Whether you believe Tysabri should come back or not, it is useful to understand the drug's efficacy. Elan did a presentation to an investor conference today, and there are some fascinating slides which illustrate the drug's effectiveness. The information is from the AFFIRM two year trial which compared Tysabri to placebo:
66% reduction in relapse rate in Year 1
67% reduction in relapse rate over Two Years
NEW or NEWLY ENLARGING T2 LESIONS:
80% reduction in Year 1
83% reduction over Two Years
NUMBER OF GADOLINIUM ENHANCING LESIONS:
93% less in Year 1
93% less over Two Years
RISK OF DISABILITY PROGRESSION:
42 % reduction over two years
All of the above information has been presented at medical conferences in the last year, but not in such a user-friendly format.
It is important to note that 6% of Tysabri patients will develop persistent neutralizing antibodies. For this group, the drug does not work at all - zip, zero, nada. If the companies were to quote the above numbers ONLY for the 94% who do not develop antibodies, they would be higher.
I wonder when the companies will release the % of people whose EDSS actually IMPROVED while on Tysabri. That is a most interesting number to know.