PTI is developing PTI-125-DX, a novel, quantitative blood-based diagnostic candidate for Alzheimer's disease (AD). A non-invasive and inexpensive AD diagnostic is sorely needed, particularly one with the ability to detect early pathological changes that precede cognitive symptoms. PTI-125-DX measures the ratio of two protein fragments in plasma and is a companion diagnostic/biomarker for our therapeutic candidate PTI-125. PTI-125 disrupts and prevents filamin A (FLNA)'s association with the ?7-nicotinic acetylcholine receptor (?7nAChR), which amyloid beta 1-42 (A?42) hijacks to hyperphosphorylate tau protein. We have tested over 220 plasma samples and show two orders of magnitude significant differences between patients with AD diagnoses (confirmed by imaging or CSF markers) and age-matched normal controls. These two groups are distinguished with 98-100% accuracy. In one of two blinded studies, PTI- 125-DX distinguished MCI with confirmed AD pathology (MCI-AD) from MCI with suspected non- amyloid pathology (MCI-SNAP) with 92% accuracy; in the other, this distinction needs confirmation by imaging. In this proposal, we will compare additional MCI-AD and MCI-SNAP samples and determine disease specificity of the assay by testing archived plasma samples from patients with dementia with Lewy bodies, Frontotemporal Dementia and Parkinson's disease alongside AD, MCI-AD, MCI-SNAP, early-onset familial AD (FAD), cancer and elderly or young controls. As PTI-125-DX is currently in Western blot format, we will develop an ELISA assay and compare it to an automated Western blot format using ProteinSimple's Wes?. In Phase II, we will generate proprietary antibodies by immunizing with carefully selected peptides and recombinant proteins; these polyclonal antibodies will be screened and tested to determine optimal combinations. The corresponding immunogens will then be used to develop monoclonal antibodies. The sandwich ELISA we envision will capture all fragments of interest and separately detect two specific protein fragments. With final monoclonal antibodies and a final ELISA (or Wes) format selected, we will perform a new blinded study of up to 250 de-identified plasma samples from the AIBL study. At the conclusion of this work, PTI-125-DX will be ready for commercialization or partnering.

Public Health Relevance

Pain Therapeutics, Inc. (PTI) is developing PTI-125-DX, a novel, quantitative blood-based diagnostic test for Alzheimer's disease. In two separate blinded studies of over 220 samples, PTI- 125-DX differentiated AD from elderly normal control subjects with 98-100% accuracy and mild cognitive impairment due to AD (MCI-AD) from MCI suspected non-amyloid pathology (MCI- SNAP) with 92% accuracy. In the current proposal, we will first determine specificity of the assay for AD or MCI due to AD versus other dementias. In Phase II, we will synthesize or clone peptides and protein fragments to use as immunogens to generate proprietary polyclonal and then monoclonal antibodies. We will convert the existing Western blot assay to ELISA or automated Western blot, and with final format and monoclonal antibodies, perform a new blinded study of clinical trial plasma samples.

National Institute of Health (NIH)
National Institute on Aging (NIA)
Small Business Innovation Research Grants (SBIR) - Phase II (R44)
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Special Emphasis Panel (ZRG1)
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Hsiao, John
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Cassava Sciences, Inc
United States
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