Safety, PK and Biodistribution of 18F-OP-801 in Patients With ALS, AD, MS, PD and Healthy Volunteers

Microglia and macrophages have emerged as key players in neurodegenerative and neuroinflammatory disorders of the central nervous system (CNS) such as amyotrophic lateral sclerosis, Alzheimer's disease (AD), multiple sclerosis (MS) and Parkinson's disease (PD). Treatments that selectively target these cells will need to cross the blood-brain barrier (BBB) at levels high enough to produce therapeutic effects. Unfortunately, it is difficult to directly measure the amount of a therapeutic that actually reaches the CNS target tissue. Development of biomarkers that allow direct visualization of cellular targeting across the BBB could offer profound insight into drug actions on innate immune cells in the brain. Furthermore, the ability to track accumulation of activated microglia in the brain could allow early identification of patients at risk for neurodegenerative or neuroinflammatory disease, precise stratification of patients for clinical trials and an efficacy measure for therapies that target neuroinflammation. Positron emission tomography (PET) is a noninvasive imaging technology that can provide quantitative biological information in vivo, and it plays an important role in disease diagnosis, therapy assessment, and drug development. PET allows evaluation of the biological process without pharmacological effects because the amount of radiotracer used in imaging studies is very low. Several PET diagnostics track neuroinflammation in the brain, but current methods are limited by high background signal in healthy tissues. 18F-OP-801 is selectively taken up only by activated but not resting microglia, offering the potential to detect neuroinflammation at lower levels and earlier stages of disease than any current clinical PET radiotracer. We propose to use 18F-OP-801 to image activated microglia and brain macrophages in subjects with ALS, AD, MS, and PD to assess the compound's utility as a biomarker of neuroinflammation