Simufilam 100 mg for Mild-to-Moderate Alzheimer's Disease

The primary objective of this study is to investigate the safety and efficacy of simufilam (PTI-125) in enhancing cognition and slowing cognitive and functional decline following 52-week, repeat-dose oral administration in participants with mild-to-moderate AD. Secondary objectives include the assessment of simufilam's effect on neuropsychiatric symptoms and caregiver burden. A third objective is to investigate the effect of simufilam treatment on plasma biomarkers. A limited number of research sites will be invited to participate in the pharmacokinetic (PK) and plasma biomarker sub-study. Collection of PK samples will enable an exposure-response analysis. Approximately 100 subjects will participate (50 per group). Plasma samples will be collected during the Screening Visit and again at Weeks 28 and 52. Change from Baseline for plasma biomarkers represent additional secondary endpoints.

Safety will be evaluated by adverse event monitoring, vital signs, clinical labs, and the Columbia Suicide Severity Rating Scale at every visit. Subjects will undergo magnetic resonance imaging (MRI) during screening to ensure entry criteria are met (unless recent MRI confirms entry criteria). Resting electrocardiograms will be conducted at Baseline (Study Day 1) and Weeks 4, 28, and 52. A complete physical and neurological examination will be performed at screening, and brief examinations will be performed at all other visits. Weight will be measured during the Screening Period, at Baseline (Study Day 1), and at all other visits.

An independent Data Safety Monitoring Board (DSMB) will meet periodically to review subject safety assessments and determine if dosing may continue. A charter will be developed with specific guidance for the DSMB.

Key Inclusion Criteria:

• Meets National Institute on Aging and Alzheimer's Association Research Framework criteria for individuals in clinical Stage 4 or 5 of the Alzheimer's continuum.
• Evidence for AD pathophysiology, confirmed either prior to or during screening.
• MMSE score ≥ 16 and ≤ 27 at screening.
• Clinical Dementia Rating - Global Score must be 0.5, 1 or 2.
• If receiving background AD medications, the dosing regimen must be stable for at least 12 weeks prior to randomization. Chronic medications for conditions other than AD (such as depression) must be prescribed at a stable dose for at least 4 weeks prior to screening.
• The subject has not been a cigarette smoker or chewed tobacco for at least 3 years.
• Availability of a study partner.
• Individuals who have participated in a clinical study with an investigational drug targeting the underlying AD process may be permitted to participate in this study.
• Completed a COVID-19 vaccine primary series ("fully vaccinated") at least 2 weeks prior to randomization or had an unambiguous COVID-19 infection diagnosed more than 3 months before the start of the Screening Period.

Key Exclusion Criteria:

• A neurologic condition other than AD that significantly contributes to the subject's dementia.
• Any current primary psychiatric diagnosis other than AD if it is likely to confound cognitive assessment or ability to comply with study procedures.
• Geriatric Depression Scale (15-item) score > 8. (Note - a subject with a score > 8 may continue in screening if, in the judgment of the Investigator, the elevated score is not attributed to a major depressive episode).
• Suicidal ideation during the past 3 months or suicidal behavior during the past 12 months.
• Alcohol or substance use disorder within 2 years of screening.
• MRI presence of cerebral vascular or other significant pathology.
• History of transient ischemic attack or stroke within 12 months of screening
• Seizure within 12 months of screening.
• Severe head trauma or head trauma considered likely to be contributing to the subject's cognitive impairment.
• Sleep apnea that is considered likely to be contributing to the subject's cognitive impairment.
• Insufficiently controlled diabetes mellitus or hypertension.
• Body mass index < 18.5 or > 37.5.
• History or diagnosis of clinically significant cardiac disease
• Currently or previously prescribed/administered aducanumab, lecanemab, or any anti-amyloid monoclonal antibody, more than 2 doses.