The same is true for life extension in mice. We can massively extend the mouse life span but it doesn’t replicate in humans.

The reason there is pretty easy to grasp. Mice are a short lived more R-selected (lots of offspring, lower parental investment) species. They haven’t been heavily selected for longevity, which means there’s more low hanging fruit, more opportunities to tweak something and make a mouse live longer.

Humans meanwhile are among the longest lived large mammals and are extremely K-selected (few offspring, high parental investment). That means evolution has probably already tweaked all the easy life extension related knobs in humans. Going further will require going beyond the capacities of existing mammalian physiology, which is a lot harder. Probably possible, but requires a lot deeper of an understanding of what’s happening and more radical interventions.