Usually easier to get approval in other countries if the FDA approves it first. However the main reason is that even with more patients overseas the cost of medicines is lower so the profit potential is greater in the U.S.

I'm still trying to remember the name of the biopharma I was invested in, in 2008-2009. They were approved in Canada and Europe but the FDA gave them the run around. March 2009 they were facing delisting at .88 and then got bought out for $5. The two bios I invested in after that killed the profit I made there (and more) and I abandoned bios until last year.