IIRC There's already a special case where you can volunteer to try things if you're dying. If you have a rare cancer and doctors are like "Six months maybe less" and there's some crazy Hail Mary drug, which could work but isn't tested yet, you can volunteer to try it and see what happens. You can't pay (so it's for science, not a chance to get rich selling false hope), and you must be advised by doctors who have no financial interest, something like that. Judges were like, eh, you're dead anyway, what's the worst that could happen?

This trial was phase I/IIa which I believe means it's combining safety in humans with initial efficacy data. The thinking is, the real treatment is a single dose. If we give participants less than a full size dose we don't learn much from that. If we give them a real dose, we might as well see if it works.

So their endpoints were firstly how is the treatment tolerated, then secondly does it reduce the need to take clotting factors? Hence this good news story.