Abstract Background Despite dose escalation of multimodal therapy, brain tumors remain the leading cause of cancer deaths in children. Cellular therapy has garnered interest, however novel strategies are needed to address key challenges including tumor heterogeneity and antigen-negative relapse. EphA2 is expressed highly in pediatric brain tumors, but minimally in healthy tissues. Our lab’s previous research shows that chimeric antigen receptor (CAR) T cells modified with LIGHT show both antigen-directed and antigen-independent killing through interactions between LIGHT and lymphotoxin-β receptor (LTβR) on cancer cells. We aimed to evaluate the efficacy of LIGHT-armored EphA2 CAR-T cells against medulloblastoma. Methods We assessed EphA2 and LTβR expression by interrogating RNA sequencing of pediatric brain tumors in our institutional cohort and through the Pediatric Brain Tumor Atlas. We generated EphA2-targeting and LIGHT-armored EphA2-targeting CAR-T cells with a CD28z signaling domain from 4 independent donors. Non-transduced t cells were negative controls. We evaluated antitumor efficacy of LIGHT-armored CAR-T cells against Daoy, which endogenously expresses EphA2. We co-cultured firefly-luciferase expressing tumor cells with various CAR T cells. In vitro cytotoxicity was measured using bioluminescence. Results RNA sequencing demonstrated high EphA2 and LTβR expression in medulloblastoma and other high risk brain tumors. EphA2 expression was confirmed via immunohistochemical staining and flow cytometry. We observed statistically significant increased in vitro cytotoxicity of Daoy by LIGHT-armored CAR-T cells comparison to EphA2 targeting CAR T cells and controls at effector:tumor ratios of 1:2 (p 0.005) and 1:4 (p 0.01) Conclusions In our study, LIGHT-armored EphA2-targeting CAR-T cells enhanced anti-tumor cytotoxicity against Daoy. We believe this augmented cytotoxicity is due to improved proliferation and increased efficacy against antigen heterogeneous cancer cells mediated by the LIGHT/LTßR signaling axis. Additional in vitro and in vivo studies are underway to compare antitumor efficacy of LIGHT-Armored CAR-T cells against variably EphA2 expressing cell lines and mouse models.
Fong et al. (Fri,) studied this question.