Abstract C119: Combining forces: Integrating engineered bacterial therapeutics with targeted therapies for advanced-stage non-small cell lung cancer
Authors: Deb Dhruba , Danino Tal 
Published: December 2023

Abstract
Currently there are about 400 single-agent targeted therapies in various stages of clinical trials for non-small cell lung cancer (NSCLC) worldwide. However, less than 10% of them have been utilized in combination treatment to improve efficacy of advanced-stage NSCLC due to safety issues. As a result, emerging and safe treatment modalities such as engineered bacteria therapy, commonly known as “bugs as drugs”, in ongoing clinical trials (NCT00004988, NCT04589234, NCT05038150) for advanced-NSCLCs - have not been combined with current standards of care. We hypothesized that If advanced-stage NSCLC tumors are dependent on altered growth signaling upon single-agent bacteria therapy, blocking those signaling with current targeted therapy may provide a promising combination treatment strategy to achieve better efficacy. To test this, we first treated NSCLC-derived spheroids with engineered bacteria producing Theta toxin after localizing in the hypoxic core and eliminating spheroids from inside. Second, we characterized the signaling pathways of bacteria-treated NSCLC spheroids by RNA-seq followed by Gene Set Enrichment Analysis. Third, we blocked altered signaling with current targeted therapies to achieve better efficacy. Finally, we designed an optimum combination treatment and validated it in vivo in xenografted NSCLCs. We found that bacterially secreted Theta toxin significantly altered PI3K/AKT/mTOR signaling, cell cycle checkpoint and DNA repair pathways (normalized p-value &lt; 0.5 and falls discovery rate q-value &lt; 0.5) in multiple NSCLC spheroids, including one established from a chemotherapy and radiation-resistant tumor. We chose current targeted inhibitors of AKT (MK2206), CHK (AZD7762), WNT (IWR-1), ERK (SCH772984), MEK (Selumetinib), and 2 chemotherapy drugs (paclitaxel, pemetrexed) to treat these bacterially-treated NSCLC spheroids. We found that blocking AKT or CHK signaling in combination with bacteria therapy significantly decreased (p&lt;0.002) NSCLC spheroid viability. Honing in on AKT signaling, we validated bacterially secreted Theta toxin induced AKT phosphorylation in NSCLC cells in vitro that we were able to block with MK2206 treatment. Finally, we tested this combination of bacterially secreted Theta toxin and MK2206 in xenografted NSCLC tumors. The combination treatment significantly improved efficacy in all tumors (p&lt;0.001) compared to single-agent therapy (either engineered bacteria or MK2206 alone) without any additional toxicity suggesting a promising translational treatment strategy. We conclude that our modular experimental and analytical pipeline can be exploited to characterize engineered bacteria therapies and combine them with specific targeted therapy to expedite the translation of an untapped area of drug development with biological therapeutic agents for advanced-stage NSCLC.
Citation Format: Dhruba Deb, Tal Danino. Combining forces: Integrating engineered bacterial therapeutics with targeted therapies for advanced-stage non-small cell lung cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C119.