Study to Assess the Efficacy of XPro1595 in Patients With Mild Cognitive Impairment With Biomarkers of Inflammation

Change from Screening to Week 12 in Cogstate Composite mean score.

Cogstate is a brief, computerized, neuropsychological battery to evaluate cognitive impairments in mild cognitive impairment (MCI), and Alzheimer's disease (AD). CogState assesses attention and memory functions - including Information processing speed, Visual attention, Working memory and Visual learning. Cogstate scores are measured on a linear scale (with no maximum score). A reduction in scores compared to baseline signifies an improvement in cognitive functions.

The Cogstate battery will be administered at Screening and each week for 12 weeks.

To assess the efficacy of XPro1595 compared with placebo on cognitive performance in patients with MCI

Change from Screening to Week 12 in myelin content.

Change from Screening to Week 12 in blood inflammatory and neurodegeneration biomarkers (on blood inflammatory and neurodegeneration biomarker amyloid)

To assess the efficacy of XPro1595 compared with placebo on blood inflammatory and neurodegeneration biomarkers (on blood inflammatory and neurodegeneration biomarker amyloid)

Change from Screening to Week 12 in blood inflammatory and neurodegeneration biomarkers (on blood inflammatory and neurodegeneration biomarker pTau)

To assess the efficacy of XPro1595 compared with placebo on blood inflammatory and neurodegeneration biomarkers (on blood inflammatory and neurodegeneration biomarker pTau)

Change from Screening to Week 12 in MRI neuroinflammation (White matter Free Water)

To assess the efficacy of XPro1595 compared with placebo on imaging neuroinflammation

Change from Screening to Week 12 in regional brain glucose uptake as measured by F-fluorodeoxyglucose-Positron Emission Tomography (FDG-PET) scans

Alzheimer's Disease (AD) is characterized by a chronic brain glucose deficit. White matter glucose deterioration is also evident in Mild Cognitive Impairment (MCI) and specific to limbic fascicles. We will quantify the change in regional brain glucose uptake for gray matter and white matter tracts using PET imaging and the F-fluorodeoxyglucose (FDG) radiotracer. PET maps will be registered to Magnetic Resonance (MR) anatomical images and corrected for partial volume effect. Standard uptake value ratios (SUVr) will be calculated using the cerebellum as a reference region.

FDG-PET scans will be performed at Screening and Week 12.

To assess the efficacy of XPro1595 compared with placebo on imaging markers of brain quality

Change from Baseline to Week 12 in MRI Apparent Fiber Density (AFD)

To assess the efficacy of XPro1595 compared with placebo on axonal integrity in patients with MCI

Change from Screening to Week 12 in Neuropsychiatric Inventory (NPI-12) study partner items

To assess the effect of XPro1595 compared with placebo on non-cognitive behavioral symptoms in patients with MCI

Change from Screening to Week 12 in brain activity as measured by electroencephalogram (EEG) scans (Change in brain activity as measured by the EEG in microvolts).

Specifically, a series of EEG markers previously associated with AD (Horvath et al. 2018) including high and low frequency band powers, the P300, and Mismatch Negativity (MMN) event-related potentials will be evaluated.

An EEG scan will be administered at Screening and each week for 12 weeks.

To assess the efficacy of XPro1595 compared with placebo on brain activity in patients with MCI

Change from Baseline to Week 12 in language and speech patterns using Winterlight Labs analysis

To assess the effect of XPro1595 compared with placebo on speech and language in patients with MCI

Change from Screening to Week 12 in Alzheimer's Disease Cooperative Study - Mild Cognitive Impairment Activities of Daily Living (ADCS-MCI ADL)

The 23-item ADCS-MCI-ADL Scale has good test-retest reliability, will be utilized to assess performance functioning in MCI patients (Galasko et al., 1997; Douglas Galasko et al., 2006; Pedrosa et al., 2010). The ADCS-ADL includes 18 items from traditional basic ADL scales and 5 items from instrumental activities of daily living scales (IADL) The possible range of total scores for the ADL Scale is 0-53 and higher scores indicate better functioning. The internal reliability was .91( Galasko et al., 1997; Douglas Galasko et al., 2006; Pedrosa et al., 2010).

The ADCS-MCI ADL will be performed at Screening and Week 12.

To assess the effect of XPro1595 compared with placebo on Activities of Daily Living (ADL) in patients with MCI

Change from Screening to Week 12 in Clinical Dementia Rating Scale Sum of Boxes (CDR-SB)

The CDR scale is a clinician-rated dementia staging system that tracks the progression of cognitive impairment in 6 categories (memory, orientation, judgement and problem solving, community affairs, home and hobbies, and personal care). Each category is scored on a 5-point scale in which None = 0, Questionable = 0.5, Mild = 1, Moderate = 2, and Severe = 3. The global CDR score is established by clinical scoring rules and has values of 0 (no dementia), 0.5, (questionable dementia), 1 (mild dementia), 2 (moderate dementia), and 3 (severe dementia). The Clinical Dementia Rating Scale Sum of Boxes (CDR-SB) is obtained by adding the ratings in each of the 6 categories and ranges from 0 to 18 with higher scores indicative of greater impairment.

To assess the effect of XPro1595 compared with placebo on cognition and global function in patients with MCI

Clinically significant abnormalities of laboratory values, physical findings, electrocardiogram findings and other safety assessments will be recorded as adverse events if the findings meet the defined criteria for adverse events.