You don't know its proving difficult, Frrol. You actually have no idea. And, if we stick to what the company said, and keeps saying, they will start 3 trials by years end. If they are confident enough to keep reiterating the start of the 3 trials, I would say things are going according to a timeline that is still on track.
I wrote a post a week or so ago, which proposed what I thought was a very reasonable cause for delay of trial start. I will say again, it is very possible that the FDA in the new "master protocol" protocol, might require the trials to start within a certain timeframe of one another. Being endpoints will correlate within all 3 trials (assuming master protocol), it would make perfect sense that the trials run simultaneously to some degree. The whole point of a master protocol is to provide a quicker route to approval for a drug which is safe and has the potential to treat multiple indications. My take is in order to do this, trials should more less occurr at the same time. Not sure what you all think here, but if this is the case, Rett was probably put off for a few months until PK and AD were farther along in the planning stage.