Least squares mean change from baseline at week 78 was assessed for the ADAS-Cog score. ADAS-Cog measures cognition by assessing 11 metrics impaired in Alzheimer's Disease (AD): speech; speech comprehension; word finding; word recall; object/finger naming; orientation; obeying commands; ideational praxis; constructional praxis; word recognition; and remembering instruction. For each metric, scores range from 0 (no impairment) to (depending on the metric) either 5 (8 metrics), 8, 10, or 12 (1 metric each); higher scores indicate more severe impairment. Individual scores sum to a total ADAS-Cog score, ranging from 0-70. Higher total scores indicate greater cognitive impairment and AD severity. Further, increases in AD severity over time would be reflected by increases in ADAS-Cog score.

All randomized participants with a baseline and ≥1 within-analysis-window ADAS-Cog observation subsequent to ≥1 dose of study drug (FAS population). Per protocol, the 200 participants enrolled before IA (all arms) and all participants receiving 60mg Verubecestat (Arm C) were excluded.

Least squares mean change from baseline at week 78 was assessed for the ADCS-ADL score. The ADCS-ADL score measures the performance of activities of daily living, calculated from a 24-question survey. For each of the 24 questions, scores range from 0 (no independence) to (depending on the question) either 2 (1 question), 3 (17 questions), 4 (5 questions), or 5 (1 question), with higher scores indicating greater independence in activity performance. Scores from individual questions are summed into a total ADCS-ADL score, with total scores ranging from 0 to 78. Lower scores indicate less independence in activity performance and, as a result, greater AD severity. Further, increases in AD severity over time would be reflected by decreases in ADCS-ADL score.

All randomized participants with a baseline and ≥1 within-analysis-window ADCS-ADL observation subsequent to ≥1 dose of study drug (FAS population). Per protocol, the 200 participants enrolled before IA (all arms) and all participants receiving 60mg Verubecestat (Arm C) were excluded.

Mean change from baseline at week 104 was assessed for the ADAS-Cog score. ADAS-Cog measures cognition by assessing 11 metrics impaired in Alzheimer's Disease (AD): speech; speech comprehension; word finding; word recall; object/finger naming; orientation; obeying commands; ideational praxis; constructional praxis; word recognition; and remembering instruction. For each metric, scores range from 0 (no impairment) to (depending on the metric) either 5 (8 metrics), 8, 10, or 12 (1 metric each); higher scores indicate more severe impairment. Individual scores sum to a total ADAS-Cog score, ranging from 0-70. Higher total scores indicate greater cognitive impairment and AD severity. Further, increases in AD severity over time would be reflected by increases in ADAS-Cog score. Per study protocol, the baseline measurement to be used was the baseline measurement obtained in Part I.

All randomized participants continuing to Part II, with a baseline and ≥1 within-analysis-window ADAS-Cog observation subsequent to ≥1 dose of study drug (FAS population), having an ADAS-Cog observation at week 104. Per protocol, the 200 participants enrolled before IA (all arms) and all participants receiving 60mg Verubecestat were excluded.

Mean change from baseline at week 104 was assessed for the ADCS-ADL score. The ADCS-ADL score measures the performance of activities of daily living, calculated from a 24-question survey. For each of the 24 questions, scores range from 0 (no independence) to (depending on the question) either 2 (1 question), 3 (17 questions), 4 (5 questions), or 5 (1 question), with higher scores indicating greater independence in activity performance. Scores from individual questions are summed into a total ADCS-ADL score, with total scores ranging from 0 to 78. Lower scores indicate less independence in activity performance and, as a result, greater AD severity. Further, increases in AD severity over time would be reflected by decreases in ADCS-ADL score. Per study protocol, the baseline measurement to be used was the baseline measurement obtained in Part I.

All randomized participants continuing to Part II, with a baseline and ≥1 within-analysis-window ADCS-ADL observation subsequent to ≥1 dose of study drug (FAS population), having an ADCS-ADL observation at week 104. Per protocol, the 200 participants enrolled before IA (all arms) and all participants receiving 60mg Verubecestat were excluded.

The number of participants experiencing an adverse event (AE) in Part I was assessed. An AE is defined as any untoward medical occurrence in a patient or clinical investigation subject administered a pharmaceutical product and which does not necessarily have to have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign, symptom, or disease temporally associated with the use of a medicinal product, whether or not considered related to this medicinal product. Any worsening of a preexisting condition that is temporally associated with the use of the Sponsor's product is also an AE.

Includes all randomized participants in Part I receiving ≥1 dose of trial treatment.

The number of participants experiencing an adverse event (AE) in Part II was assessed. An AE is defined as any untoward medical occurrence in a patient or clinical investigation subject administered a pharmaceutical product and which does not necessarily have to have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign, symptom, or disease temporally associated with the use of a medicinal product, whether or not considered related to this medicinal product. Any worsening of a preexisting condition that is temporally associated with the use of the Sponsor's product is also an AE.

Includes all randomized participants continuing to Part II, receiving ≥1 dose of trial treatment in Part II. For included participants, the data reflect AEs occurring in Part II only.

The number of participants discontinuing from study drug due to an AE in Part I was assessed. An AE is defined as any untoward medical occurrence in a patient or clinical investigation subject administered a pharmaceutical product and which does not necessarily have to have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign, symptom, or disease temporally associated with the use of a medicinal product, whether or not considered related to this medicinal product. Any worsening of a preexisting condition that is temporally associated with the use of the Sponsor's product is also an AE.

Includes all randomized participants in Part I receiving ≥1 dose of trial treatment.

The number of participants discontinuing from study drug due to an AE in Part II was assessed. An AE is defined as any untoward medical occurrence in a patient or clinical investigation subject administered a pharmaceutical product and which does not necessarily have to have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign, symptom, or disease temporally associated with the use of a medicinal product, whether or not considered related to this medicinal product. Any worsening of a preexisting condition that is temporally associated with the use of the Sponsor's product is also an AE.

Includes all randomized participants continuing to Part II, receiving ≥1 dose of trial treatment in Part II. For included participants, the data reflect treatment discontinuations occurring in Part II only.

Least squares mean change from baseline at week 78 was assessed for CDR-SB score. The CDR-SB score is a clinical rating of global cognitive function, comprised of 6 domains including: memory; orientation; judgment and problem solving; community affairs; home and hobbies; and personal care. For each domain, the degree of impairment is assessed by a semi-structured interview of the participant as well as the participant's caregiver. For each domain, potential scores range from 0 (no impairment) to 3 (severe impairment). Scores from each individual domain are summed to the total CDR-SB score, with total scores ranging from 0-18. Higher scores indicate more severe cognitive impairment. Further, increases in cognitive impairment would be reflected by increases in CDR-SB score.

All randomized participants with a baseline and ≥1 within-analysis-window CDR-SB observation subsequent to ≥1 dose of study drug (FAS population). Per protocol, the 200 participants enrolled before IA (all arms) and all participants receiving 60mg Verubecestat (Arm C) were excluded.

Least squares mean percent change from baseline at week 78 was calculated for Total Hippocampal Volume (THV) as measured by volumetric magnetic resonance imaging (vMRI). Longitudinal analysis of within-participant THV is computed using a change analysis algorithm using tensor-based morphometry. This technique produces one measure of volume change calculated from the registration of serial vMRI scans at the follow-up time point relative to baseline. Negative percent changes from baseline indicate decreases in THV (i.e. increased hippocampal atrophy).

All randomized participants with a baseline and ≥1 within-analysis-window THV observation subsequent to ≥1 dose of study drug (FAS population). Per protocol, the 200 participants enrolled prior to IA (all arms) and all participants receiving 60mg Verubecestat (Arm C) were excluded.

Least squares mean fold change from baseline at week 78 was calculated for Total Tau concentration in CSF, a measure of brain tau pathology. Per protocol, CSF Total Tau concentration was analyzed as part of a substudy in Part I, with testing occurring only at select trial sites. Least squares mean fold change from baseline >1 indicates increased Total Tau concentration in the CSF.

All randomized participants with a baseline and ≥1 within-analysis-window CSF Total Tau observation subsequent to ≥1 dose of study drug (FAS population). Per protocol, the 200 participants enrolled prior to IA (all arms) and all participants receiving 60mg Verubecestat (Arm C) were excluded.

Least squares mean change from baseline at week 78 was calculated for SUVR, a measure of brain cortical amyloid load. Per protocol, SUVR was analyzed as part of a substudy in Part I, with testing occurring only at select trial sites. Participants receive the PET tracer [18F]Flutemetamol (IV). After 90 minutes, participants receive 4 PET scans (5 minutes each in duration). Using these PET scan images, specific brain ROIs (frontal, temporal, and parietal lobes; anterior and posterior cingulate and precuneus) are used to calculate regional SUVRs, defined as the relative ratio of pixel intensities at a specific ROI compared to a reference region (RR; subcortical white matter). These regional SUVRs are then averaged to compute a composite cortical SUVR for each participant. Higher composite cortical SUVR values indicate increased amyloid load, with negative changes in composite cortical SUVR over time indicating decreases in brain amyloid load.

All randomized participants with a baseline and ≥1 within-analysis-window SUVR observation subsequent to ≥1 dose of study drug (FAS population). Per protocol, the 200 participants enrolled prior to IA (all arms) and all participants receiving 60mg Verubecestat did not receive SUVR testing and were excluded.

The percentage of participants achieving responder status at week 78 was assessed. To determine which participants were considered responders, a linear regression was conducted at the participant level, yielding an estimated 78-week rate of change (i.e., a slope) for each participant with respect to ADAS-Cog and ADCS-ADL. To be declared a responder, a participant must have: 1) ADAS-Cog and ADCS-ADL observations at baseline and 78 weeks of treatment; 2) an ADAS-Cog slope > 4.0 over 78 weeks, and 3) an ADCS-ADL slope > -6.3 over 78 weeks. A participant failing to meet any of these criteria was designated as a non-responder at Week 78.

All randomized participants in Part I receiving ≥1 dose of trial treatment. Per protocol, the first 200 participants enrolled prior to IA (across all arms) and all participants receiving 60mg Verubecestat (Arm C) were excluded from analysis.

Least squares mean change from baseline at week 78 was assessed for NPI score. NPI is a clinical assessment of psychiatric status, covering 12 domains: delusion; hallucination; agitation/aggression; depression/dysphoria; anxiety; elation/euphoria; apathy/indifference; disinhibition; irritability/lability; aberrant motor behavior; sleep/nighttime behaviors; and appetite/eating disorders. Based on an interview of the participant's caregiver, each domain is assessed for symptom frequency [range: 1 (occasional) to 4 (very frequent)] and severity [range: 1 (mild) to 3 (severe)]. Domain scores [range: 0 to 12] are calculated as the product of the frequency and severity scores (i.e. frequency x severity); if no symptoms are present, domain score is 0. The 12 domain scores sum to a total NPI score [range: 0 (no symptoms in any domain) to 144]. Higher scores reflect more severe psychiatric impairment, with increases in impairment reflected by increases in NPI score.

All randomized participants with a baseline and ≥1 within-analysis-window NPI observation subsequent to ≥1 dose of study drug (FAS population). Per protocol, the 200 participants enrolled prior to IA (all arms) and all participants receiving 60mg Verubecestat (Arm C) were excluded.

Least squares mean change from baseline at week 78 was assessed for MMSE score. The MMSE is a cognitive assessment of 5 domains including: orientation; attention; memory; language; and constructional praxis. These domains are assessed over the course of 11 total questions related to the participant. Participants are scored based on the number of correct responses; depending on the question, potential scores range from 0 (no correct response) to either 1 (4 questions), 2 (1 question), 3 (3 questions), or 5 (3 questions). Scores from each question are summed to the total MMSE score, with total scores ranging from 0-30. Higher scores indicate better cognitive performance. Further, deterioration in cognitive performance would be reflected by decreases in MMSE score.

All randomized participants with a baseline and ≥1 within-analysis-window MMSE observation subsequent to ≥1 dose of study drug (FAS population). Per protocol, the 200 participants enrolled prior to IA (all arms) and all participants receiving 60mg Verubecestat (Arm C) were excluded.