CD276 as a novel CAR NK-92 therapeutic target for neuroblastoma

Abstract

Despite advanced understanding of its biology and improvements in standard of care treatment, the outcome for children with neuroblastoma (NB), the most common solid extracranial tumor in pediatrics, remains poor. Particularly, frequent relapse and high mortality rates of high-risk NB patients necessitate new therapeutic approaches such as chimeric antigen receptor (CAR)-modified immune cells. CAR T cells recently showed incredible clinical response targeting CD19 and CD22 in hematological malignancies. However, targeting solid cancers remains a difficult challenge and production of autologous CAR T-cell products still requires an extensive manufacturing process. The well-established natural killer (NK)-92 cell line provides a promising alternative to produce “off-the-shelf” CAR-modified effector cells. In the present study, we demonstrate that the immune checkpoint molecule B7-H3 (CD276) is aberrantly expressed on NB cells. Second generation CD276-CAR-engineered but not parental NK-92 cells were capable of specific and long-term elimination of NB cells in vitro while sparing CD276-negative cancer cells. Furthermore, CD276-CAR NK-92 cells showed increased cytotoxicity in a three-dimensional NB spheroid model which can recapitulate in vivo morphology as well as cell connectivity, polarity, gene expression, and tissue architecture, thereby, bridging the gap between in vitro and in vivo models. CD276-CAR NK-92 cells produced a multitude of NK effector molecules as well as pro-inflammatory cytokines that can stimulate the immune system. CD276-CAR surface expression and cytotoxic effector function remained stable for more than 6 months. Data show that CD276-CAR NK-92 may be a promising treatment option for patients with high-risk NB.