Flex Hinge Bispecific Antibodies for Ultra Sensitive Detection of Beta Amyloid Species in Plasma

PROJECT SUMMARY ABSTRACT Alzheimer s disease AD is a devastating progressive neurodegenerative disease affecting an estimated of Americans over years of age and over years of age The initial pathological sign of AD the build up of beta amyloid A plaques in the brain often precedes impairment of cognition Although these plaques can be imaged by A PET brain scans or detected via analysis of A peptides in the cerebrospinal fluid these methods are costly invasive and inconvenient Recently with clinical studies indicating that therapeutics may be more effective in treating AD at the earliest stages of the disease and that anti A therapy can remove A from the brain the need for a simple inexpensive diagnostic blood test for AD onset and progression is even greater It has been difficult to develop a blood test based on A in part because of the low concentration of A peptides in blood and the high concentration of other proteins We have approached this protein design problem by developing methods to link the antigen binding domains Fabs of antibodies to beads using flexible and extendible non peptidyl hinges The flexibly linked Fabs on the beads are able to efficiently capture exceptionally low levels of A attomoles in blood by binding cooperatively in a two handed fashion These Flex Hinge Fab beads combined with MALDI TOF mass spectrometry have revealed previously unknown forms of A including a novel A biomarker in plasma that acts as a precise qualitative and quantitative proxy for brain A PET imaging correlating with the stages of AD In this Phase I SBIR we shall improve upon these results in two key ways instead of using Flex Hinge Fab beads we shall produce Flex Hinge Bispecific Antibody beads that we expect to have even greater sensitivity and utility through improved cooperativity and reduced variability and we shall move to Orbitrap technology which has greater sensitivity and resolution for A peptides compared to MALDI We shall use these Flex Hinge Bispecific Antibody beads and Orbitrap technology to examine clinical samples from the Swedish BioFINDER study to confirm the utility of the novel A biomarker and identify additional A biomarker s in plasma Phase II studies shall evaluate this assay with larger sample sets Ultimately we intend to turn our test into a kit that will be broadly available and become routine for monitoring AD much as cholesterol testing is used for monitoring cardiovascular disease PROJECT NARRATIVE Sensitive reliable and non invasive assays that are capable of detecting Alzheimer s disease at its early stages and guiding new therapies are desperately needed Although current Alzheimer s diagnostics such as brain imaging and spinal taps are expensive invasive and cumbersome they provide an opportunity to identify optimal biomarkers that can be used in simple diagnostic assays The non invasive blood test for such biomarkers developed in this proposal would be a major advance in the field of Alzheimer s diagnosis monitoring and treatment guidance