Development of a novel dendritic cell-based immunotherapy targeting cancer stem cells.

Abstract

e14009 Background: Dendritic cells (DCs) are one of the central tools in cellular anti-tumor immunotherapy, being characterized by their capacity for acquiring and processing antigens and ability to produce strong antitumor immune responses. The production of clinical grade ex-vivo monocyte-derived DCs (Mo-DCs) is the most frequent approach for antitumor vaccines production. Recently, therapeutic resistance to radio/chemotherapy and disease recurrence was shown to be in part due to a small cancer stem cell (CSCs) population present in tumors. Methods: Here, we aim to target and eradicate CSCs by developing a novel DC-based immunotherapy vaccine for pancreatic and non-small cells lung cancer (NSCLC), comparing the loading of CSCs vs. classical tumor lysates. Results: CSCs from PANC-1 (pancreatic cancer) and A549 (NSCLC) cell lines were successfully isolated and characterized, overexpressing stem-like markers: NANOG, OCT4, SOX2 and CD133. CSCs resistance to Gemcitabine was also assessed. Before comparing the 2 types of vaccine loading, we also analyzed the impact of 3 GMP free-serum culture media on the phenotype and functional abilities of Mo-DCs. DCs cultured in X-VIVO 15 and AIM-V media show enhanced production of IL-12 and are able to induce a superior stimulation of T cells, mainly CTLs and Th1 subsets. By contrast, DCs cultured in DendriMACS are more prone to induce Treg polarization. Conclusions: Overall, our data demonstrate that blood monocytic precursors present considerable plasticity allowing a tailored differentiation of DCs just by changing the nutritive support. We also highlight the need of critically defining the culture medium to be used in DC cancer immunotherapy in order to attain desired cell characteristics and by consequent robust responses. Finally, our preliminary results indicate that loading DCs with CSCs antigens may be an effective strategy to target and destroy this resilient cancer cell population.