1. If IMPACT is more like 9901 than 9902a, then interim power is at least 90%
Must be running East again :-)? That's far too high. My estimate for interim assuming D9901 is about 70% give or take a few points.
About D9902a, with very high probability, the trial would have achieved stat sig if the enrollment size was about 700. Interestingly, if you fit an exponential curve to the latter part of the survival curves to extrapolate the survival times for the 36-months survivor, the trial HR gets to larger than 1.45. This is yet another piece of evidence showing how the late effect of Provenge is a really big deal in any effort to try guessing the success of IMPACT.