You are correct , the more patients the easer is to show SS in any study..
But the first time HGEN changed primary endpoint , it was before interim results what I remember , since it has nothing to do with DSMC.
Interim time , DSMC is evaluating what is happening during the study,,, If they will see to many side effects , or no positive effect at all , they will recommend to stop..if results unusually good , they will recommend to stop and some type of approval..
If they see some improvement and no serious side effects ..but not at this point SS results , they usually recommend to increase number of patients , and lets hope it will work for you.
All IMO..