Inclusion Criteria:

• Subjects or their Legally Authorized Representative (LAR) must provide written informed consent to the study procedures prior to any study procedures.
• Subjects must have a caregiver/ study partner who in the opinion of the site principal investigator, has contact with the study subject for a sufficient number of hours per week to provide informative responses on the protocol assessments, oversee the administration of study drug, and is willing and able to participate in all clinic visits and some study assessments.
• Men or women 50-85 years of age (inclusive), meeting criteria for probable Dementia with Lewy Bodies (DLB).
• Men willing to comply with acceptable form of contraception or women of non-childbearing.
• Willingness to undergo a lumbar puncture (LP) during the screening period and at the end of the 6-month treatment period.
• Formal education of eight or more years.
• Subjects living at home or in an assisted living facility.
• Subjects shall be generally healthy with mobility, vision and hearing sufficient for compliance with testing procedures.
• Must be able to complete all screening evaluations.

Exclusion Criteria:

• Any neurological condition that may be contributing to cognitive impairment above and beyond those caused by the subject's DLB, including any co-morbidities detected by clinical assessment or MRI (or CT scan due to contraindication of MRI, if approved by medical monitor).
• History of transient ischemic attacks or stroke within 12 months of screening.
• Parkinsonian (extrapyramidal) features with Modified Hoehn and Yahr stage 4 or higher or any diagnosis of Parkinson’s disease or parkinsonism that preceded cognitive decline by more than one year.
• Hospitalization (except for planned procedures) or change of chronic concomitant medication within one month prior to screening.
• Any major psychiatric diagnosis, including schizophrenia, bipolar disorder, and current major depressive disorder as per Diagnostic and Statistical Manual of Mental Disorders Fifth Edition.
• Geriatric Depression Scale score > 6. (Subjects with a GDS > 6 may be allowable if the investigator does not believe the subject is clinically depressed. Investigators should contact the medical monitor to discuss eligibility).
• Subjects living in a continuous care nursing facility.
• Contraindication to the MRI examination for any reason (CT scan may be substituted for an MRI if subjects are unable to tolerate an MRI or an MRI is contraindicated for medical reasons, if the proposed CT scan is discussed and approved by the medical monitor on a case-by-case basis).
• Screening MRI (or historical MRI or CT scan due to contraindication of MRI if approved by medical monitor) or historical MRI/CT scan, if applicable. of the brain indicative of significant abnormality, including, but not limited to, prior hemorrhage or infarct >1 cm3 , > 3 lacunar infarcts, cerebral contusion, encephalomalacia, aneurysm, vascular malformation, subdural hematoma, hydrocephalus, space-occupying lesion (e.g., abscess or brain tumor such as meningioma). If a small incidental meningioma is observed, the medical monitor may be contacted to discuss eligibility.
• Clinical, laboratory findings or medical history consistent with:
  • Other primary degenerative dementia, (frontotemporal dementia, Huntington’s disease, Creutzfeldt-Jakob Disease, Down syndrome, etc.);
  • Other neurodegenerative condition (amyotrophic lateral sclerosis, etc.);
  • Seizure disorder;
  • Other infectious, metabolic or systemic diseases affecting the central nervous system (syphilis, present hypothyroidism, present vitamin B12 or folate deficiency, other laboratory values etc.).
• Clinically significant, advanced or unstable disease that may interfere with outcome evaluations, such as:
  • Chronic liver disease, liver function test abnormalities or other signs of hepatic insufficiency (ALT, AST, alkaline phosphatase > 1.5 ULN, lactate dehydrogenase (LDH) > 1.5 x ULN);
  • Respiratory insufficiency which requires the use of supplemental oxygen;
  • Renal insufficiency eGFR < 50 mL/min based on the CKD‐EPI formula;
  • Heart disease (myocardial infarction, unstable angina, heart failure, cardiomyopathy within six months before screening);
  • Bradycardia (100 beats/min.). If heart rate is below 50 beats/min or above 100 beats/min, the heart rate assessment may be repeated to assess eligibility;
  • Poorly managed hypertension (systolic > 160 mm Hg and/or diastolic > 95 mm Hg) or hypotension (systolic 7.5% in subjects with diabetes, only those subjects with known diabetes are required to get a HbA1c at screen.
• History of cancer within 3 years of screening with the exception of fully excised non-melanoma skin cancers or non-metastatic prostate cancer that has been stable for at least 6 months.
• Seropositive for human immunodeficiency virus (HIV).
• History of acute/chronic hepatitis B or C and/or carriers of hepatitis B (seropositive for hepatitis B surface antigen [HbsAg] or anti-hepatitis C [HCV] antibody).
• Clinically significant abnormalities in screening laboratory tests, including:
  • Hematocrit less than 35% for males and less than 32% for females, absolute neutrophil cell count of 1500/uL (with the exception of a documented history of a chronic benign neutropenia, absolute lymphocyte count 1.4 or other coagulopathy, confirmed by repeat assessment of:
  • Hematocrit;
  • Neutrophil count;
  • Lymphocyte count;
  • Platelet count.
• Disability that may prevent the subject from completing all study requirements (e.g., blindness, deafness, severe language difficulty, etc.).
• Within 4 weeks of screening visit or during the course of the study, concurrent treatment with antipsychotic agents, antiepileptics, centrally active antihypertensive drugs (e.g., clonidine, l-methyl dopa, guanidine, guanfacine, etc.), sedatives, opioids, mood stabilizers (e.g., valproate, lithium); or benzodiazepines, with the following exceptions:
  • At the discretion of the investigator, lorazepam or another anxiolytic may be administered as per local standard of care prior to MRI scan or optional lumbar puncture. Note neurocognitive testing should not be done within 24 hours of administration of conscious sedation;
  • Stable use of clonazepam for at least 30 days as indicated for REM Sleep Behavioral Disorder (RBD);
  • Stable use of atypical antipsychotics (e.g., quetiapine, pimavanserin) for at least 30 days as indicated for delusions and hallucinations secondary to DLB.
• Any disorder that could interfere with the absorption, distribution, metabolism, or excretion of drugs (e.g., small bowel disease, Crohn’s disease, celiac disease, or liver disease).
• Nootropic drugs except stable AD meds (acetylcholinesterase inhibitors or memantine).
• Suspected or known drug or alcohol abuse; i.e., more than approximately 60 g alcohol (approximately 1 liter of beer or 0.5 liter of wine) per day indicated by elevated MCV significantly above normal value at screening.
• Suspected or known allergy to any components of the study treatments.
• Enrollment in another investigational study or intake of investigational drug within the previous 30 days or five half-lives of the investigational drug, whichever is longer.
• Intake of drugs or substances potentially involved in clinically significant induction or inhibition of CYP3A4 or P-gp mediated drug interactions with CT1812, within 4 weeks or five half-lives of the interacting drug prior to administration of CT1812 and throughout the course of the study. Grapefruit juice should be avoided in the two weeks prior to dosing and throughout the course of the study. 
• Any prior exposure to immunomodulators, anti Aβ vaccines, or passive Aβ immunotherapies (e.g., monoclonal antibodies) and/or exposure to BACE inhibitors within the past 30 days.
• Any condition, which in the opinion of the investigator or the sponsor makes the subject unsuitable for inclusion.
• Any vaccination within one week of the baseline visit.

Eligibility last updated 5/23/23. Questions regarding updates should be directed to the study team contact.