One of the reasons that the pricing regulatory body uses when...

One of the reasons that the pricing regulatory body uses when they wish to knock a product back could be,  To expensive when it only works on x% and we can't be sure that you can maintain that effectively. 
Put a guarantee in place. They would then only be left with, it's too dear. A very weak case when considering a child's life. 
Now consider the approval process, what is the most likely reason that the FDA might say no?
I think we would all agree that it won't be because of safety and I'm convinced that the various trials and other data especially as far as aGVHD is concerned is outstanding . If  the FDA find any  reason to say no , it will be something about the ongoing processes between manufacturing and treatment and MSB's abilities and willingness  to continually  monitor and control them.
Put in place a guarantee and most of the work that the FDA would have to do is done.
Might even speed up the entire process by several months! 
Best luck to all.