Engineered bacterial in situ vaccines against oral cancer.

PROJECT SUMMARY. Immunotherapy has become an emerging standard-of-care (SOC) for many different cancer types. However, only 15-20% of patients receive durable benefit. Other limitations include the toxicity of systemically-delivered immunomodulators which may require frequent, high doses and lead to immune-related adverse events (irAEs).

The risk of severe, and potentially fatal, irAEs increases as the field moves towards immune/immune and immune/SOC combination therapies. As the “front line” of tumor/immune interaction, the tumor immune microenvironment (TIME) is a critical locus of immunomodulation, where the kinds of immunocytes in the TIME

predict the likelihood of response to diverse immunotherapies. One strategy to favorably modulate the TIME following standard-of-care surgical resection, is to localize and sustain immunotherapy at the resection site and tumor-draining lymph nodes, reversing the immunosuppressive post-surgical wound healing immune

microenvironment while promoting anti-tumor effector cell immunity. This in situ therapeutic cancer vaccination approach can enhance local concentration of potent therapies while minimizing systemic exposure and likelihood and severity of irAEs. The use of synthetically engineered microbes as platforms for cancer immunotherapy

provides the potential to intelligently direct and modulate immune cells in situ. Our biomaterial-encapsulated

engineered bacteria are at the forefront of this field, with the ability to carry out targeted localization of engineered non-pathogenic E. coli releasing TIME-modulating therapeutic molecules. This allows for reduced off-target toxicity, dose-sparing, and targeting of multiple immune pathways to address the heterogeneous nature of

cancers. The overall hypothesis of this proposal is that our living in situ vaccination platform EcN-IL12Vax can achieve localized and controlled delivery of immunostimulatory cytokines, targeting the post-tumor resection immune microenvironment and tumor-draining lymph nodes (TDLNs) to produce robust anti-tumor responses

that eliminate both local tumor recurrence and lymph node metastases. Importantly, we hypothesize that our use of bacteria will stimulate the innate immune system while their IL-12 secretion will stimulate the adaptive immune system, thereby leading to enhanced residual tumor killing. We will characterize the immune response and

efficacy of EcN-IL12Vax in two Specific Aims: Aim 1 will develop potent and programmable non-pathogenic E. coli as part of a biomaterial-encapsulated engineered bacterial in situ vaccination platform capable of secreting the immunostimulatory cytokine IL-12. Aim 2 will examine how the duration of IL-12 secretion from EcN-IL12Vax

affects both the efficacy and durability of the immunologic response within the immunosuppressive tumor resection cavity immune microenvironment and tumor-draining lymph nodes. This transformative approach will provide the field with an invaluable in situ cancer vaccine platform that can be modified and leveraged for other

solid cancers in future studies and could enable further exploration of additional cytokines and therapeutics with substantial toxicity at narrow concentration windows where they are both safe and effective.