Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Novel immunotherapeutic approaches such as chimeric antigen receptor (CAR)-expressing immune cells are showing promising results against cancer. Among these are the CAR Natural Killer (NK) cells that can be produced from either established cell lines such as NK-92 or allogenic NK cells, which can attack cancer cells. However, some challenges are encountered, when targeting solid tumors, in general and in particular glioblastoma, including the immunosuppressive tumor microenvironment, the antigen escape, the on-target/off-tumor toxicity and neurotoxicities. In addition to the inability to control the activity of conventional CAR NK cells once they are transferred into the patient in case of toxicities occur. Therefore, we aimed to develop a safer and more tumor-specific CAR NK cell platform called the Reverse CAR (RevCAR) NK-92 system. This system consists of two components, the NK-92 cells expressing RevCARs having an extracellular short peptide epitope incapable of recognizing surface antigens by itself, unless redirected by the other component of the system, which is a bispecific molecule called Rev Target Module (RevTM). The RevTM contains two scFvs, one is targeting the respective E5B9 or E7B6 epitope of the RevCAR NK-92 cells and the other one binds to the tumor associated antigen (TAA) of interest. Only in the presence of the respective RevTM, RevCAR NK cells can be directed towards tumor cells, resulting in tumor lysis. By dosing of the short-living RevTMs, we enabled the control of the RevCAR NK cell activity. Furthermore, the modular character of the RevCAR system provides the flexibility for targeting of different TAAs of interest simply by exchanging RevTMs with different specificities. Out of these TAAs, the fibroblast growth factor-inducible 14 (Fn14) surface receptor and its ligand (tumor necrosis factor-related weak inducer of apoptosis (TWEAK)) have been shown to be upregulated in many solid tumors, like glioblastoma. The activation of TWEAK/Fn14 pathway enhances the proliferation, invasion, and migration of tumor cells, and thus a specific targeting of Fn14 is considered a promising approach in glioblastoma therapy. Therefore, we employed here our RevCAR NK-92 system to specifically target Fn14-expressing glioblastoma cells. Through in vitro and in vivo analyses, we showed for the first time that glioblastoma cells were efficiently killed by redirected RevCAR NK-92 cells using picomolar concentrations of the novel Fn14-specific RevTM which was associated with increased IFNγ secretion. Hence, these findings give an insight into the clinical potential of the RevCAR NK-92 system for a safer, specific and more tailored immunotherapy against glioblastoma.