Multiplexed immunoassay for building patient-specific molecular profiles of CSF amyloid beta and TAU

ABSTRACT This project will develop a multiplexed immunoassay for measuring patient-specific molecular profiles of the two protein markers of Alzheimer’s disease (AD): amyloid beta (ABeta) and TAU from human cerebrospinal fluid (CSF). Both proteins are structurally complex due to the existence of multiple differentially cleaved forms (ABeta) and 6 isoforms containing 50+ phosphorylation sites (TAU). CSF provides a rich source of potential biomarkers, which can be extensively mined to build diagnostic and prognostic signatures of AD and AD-related dementias (ADRD) or to develop personalized patient profiles for drug discovery. At present, those efforts are constrained by the lack of technical capability to resolve multiple ABeta and TAU proteoforms, more specifically by the lack of products for multiplexed capture and enrichment of ABeta and TAU for quantitative mass spectrometry-based proteomics. This proposal seeks to build upon an earlier successful product development project performed by Adeptrix for a pharma customer. Using our BAMS™ platform, we were able to identify at least 14 novel low abundance CSF ABeta peptides and dramatically expand the sequence coverage of CSF TAU by adding two new types of probes, which complement the existing conventional probes for total (tTAU) and phospho-TAU (pTAU). The proposed immunoassay, termed ABeta/TauScan™ will address the current need of biologists, clinicians, and pharma for comprehensive molecular profiling tools for studying protein markers of neurodegeneration. Furthermore, it will open a path to developing similar assays for other protein targets, such as neurofilament light polypeptide (NFL) and alpha-synuclein. While ABeta/TauScan™ is intended primarily for CSF, post Phase II the reagents will be evaluated for use in serum/plasma. Throughout this project we will work closely with academic, clinical and industry partners to ensure the robust analytical performance of ABeta/TauScan™. Once the assay is created, it will be validated by screening 300 CSF samples representing cognitively normal (CN) subjects, mild cognitive impairment (MCI) and AD subjects and establishing a molecular signature of CN to MCI to AD progression that will contain at least one novel marker for improved assay sensitivity and specificity.