PROJECT SUMMARY
The engineering of immune cells such as chimeric antigen receptor (CAR)-T cells is driving a new era of cancer
therapy. What makes this approach transformative is the ability to genetically program living cells to intelligently
sense and respond to environments, adding specificity and efficacy that is not possible to obtain with molecular
and antibody-based therapeutics. While CAR-T cell therapy has demonstrated remarkable success for hemato-
logical malignancies, it has been faced with many challenges in solid tumor treatment including limitations in
targeting safe tumor antigens, poor infiltration into tumors, and increased T cell dysfunction in the suppressive
tumor microenvironment. Thus, there is a pressing need to develop technologies to enhance the safety and
efficacy of this promising approach for solid tumors. Over the last few decades, microbiome and mechanistic
studies have elucidated that bacteria selectively colonize tumor necrotic cores due to reduced immune surveil-
lance. Where CAR-T cells struggle to target, locate, and infiltrate solid tumors, bacteria naturally home to, colo-
nize, and remain indifferent to the antigenic profile of tumors. Due to advances in engineering capabilities from
synthetic biology, microbes represent a natural platform for development as 'smart’ therapeutic delivery vehicles
for cancer. In this way, probiotics can infiltrate tumors and be engineered as beacons for directing and enhancing
CAR-T cell activities. This project proposal seeks to engineer a bridge between these two complimentary forms
of cellular therapies for the treatment of triple negative breast cancer (TNBC). The objective of this proposal is
to engineer bacteria and CAR-T cells together, developing a ProCAR (probiotic guided CAR-T cell) system that
will improve the limitation of individual agents. Specifically, probiotics will be engineered to home to tumors and
locally produce immune-stimulants to enhance CAR-T cell therapies – while CAR-T cells will be engineered to
sense these molecules. The overarching innovation of this proposal is engineering communities of living medi-
cines, where tumor colonizing bacteria are reengineered as beacons for directing and enhancing CAR-T cell
cytotoxicity. This will be a fundamentally new approach to genetically engineering interactions between living
medicines, combining the advantages of CAR-T cells and tumor-specific bacteria for cancer therapy, and further
building the foundation for engineered communities.