Abstract 3568: Robust and potent dendritic cells for cancer immunotherapy

Abstract

Abstract Background: Dendritic cells (DCs) are fundamental to adaptive immunity by detecting, engulfing and presenting foreign or changed antigenic peptides to lymphocytes that thereafter initiate antigen-specific immune attacks. DC-based immunotherapy against cancer has been promising for a long time, but has not yet met expectations. Cancer cell heterogeneity and numerous immune evasion mechanisms represent challenges. According to textbook renderings, DCs may induce either tolerance or immune activation depending upon the nature of the encountered antigen and the status of the microenvironment. Recently, we have discovered a more complicated scenario according to which monocyte-derived DCs (moDCs) exhibit dual pro- and anti-inflammatory features, suggesting that selected conditions that enhance pro-inflammatory features and counteract tolerogenic features could generate more robust and potent DCs for cancer therapy. Materials and Methods: Healthy blood donor buffy coats were used for the isolation of monocytes and conventional CD141+ and CD1c+ natural circulating DCs. IL-4 and GM-CSF were used to differentiate monocytes into immature moDCs. Toll-like receptor agonists were used to induce DC maturation, and specific agonists and inhibitors were tested in different DC variants. Flow cytometry, ELISA determination of cytokine secretion, HPLC-based quantitation of kynurenine secretion, genome-wide gene expression analyses and functional assays, such as antigen uptake, migration and the mixed leukocyte reaction were used for evaluation of treated DCs. Results: Conventional DCs were more susceptible to apoptosis, and dependent upon culture conditions, than moDCs. Inhibition of β-catenin signaling stimulated several pro-inflammatory features, e.g. increased IL-12 and decreased IL-10 secretion, with reciprocal effects caused by β-catenin stimulation. Maturation of moDCs was accompanied by very strong induction of indoleamine 2, 3-dioxygenase 1 (IDO1) transcription and paralleled by increased kynurenine secretion, but this was partially counteracted by β-catenin stimulation. Conclusions: Preparation of more potent DCs for cancer therapy needs to take into account DC longevity and conflicting activation patterns of pro- and anti-inflammatory abilities. Citation Format: Waqas Azeem, Seyed Mohammad Lellahi, Yaping Hua, Anne Margrete Øyan, Benjamin Gabriel, Karl-Henning Kalland. Robust and potent dendritic cells for cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3568.