Identifying and exploiting molecular abnormalities of tumor vasculature - PROJECT SUMMARY Cancer remains the second leading cause of death in the USA, with ~600K lives lost in 2022. Therefore, there remains an urgent need to develop new therapies or enhance existing therapies for cancer patients. A major focus of such efforts is understanding how variability in the tumor microenvironment affects treatment efficacy. Increasingly, the aberrant properties of tumor vasculature are recognized as barriers to efficient delivery and distribution of bloodborne therapies. Although it has long been known that tumor blood vessels exhibit morpho- logical and functional differences from normal blood vessels, the molecular bases for these features have not been firmly established. The purpose of this application is to test the hypothesis that vascular cells from di- verse human cancers share molecular phenotypes that can be exploited as biomarkers and for therapeutic purposes. In Aim 1, we will identify molecular markers that optimally distinguish tumor vasculature from normal vasculature by performing integrative gene coexpression analysis of bulk transcriptomes representing tens of thousands of samples from cancerous and normal human tissues. We will also validate candidate markers his- tologically and functionally. In Aim 2, we will determine whether loss or inhibition of ENPEP, a marker of glio- blastoma (GBM) vasculature, promotes favorable outcomes in orthotopic mouse models of this disease. We will compare tumor progression and survival between Enpep -/- and wild-type mice using a murine allograft model of GBM. Using allograft and xenograft models of GBM, we will also evaluate the anti-tumor efficacy of firibastat, a first-in-class, brain-penetrating, oral prodrug that selectively inhibits ENPEP. In Aim 3, we will de- velop and validate novel antibodies for binding cell-surface markers of tumor vasculature. We will employ an industrialized phage display platform to generate panels of recombinant antibodies that target cell-surface markers of tumor vasculature and validate antibody specificity and functional significance using in vitro and in vivo assays. Expected outcomes include identification of optimal markers of tumor vasculature in diverse hu- man cancers, clarification of the role of ENPEP in GBM progression, and development of novel zip code rea- gents for targeting tumors via the bloodstream with potential applications as biomarkers or therapeutics.
