It'll probably be one I don't own or one I own and don't want to be sold out at even a 100% premium. So under my scenario all three of yours would fit :)
If we are making this a pole and its limited to US (or US exchange listed) and public I might guess CRME (if they ever get approved) but obviously it won't be them since I have now jinxed them (even though I have no position).
This makes the third biotech buyout in the past month—and the fourth in the past year––to go off at a colossal premium. The others were Coley, Iomai, and Kosan.