https://pubs.acs.org/doi/10.1021/acschemneuro.6c00252
In mice. This is a repeating trend in Alzheimer's research, where the amyloid-beta treatment works in the mouse model but not on humans, because the mouse model induces the amyloid-beta issue (mice don't really get Alzheimer's) and then we treat it.
It is a repeating trend in all medical research. However enough does turn out to work in humans that we eventually make useful progress.
In general, sure, but in this specific instance (treating Alzheimer's by clearing amyloid-beta) it's been shown over and over again to not work in humans.