tysabri decison already!  

catastrophegirl 40F
975 posts
6/7/2006 1:33 pm

Last Read:
6/9/2006 11:11 pm

tysabri decison already!

i've got a friend in the pharmaceuticals industry and today she passed on this tidbit of info:

BioWorld Today via NewsEdge Corporation :

By Aaron Lorenzo Washington Editor
The FDA is allowing Tysabri to return to the market in a limited capacity for multiple sclerosis patients, three months after an advisory committee voted unanimously in favor of doing so.

The companies behind Tysabri (natalizumab), Biogen Idec Inc. and Elan Corp. plc, expect to make it available next month after the FDA signs off on all aspects of an accompanying risk-management plan, which is designed to ensure that patients are educated and provide continuing data.

"The benefits of this drug outweigh the risks for this particular condition," said Steven Galson, the director of the FDA's Center for drug Evaluation and Research, during a conference call. He added that patients are ready to take the drug, despite its well-chronicled risks. "That's why we're doing it."

The product's reintroduction represents a 180-degree about-face for Tysabri, which last year was removed voluntarily from the market by Biogen Idec because of its link to a viral infection called progressive multifocal leukoencephalopathy (PM, which can lead to death.

Because of that risk, the FDA is recommending its use be restricted to patients who have had an inadequate response to, or are unable to tolerate, alternate MS therapies. The monoclonal antibody is indicated for use as a monotherapy "because we don't know enough" about possible interactions with other immunosuppressive drugs, Galson said.

Notably, though, the label does not preclude first-line use.

Prior to initiating therapy with Tysabri, physicians are to obtain MRI scans on patients to help differentiate potential future MS symptoms from PML.

Tysabri's risk-management plan, dubbed the TOUCH Prescribing Program, is designed to inform physicians and patients of the product's benefits while minimizing its potential PML risks.

Patients must enroll in the program to receive the drug, which will only be prescribed, distributed and infused by prescribers, infusion centers and pharmacies registered with the program. Patients are to be evaluated at three and six months after the first infusion, and every six months thereafter.

"There is a lot of built-in, rapid and immediate follow-up of patients in the program," explained Russell Katz, who works within the FDA's Office of drug Evaluation. He stressed the program's dual role in educating patients and physicians, as well as informing the companies and regulatory officials about PML infection rates, currently estimated at one in 1,000.

Biogen Idec, of Cambridge, Mass., is compelled to inform the FDA of new PML cases within 15 days.

Adherence to such a rigid risk-management plan was recommended by the FDA's Peripheral and Central Nervous System drugs Advisory Committee earlier this year. The panel met over two days to contemplate data from Biogen Idec, other findings from the FDA, as well as pro and con arguments from patients, their advocates and physicians. At the time, FDA officials acknowledged the likelihood of future cases of PML and warned against its dire consequences. (See BioWorld Today, March 8, 2006, and March 9, 2006.)

"We don't know how to predict who's going to get it," Katz reiterated, adding that "this is balanced against the significant benefit that we believe the drug confers."

Tysabri initially received FDA approval in November 2004, but was withdrawn by Biogen Idec in February 2005. In addition, all clinical trials were brought to a halt. Such studies resumed this past February.

Galson characterized the re-approval as "very rare."

The principal products used for MS include four disease-modifying therapies: Avonex (beta interferon 1a, also from Biogen Idec), Betaseron (beta interferon 1b, from Berlex Laboratories Inc.), Copaxone (glatiramer acetate, from Teva Pharmaceuticals Inc.) and Rebif (beta interferon 1a, from Serono SA). An immunosuppressant, Novantrone (mitoxantrone, from Serono), also is used.

soooo... now on to finding out more about the clinical trials!!!

rm_corezon 53F
3376 posts
6/8/2006 4:35 pm

that's pretty peculiar, makes me want to read up on that one...with a med tech and pathology background that makes me wonder if that particular virus is one associated with the genetic turnon of MS anyhow; which has long been postulated to have a viral origin which then triggers the autoimmune response.

rm_corezon 53F
3376 posts
6/8/2006 4:43 pm

I also wonder if there is a completely objective way to diagnose PML (RNA amplification assay, for example) I haven't heard of one so if there is it isn't widely available for sure...or if they are doing most of the diagnosing from symptoms and other laboratory data including blood counts and bone marrow studies.

rm_corezon 53F
3376 posts
6/8/2006 4:56 pm

So maybe the virus causes MS but is only triggered to cause PM when this monoclonal antibody is used...if they can track the virus by RNA amplification then why not screen all suspected MS cases early and create a monoclonal antibody directed at the virus that you can treat MS patients with? (yes, just thinking here; not sure what the antiviral Retrovir used for HIV actually is, chemically/biochemically speaking)

Modern medicine is just now beginning to find ways to use monoclonal antibodies in vivo to treat diseases (we have used them for years in in vitro assays), obviously, hadn't heard of this drug yet but it sounds very new technologically. Years ago "they" were postulating creating targeted antibodies that were capable of entering cells invivo and only targeting the disease RNA but I didn't think we had advanced very far in this area. This sounds like the cusp of that advance starting in actual clinical practice.

rm_corezon 53F
3376 posts
6/8/2006 4:58 pm

Just for the sake of argument, the cbc's, bone marrows, MRI's may be suggestive of certain causative agents but they really aren't truly definitive. Only finding the little buggers is.

rm_corezon 53F
3376 posts
6/8/2006 5:03 pm

IE, when the little bugger is thought to be a virus or a bacterium or other microscopic pathogen. I am aware of the genetic component in all autoimmune diseases but they are all thought to have a trigger (virtually anything that stresses the immune system including pregnancy, so they aren't all necessary due to viral or bacterial triggers) turn on that changes or activates that particular gene loci.

Sorry to hog your blog, this is my professional field of interest in general and it fascinates me.

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