Abstract 486: Paclitaxel nanoformulation attenuates pancreatic tumor desmoplasia and alter tumor immune responses

Abstract Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal types of cancer with a 5-year survival rate of less than 13% due to the lack of effective diagnostic/therapeutic modalities. Paclitaxel (PTX) has been tested in pancreatic cancer (PanCa) therapy with marginally better clinical outcomes, but remains limited by its poor hemocompatibility, biodistribution, and intracellular accumulation in tumor cells. Gemcitabine (GEM) is the most effective therapy for PanCa. However, it shows only a marginal survival benefit of 6 months. The poor therapy response is attributed to high desmoplasia, unfavorable tumor microenvironment (TME), and excessive recruitment of immune suppressive cells. We have recently engineered a multi-layered Pluronic F127 and polyvinyl alcohol stabilized and poly-L-lysine coated paclitaxel loaded poly (lactic-co-glycolic acid) nanoparticle formulation (PPNPs), which effectively inhibits pancreatic tumor. In this study, we demonstrate that PPNPs effectively sensitize tumor cells to GEM via attenuation of tumor desmoplasia. Our findings also show that PPNPs synergize GEM therapy response in cell lines and in vivo mouse models. Mechanistically, PPNPs target the TME via inhibition of the sonic hedgehog (SHH) pathway and other oncogenic signaling axis that inhibits bidirectional tumor-stromal cell interaction as determined by qPCR and Western blot analyses. In addition, PPNPs effectively target tumor-associated macrophages (TAM) by repolarizing M2 into M1 phenotype via inhibiting expression of M2 markers and an increase in M1 markers in mouse macrophage cell line RAW264. 7. M2 polarization of RAW264. 7 cells were induced by culture with IL-4 (20 ng/mL) in the presence of PPNPs or vehicle control. Furthermore, PPNPs effectively increase phagocytic capacity in murine macrophages as determined by phagocytosis assay (Vybrant Phagocytosis Assay Kit). In conclusion, we observed that our novel PPNP nano formulation effectively targets TME, and facilitates GEM uptake by inhibiting the activation of SHH signaling and reprograming the tumor immune surveillance mechanisms. This study suggests that PPNPs have great potential for future clinical use in management of pancreatic cancer. Citation Format: Vivek K. Kashyap, Godwin P. Darkwah, Neeraj Chauhan, Mohammed Sikander, Eswara N. Ghali, Meghana Kolli, Bilal B. Hafeez, Murali M. Yallapu, Subhash C. Chauhan. Paclitaxel nanoformulation attenuates pancreatic tumor desmoplasia and alter tumor immune responses abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 486.