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I noticed that there has been some confusion regarding lymphoma, primary CNS lymphoma and Tysabri (natalizumab).

At the website investorvillage.com, there is a discussion (and some confusion) regarding Biogen Idec's (BIIB) and Elan's (ELN) drug -- Tysabri (high and strong efficacy, but with potential serious side effects -- is the risk of PML 1:1,000 or 1:5,000 or ...?).

Besides other opportunistic infections caused by the immunosuppressed state (look at the cerebrospinal fluid, CSF, CD4 to CD8 ratio), there has been a recent scare concerning the risk of PML.

So, let me summarize the discussion and then clarify some of the medical terms:

1. samssong73 quotes Barclays' report from their German consultant (are we all quoting the same source but in different ways? -- possibly since this KOL from Germany discussed the possibility of a U.S. case and the rumored German case, as I have discussed with Piper Jaffray & Co. Bridge Scientific Consulting LLC: you will have to guess which one) and discusses the prior known cases of lymphoma.

2. nichtmoeglich then ask whether CNS lymphoma is a previously unidentified side effect of Tysabri use.

3. lotus52 then responds that there has been lymphoma in the past in a Tysabri patient in the clinical trials (however unlikely the causation is) so there shouldn't be alarm or panic now. That 49 year-old man who had been previously treated with infliximab and 6-mercaptopurine (did this patient also have Crohn's disease or psoriasis/arthritis; I doubt this was off-label for MS). That patient had B-cell lymphoma (this is different from PCNSL) -- it originates in the B-cells in the lymph nodes, unlike PCNSL, which originates in the CNS (central nervous system itself) -- see my information page on PCNSL at www.neurologique.org under the "Links" heading.

4. lotus52 then notices the oversight at quotes us at: http://www.investorvillage.com/smbd.asp?mb=160&mn=369285&pt=msg&mid=7610732

5. Bear River then asserts that Biogen Idec did not waffle about this when Geoffrey Porges - Sanford Bernstein asked Dr. Alfred (Al) Sandrock about the PCNSL case.

6. rosemountbomber asks whether he was discussing the published case or not -- he was clearly discussing the published case; his point is that they have known about that case for over a year (why have we not?). The SVP Neurology R&D points out that Biogen does not believe that this was related to the drug; this kind of assertion is similar to EMD Serono's Dr. Viglietta's response concerning the malignancies in the oral cladribine (mylinax) trial (CLARITY). It is unclear to me how these biotechnology companies can make such assertions. This is similar to when Novartis said that the cases of melanoma were not related to FTY720 (fingolimod) or when some of their medical side still asserts that the herpes encephalitis and disseminated varicella zoster were unrelated to their investigational drug.


So, what does this all mean?

1. Lymphoma is different from PCNSL;
2. There may be more PCNSL cases we do not yet know about (it took 1 year for us to find out about the recently published case in the Annals of Neurology);
3. For now it does not appear that neurologist prescribing habits have changed;

and most importantly:



Noone knows what the future will hold.



- Dr. Daniel Kantor, MD BSE
Medical Director
Neurologique

info@neurologique.org
www.neurologique.org