This award will train dentist-scientist Dr. Kyle Vining in immuno-oncology and help him transition to an independent research career focused on developing novel strategies to re-program myeloid fate in head and neck cancer. Several immunotherapies are approved for head and neck squamous cell carcinoma (HNSCC), but despite these advances, the reported response rate was only 13% in patients treated with checkpoint blockade monotherapy with nivolumab in recurrent/metastatic HNSCC. There is an unmet clinical need to identify mechanisms of immune resistance in solid tumors. To address this problem, we focus on the yet unknown role of mechanical cues on myeloid cells in fibrotic tumors. Solid tumors are surrounded by a rigid stroma of extracellular matrix (ECM). A significant gap of knowledge remains of how mechanics can directly impact the fate of immune cells in tumors. This application will dissect the role of mechanics on myeloid cells in tumors, building on strong preliminary data that showed the stress-relaxation, or viscoelasticity, of ECM regulates immature monocytes in vitro. An artificial ECM system was developed to independently tune fibrillar collagen matrix to stiffness similar to solid tumors, with either more fluid-like, viscous or more solid-like, elastic properties. Viscous, stiff matrix maintained immature monocytes, whereas elastic, stiff matrix directed differentiation of monocytes into dendritic cells and upregulated secretion of pro- inflammatory cytokines. These data suggest the hypothesis that monocyte fate is directed by mechanical regulation in human solid tumors. The first Aim will be conducted under mentoring at Dana-Farber Cancer Institute by immuno-oncologists Dr. F. Stephen Hodi and Dr. Ravindra Uppaluri, as well as cancer immunologist Dr. Kai Wucherpfennig. These supporting data and artificial ECM will be used to identify mechanically-transduced transcriptional programs of monocytes and determine whether these molecular signatures are associated with unfavorable clinical outcomes in patient samples of oral SCC. Dr. Vining will participate in Harvard Medical School workshops and courses to learn R-programming and bioinformatics analyses, as well as work with a collaborator in bioinformatics. Finally, in the independent phase in Aim 2, Dr. Vining's lab will determine the effects of targeting mechanical regulation of monocytes fate in vitro and in vivo. The artificial ECM system will identify targets to control monocyte fate, which then will be tested in an animal model of oral cancer. In conclusion, these Aims together will determine the regulation of monocytes by mechanical cues and will develop new strategies to target myeloid cells for the treatment of HNSCC. Further, these findings will potentially launch new areas of investigation into how mechanical cues regulate myeloid cells in homeostasis, disease, and regeneration.