I personally heard about it from friends in Europe in 2015/16 then I watched it til the year before PDUFA was expected then started flipping a sack from .70's to 1.30 range over and over building freebies.
But, your questions about OTC stocks overseas, those are the most highly prized stocks in the OTC and are most of the stocks in the top $$ range.
There are many OTC's with Billion dollar valuations.
My wife showed me a fascinating face book video and story that she saw from a wound care nurse group she belongs to. Maybe the only useful thing I've ever seen on face book.
For me, it was seeing that before/after pic on Reddit of the blond boy that had a 2nd degree scalding burn on his chest. I bought $10k of the stock the next day @ $1.06. Later on, $15k @ $5 per share. My gain percentage as of today is 444.04%. I'm just sitting on it until the company gets sold or the stock reaches $100.