Project Summary T-cell priming is orchestrated in the sequestered environment of lymph nodes (LNs) where a cascade of co- inhibitory and co-stimulatory signals from an assembly of cell types determines systemic, immunodominant responses to regionally presented antigens (Ag). Yet tumor draining LNs (tdLNs) are often tolerized against tumor Ags (tAgs), rendering an otherwise inhospitable environment permissive to regional LN metastases and eventual dissemination throughout the body. While checkpoint blockade immunotherapy (CBI) cancer therapy is meant to re-invigorate T-cell priming and effector function against tAgs, these therapies are administered i.v. without regard to all the other non-tAgs that are present in the body. As a result of this Ag-indiscriminate activity, CBI can cause immune related adverse events (irAEs) that limit the use of current and emerging CBI. In addition, because tdLNs are already tolerized to tAgs by the time of cancer detection, the effectiveness of CBI to potently prime tAg-specific T-cell responses may be limited. While CBI does result in durable cancer cures, most cancer types are non-responsive and the majority of patients with cancers known to be responsive either do not benefit from CBI treatment or experience relapse and irAEs. In this application, multi-disciplinary teams from the University of Texas and University of Bern collaborate to deliver both tAg and CBI to non-tdLNs in order to mount efficient, tAg-directed CBI without the irAEs that impact other CBI combinational therapies. Specifically, the team proposes to develop and use a translatable, plant-based, virus-like-particle (VLP) platform presenting private tumor neoantigens (tNeoAgs) and to combine it with CBI delivered to lymphatic watersheds in syngeneic mouse models of triple negative breast cancer (TNBC). Effectiveness of the approach is evidenced by strong preliminary data showing enhanced anti-tumor responses accompanied by clonal expansion of cytolytic, tAg-specific tumor infiltrating lymphocytes from bioinformatic analyses of single cell RNA sequencing. The team further proposes to separately dose different VLP-tNeoAgs with CBI to discrete lymphatic watersheds to mount multiple, immunodominant responses to combat tumor immune escape and regrowth. The team will also test safety of the approach in a transgenic mouse susceptible to induced lymphatic infiltration in normal tissues as a clinical readout of irAEs following CBI dosing. Because the teams have translated their respective technologies into clinical studies, the developments made herein could be rapidly implemented to improve the efficacy of current and emerging CBI, establish the concept of personalized cancer vaccines, and expand the use of CBI in TNBC patients who have limited treatment options.

Narrative Most cancer types are not responsive to checkpoint blockade immunotherapy and the majority of patients with cancers known to be responsive do not benefit from it. This research proposal will use state-of the-art technologies of imaging, world-renowned expertise in cancer vaccine design and production, single cell RNA sequencing, immunoprofiling, and multiplex immunofluorescence to show that by harnessing the lymphatics, immune responses can be personalized. The implications for this research extend beyond cancer to autoimmune and infectious diseases that benefit by immunomodulatory interventions.