Thank you Dr. Gross for a very well-balanced opinion of Tysabri.  I have had 19 infusions of Tysabri so far.

I would like to note however that you stated: "Tysabri is a monoclonal antibody for select cases of relapsing/remitting MS that was introduced in 2004. It is often quite beneficial but reserved for those MS patients who have had a less than optimal response to or cannot tolerate conventional immunomodulators such as Copaxone, Betaseron, Avonex or Rebif. Due to a few cases of Progressive Multifocal Leukoencephalopathy (PML), the drug had to be withdrawn but was reintroduced into the US market via a restricted distribution program in 2005"... this is not correct.  For your readers, please note that Tysabri is for all forms of relapsing MS, which include Relapsing Remitting, Progressive Relapsing, and SPMS with relapses.  Also, Tysabri can and has been used as a first-line defense, therefore it is not reserved for a second line defense.  See:

http://www.fda.gov/ohrms/dockets/ac/07/briefing/2007-4313b1-02-FDA-Errata.pdf.

Lastly, Tysabri was voluntarily removed in 2005 due to 3 unexpected cases of PML, not a few.  Your readers should also be aware of the fact that of the 3 cases of PML, all 3 trial patients were severely immune compromised and had drug interactions with Tysabri (which included Avonex and Azathioprine) and additionally, the 2 trial patients that passed away from PML did not have MS.