Generation of personalized tumor Biopsy-Derived Natural Killer (BDNK) cells.

86 Background: Natural killer (NK) cells play promising roles in cancer surveillance and possess multiple unique characteristics for allogenic cell transfer (ACT) in the cancer immunotherapy. However, most studies were applicable to ex vivo expanded NK cells from the peripheral blood, which requires massive amount of cell numbers for the initial isolation and expansion. Moreover, recent studies have demonstrated a phenotypic heterogeneity between peripheral and tissue resident NK cells. Methods: In this study, we aim to establish the ex vivo expansion of tumor infiltrating NK cells directly from diagnostic breast core biopsies followed by functional validation through in vitro assays. Results: A total of 20 breast TILs models, including T and NK cells, were successfully established through genetically modified K562 feeder cells co-culture approach. These models represented all the major sub-types (hormone positive and negative) of breast cancers. Next, we extensively evaluated the tumor-reactivity of the selected NK models via effector:target cytotoxicity assays. Interestingly, non-invasive breast tumor line has exhibited a strong preferential kill by NK cells whereas the invasive line counterpart was able to escape NK cell-mediated cytotoxicity. Conclusions: The resource generated in this study has revealed tumor infiltrating NK cells as a potential tool for cell-based therapy in solid tumors. Furthermore, this study provides a platform to investigate the immune-resistance mechanism involved between tumor and NK cells, thus, paving the way to the discovery of novel cancer immunotherapy targets.