Abstract 2808: GD2-specific genetically engineered NK cell therapy is effective in a drug-resistant neuroblastoma xenograft mouse model

Abstract

Abstract Background: Drug-resistant neuroblastoma remains a major challenge in pediatric oncology. A human NK cell line NK-92-scFv(ch14.18)-z engineered to express a GD2-specific chimeric antigen receptor (CAR) may help to address this problem. We investigated the cytotoxicity of NK-92-scFv(ch14.18)-z in a panel of GD2+ drug-resistant neuroblastoma cell lines and analyzed the anti-tumor efficacy of NK-92-scFv(ch14.18)-z in a drug-resistant neuroblastoma xenograft mouse model. Methods Cytotoxic activity of GD2-specific NK-92-scFv(ch14.18)-z towards a panel of GD2+ cell lines (CHLA-20, SK-N-BE(2), CHLA-136, CHLA-79, LA-N-1, LA-N-5), some of which exhibit partial or multidrug resistance, was analyzed in a 51Cr release assay. We investigated the impact of GD2 recognition on NK-92-scFv(ch14.18)-z-mediated lysis by blocking the CAR through the addition of an anti-idiotype antibody (anti-IdAb) and also by downregulating GD2 on target cells induced by the glucosylceramide synthase (GCS) inhibitor PPPP. We then employed ELISA to determine the production of effector molecules granzyme B and perforin in response to activation with immobilized GD2. Anti-tumor efficacy of NK-92-scFv(ch14.18)-z and IL-2 was analyzed in a drug-resistant GD2+ xenograft mouse model by peritumoral injections of the GD2-specific NK cell line. Results NK-92-scFv(ch14.18)-z effectively lysed GD2+ drug-resistant NB cell lines. This effect was almost completely abrogated by blocking the CAR with an anti-IdAb. Decreased GD2 expression on target cells also resulted in diminished lysis mediated by NK-92-scFv(ch14.18)-z. Quantification of granzyme B and perforin production with ELISA revealed that the plate-bound antigen GD2 alone was sufficient to induce activation of NK-92-scFv(ch14.18)-z. Importantly, repeated peritumoral subcutaneous injections of a combination of NK-92-scFv(ch14.18)-zeta and IL-2 significantly prolonged survival time of mice challenged with aggressively growing subcutaneous CHLA-20 tumors in a xenograft mouse model. Conclusions These encouraging results indicate that GD2-directed immunotherapy with genetically engineered NK cells is an appropriate treatment strategy especially in relapsed NB that exhibit drug resistance. Citation Format: Diana Seidel, Anastasia Shibina, C. Patrick Reynolds, Winfried S. Wels, Nicole Huebener, Holger N. Lode. GD2-specific genetically engineered NK cell therapy is effective in a drug-resistant neuroblastoma xenograft mouse model. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2808. doi:10.1158/1538-7445.AM2014-2808