There are two things terribly wrong with the idea of a "Constitutional right" to experimental drugs. First, such a right is impossible, because one can't have a right to something that someone else must produce. Second, we should already have the right to access experimental drugs (at our own costs), but the FDA stands in the way. All that needs to happen is that the FDA is disbanded, or at the very least its restrictions on experimental drugs need to be lifted.
Just as it's wrong for government to try to create a "right" that requires expropriating the property of one person to give it to another, it's wrong for government to prohibit individuals from accessing any product they want to buy.
There's a grievous misconception regarding the Constitution and rights in this country, and it's not getting any better.