Inclusion of 4-1BB Costimulation Enhances Selectivity and Functionality of IL13Ralpha2-Targeted Chimeric Antigen Receptor T Cells.
Publication Year:
2023
PubMed ID:
36968221
Funding Grants:
Public Summary:
Chimeric antigen receptor (CAR) T cell immunotherapy is emerging as a powerful strategy for cancer therapy; however, an important safety consideration is the potential for damage to normal tissue. Our group has developed CAR T cells that target cancer cells in glioblastoma (GBM). There remains limited understanding of how this CAR design impacts the activity and selectivity for the intended tumor cells versus unintended normal cells. In this study, we compared different CAR designs. In vitro coculture assays with CAR T cells with tumor cells establish that second-generation CAR designs outperform first-generation and third-generation CARs. The second-generation CAR provided superior antitumor potency in mouse models. These findings support the use of the second-generation IL13-BBzeta CARs for greater selective recognition cancer cells over normal tissue, higher proliferative potential, and superior antitumor activity. SIGNIFICANCE: This study reveals how modulating CAR design outside the antigen targeting domain improves selective tumor recognition. Specifically, this work shows improved specificity, persistence, and efficacy of 4-1BB-based IL13-ligand CARs. Human clinical trials evaluating IL13-41BB-CAR T cells are ongoing, supporting the clinical significance of these findings.
Scientific Abstract:
Chimeric antigen receptor (CAR) T cell immunotherapy is emerging as a powerful strategy for cancer therapy; however, an important safety consideration is the potential for off-tumor recognition of normal tissue. This is particularly important as ligand-based CARs are optimized for clinical translation. Our group has developed and clinically translated an IL13(E12Y) ligand-based CAR targeting the cancer antigen IL13Ralpha2 for treatment of glioblastoma (GBM). There remains limited understanding of how IL13-ligand CAR design impacts the activity and selectivity for the intended tumor-associated target IL13Ralpha2 versus the more ubiquitous unintended target IL13Ralpha1. In this study, we functionally compared IL13(E12Y)-CARs incorporating different intracellular signaling domains, including first-generation CD3zeta-containing CARs (IL13zeta), second-generation 4-1BB (CD137)-containing or CD28-containing CARs (IL13-BBzeta or IL13-28zeta), and third-generation CARs containing both 4-1BB and CD28 (IL13-28BBzeta). In vitro coculture assays at high tumor burden establish that second-generation IL13-BBzeta or IL13-28zeta outperform first-generation IL13zeta and third-generation IL13-28BBzeta CAR designs, with IL13-BBzeta providing superior CAR proliferation and in vivo antitumor potency in human xenograft mouse models. IL13-28zeta displayed a lower threshold for antigen recognition, resulting in higher off-target IL13Ralpha1 reactivity both in vitro and in vivo. Syngeneic mouse models of GBM also demonstrate safety and antitumor potency of murine IL13-BBzeta CAR T cells delivered systemically after lymphodepletion. These findings support the use of IL13-BBzeta CARs for greater selective recognition of IL13Ralpha2 over IL13Ralpha1, higher proliferative potential, and superior antitumor responsiveness. This study exemplifies the potential of modulating factors outside the antigen targeting domain of a CAR to improve selective tumor recognition. SIGNIFICANCE: This study reveals how modulating CAR design outside the antigen targeting domain improves selective tumor recognition. Specifically, this work shows improved specificity, persistence, and efficacy of 4-1BB-based IL13-ligand CARs. Human clinical trials evaluating IL13-41BB-CAR T cells are ongoing, supporting the clinical significance of these findings.