Safety and Efficacy Study Evaluating TRx0237 in Subjects With Mild to Moderate Alzheimer's Disease

Inclusion Criteria:

- Diagnosis of all cause dementia and probable Alzheimer's disease

- Clinical Dementia Rating (CDR) total score of 1 (mild) to 2 (moderate) and MMSE score
of 14-26 (inclusive)

- Age < 90 years

- Modified Hachinski ischemic score of ≤ 4

- Females, if of child-bearing potential, must practice true abstinence or be competent
to use adequate contraception and agree to maintain this throughout the study

- Subject, and/or, in the case of reduced decision-making capacity, legally acceptable
representative(s) consistent with national law is/are able to read, understand, and
provide written informed consent

- Has one (or more) identified adult caregiver who is willing to provide written
informed consent for his/her own participation; is able to read, understand, and speak
the designated language at the study site; either lives with the subject or sees the
subject for ≥2 hours/day ≥3 days/week; agrees to accompany the subject to each study
visit; and is able to verify daily compliance with study drug

- If currently taking an acetylcholinesterase inhibitor and/or memantine at the time of
Screening, the subject must have been taking such medication(s) for ≥3 months. The
dosage regimen must have remained stable for ≥6 weeks and it must be planned to remain
stable throughout participation in the study.

- Able to comply with the study procedures

Exclusion Criteria:

- Significant central nervous system (CNS) disorder other than Alzheimer's disease

- Significant focal or vascular intracranial pathology seen on brain MRI scan

- Clinical evidence or history of stroke, transient ischemic attack, significant head
injury or other unexplained or recurrent loss of consciousness ≥15 minutes

- Epilepsy

- Major depressive disorder, schizophrenia, or other psychotic disorders, bipolar
disorder, or substance (including alcohol) related disorders

- Metal implants in the head (except dental), pacemaker, cochlear implants, or any other
non-removable items that are contraindications to MRI

- Resides in hospital or moderate to high dependency continuous care facility

- History of swallowing difficulties

- Pregnant or breastfeeding

- Glucose-6-phosphate dehydrogenase deficiency

- History of significant hematological abnormality or current acute or chronic
clinically significant abnormality

- Abnormal serum chemistry laboratory value at Screening deemed to be clinically
relevant by the investigator

- Clinically significant cardiovascular disease or abnormal assessments

- Preexisting or current signs or symptoms of respiratory failure

- Concurrent acute or chronic clinically significant immunologic, hepatic, or endocrine
disease (not adequately treated) and/or other unstable or major disease other than
Alzheimer's disease

- Diagnosis of cancer within the past 2 years prior to Baseline (other than basal cell
or squamous cell skin cancer or Stage 1 prostate cancer) unless treatment has resulted
in complete freedom from disease for at least 2 years

- Prior intolerance or hypersensitivity to methylthioninium-containing drug, similar
organic dyes, or any of the excipients

- Treatment currently or within 3 months before Baseline with any of the following
medications:

- Tacrine

- Clozapine, olanzapine (and there is no intent to initiate therapy during the
course of the study)

- Carbamazepine, primidone

- Drugs with a warning or precaution in the labeling about methemoglobinemia at
approved doses

- Current or prior participation in a clinical trial as follows:

- Clinical trial of a product for cognition within 3 months of Screening (unless
confirmed to have been randomized to placebo)

- A clinical trial of a drug, biologic, therapeutic device, or medical food in
which the last dose/administration was received within 28 days prior to Baseline