Not great. Gantenerumab is a monoclonal antibody against aggregated Aβ:

"Among persons with early Alzheimer’s disease, the use of gantenerumab led to a lower amyloid plaque burden than placebo at 116 weeks but was not associated with slower clinical decline."
#alzheimers

https://www.nejm.org/doi/full/10.1056/NEJMoa2304430?query=featured_home