A Phase III, Randomized, Double-Blind, Placebo-Controlled, Parallel-Group, Multicenter, Efficacy and Safety Study of Gantenerumab in Patients With Mild Alzheimer's Disease; Part II: Open-Label Extension For Participating Patients

Part 1 is a multicenter, randomized, double-blind, placebo-controlled, parallel-group study
will evaluate the efficacy and safety of gantenerumab in participants with mild Alzheimer
disease. Participants will be randomized to receive either gantenerumab subcutaneously every
4 weeks or placebo subcutaneously every 4 weeks. Approved Alzheimer medication is allowed if
on stable dose for 3 months prior to screening. Part 2 is an open-label extension (OLE).

A positron emission tomography (PET) imaging substudy will be conducted within the main
study. Eligible participants who provide separate informed consent will undergo PET imaging
scans using the radioligand florbetapir as a pharmacodynamic measure of changes in brain
amyloid load over time.