Targeting the Epigenome to Improve Responses to Immunotherapy

Project Summary Conventional dendritic cells (cDCs) are central regulators of the adaptive immune response, and have been shown to be required for the induction of T cell-mediated anti-tumor immunity. In particular, a subset of cDCs (cDC1) is responsible for transporting tumor antigens to the lymph node and cross presenting antigen in order to activate cytotoxic T lymphocytes, thereby inducing an anti-tumor response. We have recently observed TIM- 3 (T-cell immunoglobulin and mucin domain containing-3) expression on cDCs in human and murine mammary tumors, and found that TIM-3 blockade improved response to standard-of-care paclitaxel chemotherapy in models of triple-negative and luminal B disease. This occurred through increased chemokine expression by cDCs, without a corresponding in T cell infiltration, leading me to hypothesize that the spatial localization of cDCs and T cells within tumors is a critical determinant of successfully immunotherapy. In the F99 portion of this application I will therefore seek to determine if TIM-3 blockade alters the spatial organization of T cells, and if this is responsible for therapeutic efficacy. In the K00 phase of this proposal I will expand these studies to evaluate whether cDC/T cell clustering is a prerequisite for response to immune checkpoint blockade and other therapeutic modalities.