<<<I think most of the Avonex increase is due to price increases.>>.
I believe this to be the case as well. These things do not happen in a vacuum. Biib is finally starting to emphasize tysabri because it sees its unit growth in Avonex starting to fade, and just behind that is future generic competition.
BIIB has not choice now but to push tysabri up the line to a more mainstream drug. Tysabri is already the only drug clinically proven, by one recent study, and I recall another such study a year or so ago, to demonstrate disease reversal. Each year tysabri appears to create, or at least I think it very probable, that it will create more and more distance between its efficacy and the gradual deterioration for those patients on the CRABS.
MS is a cumulative disease. Even if your not having attacks the disease is still cumulatively attacking your system over time. CRABS do not do much to impact this cumulative attack. They do provide relief from acute attacks, diminishing the attacks to an extent, but they do nothing for disease reversal or really doing much to slow the progression of the disease down.
Each year a tysabri patient, I believe, will show less disease deterioration vs. a CRAB patient, and the curves will just continue to separate.
Now if PML can remain as rare as it has been, and we get more 2, 3, and 4 year safety data, I cannot see tysabri doing anything but growing in marketshare (assuming of course that PML does remain as rare as it has presently demonstrated itself to be).
Tinker
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