Introduction:
Following the September 2006 Health Canada approval of Tysabri® (natalizumab) for relapsing multiple sclerosis, Biogen Idec and Elan Pharmaceuticals commercially launched the drug in Canada. The drug is given by monthly intravenous infusion.
About Tysabri and Its Availability
Q. What is Tysabri (pronounced Tie-SAB-bree) and how does it work?
A. Tysabri (whose scientific name is natalizumab, pronounced: nat-tal-IZ-zue-mab) is a laboratory-produced monoclonal antibody. It was formerly called Antegren. It had been approved for marketing by Health Canada for relapsing forms of MS, based on data from the first year of two, two-year clinical trials.
Tysabri is designed to hamper the movement of potentially damaging immune cells from the bloodstream, across the "blood-brain barrier," and into the brain and spinal cord. The drug inhibits this movement by attaching to alpha 4-integrin, a protein on the surface of immune T-cells that normally enables them to adhere to and pass through the blood-brain barrier. Because of this mode of action, Tysabri is called a selective adhesion molecule inhibitor (or "SAM").
This approach was initially studied in animal models, which showed that monoclonal antibodies could block such immune cell movement and ameliorate disease. These animal studies led to the successful human studies.
Q. Who should take Tysabri?
A. Tysabri has been approved for persons with relapsing remitting multiple sclerosis.
Relapsing MS means that individuals experience flare-ups of symptoms in the form of periodic attacks, which then subside with total or partial recovery.
According to the Health Canada approval, Tysabri is generally recommended for people who have had inadequate response to, or are unable to tolerate, other approved MS therapies. The question of who should take Tysabri is something that can only be answered through discussions between an individual and his or her neurologist.
Q. Who should not take Tysabri?
A. People should NOT take Tysabri if they have:
· An allergy or sensitivity to natalizumab or anything else that is in this medication.
· A serious problem with their immune system (for example, due to a disease such as leukemia or human immunodeficiency virus[HIV], or from using some other mediations that weaken the immune system)
· A type of rare infection of the brain called progressive multifocal leukoencephalopathy[PML] or have had it in the past.
Q. In terms of who can be prescribed Tysabri, who determines what constitutes an "inadequate response" to currently approved MS therapies?
A. Canada’s approval of Tysabri does not specifically define "inadequate response," nor does it define what constitutes an inability to tolerate alternate MS therapies. Therefore, the decision about whether to take or switch to Tysabri must be made after careful consideration by a person with MS together with his or her personal physician.
Q. How much will Tysabri cost?
A. The wholesale price of Tysabri which is administered 13 times per year, is $39,640 annually as stated in Biogen Idec’s submission to the Common Drug Review (CDR)-(see next question.)
Q. Will Tysabri be reimbursed by my provincial drug plan?
A. None of the provincial governments are as yet reimbursing the cost of Tysabri. Biogen has submitted to the Common Drug Review (CDR) process. This is the first step in applying to most provincial drug formularies for listing. CDR is the government agency that determines whether a drug is cost-effective and should be covered by public drug programs. Provincial drug programs use this information in making their decisions. According to Biogen Idec, CDR should make a preliminary decision by late February with a public decision in March.
The Society will work closely with the companies to ensure that they pursue their commitment of providing access for those people with MS for whom this treatment may be appropriate.