Okay, but Biogen has 9 years to do the confirmatory study and they've indicated that they'll take their sweet, sweet, time with it. Also, it's not like we have 0 evidence: we have two, 4-5 year long studies that show how well it works: and the benefit in one was marginally positive and the effect of aduhelm was negative in the other.

Sarepta's Eteplirsen was in a similar situation: little data to back it up and a very controversial decision. They also had to do confirmatory studies, but it took them 3 years after the approval was done for the study to begin.