Microbial-based cancer therapy armored with membrane-bound cytokines for targeted immune modulation and safety-controlled delivery

This MPI R01 application is aligned with the PAR-25-107, advancing microbial-based cancer therapy. Over the decades, standard cancer treatments such as chemotherapy and radiation often fail in solid tumors due to poor vascularization, tumor hypoxia, and immune suppression. In recent years, immune checkpoint inhibitors such as anti-PD-1 (aPD-1) have transformed cancer treatment but remain ineffective in many solid tumors due to a lack of pre-existing immune infiltration and an immunosuppressive tumor microenvironment (TME). Meanwhile, adoptively transferred cell therapies, including chimeric antigen receptor (CAR) T and NK cells, face major obstacles such as inefficient trafficking to solid tumors, and rapid exhaustion post-transfer. To overcome barriers to chemotherapy, radiation treatment, cancer immunotherapy, microbial-based cancer therapy has emerged due to its selectivity in solid tumors and enhanced anti-tumor immunity via synthetic biology. As self-regenerating cancer therapeutics, microbial therapies offer significant advantages for global health and low-resource settings. However, modern microbial therapies face challenges, including limited efficacy due to rapid clearance and systemic toxicity of therapeutic agents. To address these limitations, we recently engineered nonpathogenic tumor-tropic E. coli to display membrane-anchored immune cytokines, such as decoy-resistant IL-18 (DR-18), enhancing tumor-localized immune activation while minimizing systemic exposure. Our publication shows that E. coli displaying DR-18 significantly improves immune cell infiltration, reduces toxicity of systemic delivery of cytokines, synergizes with immune checkpoint blockade, and enhances the efficacy of CAR- NK therapy in preclinical mouse models. Building on our preliminary data, this proposal has three specific aims: (1) To elucidate the mechanisms by which tumor-tropic E. coli displaying DR-18 synergize with host anti-tumor immunity by profiling cytokine/chemokine responses and leveraging bacterial surface display to enhance immune cell recruitment. (2) To optimize bacterial safety and efficacy through scaffold protein engineering, genomic integration for stability, and a CRISPR-based failsafe switch to ensure controlled elimination and biosafety. (3) To validate the therapeutic potential of our engineered bacteria in patient-derived tumor spheroids and xenograft (PDX) models of mesothelioma and ovarian cancer using mesothelin-specific CAR NK or T cells, considering the high expression of mesothelin in these two cancer types and our publication record in this area. The combination of syngeneic and xenograft models will help bridge preclinical findings to human cancer biology. Our interdisciplinary team, bringing expertise in therapeutic microbial engineering (Dr. Li), NK cell therapy (Dr. Romee), and cancer immunology (Dr. Barbie), will develop a clinically viable microbial immunotherapy platform. By integrating bacterial surface display with immune modulation, this approach overcomes key barriers in cancer immunotherapy, potentially advancing solid tumor treatment through a safe, tumor-targeted microbial therapy. Project Number: 1R01CA299949-01A1 | Fiscal Year: 2026 | NIH Institute/Center: National Cancer Institute (NCI) | Principal Investigator: Jiahe Li (+1 co-PI) | Institution: UNIVERSITY OF MICHIGAN AT ANN ARBOR, ANN ARBOR, MI | Award Amount: $669,278 | Activity Code: R01 | Study Section: Translational Immuno-oncology Study Section[TIO] View on NIH RePORTER: https://reporter.nih.gov/project-details/11295605