A Study to Assess the Effects of ACI-24.060 in Alzheimer's Disease and in Down Syndrome (ABATE Study)

Study Overview
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Brief Summary
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The purpose of this study is to assess the safety, tolerability, immunogenicity and pharmacodynamic effects of ACI-24.060 in subjects with prodromal Alzheimer's disease and in non-demented adults with Down syndrome.

Detailed Description
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This phase 1b/2 study will be in 2 parts. Study Part 1 will involve subjects with prodromal Alzheimer's disease. Study Part 2 will involve subjects with Down syndrome.

Official Title
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A Phase 1b/2, Multicenter, Adaptive, Double-blind, Randomized, Placebo-controlled Study to Assess the Safety, Tolerability, Immunogenicity, and Pharmacodynamic Effects of ACI-24.060 in Subjects With Prodromal Alzheimer's Disease and in Adults With Down Syndrome (ABATE)

Conditions
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Alzheimer's Disease, Prodromal Alzheimer's Disease, Amyloid Plaque, Beta-Amyloid, Alzheimer's Disease in Down Syndrome

Intervention / Treatment
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* Biological: Placebo
* Biological: ACI-24.060 at Dose A
* Biological: ACI-24.060 at Dose B
* Biological: ACI-24.060 at Dose C
* Biological: ACI-24.060 at Dose D
* Biological: Placebo
* Biological: ACI-24.060 at Dose X
* Biological: ACI-24.060 at Dose Y


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Study Part 1 Age ≥50 and ≤85 years at screening. Diagnosis of prodromal AD: MCI due to AD according to National Institute on Aging Alzheimer's Association (NIA-AA) criteria. PET scan at screening consistent with the presence of amyloid pathology. Clinical Dementia Rating (CDR)-Global Score of 0.5. Subjects either not taking any marketed treatment for AD or receiving a stable dose of an acetylcholinesterase inhibitor (ACHEI) and/or memantine for at least 2 months prior to baseline. Study Part 2 Age ≥35 and ≤50 years at screening (subjects with DS with age ≥35 and ≤39 years may be considered on the condition that there is prior evidence of amyloid results compatible with AD pathology at PET-scan and/or in biofluids). Male or female subjects with DS with a cytogenetic diagnosis being either trisomy 21 or complete unbalanced translocation of the chromosome 21. PET scan at screening consistent with the presence of amyloid pathology. Mild to moderate intellectual disability as per Diagnostic and Statistical Manual of Mental Disorders (DSM-5) classification. Subjects must have a study partner who has direct and regular contact, at least 10 hours per week, with the subject and who is able to provide reliable answers to questions related to the subject, according to the study investigator. Exclusion Criteria: Any unstable and/or clinically significant medical condition likely to hamper the evaluation of safety and/or efficacy of the study vaccine (eg, moderate and/or severe untreated obstructive sleep apnea, clinically significant reduction in serum B12 or folate levels, clinically significant abnormalities of thyroid function, stroke, or other cerebrovascular conditions), as per investigator's judgement. DSM-5 criteria for drug or alcohol abuse or dependence currently met within the past 5 years. History or presence of uncontrolled seizures. If history of seizures, they must be well controlled with no occurrence of seizures in the 2 years before study screening. The use of antiepileptic medications is permitted. Concomitant or past history psychiatric or neurologic disorder other than those considered to be related to AD (eg, head injury with loss of consciousness, symptomatic stroke, Parkinson's disease, severe carotid occlusive disease, transient ischemic attacks [TIAs], hemorrhagic and/or non-hemorrhagic stroke). History of meningitis or meningoencephalitis. History of moderate or severe traumatic brain injury. History of inflammatory neurological disorders. History or presence of immunological or inflammatory conditions, including neurological disorders, judged to be clinically significant by the investigator. History of severe allergic reaction (eg, anaphylaxis) including, but not limited to severe allergic reaction to previous vaccines, foods, and/or medications. Significant risk of suicide, defined using the C-SSRS as the subject answering yes to suicidal ideation questions 4 or 5 or answering yes to suicidal behavior within the past 12 months. MRI scan at screening showing a single area of cerebral vasogenic edema, superficial siderosis, or evidence of a previous macro-hemorrhage or showing more than 4 cerebral microhemorrhages (regardless of their anatomical location or diagnostic characterization as possible or definite). Evidence of space occupying lesions other than benign meningioma of less than 1 cm diameter, more than 2 lacunar infarcts, or 1 single infarct larger than 1 cm in diameter. Screening MRI scan showing structural evidence of alternative pathology not consistent with AD and is considered to be at the origin of subject's symptoms. Deviations from normal values for hematologic parameters, liver function tests, and other biochemical measures, judged to be clinically significant by the investigator. Subjects with a positive Human Immunodeficiency Virus (HIV-1 and 2) test at screening. Subjects with clinical or laboratory evidence of active hepatitis B or C at screening (eg, HBV or HCV antigens). Subjects with positive syphilis serology consistent with active syphilis at screening. MRI examination cannot be done for any reason, including but not limited to metal implants contraindicated for MRI and/or severe claustrophobia. Any contraindication for PET scan imaging. Any contraindication to lumbar puncture in subjects undergoing this procedure (note: lumbar puncture is optional in subjects with DS). Previous treatment with ACI-24 or any other active immunotherapy against AD at any time in the past unless there is firm evidence that the subject received placebo only and the placebo formulation is not expected to induce any specific immune response. Previous treatment with any investigational and/or marketed passive immunotherapy against AD within 6 months before screening or 5 half-lives, whichever is longer, unless there is firm evidence that the subject received placebo only. Ongoing treatment with any approved anti-amyloid passive immunotherapy for Alzheimer's disease. Use of acetylcholinesterase inhibitor or glutamatergic drugs (eg, memantine, topiramate, lamotrigine) if not on stable dose for at least 2 months before screening. Any vaccine received within the 2 weeks before screening, including an anti-influenza or anti-COVID 19 vaccine received within 4 weeks before randomization. Subjects with treated hypothyroidism not on a stable dose of replacement medication for at least 2 months before screening and having clinically significant abnormal serum T4 and/or thyroid stimulating hormone at screening. Subjects undergoing lumbar puncture and being treated with any anticoagulants or antiplatelet drugs, except aspirin at doses of 100 mg daily or lower. Use of antidepressants (other than selective serotonin reuptake inhibitors/serotonin-norepinephrine reuptake inhibitors at stable dose); typical antipsychotics; γ-aminobutyric acid agonists (eg, gabapentin); or stimulants (eg, methylphenidate, modafinil). Stable doses of atypical antipsychotics or benzodiazepines are only allowed if this is not considered to influence the safety and the efficacy of the study vaccine according to the site investigator and the sponsor medical monitor. Chronic use of opioid analgesics. A limited treatment duration for acute conditions until 24 hours before cognitive assessment is allowed. Current use of immunosuppressant or immunomodulating drugs or their use within the 6 months before study screening. Current use of oral steroids or their use within the 3 months before study screening. Additional Exclusion Criteria in Study Part 2 The following are exclusion criteria at the time of randomization but will not be considered as exclusionary after treatment assignment: Clinical diagnosis of AD dementia in DS as per International Classification of Diseases 10 (ICD-10). DSQIID >20. Intelligence quotient score <40 (KBIT-2).

Ages Eligible for Study
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Minimum Age: 35 Years
Maximum Age: 85 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Sequential Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Placebo for Study Part 1 (Prodromal AD)<br>Prodromal AD participants receive placebo at predefined time points over 48 weeks | Biological: Placebo<br>* Administration of Placebo<br>|
| Experimental: ACI-24.060 at Dose A<br>Prodromal AD participants receive dose A of ACI-24.060 at predefined time points over 48 weeks | Biological: ACI-24.060 at Dose A<br>* Administration of Dose A of ACI-24.060<br>|
| Experimental: ACI-24.060 at Dose B (Optional)<br>Prodromal AD participants receive dose B of ACI-24.060 at predefined time points over 48 weeks. This arm is optional. | Biological: ACI-24.060 at Dose B<br>* Administration of Dose B of ACI-24.060<br>|
| Experimental: ACI-24.060 at Dose C (Optional)<br>Prodromal AD participants receive dose C of ACI-24.060 at predefined time points over 48 weeks. This arm is optional. | Biological: ACI-24.060 at Dose C<br>* Administration of Dose C of ACI-24.060<br>|
| Experimental: ACI-24.060 at Dose D (Optional)<br>Prodromal AD participants receive dose D of ACI-24.060 at predefined time points over 48 weeks. This arm is optional. | Biological: ACI-24.060 at Dose D<br>* Administration of Dose D of ACI-24.060<br>|
| Placebo Comparator: Placebo for Study Part 2 (Down syndrome)<br>Participants with Down syndrome receive placebo at predefined time points over 74 weeks | Biological: Placebo<br>* Administration of Placebo<br>|
| Experimental: ACI-24.060 at Dose X<br>Participants with Down syndrome receive dose X of ACI-24.060 at predefined time points over 74 weeks. Dose X will be a dose already tested in Study Part 1. | Biological: ACI-24.060 at Dose X<br>* Administration of Dose X of ACI-24.060. Dose X will be a dose already tested in Study Part 1<br>|
| Experimental: ACI-24.060 at Dose Y (Optional)<br>Participants with Down syndrome may optionally receive a dose Y of ACI-24.060 at predefined time points over 74 weeks. | Biological: ACI-24.060 at Dose Y<br>* Administration of Dose Y of ACI-24.060<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of participants with Adverse Events (AEs) assessed by intensity (mild, moderate or severe) and causal relationship (unrelated, unlikely, possibly or probably related) |  | From Screening to Week 74 (Study Part 1) | 
| Number of participants with Adverse Events (AEs) assessed by intensity (mild, moderate or severe) and causal relationship (unrelated, unlikely, possibly or probably related) |  | From Screening to Week 100 (Study Part 2) | 
| Number of participants with abnormal MRI results |  | From Baseline to Week 74 (Study Part 1) | 
| Number of participants with abnormal MRI results |  | From Baseline to Week 100 (Study Part 2) | 
| Number of participants with abnormal physical and neurological examination results |  | From Baseline to Week 74 (Study Part 1) | 
| Number of participants with abnormal physical and neurological examination results |  | From Baseline to Week 100 (Study Part 2) | 
| Number of participants reporting suicidal ideation or behavior using Columbia-Suicide Severity Rating Scale (C-SSRS) |  | From Baseline to Week 74 (Study Part 1) | 
| Number of participants reporting suicidal ideation or behavior using Columbia-Suicide Severity Rating Scale (C-SSRS) |  | From Baseline to Week 100 (Study Part 2) | 
| Change from baseline in Anti-Abeta antibody titers in blood |  | From Baseline to Week 100 (Study Part 2) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline in Anti-Abeta antibody titers |  | From Baseline to Week 74 (Study Part 1) | 
| Change from baseline on brain amyloid levels | Brain amyloid load measured via PET imaging. An increase indicates a worsening. | From Baseline to W100 (Study Part 2) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Alzheimer Disease, Dementia, Brain Diseases, Central Nervous System Diseases, Prodromal Alzheimer's Disease, Amyloid Plaque, Beta-Amyloid, Down syndrome, Vaccine, Immunogenicity