I haven't listened to their JPM presentation, but with that caveat I'd say that it is data mining, but there is some logic here.
The PTC presentation actually sets out the case to some extent. Their claim is that these therapies are never going to significantly improve muscle strength, they are just going to slow (or hopefully even stop) the natural decline that starts at some point.
But the problem is that the decline potentially starts at different ages - in fact in very young patients there is improvement prior to decline with normal maturation, and in older patient the decline starts at different ages. So to demonstrate that any drug works in a reasonable sized trial you have to somehow discriminate between those kids in decline and those still stable or improving. Their claim is that none of these drugs will show efficacy in a group that is still stable.
The PTC trial is for patients between 7 and 16, stratified two ways - patients younger or older than 9, and by less or more than 350m initial walk. Their claim seems to be that the <350m kids are the key - these are the ones that have already started their decline.
The caveat here is that I am really not a DMD guy - never owned any of these stocks prior to my modest recent position in PTC, and so I really am not familiar with the twists and turns in this story.
Peter
