Enhancing T cell immunity in tumor-draining lymph nodes

Tumors systematically reprogram proximal lymph nodes by release of systemic and lymph- borne signals to generate a receptive site for future metastatic seeding while simultaneously modulating immune responses. This remodeling process dampens immune mechanisms in the tumor-draining lymph node (TDLN), leading to compromised anti-tumor immunity. TDLN sustain an immune cell subset that has been described to emerge in cancer patients, which does not reach a sufficiently activated phenotype and as a consequence fails to eradicate tumor cells. However, these so-called progenitor exhausted T cells (TPEX) still retain the potential to fuel tumor-directed T cell immunity and respond to immunotherapies such as immune checkpoint blockade (ICB). TPEX phenotype and effector function is likely controlled and maintained by the microenvironment of the premetastatic TDLN niche, which includes various cell types that are in contact with TPEX. This suggests, that targeting immunotherapy to the TDLN is a promising strategy to specifically activate TPEX and thereby control tumor growth. No approach to specifically target immunotherapy to TDLN exists, hindering research in this area. In this project, I aim to (1) establish a cell infusion-based TDLN delivery method; and (2) assess the mode of action of immune checkpoint blockade in TDLN. Conceptually, this project consists of a method development part with a proof-of-concept study demonstrating the effect of activating stimuli on TPEX function in TDLN (Aim 1), as well as a mechanistic study dissecting ICB activity in the TDLN (Aim 2). We will develop a cell-based delivery system to target therapeutics to TDLN in a model of oral carcinoma. Cell-based therapy is based on transplantation of immature myeloid cells that have been recently described as efficient vehicle to deliver immunotherapy into tumors. We will engineer myeloid cells to express LN homing factors triggering their migration into TDLN where they will secrete multiple immunotherapies such as immune-stimulating cytokines or nanobodies blocking inhibitory receptors. This project will for the first time (1) establish a novel and elegant platform to target therapeutics to TDLN, thereby filling a technological gap; (2) test the concept of immunotherapy secreted in TDLN, thereby exploring the approach of directly targeting tumor- directed TPEX; and (3) dissect ICB mechanisms in TDLN, thereby expanding our basic understanding of how ICB modulates anti-tumor immunity. Results will significantly expand tools, empowering future research on immunosuppressive mechanisms and metastasis in the TDLN. In addition, we will test novel immunotherapy avenues that will not only yield mechanistic insights into tumor-directed T cell responses, but also could be further developed for clinical application.