Direct therapeutic intervention of the tumor microenvironment with a potent inhibitor of fibronectin assembly

PROJECT SUMMARY Among the hallmarks of cancer, the extracellular matrix contributes to the regulation of each of the hallmark principles underlying tumor progression. Importantly, extracellular matrix stiffness and fiber organization enhance overall breast cancer progression and are associated with poor patient outcome. Biophysical and

biochemical cues from fibrillar matrix stiffness have emerged as key regulators of steps in the metastatic cascade, including increased tumor cell invasion, inflammatory signaling, circulating tumor cells, and metastatic outgrowth. Moreover, emerging studies demonstrate that biophysical cues from the ECM impact tumor intrinsic

and extrinsic factors implicated in immunotherapy resistance. Taken together, this data suggests that stromal matrix stiffness may be one of the underlying mechanisms driving immunosuppression in the breast tumor microenvironment. Despite the growing evidence that biophysical cues play a key role in disease progression

and the mounting interest in therapeutically targeting tumor ECM, there has yet to be an effective therapy directly targeting the stromal matrix in breast cancer. Therefore, we propose to develop a therapeutically useful agent to directly disrupt extracellular matrix assembly, deposition, and organization within the primary and metastatic

tumor microenvironments for the clinical treatment of breast cancer. We hypothesize that directly targeting FN assembly with PEGylated-FUD will subsequently reduce tumor fibrosis by inhibiting collagen deposition and fiber alignment resulting in decreased tumor growth and metastatic progression. We further hypothesize that reduced fibronectin and collagen deposition will limit mechanical activation of pro-tumor

inflammation resulting in enhanced therapeutic efficacy in combination with immune checkpoint blockade. We will test our hypothesis in the following aims: Aim 1: Determine the efficacy of PEGylated FUD as an anti-cancer therapy in pre-clinical models of breast cancer. Aim 2. Evaluate the impact of PEGylated-FUD on

immunosuppressive signaling to enhance anti-PD-L1 therapy for treatment of metastatic disease.