Safety Assessment of Leronlimab and Its Effect on Brain Inflammation in Alzheimer's Disease

The present study will administer the drug leronlimab to 20 participants who are above 50 years old with Alzheimer's disease (AD) or mild cognitive impairment (MCI) due to AD. While leronlimab is considered safe in other diseases like Human Immunodeficiency Virus (HIV) and certain types of cancer, its safety and tolerability in AD will be tested for the first time. The main purpose of this study is to learn: 1. Is this drug safe for participants with AD and MCI due to AD? 2. Does leronlimab change levels of brain inflammation? The results of this study could lead to future studies with more participants that will test whether leronlimab may slow or prevent the decline in thinking abilities and brain function in this group of participants. Using leronlimab for Alzheimer's disease is experimental, which means that the Food and Drug Administration (FDA) has not approved leronlimab for this purpose. Participants will be asked to take leronlimab once a week for 12 weeks in our clinic or in their own home. Participants will also be asked to complete the below procedures before and after taking leronlimab for 12 weeks: 1. Undergo 2 types of brain scans, Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRI). 2. Visit our clinic for routine lab work, an electrocardiogram (ECG), and a physical exam. 3. Donate blood so the researchers can better understand how leronlimab affects levels of inflammation and proteins related to AD in the blood. 4. Undergo a series of tests and questionnaires that test thinking abilities. 5. Have weekly phone calls with researchers to let them know if there are side effects while taking this drug.