It can't though. You still need to run real trials on living humans, living their lives and taking experimental drugs/procedures/interventions and running statistics on them.
AI can do everything you described except the "living out a human life" part - but it can iterate on ever better simulations of that, or worse, it may reward-hack and... well, I'd rather not be the human in that story.
Do you really think humans are going to be the users? Sure for tomorrow and next month, but the clock is ticking. I got mad at our internal CS peeps the other day. They were demanding an internal tool. I was like we went through hell this summer replacing the front end so it's agent usable, just get Claude to do that. They were like oh...