Study of ASN51 in Adults With Early Alzheimer's Disease

Key Inclusion Criteria: 1. Male or female age 50 to 80 years. 2. A clinical diagnosis of Alzheimer's disease (AD) at either the mild cognitive impairment or mild AD dementia stage per National Institute on Aging and the Alzheimer's Association, consistent with Stage 3 and Stage 4 in the Food and Drug Administration (FDA) draft guidance for early AD. 3. Mini-Mental State Examination score of 20 to 28 (inclusive). 4. A plasma pTau217 result consistent with the presence of amyloid pathology. 5. Must have a care partner who, in the investigator's judgment, has frequent and sufficient contact with the participant as to be able to provide accurate information about the participant's cognitive and functional abilities. The care partner must be literate and provide informed consent. Key Exclusion Criteria: 1. Any medical or neurological/neurodegenerative condition (other than AD) that, in the opinion of the Investigator, might be a contributing cause to the participant's cognitive impairment (e.g., current history of substance abuse, uncontrolled vitamin B12 deficiency or abnormal thyroid function, stroke or other cerebrovascular condition, normal pressure hydrocephalus, Parkinson's Disease, Lewy body dementia, cerebral amyloid angiopathy, frontotemporal dementia) or could lead to discontinuation, lack of compliance, interference with study assessments, or safety concerns. 2. Non-amnestic presentation of AD as judged by the investigator. 3. Woman of childbearing potential. 4. Any prior or ongoing exposure to active or passive anti-amyloid immunotherapy, anti-tau immunotherapy, an anti-tau antisense oligonucleotide or gene therapy, or O-linked-β-N-acetylglucosaminidase (O-GlcNAcase) inhibitor. Other protocol defined inclusion and exclusion criteria could apply.