Obviously T-DM1 is eligible for this, so there is no real market driver in any such news. But I am aware of no public statements wrt T-DM1s fast track designation, now or ever.
Assuming we are truly talking Fast Track, it would be kind of odd if Roche (or DNA) had not requested it way back before the RTF'd submission a couple years ago. The designation goes for the IND, not an NDA/BLA, so it would presumably still be in force.
If the OP is using the "sloppy" terminology and means either Accelerated Approval or Priority Review, this is nonsense. Neither of these are decided prior to submission.
It would be nice if the OP was correct, as we might have somebody with an information source. But I think it is more likely blowing smoke. We shall see.