PROJECT SUMMARY: TR&D 2 Cancer can rarely be eradicated with single-agent therapy. More information than is capable of being carried by one small molecule is often required. We can synthesize nanomedicines engineered to perform multiple tasks in sequence, leveraging the tumor milieu for initiation of these tasks. For instance, we now have the ability to design technology meaningful for management of a variety of cancers, including colorectal (CRC), melanoma and even pancreatic ductal adenocarcinoma (PDAC), one of the most insidious and lethal malignancies. Here we will develop platform technology to enable treatment of those cancers whether localized or metastatic. The goal will be to reprogram malignant cells and the related tumor microenvironment (TME) to eradicate tumor in situ. The nanoparticle (NP) that we will ultimately produce will be optimized with respect to the key properties of targetability (pharmacokinetics), payload delivery and efficacy. It will be a combination of two separate platforms optimized for other purposes and previously leveraged for other malignancies. The first platform involves use of mesoporous silica nanoparticles (MSN), which will be utilized to test two different targeting moieties and a therapeutic agent, TLY012, while the second uses a poly(beta-amino ester) (PBAE) structure, and is designed to deliver nucleic acids intracellularly, including for reprogramming the TME. We will use these two different platforms, and the corresponding experience and new preliminary data, to develop a hybrid particle that combines the best properties of each. Aims 1 and 2 will be dedicated primarily to the synthesis and testing of the MSN, which are adept at presenting cell surface molecules and delivering therapeutics upon target engagement. Aim 3 will involve development of the PBAE NPs for theranostic intracellular delivery of plasmid, including encoding an immunostimulatory cytokine, while the final aim will be concerned with synthesis, testing and optimization of the combination NP, designed to overcome both extracellular and intracellular bottlenecks. We will focus on CRC, which is the second deadliest cancer, melanoma, and PDAC, the third deadliest cancer. There is a variety of phenotypes associated with PDAC, in particular, which can be primarily cystic, mucinous, or can be fenced in behind a desmoplastic stroma. We are excited to pursue PDAC because we have shown that TLY012 can reprogram the TME to decrease desmoplasia and increase cytotoxic T cell infiltration.