Tysabri (natalizumab)
An approved treatment for Multiple Sclerosis.
The same compound appears under different names depending on the context. Here is how to identify Natalizumab wherever you encounter it, plus the key facts at a glance.
- Generic name
- Natalizumab
- Brand name
- Tysabri
- Drug class
- Monoclonal antibody (anti-integrin)
- Manufacturer
- Biogen
- How it's taken
- Given as an intravenous infusion taking about 1 hour, once a month at a hospital or infusion center.
A highly effective IV infusion that blocks the molecular highways immune cells use to enter the brain and spinal cord, dramatically reducing MS relapses and new brain lesions.
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Where Natalizumab fits
High-efficacy therapy approved as a single treatment for relapsing forms of MS in adults (clinically isolated syndrome, relapsing-remitting MS, and active secondary progressive MS). Doctors weigh its benefit against the PML risk. Requires JCV antibody monitoring due to PML risk.
How Natalizumab works
Natalizumab blocks a protein on white blood cells that allows them to cross into the brain and spinal cord. By stopping this, the drug prevents immune cells from entering the nervous system and attacking nerve cells, reducing inflammation and damage.
Mechanism: Anti-alpha-4-integrin monoclonal antibody that blocks immune cell adhesion and migration across the blood-brain barrier
Side effects and safety
Common side effects include urinary tract infections, headaches, nausea, and fatigue. The most serious risk is a rare brain infection called PML (progressive multifocal leukoencephalopathy), which can cause death or severe disability. Risk is higher if you're positive for the JC virus. PML is the subject of the label's boxed warning, the FDA's strongest warning. The label also warns about serious herpes virus infections of the brain, its lining, or the eye that can be fatal or cause blindness; serious liver injury, including liver failure needing a transplant; serious allergic reactions such as anaphylaxis; other infections; and low platelet counts that can cause bleeding (babies exposed during pregnancy can also have low platelets and anemia).
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Natalizumab
Given as an intravenous infusion taking about 1 hour, once a month at a hospital or infusion center. Because of PML risk, the drug is only prescribed through a special Risk Management Program.
Availability and cost
Approved biosimilar: Tyruko
Anti-integrin monoclonal antibody requiring monthly IV infusions and enrollment in a risk management program (TOUCH). One approved biosimilar (Tyruko) exists.
Help paying for Tysabri
Pick your insurance to see which help fits. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE; charity funds are the usual route there.
- Copay help
Biogen Copay Program may lower Tysabri drug cost for eligible commercially insured patients; annual cap applies. Medicare, Medicaid, VA/DoD and other federal plans excluded.
For: private insurance · source - Infusion cost help
Infusion Copay Assistance Program pays up to $250 per infusion. Not for MA or RI residents or anyone on federal or state programs.
For: private insurance · source - Insurance and case manager help
Biogen Support Coordinators explain coverage and costs, help with prior authorization, and look for options for government-insured, uninsured or underinsured patients.
The official page does not say who qualifies. Ask the program. · source
Good to know: No Biogen free-drug program is described on the page; for uninsured or underinsured patients, coordinators research other possible financial help.
- From a charity · TotalAssist (formerly PAN Foundation)Multiple Sclerosis fundOpen
Pays for: Out-of-pocket costs for approved medications, up to $8,000 per year. Requires Medicare, Medicaid or TRICARE.
- From a charity · The Assistance FundMultiple Sclerosis fundWaitlist
Pays for: Copays, coinsurance, deductibles and other health-related expenses.
The foundation says: “WAITLIST — Accepting Waitlist Patients. TAF is currently accepting requests to join the enrollment waitlist for this program. Waitlists a…”
Clinical trial results
Approved by the FDA in 2004. One-year trials showed it reduced relapses by more than 60%. It was the first monoclonal antibody approved for MS and dramatically improved outcomes for many patients.
Development history
Natalizumab was withdrawn from the market temporarily in 2005 when PML cases were discovered. It was reintroduced in 2006 with strict safety monitoring. Now over 20 years in use, it remains an effective option despite the PML risk.
Explore Multiple Sclerosis trials
Other Multiple Sclerosis treatments
Common questions about Natalizumab
▸What is Natalizumab (Tysabri)?
A highly effective IV infusion that blocks the molecular highways immune cells use to enter the brain and spinal cord, dramatically reducing MS relapses and new brain lesions.
▸How does Natalizumab work?
Natalizumab blocks a protein on white blood cells that allows them to cross into the brain and spinal cord. By stopping this, the drug prevents immune cells from entering the nervous system and attacking nerve cells, reducing inflammation and damage.
▸What are the side effects of Natalizumab?
Common side effects include urinary tract infections, headaches, nausea, and fatigue. The most serious risk is a rare brain infection called PML (progressive multifocal leukoencephalopathy), which can cause death or severe disability. Risk is higher if you're positive for the JC virus. PML is the subject of the label's boxed warning, the FDA's strongest warning. The label also warns about serious herpes virus infections of the brain, its lining, or the eye that can be fatal or cause blindness; serious liver injury, including liver failure needing a transplant; serious allergic reactions such as anaphylaxis; other infections; and low platelet counts that can cause bleeding (babies exposed during pregnancy can also have low platelets and anemia).
▸How is Natalizumab taken?
Given as an intravenous infusion taking about 1 hour, once a month at a hospital or infusion center. Because of PML risk, the drug is only prescribed through a special Risk Management Program.
▸Is Natalizumab FDA approved?
Yes, Natalizumab (Tysabri) is FDA approved (2004) for the treatment of Multiple Sclerosis.
▸What is the PML risk with natalizumab?
Progressive multifocal leukoencephalopathy (PML) is a rare but serious brain infection caused by the JC virus that can occur in patients taking natalizumab. The risk depends on three factors: JC virus antibody status (positive or negative), duration of treatment (risk increases after 2 years), and prior immunosuppressant use. JC virus-negative patients have a very low risk (approximately 1 in 10,000). JC virus-positive patients with high antibody levels treated for over 2 years have a significantly higher risk. Regular JC virus testing every 6 months is standard practice.
▸What is the TOUCH prescribing program?
The TOUCH (Tysabri Outreach: Unified Commitment to Health) program is a mandatory risk management program required for all natalizumab patients, prescribers, infusion centers, and pharmacies. It ensures that everyone involved understands the PML risk and that appropriate monitoring is in place. Patients must read and sign a patient agreement, and prescribers must be enrolled and complete training. This program was put in place when natalizumab was reintroduced to the market in 2006 after the initial PML cases.
▸Is there a biosimilar for natalizumab?
Yes. Tyruko (natalizumab-sztn) was approved as the first biosimilar to Tysabri. Biosimilars are highly similar to the original biologic drug with no clinically meaningful differences in safety or efficacy. The availability of a biosimilar may offer a lower-cost alternative for patients. Your neurologist and insurance plan can help determine whether the biosimilar is appropriate and covered.
▸Why was natalizumab temporarily withdrawn from the market?
Natalizumab was voluntarily withdrawn in February 2005, just 3 months after its initial approval, when 2 patients in clinical trials developed PML and one died. The withdrawal allowed Biogen and the FDA to investigate the risk and develop the TOUCH safety program. Natalizumab was reintroduced in June 2006 with the mandatory risk management program in place. Despite the PML risk, it remains one of the most effective MS therapies available.
▸Can natalizumab be given less frequently than monthly?
Extended interval dosing (every 6-8 weeks instead of every 4 weeks) has been studied and is used by some neurologists, particularly for JC virus-positive patients. Some evidence suggests that extending the dosing interval may reduce PML risk while maintaining therapeutic benefit, though this approach is not yet reflected in the official prescribing label. Your neurologist can discuss whether extended interval dosing is appropriate for your situation.