I must admit I'm not a very medically literate person - someone please break this down - is this good news or bad news? Were we expecting more people or lesser people to develop blood cancer?
We didn't expect the rate of oncogenesis from off-target gene insertion. It's bad news.
At the same time, this is a treatment for a terrible, terrible disease; so far the consequences seem smaller than what cerebral adrenoleukodystrophy would deal out on its own.
So it's bad news about something which is probably still a good therapy (but we sure would like a better one).