Reprogramming the pancreatic ductal adenocarcinoma microenvironment: a novel integrin-targeted cytotoxin, ProAgio, potentiates chemotherapy

Abstract Background Pancreatic ductal adenocarcinoma (PDAC) growth and metastasis are influenced by the tumor microenvironment (TME), which includes immune cells, endothelial cells, macrophages, and cancer-associated fibroblasts (CAFs). Since the novel integrin-targeted cytotoxin ProAgio can inhibit activated CAFs and endothelial cells, we investigated its combination with standard of care chemotherapies in genetically engineered mouse (GEM) and orthotopic murine models of PDAC. Methods We established metastatic murine KPC-Ganji & Bassel-Luc (mKPC-GB-Luc) cell lines and validated them using bulk RNA sequencing. Two in vivo orthotopic mouse model were used to evaluate ProAgio with chemotherapy. mKPC-GB-Luc was used to evaluate the 5FU, oxaliplatin, and irinotecan (FOI combination), and KPC-ML1-Luc was used to evaluate the gemcitabine, nab-paclitaxel (GPTx combination). Immunohistochemistry was used to measure integrin β3, E-cadherin, and HIF-1α. Hypoxia was evaluated using pimonidazole. Stem cells, CAFs, and immune cell subtypes were quantified by flow cytometry. We evaluated the combination of ProAgio plus gemcitabine in a KPC genetically engineered mouse model (KPC GEM). Two sets of KPC GEM were developed. The first set was used for a survival study. The second set was terminated early and tumors were used for single-cell RNA seq and sequential multiplex immunofluorescence (COMET). Results Compared with the chemo regimen (GPTx or FOI), ProAgio, or sham, the combination of ProAgio plus chemo significantly modulated the TME, reduced tumor weight, reduced hypoxia, and eliminated metastasis to the lungs and liver. The combination of ProAgio and gemcitabine increased overall survival in KPC GEM mice compared with either treatment alone. Single-cell RNA sequencing, flow cytometry, immunofluorescence, immunohistochemistry, and COMET analyses demonstrated that ProAgio plus chemotherapy reprogrammed the PDAC-TME by changing activated CAFs toward a qCAFs (quiescent CAFs), macrophages from protumor to proinflammatory polarization, and activating natural killer (NK) cells, CD4⁺, and CD8⁺ T cells. Combination therapy inhibited PDAC stemness. ProAgio-treated CAFs in vitro exhibited reduced secretion of glycine and cysteine, vital metabolites that support stemness and tumor progression. Conclusions These results confirm the novel mechanism of action of ProAgio, which includes reducing hypoxia and modulating TME. The current data provide evidence for potentiation of chemotherapy efficacy by ProAgio.