seel - Can they use the same people in PH II and P

seel - Can they use the same people in PH II and PH III as they did in PH I ? True that they add more in later trials but if someone shows IMPROVEMENT in PH I does that get them kicked out of later trials as they are not at the same starting point as newly screened participants ? TIA

If I were in PH I and had a DEATH SENTENCE starting out and was showing good improvement , I think I'd be PUSHING HARD to stay.