I'm not certain that marketing plays that huge of a role. They make the only drug on the market to treat hemolytic uremic syndrome, every medical student has to learn about it. Must be some other costs, or hiding of true profit as you suggest.
Sunk costs on failed treatments, generally. I don't remember the stat well enough, but it's something like a double-digit quantity of candidates fail for each single one that receives FDA approval.
Here's hoping someone else can investigate and share the exact number. I'm at a stoplight.
