Therapeutic effects against high-grade glioblastoma mediated by engineered induced neural stem cells combined with GD2-specific CAR-NK.

Purpose: High-grade glioblastoma is extremely challenging to treat because of its aggressiveness and resistance to conventional chemo- and radio-therapies. On the contrary, genetic and cellular immunotherapeutic strategies based on the stem and immune cells are emerging as promising treatments against glioblastoma (GBM). We aimed to developed a novel combined immunotherapeutic strategy to improve the treatment efficacy using genetically engineered PBMC-derived induced neural stem cells (iNSCs) expressing HSV-TK and second-generation CAR-NK cells against GBM.

Methods: iNSCs cells expressing HSV-TK (iNSCs^TK) and GD2-specific CAR-NK92 (GD2NK92) were generated from PBMC-derived iNSCs and NK92 cell lines, respectively. The anti-tumor effect of iNSCs^TK and the combinational therapeutics of iNSCs^TK and GD2NK92 were evaluated by GBM cell line using in vitro and in vivo experiments.

Results: PBMC-derived iNSCs^TK possessed tumor-tropism migration ability in vitro and in vivo, which exhibited considerable anti-tumor activity via bystander effect in the presence of ganciclovir (GCV). iNSCs^TK/GCV could slow GBM progression and prolong median survival in tumor-bearing mice. However, the anti-tumor effect was limited to single therapy. Therefore, the combinational therapeutic effect of iNSCs^TK/GCV and GD2NK92 against GBM was investigated. This approach displayed a more significant anti-tumor effect in vitro and in xenograft tumor mice.

Conclusions: PBMC-derived iNSCs^TK showed a significant tumor-tropic migration and an effective anti-tumor activity with GCV in vitro and in vivo. In addition, combined with GD2NK92, iNSCs^TK therapeutic efficacy improved dramatically to prolong the tumor-bearing animal model's median survival.