Loss of IFNgR1 signaling glioblastoma drives resistance to CAR T cell binding avidity and cytotoxicity due to lower downstream expression of ICAM-1

Abstract

Abstract Though CAR T cell therapy has had success treating hematologic malignancies, these treatments have shown only modest efficacy in solid tumors. Little is known about the necessary molecular components required for CAR T cell cytotoxicity, especially in the context of solid tumors. We investigated the role of IFNgR signaling on solid tumors and discovered across tumor types (including glioblastoma, pancreatic, ovarian and lung) loss of IFNgR1 signaling resulted lower CAR T cell cytotoxicity in vitro and that this was irrespective of target antigen (including endogenous EGFR, IL13Ra2, mesothelin, and exogenous CD19). We also validated this in orthotopic xenograft models of glioblastoma and pancreatic cancer in vivo. CAR T cells exposed to wildtype (WT) or IFNgR1 KO tumor had similar transcriptional profiles, but the tumor cells had different signatures in response to CAR T cell co-culture. Further investigation showed marked upregulation of cell adhesion pathways in WT cells compared to IFNgR1 KO. We utilized microscopy with acoustic force and discovered CAR T cells had lower cell binding avidity to cells lacking IFNgR1 compared to WT cells. Following CAR T cell exposure, Intercellular Adhesion Molecule 1 (ICAM-1) was strongly upregulated at both the transcriptional and protein levels in WT cells but not IFNgR1 KO cells. We overexpressed ICAM-1 on IFNgR1 KO tumor cells and observed that CAR T cell binding avidity and cytotoxicity was restored to that of WT levels. This work highlights the importance of CAR T cell binding avidity and adhesion for optimal cytotoxicity. Better understanding of CAR T cell function will inform future construct design for successful therapies against solid tumors. RCL was supported by T32 GM007306, T32 AI007529, and the Richard N. Cross Fund. ML was supported by T32 2T32CA071345-21A1. SRB was supported by T32CA009216-38. NJH was supported by the Landry Cancer Biology Fellowship. JJ is supported by a NIH F31 fellowship (1F31-MH117886). GG was partially funded by the Paul C. Zamecnik Chair in Oncology at the Massachusetts General Hospital Cancer Center and NIH R01CA 252940. MVM and this work is supported by the Damon Runyon Cancer Research Foundation, Stand Up to Cancer, NIH R01CA 252940, R01CA238268, and R01CA249062.