Studies:
Tysabri is a laboratory-produced monoclonal antibody. It is designed to hamper movement of potentially damaging immune cells from the bloodstream, across the “blood-brain barrier” into the brain and spinal cord. Tysabri was evaluated in a pair of two-year, controlled clinical trials:
Study I compared Tysabri to placebo in patients who had not received any interferon-beta or glatiramer acetate for at least the previous six months.
Study II involved patients who had experienced one or more relapses while on treatment with Avonex®. Half of the group took Tysabri in addition to their Avonex; half of the group took Avonex plus a placebo.
In both studies, those taking the medication had a reduced risk of disability progression and experienced fewer exacerbations (relapses) compared with the group taking a placebo. Tysabri has not been studied in people with primary progressive MS or in children.
Study I compared Tysabri to placebo in patients who had not received any interferon-beta or glatiramer acetate for at least the previous six months.
Study II involved patients who had experienced one or more relapses while on treatment with Avonex®. Half of the group took Tysabri in addition to their Avonex; half of the group took Avonex plus a placebo.
In both studies, those taking the medication had a reduced risk of disability progression and experienced fewer exacerbations (relapses) compared with the group taking a placebo. Tysabri has not been studied in people with primary progressive MS or in children.
Why is Tysabri Different?
The difference between Tysabri and the other interferon drugs is that Tysabri is an antibody. It inhibits white blood cells from entering the blood brain barrier and attacking the nerves. The interferon drugs are proteins which defend cells against viral attacks. “The way that Tysabri works has been studied, but the exact way that Tysabri works in unknown.”
Tysabri is an injection intravenously once a month, which differs from other MS treatment. “Tysabri is available only through the Touch Prescribing Program, which stands for Tysabri Outreach: Unified Commitment to Health. Only prescribers and patients enrolled in the Touch Prescribing Program can prescribe and receive Tysabri. Only certain pharmacies and infusion sites authorized by the Touch Prescribing Program can dispense and infuse Tysabri.”
The difference between Tysabri and the other interferon drugs is that Tysabri is an antibody. It inhibits white blood cells from entering the blood brain barrier and attacking the nerves. The interferon drugs are proteins which defend cells against viral attacks. “The way that Tysabri works has been studied, but the exact way that Tysabri works in unknown.”
Tysabri is an injection intravenously once a month, which differs from other MS treatment. “Tysabri is available only through the Touch Prescribing Program, which stands for Tysabri Outreach: Unified Commitment to Health. Only prescribers and patients enrolled in the Touch Prescribing Program can prescribe and receive Tysabri. Only certain pharmacies and infusion sites authorized by the Touch Prescribing Program can dispense and infuse Tysabri.”
Side Effects
Tysabri has many side effects like the other MS treatments; however, it also increases your chance of getting a rare brain infection called progressive mulitfocal leukiencephalopathy. The chances of getting this infection increase because no white blood cells can enter the brain to fight infection. This brain infection usually causes death or severe disability.
There were three cases where patients taking Tysabri were diagnosed with the fatal brain infection, which caused Biogen to withdraw Tysabri from the market in 2005. The FDA formally agreed to allow Tysabri back on the market, even though they still do not understand the exact correlation between Tysabri and PML. However, now being approved for the second time the FDA is requiring that patients try other MS treatments first before Tysabri, acknowledging Tysabri as a second-line drug.
