They will come up with some endpoint for their randomized trial based on bone scan reduction/pain reduction with secondary endpoint OS.
Seems highly unlikely that the FDA would accept bone scan data as any significant part of the endpoint - because the lack of the historical data brings up all the questions (and more) that I just asked.
Nobody in the control arm who has already had docetaxel will show improvements on the primary endpoint, and so the DSMB will be quickly faced with a considerable favorable imbalance and will have little alternative but to stop the trial.
Probably not entirely true - patients who have progressed under chemo are often still sensitive to it, just less so. And if XL184 is about the same efficacy as docetaxel (my current guess) then the other 50% of the patients will hide the small benefit seen in docetaxel pre-treated patients unless it is a very big trial. I have my doubts this management team would run the necessary trial.
Now, if EXEL went after 2nd line I think they have a much better shot with a smaller trial. But I'd be very surprised if this management did that.