EXECUTIVE SUMMARY Cancers rich in dense stromal tissue are more difficult to treat and carry a worse prognosis than cancers without the stroma-rich phenotype. The fibrous stroma surrounding certain tumors effectively excludes many current therapies, including antibody- or cell-based therapies and large (>30nm) nanoparticles. Duo Oncology develops ultrasmall nanomedicines (10nm-30nm) that penetrate and accumulate in stroma-rich tumors but not healthy organs. Specifically, our innovative ultrasmall nanomedicine, DUO-307, penetrates stroma rich tumors and changes the tumor immune microenvironment through the combined actions of its gemcitabine prodrug (PGEM) and co-encapsulated small molecule immunotherapy, chemokine receptor type 2 antagonist (CCR2a; PF-04136309). It is a unique chemo-immunotherapy that is directly cytotoxic to the tumor and increases the expression of programmed death receptor 1 (PD-1), which synergizes with immune checkpoint inhibitor therapy. The proposal funded by the NCI and entitled, “A novel dual-carrier ultrasmall nanomedicine for the treatment of stroma-rich pancreatic cancer”, aims to propel DUO-307 toward commercialization through the completion of three specific aims: • Aim 1, conducted in collaboration with Drs. Lance Munn and Gabriel Duda of Massachusetts General Hospital, will provide an optimized formulation of DUO-307. Our collaborators will grow and harvest human pancreatic cancer patient derived xenografts (PDX) to be used in a vascularized tissue explant (VTE) culture system. Tumor tissue samples will be exposed to increasing concentrations of PGEM to determine the quantity of chemokine ligand 2 (CCL2) produced when maximal GEM-associated apoptosis is achieved. We will then use a human monocyte chemotaxis assay to determine the optimal amount of CCR2a to co-load into our DUO-307 nanomedicine. The optimized formulation will then be characterized for particle size, drug loading efficiency, and stability. Progress has already been made toward the completion of this aim. Qualified PGEM nanoparticles were manufactured and delivered to Dr. Munn’s laboratory. PDX pancreatic tumor samples have been implanted into mice and once they reach the appropriate size will be harvested for experimental use in the VTE cultures. • Aim 2 will evaluate the safety of the optimized DUO-307 formulation. A dose escalation study in naïve mice will be conducted to determine the maximum tolerated dose. A single cycle dosing schedule will be used and terminal clinical chemistry and blood cell counts will be the primary outcomes of interest. • Aim 3 will test the efficacy of DUO-307 in combination with anti-PD-1 therapy in an orthotopic KrasG12D/+; LSL-Trp53R172H/+; Pdx1-Cre (KPC) mouse model of pancreatic cancer. This aim will be conducted in collaboration with Dr. Song Li at the University of Pittsburgh and will evaluate DUO-307’s ability to inhibit tumor growth, reduce tumor associated macrophage populations, and ultimatel...