Glioblastoma multiforme (GBM) is a particularly aggressive form of brain cancer and despite extensive efforts to develop new treatments, GBM continues to be fatal. Earlier clinical studies from our laboratory have demonstrated that adoptive immunotherapy using cytomegalovirus (CMV)-specific T cells can be safely used for the treatment of patients with primary or recurrent GBM and may improve the overall survival of patients. With this knowledge, we have developed a novel strategy to combat GBM. We have used CMV-specific T cells as a platform on which to deliver a chimeric antigen receptor (CAR) targeting Ephrin receptor A3 (EphA3), which is highly expressed on GBM; in particular, by the tumour vasculature and glioma stem cells.
EphA3 CAR T cells were successfully generated, expanded and shown to selectively kill EphA3+ GBM cell lines in vitro. Furthermore, these effector cells demonstrated curative efficacy in an orthotopic xenograft model of GBM. EphA3 CAR T cells are equally effective in targeting patient-derived neurospheres and infiltrate, desegregate, and kill GBM-derived organoids. EphA3 CARs can be expressed on CMV-specific T cells and demonstrate dual-targeting potential against EphA3 and CMV antigens.
We have demonstrated the cytolytic potential of EphA3 CAR T cells and the dual-targeting potential of CMV-specific EphA3 CAR T cells. CMV EphA3 CAR T cells are specifically designed to target GBM vasculature and glioma stem cells and recognise CMV antigens expressed in GBM cells. These CAR T cells retain in vivo proliferation potential, brain-homing characteristics, and safety features that have been clinically demonstrated with CMV-specific T cells. Our long-term goal is to develop this as an “off-the-shelf” allogeneic CAR T therapy, which will be manufactured from healthy volunteers, stored as a bank and readily offered to GBM patients based on HLA matching through a computer-based algorithm selection process.