If I just put on my optimistic hat, it the data is positive then...

If I just put on my optimistic hat, it the data is positive then the mgmt probably want the market to continue to rise so they can increase the stock price for the next step be it a CR or licensing deal. If the data is not impressive or negative they may have put in a TH to stop any fall in SP prior to announcing the result followed by a CR? Just my layman guess at how or why the company may be choosing to not got into a TH.

Also, if the CEO and may be only one or two top people are working with their scientific and clinical advisors/ boards then the group would be very small and they may have already signed confidentiality/ NDAs in place, and like others have said here, mgmt’s tend to have price sensitive info all the time- if in the past experience there haven’t been leaks there is no reason to suspect one now. There will be the usual speculation on sudden price rise or fall that there was leak, but it in this case the rise is accurately attributed to the results anticipation and preso at the prestigious ASH early next week. The surprise should have been why did the market wait till the last minute.

Just my guess.