A Study to Confirm Safety and Efficacy of BAN2401 in Participants With Early Alzheimer's Disease

Core Study:

Inclusion Criteria

Diagnosis:

Mild Cognitive Impairment (MCI) due to Alzheimer's disease - intermediate likelihood:

- Meet the National Institute of Aging - Alzheimer's Association (NIA-AA) core clinical
criteria for MCI due to Alzheimer's disease - intermediate likelihood.

- Have a global CDR score of 0.5 and CDR Memory Box score of 0.5 or greater at Screening
and Baseline

Mild Alzheimer's disease dementia:

- Meet the NIA-AA core clinical criteria for probable Alzheimer's disease dementia

- Have a global CDR score of 0.5 to 1.0 and a CDR Memory Box score of 0.5 or greater at
Screening and Baseline

Key Inclusion Criteria that must be met by all participants:

- Objective impairment in episodic memory as indicated by at least 1 standard deviation
below age-adjusted mean in the Wechsler Memory Scale IV-Logical Memory (subscale) II
(WMS-IV LMII)

- Positive biomarker for brain amyloid pathology

- Male or female participants aged greater than or equal to (>=)50 and <=90 years, at
the time of informed consent

- Mini mental state examination (MMSE) score greater than or equal to 22 at Screening
and Baseline and less than or equal to 30 at Screening and Baseline

- Body mass index (BMI) greater than 17 and less than 35 at Screening

- If receiving an approved Alzheimer's disease treatment such as acetylcholinesterase
inhibitor (AChEIs) or memantine or both for Alzheimer's disease, must be on a stable
dose for at least 12 weeks prior to Baseline. Treatment-naïve participants for
Alzheimer's disease can be entered into the study. Unless otherwise stated,
participants must have been on stable doses of all other (ie, non-Alzheimer's
disease-related) permitted concomitant medications for at least 4 weeks prior to
Baseline.

Exclusion Criteria

- Any neurological condition that may be contributing to cognitive impairment above and
beyond that caused by the participant's Alzheimer's disease

- History of transient ischemic attacks (TIA), stroke, or seizures within 12 months of
Screening

- Any psychiatric diagnosis or symptoms (e.g., hallucinations, major depression, or
delusions) that could interfere with study procedures in the participant

- Geriatric Depression Scale (GDS) score >=8 at Screening

- Contraindications to magnetic resonance imaging (MRI) scanning, including cardiac
pacemaker/defibrillator, ferromagnetic metal implants (e.g., in skull and cardiac
devices other than those approved as safe for use in MRI scanners

- Evidence of other clinically significant lesions on brain MRI at Screening that could
indicate a dementia diagnosis other than Alzheimer's disease

- Any other medical conditions (eg, cardiac, respiratory, gastrointestinal, renal
disease) which are not stably and adequately controlled, or which in the opinion of
the investigator(s) could affect the participant's safety or interfere with the study
assessments

- Participants who have any known prior exposure to BAN2401

Extension Phase:

Inclusion Criteria:

• Participants who have completed Visit 42 (Week 79) of the Core Study