Optimizing EphA2-CAR T Cells for the Adoptive Immunotherapy of Glioma

Glioblastoma is the most aggressive primary brain tumor in humans and is virtually incurable with conventional therapies. Chimeric antigen receptor (CAR) T cell therapy targeting the glioblastoma antigen EphA2 is an attractive approach to improve outcomes because EphA2 is expressed highly in glioblastoma but only at low levels in normal brain tissue. Building upon our previous findings in this area, we generated and evaluated a panel of EphA2-specific CARs. We demonstrate here that T cells expressing CD28.zeta and 41BB.zeta CARs with short spacers had similar effector function, resulting in potent antitumor activity. In addition, incorporating the 41BB signaling domain into CD28.zeta CARs did not improve CAR T cell function. While we could not determine functional differences between CD28.zeta, 41BB.zeta, and CD28.41BB.zeta CAR T cells, we selected CD28.zeta CAR T cells for further clinical development based on safety consideration.