10. Aubagio
2013 Revenue:
$221 million

When French drugmaker Sanofi ($SNY) got FDA approval for Aubagio in September 2012, it had visions of grabbing market share and blockbuster sales for the oral MS drug. It just needed to beat out competitors, like a drug from Biogen Idec ($BIIB), which had yet to be approved.

That drug was approved 7 months later as Tecfidera, and it has since kicked the legs out from under Sanofi's expectations. Tecfidera sold three times more in 8 months than Aubagio did in a full year.

Actually, Sanofi has seen its dreams for a major play in the MS space get a serious reality check in the last 12 months. Besides the less-than-stellar sales of Aubagio, the FDA late last year decided against approving Lemtrada, the primary asset picked up in 2011 when it paid $20.1 billion to buy Genzyme. The FDA said the drug did not display enough benefit to outweigh its risks. The drugmaker made a new run at the agency in May with a new take on the old data. The FDA is expected to decide before the end of the year. -- Eric Palmer (email | Twitter)

For more:
Sanofi's MS pill Aubagio wins final thumbs-up from U.K. cost-effectiveness watchdogs
U.K. gatekeepers unsure Sanofi's MS drug Aubagio worth the price
Europe gives Sanofi's MS drugs big push
Early copies of Sanofi's Aubagio could roil European MS market
Biogen Idec, Sanofi secure European nods for blockbuster MS hopefuls