Ex vivo activation of CD56⁺ immune cells that eradicate neuroblastoma

Abstract

Despite the use of intensive contemporary multimodal therapy, the overall survival of patients with high-risk neuroblastoma is still less than 50%. Therefore, immunotherapy without cross-resistance and overlapping toxicity has been proposed. In this study, we report the development of a novel strategy to specifically activate and expand human CD56+ (NCAM1) natural killer (NK) immune cells from normal donors and patients with neuroblastoma. Enriched CD56+ cells from peripheral blood were mixed with CD56+ fraction at 1:1 ratio and cultured in the presence of OKT3, interleukin (IL)-2, and -15 for five days and then without OKT3 for 16 more days. The final products contained more than 90% CD56+ cells and could kill neuroblastoma cells effectively that were originally highly resistant to nonprocessed NK cells. Mechanistically, cytolysis of neuroblastoma was mediated through natural cytotoxicity receptor (NCR), DNAX accessory molecule-1 (DNAM-1; CD226), perforin, and granzyme B. Successful clinical scale-up in a good manufacturing practices (GMP)-compliant bioreactor yielded effector cells that in a neuroblastoma xenograft model slowed tumor growth and extended survival without GVHD. Investigation of CD56+ cells from patients with neuroblastoma revealed a similar postactivation phenotype and lytic activity. Our findings establish a novel and clinically expedient strategy to generate allogeneic or autologous CD56+ cells that are highly cytotoxic against neuroblastoma with minimal risk of GVHD. © 2013 American Association for Cancer Research.