Any drug that targets a population of a million people (US only) is a buster, particularly, since these drugs may have a price tag of $10,000 or so per year, even at 1/10 of that price and a low initial penetration (just 10%) it should be $100 MM annually, with Europe and the rest of the world, who knows. The question is how is the earnings partition between ELN and BIIB on that one, I have not the slightest. Interestingly, this drug may find many other applications in other diseases involving the immune system (autoimmune failures, like rheumatoid arthritis, MS etc), so a potential billion bucks market is not impossible, and that is a big drug.