It's tough to show superiority over Sutent, so now you are dealing with a non-inferiority trial.
I was listening to the William Blair webcast, and the CEO confirmed that this was the main reason for choosing Nexavar as the comparator, but also made a comment acknowledging the difference between regulatory success and commercial success.
If they could have afforded it, I still think showing non-inferiority vs. Sutent would have been better than showing superiority over Nexavar, even if they want to position tivozanib as a more tolerable option than its competitors. Of course, if median PFS in the tivozanib arm ends up being something like 15 months then that's a different matter.
I wonder whether going forward they will decide to do a head-to-head trial vs. Sutent (or even pazopanib), or whether they would rather focus on other indications. My guess is the latter.