That explains why the rate of success in rare disease is so much higher, right? If $SRPT thinks their phase 2 data is good enough for acc approval, then why not use same incl criteria as ph 2? They can always exclude those not doing well once the trial starts(TIC). Companies like STPT popping up all over because single mutation disease easier to crack. Shorter R&D timelines, more lenient TX by FDA and EA, cheaper to develop, higher probability of success, charger whatever the hell they want.
I am not criticizing because it's a great ROI business model and rare disease needs focused research. But barrier to entry and prob of success is higher, and in my book, that means easier. Easier is a good thing so no need to be defensive about it