PROJECT SUMMARY The purpose of the Bioanalysis Core is to provide centralized bioanalysis support. This Core will promote standardization and efficiency of analysis and provide essential information that can be shared and compared across all three Projects in the Program. This new, reorganized Core will provide support for all aspects of clinical and preclinical tissue and biofluid distribution of existing photodynamic sensitizers (PS) used in clinical and preclinical studies and any newly developed PS for photodynamic therapy (PDT). These data are essential for interpreting PDT activity in patients and animal models. PSs described in Project 2 have absorption in the red or NIR regions of the visible spectrum and are strongly fluorescent. As such, standardized detection methods have been developed to exploit the photophysical properties of these compounds. The Bioanalysis Core will evaluate the tumor tissue retention of select compounds in mice bearing established and patient- derived human tumors using fluorescence spectrophotometry (and, if possible, liquid scintillation counting to detect radioisotopically-labeled [14C] photosensitizers). Fluorescence spectrophotometry will be used to determine photosensitizer levels in human serum and solubilized biopsy and surgical specimens. Core A will measure SADA (serum alkaline DNase) as a circulating biomarker that has the potential to predict PDT response in head and neck patients. This will involve routine blood collection from patients followed by standard spectrophotometric analysis of SADA activity. The Core will also collect blood and isolate and store immune cells from our head and neck patients for analysis. Specifically, the individual Projects have identified a number of areas of support for both clinical and translational science studies. The specific aims of the Core are: 1) to determine photosensitizer levels in tissues and biological fluids of patients, 2) to collect, isolate and store immune cells from patients for subsequent analysis, 3) to measure noninvasive, circulating biomarker (serum alkaline DNase) and 4) to measure the retention of photosensitizers in mice bearing xenografted head and neck tumors.