Modulation of anti-tumour activity of ex vivo expanded NK and GD2CAR-NK cells against neuroblastoma

• Published in: Cytotherapy (Oxford, England) Vol. 21; no. 5; p. S20
• Main Authors: Shen, S, Ferrell, K, Chaudhry, K, Vu, A, Nordon, R, O'Brien, T
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.05.2019
• Subjects: Advanced Basic Science; Other
• ISSN: 1465-3249; 1477-2566
• DOI: 10.1016/j.jcyt.2019.03.317

Background & AimChimeric antigen receptor engineered T cells (CAR T) have shown clinical success especially in acute lymphoblastic leukemia. Innate Natural Killer (NK) cells bear functional resemblance to T cells, but display a safer cytokine profile, immediate availability and no risk of GvHD. CAR NK are thus an attractive alternative to CAR T, especially in an allogeneic setting. Our study aims to investigate the cytolytic activity of NK and GD2CAR-NK cells against GD2 positive neuroblastoma (NB), either alone or in combination with histone deacetylase inhibitor (HDACi) and Programmed death 1 (PD-1) blocker.Methods, Results & ConclusionWe have shown NK cells expanded from mononuclear cells by co-culture with irradiated K562-mbIL15-41BBL cells exhibited robust cytotoxicity against NB cells. HDACi (selective Class I inhibitor entinostat and pan-inhibitor panobinostat) up-regulated surface expression of NKG2D ligands MIC A/B & ULBPs on NB cells and significantly increased NK-mediated killing in NB cell lines and patient-derived-xenograft (PDX) samples. Immune checkpoint blockade via neutralizing antibodies against PD1/PDL1 axis (upregulated during NB and NK co-culture), when used in conjunction with HDACi, further improved efficiency of NK-mediated killing. In NB subcutaneous and metastatic xenograft model, adoptive NK cell therapy significantly prolonged event free survival, an effect further enhanced by treatment with both HDACi and PD1 blocker. Retrovirally transduced GD2CAR-NK cells significantly increased killing against GD2-positive NB cells as compared to control NK cells. Live cell imaging showed robust infiltration of GD2CAR-NK cells into 3D tumor spheroids, significantly reduced growth rate and able to destroy tumor spheroid. In a metastatic xenograft model, GD2CAR-NK treated mice showed significantly lower bioluminescence signal 11 days post tumor inoculation compared to control NK cells. However, although lower signal persisted in GD2CAR-NK group, significance was lost by day 18. Persistence of NK cells in mice was detected for one time point and no expansion observed.Taken together, our data suggest that NK cells mediate efficient killing of NB cells, enhanced by use of HDACi and PD1/PD-L1 blocker. GD2CAR-NK further enhance killing of target cells in vitro and although transiently, slowed tumor progression in vivo. Further investigation to improve transduction efficiency and NK/GD2CAR-NK cell expansion and persistence, with aim to enhance efficacy of NK/GD2CAR-NK cell therapy in vivo.