That's why drugs go for clinical trials, because of ceteris paribus: researchers can't figure out the conditions under which cetera are paria. In many human situations, just instrumentalism (a philosophical stance) would do, without even understanding the underlying reality.
It’s shocking how many fail in phase 3. You don’t go into an eye-wateringly expensive phase 3 unless it’s blindingly obvious from phase 2 (dose-ranging trial) that you have a winner. Which phase 2 you don’t embark on unless you have good safety data from phase 1 (often a combined phase 1/2 if you can swing it so you some belief it is efficacious in humans).
I once had a board member with 26 approved drugs from his long career at Roche. He told me “you don’t want to know how many failed after hundreds of millions had been spent. You’d be too discouraged.”
