Reporting interim results is frowned upon due to the bias it can generate among investigators, patients, and anybody else involved as the rest of the trial is conducted to completion. Much cleaner to just wait. Not sure why they didn't just say they were going to do it that way from the start but I think it is a good decision. Could be that an interested outside party strongly suggested it as it makes the final data readout that much more reliable. That would be my guess.
Leo promised, and then failed to deliver
please share with us your thoughts on this issue, if you dismiss my ideas, and I am all ears