Combined Inhibition of Vasculogenic Mimicry and Angiogenesis in Ovarian Cancer using Antibody Fusion Protein

PROJECT SUMMARY ABSTRACT Ovarian cancerOCis the most lethal gynecological cancer in developed countries and is the fifth leading cause of cancer related death among womenAngiogenesis plays a crucial role in the progression of growth and metastasis of all solid tumors including OCIn addition to angiogenesistumor cells may directly form and line vascular channels that can anastamose with normal blood vesselsa process known as vasculogenic mimicryVMOC is one of the earliest carcinomas in which VM was describedVM has been shown to correlate with increased tumor aggressivenessmetastatic disease and decreased survivalAlthough the VEGF antibody bevacizumab has been approved by the FDA for use in combination with chemotherapy for the treatment of advanced OCup until now therapeutic targeting of either VM aloneor angiogenesis and VM combination has been largely unexploredSince both VM and angiogenesis play a critical role in supporting growth of many solid cancers including breast and OCswe hypothesize that the combined inhibition of angiogenesis and VM will be a more potent means of inhibiting growth of such cancers in vivoWe have developed a uniquetargeted antivascular strategythat combines inhibition of both VM and angiogenesisOur strategy is based on the generation of a fusion protein where a cancer targeted antibody is C terminally fused with a biologicalpayloadendostatinPAhuEndo PA containing an alanine substitution of prolinewhich significantly increases the antiangiogenic potency of wild type endostatinAnti EGFR huEndo PA is the first candidate within this strategy that we have been testing in Triple Negative Breast CancerTNBCxenograft modelsand for which we were awarded SBIR Phase I grantRCAAnti EGFR huEndo PA demonstrates the ability to inhibit both angiogenesis and VM by TNBC cells in vitroand also demonstrated significant inhibition of metastasis in vivo in TNBC xenograft modelsWe now propose extension of this strategy to HERexpressing OC using a newly synthesized fusion proteinHERIgGhuEndo PAIn prior experiments with a prototypeHERIgGhuEndo PA we have already observed profound anti angiogenic and VM inhibition of normal endothelial cells and OC cellsrespectivelyand substantial inhibition of growth of OC xenografts in vivoWe now propose testing of an IgGbased fusionsince human IgGMAbs have shorter half livesa long and proteolysis labile hinge regionnumerous allotypic polymorphisms and are inferior to IgGin mediating ADCCThe Effects of the currently proposedHERIgGhuEndo PA fusion on angiogenesis and VM inhibition will be determined by in vitro Matrigel assayswhile SKOVas well as established patient derived xenograftPDXmodels will be utilized to test effects on tumor progression and metastasis by the fusion alonein combination with chemotherapy and or combined with bevacizumabThese studies will provide preclinical data towards filing of an IND and human Phase I testing in advanced ovarian cancer PROJECT NARRATIVE Although both vasculogenic mimicryVMand angiogenesis play a critical role in supporting growth of many cancers including ovarian cancerwhich accounts for aboutdeaths annually out of an estimatednew cases worldwidemany angiogenesis inhibitors in clinical use have little no effect on VMBased upon the results of our in vitro and in vivo work involving SKBRdirected HERbreast cancer and MDA MBdirected Triple Negative Breast Cancerwe hypothesize that combined inhibition of both angiogenesis and VM will be a more potent means of inhibiting growth of ovarian cancers in vivo as wellIt is expected that in the present study the combined inhibition of VM and angiogenesis byHERIgGhuEndo PA fusion proteingenerated by the fusion of the cancer targeted Anti HERantibody and a biologicalpayloadendostatin PAwhere alanine substitution of Prolinesignificantly increases the anti angiogenic potency of endostatinwill be a superior strategy for inhibiting tumor growth and metastasis in the setting of ovarian cancer due toidisruption of normal angiogenesis by endothelial cellsiiprevention of formation of VM channels by tumor cellsiiireduction of the ability of tumor cells and endothelial cells tocooperatein assembling new vascular networksvinhibition of ADCC activityandivreduction of tumor cell motility and peritoneal seeding