Every company (or its precursers) on my list of large cap drug stocks was once in a similar position. There is always a first phase 3. There is almost always a good sized investment in early trials with high degrees of doubt. There is rarely a big time partner until there are strong trial results...although one could argue Hepalink is no slouch. There is often failure and restart. ETC!
I have been lucky enough to be an investor in 5 companies that were successful and then acquired. Resverlogix (or one of my other current holdings) has IMO a good chance of being number 6.
I have also seen several others go down the tubes.....along with my investment.
It can be dicey, and it is not for the faint of heart.