A Study to Evaluate the Pharmacodynamic (PD) Effects of Once Weekly Administration of Gantenerumab in Participants With Early Alzheimer's Disease (AD)

HAQ comprised 4 items completed by study partner capturing confidence (Q1), convenience (Q2), ease of use (Q3), and overall satisfaction (Q4) with administering medication. Response options Q1: Not at all confident, somewhat confident, confident, very confident; Q2: Not at all convenient, somewhat convenient, convenient, very convenient; Q3: Not at all easy, somewhat easy, easy, very easy; Q4:Not at all satisfied, somewhat satisfied, satisfied, very satisfied.

AE: any untoward medical occurrence in participant administered pharmaceutical product, which does not necessarily have a causal relationship with treatment. Also, any unfavorable, unintended sign, symptom, or disease temporally associated with use of medicinal product, whether or not considered related to it. SAE: any AE that was fatal, life threatening, required prolonged inpatient hospitalization, resulted in significant disability or resulted in a congenital anomaly to mother exposed to study treatment. This was a single-arm study and all participants received gantenerumab according to predefined universal up-titration scheme as follows: 120 mg Q4W (Day 1, Week (W) 4, and W8), then 255 mg Q4W (W 12, 16, and 20), then 255 mg Q2W for 12 weeks (W 24, 26, 28, 30, 32, and 34), followed by target dose of 255 mg Q1W (W 36 to 104). Data was collected and reported in single arm for each participant who started treatment as specified and either completed or discontinued study.

C-SSRS=assessment tool used to assess lifetime suicidality of a participant (at baseline) as well as any new instances of suicidality (C-SSRS since last visit). Structured interview prompts recollection of suicidal ideation, including intensity of ideation, behavior, \& attempts with actual/potential lethality. Categories have binary responses (yes/no) \& include Wish to be Dead; Non-specific Active Suicidal Thoughts; Active Suicidal Ideation with Any Methods(Not Plan)without Intent to Act; Active Suicidal Ideation with Some Intent to Act, without Specific Plan; Active Suicidal Ideation with Specific Plan and Intent, Preparatory Acts and Behavior; Aborted Attempt; Interrupted Attempt; Actual Attempt (non-fatal);Completed Suicide. Suicidal ideation/behavior is indicated by a "yes" answer to any of the listed categories. Score of 0 is assigned if no suicide risk is present. Score of 1 or higher= suicidal ideation or behavior. Categories with non-zero values are only reported here.

ARIA are an identified risk with anti-amyloid antibodies, including gantenerumab. These changes can be identified on brain MRI. The occurrences of imaging abnormalities in vasogenic edema and sulcal effusions (ARIA-E) were evaluated.

ARIA are an identified risk with anti-amyloid antibodies, including gantenerumab. These changes can be identified on brain MRI. ARIA-H (H for hemosiderosis) are small foci of signal loss observed on MRI sequences sensitive for paramagnetic tissue properties and comprise cerebral microbleeds (small foci of bleeding in the brain parenchyma) and leptomeningeal hemosiderosis (small foci of bleeding on the surface of the brain). These changes also occur sporadically in AD.

An AE is any unfavorable and unintended sign, symptom, or disease temporally associated with the use of an investigational product or other protocol-imposed intervention, regardless of attribution. Injection reactions (local and systemic) were defined as AEs that occured during or within 24 hours after study drug administration that were judged to be related to the study drug injection.

A participant with an ADA assay result from at least one post-baseline sample was defined as a post-baseline evaluable participant. Treatment Emergent ADA was defined as a participant with a negative or missing baseline ADA result(s) and at least one positive post-baseline ADA result, or a participant with a positive ADA result at baseline who has at least one post-baseline titer results with at least a >2.5-fold increase in titer compared to baseline greater than the baseline titer result.

The change from baseline at Week 52 using the once-weekly dosing frequency was analysed using the centiloid scale. The centiloid scale anchor points are 0 and 100, where 0 represents a high-certainty amyloid negative scan and 100 represents the amount of global amyloid deposition found in a typical AD scan. The range of centiloid values can be below 0 (negative) and greater than 100.