4ONovel dendritic cell based immunotherapy for advanced cancer

Abstract Background Immune-checkpoint inhibitors (ICI) such as Ipilumimab and Nivolumab have made long-term survival a real possibility for advanced cancer patients. Despite the success, only a proportion of patients receiving ICI show meaningful clinical benefit. Developing a more personalized treatment strategy using patient’s own immune cells may be a promising approach for treating non-responding patients. Natural circulating dendritic cells (nDC) such as CD1c+ DC (cDC2) subset and plasmacytoid DC (pDC) are essential for efficient activation of immune responses after ICI therapy. Thus understanding the condition of these cells in patients and devising new strategies to improve their functions may help improve response to ICI in advanced cancer patients. Methods To investigate this we measured the number and phenotype of nDC in 29 advanced cancer patients versus 21 age and gender-matched healthy controls using flow cytometry. We further identified that inhibition of the p38 MAPK pathway using small molecule inhibitors in cDC2 cells increases their immune-stimulatory capacity, measured by functional assays. Results The number of pDC were significantly reduced in cancer patients as compared to healthy controls (1221 vs 2843 pDC/mL) (p-value