Using an external control to contextualize efficacy data from patients with prodromal and mild Alzheimer’s disease treated with gantenerumab in SCarlet RoAD and Marguerite RoAD open‐label extension studies

Gantenerumab, a human monoclonal antibody targeting aggregated beta‐amyloid (Abeta), is a potential disease‐modifying treatment for early (prodromal‐to‐mild) Alzheimer’s disease (AD). SCarlet RoAD (SR) (NCT01224106) and Marguerite RoAD (MR) (NCT02051608) were two Phase III trials with open‐label extensions (OLEs), during which participants were treated with up to 1,200 mg/month of subcutaneous gantenerumab for up to 5 years. Substantial Abeta removal was confirmed without new or unexpected safety findings. This work aims to evaluate the gantenerumab treatment effect during the SR and MR uncontrolled OLE studies by using an external control group based on the Alzheimer’s Disease Neuroimaging Initiative (ADNI) cohort.