Targeted Imaging Mass Spectroscopy for Biomarker Detection in Human Tissues

DESCRIPTION (provided by applicant): Biomarkers are measured in patient tissue biopsies to refine diagnosis, and to guide therapy. For a patient, this means receiving the therapy or drug most likely to work while avoiding the expense and toxic side effectsof alternatives. In pathology, a long-standing problem is that the most accurate methods for biomarker detection in tissues require extraction and disruption of the tissue. Because microscopic diagnosis remains the gold standard for diagnosis, methods tomeasure biomarkers in intact tissue are needed. Existing methods depend upon human eye inspection and qualitative scoring of the amount of a pigment indicating a biomarker. Biomarkers are typically performed one at a time. This causes variability in scoring, and limits the amount of testing that can be done on small tissue biopsies. Our project is to replace human eye detection with automated targeted imaging mass spectroscopy which allows simultaneous measurement of many biomarkers on each tissue biopsy. We use bar coded cleavable tags for probes (antibodies) that identify biomarker targets in intact tissue sections. The bar coded tags are like the bar code one finds on items at the grocery store. Our machine detector is the counterpart of the scanner at the grocery store checkout line. The store bar codes are almost infinitely variable but like a fingerprint, each uniquely identifies the product. Through existing chemical methods we can create many different mass tag bar codes so that many different tests can be performed on each tissue section. A laser scans the tissue, breaking the tags from their probes so that they fly off the tissue to an automatic detector. The location of the laser is precisely known so that each time a bar coded tag flies off thetissue, it is related to the standard picture used by the pathologist. The long term goal is to measure tissue biomarkers at lower cost and more accurately. PHASE I HYPOTHESIS: Using HER-2 as a model, we hypothesize that TIMS produces tissue biomarker results that are comparable to IHC detection of HER-2 in breast cancer. Specific Aim 1: Design and implement a new generation of photo cleavable (trityl) molecules conjugated to antibodies. Specific Aim 2: Development of a multiplexed TIMS protocol. PLANS FORPHASE II: Examine how many tags there are on each antibody; Determine stability and shelf life of bound and unbound trityl tags; Determine whether proteins, DNA, and RNA can be simultaneously targeted in a multiplexed assay; Examine whether the laser canbe narrowed, refining its resolution to individual cells; Determine whether laser induced release of mass tags is a linear or non-linear function of laser intensity COMMERCIAL APPLICATION: We will seek drug developers as customers. If used in early phase discovery, it is likely that TIMS would also be used prospectively in subsequent clinical trials to identify and enroll patients whose tumors contain targets appropriate for the drug. This would pull the method along into the wider diagnostics marketplace.PUBLIC HEALTH RELEVANCE: Diseases are complex and differ from patient to patient, and our ability to see these differences is improving. Patients should receive the therapy or drug most likely to benefit them while avoiding the expense and toxic side effects of ineffective alternatives. More effective measurement of markers of disease in human tissue biopsies can more accurately align patients with the treatment most likely to benefit them.