The problem is, no one wants to do those trials because rapamycin is cheap and generic. Why would Pharma spend money on something that they can't patent? Also, these kind of trials have to go on for 10+ years at a minimum - which is cost-prohibitive even if it is patentable (not to go in the weeds, but long trials count in the period of exclusivity given to pharma patents).
I believe the right approach is to use it off-label, be upfront about the potential risks, and collect lots of data so you can improve as you go. Practical anti-aging so to speak.
Another approach is through the NIH grant pathway, but that has a lot of road-blocks as well.