(447b) Engineering a Logic-Gated Drug Delivery Platform for Cancer Immunotherapy

Immune checkpoint inhibitors (ICIs) are a recently developed immunotherapy for an increasing number of cancer types. The activation of pattern recognition receptors (PRRs), such as the stimulator of interferon genes (STING), can produce type-I interferons (IFN-Is) and other cytokines to induce and amplify a coordinated immune response within the tumor microenvironment (TME). This is increasingly important for the engineering of immunostimulatory molecules that can be delivered intratumorally to “cold” tumor sites where the number of active T cells are low in order to create a more highly immunogenic “hot” TME. Recent work in our group has demonstrated that engineered nanoparticles containing cyclic-dinucleotide (CDN) STING agonists (STING-NP) offer enhanced intracellular delivery of CDNs, leading to increased tumor immunogenicity and response to ICI. However, the STING-NP strategy currently lacks tumor-specific targeting, and its efficacy and safety are limited due modest tumor distribution. Thus, controlling the spatial delivery of STING agonists to the TME is necessary to systemically treat metastatic disease safely. In this talk, I will discuss our engineering of a logic-based immunotherapy for STING activation. Here, we utilize the design/build/test cycle from synthetic biology to construct “smart” STING agonist with logic-gated activation within solid tumors. We used advanced molecular engineering strategies to design and construct a logic-gated drug delivery agent with precise drug loading of the STING agonist. Within our drug delivery agent is a single domain antibody fragment (nanobody) for selective targeting of EGFR+ tissue. Further, the loaded STING agonist features environmentally restrictive activation at the TME. The combined logic-gated activity of tumor binding with the nanobody and site-specific activation of the STING agonist is demonstrated in vitro to confirm biological activity and improve upon design features for maximum efficacy within EGFR+ cell lines. We next evaluated our logic-gated drug delivery agent in breast cancer mouse models to quantify STING activation in the TME, quantify therapeutic efficacy/toxicity, and evaluate biodistribution. The engineering strategies identified within this talk provide fundamental insights into the role of logic-gated immune activation in vivo.