PROJECT SUMMARY Decades of modulating the anti-cancer activity of fluoropyrimidine drugs (FPs) thru schedule optimization, biochemical modulation, and drug combinations have provided an important, but limited, survival advantage for treating colorectal cancer (CRC) patients with locally advanced or metastatic disease (mCRC). However, outcomes remain poor for patients with mCRC and since targeted therapies and immunotherapies provide only a limited benefit to a sub-set of CRC patients, new approaches are urgently needed. Using a simple nanoparticle design consisting of polymerizing 5FU’s active metabolite, 5-fluoro-2’-deoxyuridine-5’-O-monophosphate (FdUMP), to create ssDNA FP homopolymers, the Gmeiner lab at Wake Forest School of Medicine (WFSM) demonstrated that improved anti-tumor activity and reduced systemic toxicities could be achieved relative to 5- FU. This approach alters pharmacological properties, biodistribution, and metabolism relative to conventional FPs. A 2nd generation FP polymer, CF10, that is chemically modified to improve stability to enzymatic degradation, was tested in multiple CRC cell lines and displayed further improved potency relative to the prototype FP polymer F10. CF10 is well tolerated in vivo, localizes to orthotopic colon tumors, and displays strong anti-tumor activity in an orthotopic colon cancer model and promising anti-metastatic activity. Based on these findings, DeepCreek Pharma and WFSM/Gmeiner Lab propose to jointly investigate CF10 as a candidate for clinical development. The proposed research in phase I will focus on (Aim 1) testing if CF10 is more effective than either F10 or 5-FU at inhibiting CRC metastatic progression, including in thymidylate synthase overexpressing (TS+) CRC that is 5- FU resistant. This is important because metastatic disease is the cause of CRC lethality and elevated (TS) is a cause of 5-FU resistance and may contribute to progression of metastatic disease. (Aim 2) will focus on demonstrating CF10 displays improved anti-metastatic activity in a rat, syngeneic CRC liver metastasis model. These studies will quantify the biodistribution of CF10 and FP metabolites and test if infusion of CF10 increases uptake into the gastrointestinal (GI) tract without damaging non-malignant tissues. Translation of clinical grade CF10 produced by DeepCreek Pharma into clinical trials for treating mCRC would be the next stage following this STTR project.