Testing the Safety and Preliminary Efficacy of the New Drug ORY-2001 in Mild to Moderate Alzheimer's Disease

Inclusion Criteria: * Probable Alzheimer's Disease (AD) diagnosed according to National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria * MMSE score at Screening and Baseline Visits of at least 16 and not greater than 26 * Evidence of the AD pathophysiological process indicated by decreased levels of amyloid antigen binding (AB) and increased levels of total Tau protein or phospho-Tau protein in cerebrospinal fluid (CSF) * Outpatient consulting a general practitioner, or a psychiatrist/neurologist/geriatrician * Knowledgeable and reliable close relative/caregiver who will accompany the patient to all clinic visits during the study * Daily treatment with the same acetylcholinesterase inhibitor on a stable dose * Fertile male and female must use highly effective contraception, from the Screening Visit until 90 days after last dose. * Signed informed consent by patient (or legal representative, if applicable) and a close relative/caregiver prior to the initiation of any study specific procedure Exclusion Criteria: * Failure to perform screening or baseline examinations * Hospitalization or change of concomitant medication 1 month prior to Screening visit or during Screening Period * Clinical, laboratory or neuroimaging findings consistent with: 1. Other primary degenerative dementia; 2. Other neurodegenerative condition; 3. Cerebrovascular disease; 4. Other central nervous system diseases; * A current Diagnostic and Statistical Manual-5 (DSM-5) diagnosis of major depression, schizophrenia or bipolar disorder * Positive results for tuberculosis, human immunodeficiency virus (HIV), hepatitis C or hepatitis B (hepatitis B surface antigen \[HbsAg\]) serology at the Screening Visit * Clinically significant, advanced or unstable disease that may interfere with evaluation. * Disability that may prevent the patients from completing all study requirements. * Chronic drug intake of forbidden concomitant medication. * Treatment with anti-amyloid beta or anti-Tau protein monoclonal antibodies or other disease modifying strategies within three months or five half-lives, whichever is longer, prior to the Screening Visit * Treatment with an active vaccine targeting amyloid beta or Tau protein * Suspected or known drug or alcohol abuse * Metallic implants or any other cause precluding the performance of brain MRI * Enrolment in another investigational study or intake of investigational drug within the previous 3 months since the last dose * Suicide attempt within the last year or significant risk of suicide (in the opinion of the investigator, defined as a "yes" to suicidal ideation questions 4 or 5, or answering "yes" to suicidal behavior on the Columbia-Suicide Severity Rating Scale within the past 12 months) * Any condition that in the opinion of the investigator makes the patient unsuitable for inclusion in the study