breathing, and low blood pressure. People on Tysabri may be more susceptible to infections and should take measures to avoid them, including good hand-washing habits and avoiding people who are sick, when possible. Tysabri should also not be used by women who are pregnant and should be stopped for some time before trying to conceive (discuss this with your doctor). Women who are breastfeeding also should not use Tysabri.


Is Tysabri associated with melanoma?

Two cases of melanoma were observed in women who began using Tysabri. Researchers have not yet established a relationship between the drug and melanoma, but they're cautioning anyone with a personal or family history of melanoma to visit a dermatologist before starting the drug.

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