I was surprised when I first got involved with drug development, how rushed the process is. Phase I and Phase II trials are initiated by pharma with strikingly little understanding of how the drug works. A classic example is iniparib, which made it to a phase 3 trial but turned out not actually hit the target it was supposed to hit (PARP).

The reason for this is I think economics. There is a large advantage to being first to market, especially if the disease has no other treatments. This means that you can set your price, there is zero competition, and you disincentivize all other companies from developing similar drugs. Under these conditions, you can recoup development and trial costs in 1 - 2 years. So it is no wonder that drugs with any sort of signal are pushed quickly through early phase trials.