As off 2010, over 52,000 people worldwide are on Tysabri for M. Tysabri is generally used for people who have not responded to or can not handle other therapies.
Name: Tysabri (Natalizumab)
Type: Intravenous (IV) Infusion
Approved: First in 2004, Withdrawn in 2005, then reintroduced in 2006 (see below)
Approved For: Reducing the frequency of MS flare-ups (relapses) in patients with Relapsing Remitting Multiple Sclerosis (RRMS) as well as slowing the long term disability effects of MS. It was also approved for treating Crohns disease (an inflammatory bowel disease).
Reported Relapse Reduction Rate: 67% compared to placebo. (Average of 0.22 relapses per year)
Reported Long Term Disability Effects: In a 2 year study, Tysabri reduced the chance of a person’s disability worsening by 42% compared to a placebo . Disability levels were measured using the The Expanded Disability Status Scale (EDSS).
Recommended Dosage: Solution (300mg per 15ml vial) for dilution prior to infusion.
Schedule: Once every 4 weeks
Support Team: ActiveSource – 800-456-2255 – 24/7 phone counseling, payment assistance programs, health and wellness coaching, help setting treatment/lifestyle goals, and hosts various events teaching about MS
and connecting people who share the disease.
How Tysabri Works: Tysabri is an adhesion molecule inhibitor, designed to prevent potentially damaging immune cells
from traveling from the bloodstream, across the “blood-brain barrier”, and into the central nervous system (CNS). The below image shows the basic mode of action, in laymen’s terms, A and B are adhesion molecules and when the adhesion molecules on both the immune cells (white blood cells) and the blood brain barrier contact each other the white blood cells are allowed to cross the blood brain barrier into the central nervous system. Tysabri prevents these adhesion molecules from making contact which in turn prevents white blood cells from crossing into the CNS.
Common Side Effects: Headache, urinary tract infection (UTI), lung infection, pain in arms and legs, nose and throat infections, feeling tired, joint pain, depression, diarrhea, rash, and stomach area pain.
This is not a complete list of side effects.
Potential Risk of PML: Most people fear Tysabri because of the risk of a rare and sometimes fatal brain infection called Progressive Multifocal Leukoencephalopathy (PML) who’s symptoms are a lot like the symptoms of Multiple Sclerosis. After Tysabri was first approved by the FDA in 2004 three cases of PML arose causing Tysabri to be withdrawn from the market in 2005. In 2006 Tysabri was reintroduced to the market through the TOUCH program. TOUCH is a restricted distribution program that focuses on safety; only prescribers/patients enrolled in the TOUCH program can prescribe/receive Tysabri and the medication can only be infused in TOUCH authorized centers.
|Typical PML-lesion shown on MRI: www.emedicine.com|
Several risk factors have been identified for developing PML. First is whether you test positive for the John Cunningham virus (JC Virus) or not. The JC Virus is a pretty common virus that almost everyone has; it’s estimated that more than three quarters of the people in the United States have this virus. You can test for it with a simple blood test or the Stratify JCV Antibody ELISA test. Just because you do not have the JC virus does not mean you can’t ever get PML as you can be infected with the JC virus at any time which is why you should be periodically (every 6 months) retested for the virus. The second risk factor is how long you have been on Tysabri, it is generally said that after about 2 years your risk of developing PML increases. The third risk factor is if you have previously been treated with an immunosuppressant such as mitoxantrone, azathioprine, methotrexate, cyclophosphamide, or mycophenolate mofetil.
“A person who tests positive for anti-JCV antibodies but has no other
risk factors has a less than 1 in 1000 risk of developing PML. A person
with all three risk factors has an 11 in 1000 risk of developing PML.” –National MS Society
Rebound Effect – This is not often talked about and I am not sure why because it seems like a pretty vital piece of information! The rebound effects refers to the worsening of disease activity after stopping Tysabri. It is really hard to find the numbers so I will have to do an article specifically on the rebound effect later but for now just know this. After about 4 months or so of coming off Tysabri it looks like the disease activity drastically increases. I think I read a number (I have to check on this) like 3 times as active meaning, 3 times the number of lesions, and 3 times the number of relapses. It appears that the longer you are on Tysabri and the better the medication helps you, the more likely/harder you are to rebound. I will try to find the actual facts on this soon but I did confirm this to be true with my neurologist who is a dedicated MS specialist.
Personal Experience: Tysabri is the DMD that I am currently on and I am happy to say that before I started Tysabri I was at about 6.6/7 on the EDSS and am now around a 2! Of course I have done a lot of work on my own to get where I am today but as of August 2013 I have suffered no relapses! I have been on Tysabri since December 2012 and before I started Tysabri I was relapsing about once every month and a half! As long as I am JC negative I will probably stay on Tysabri!