EXTH-53 - IL-12 armored CAR T cell therapy for heterogeneous glioblastoma

Saturday, November 19, 2022

1:50 PM – 1:55 PM ET

Location: Ballroom B

Oral Abstract Presenter(s)

Steven Shen, MS

Duke
Durham, United States

Author(s)

Sarah L. Cook, PhD

Brain Tumor Immunotherapy Program, Duke University
Durham, United States

Author(s)

CS

Carter Suryadevara

Duke
Durham, United States
Kelly M. Hotchkiss, PhD (she/her/hers)

Brain Tumor Immunotherapy Program, Duke University
Durham, United States
DS

David Snyder, B.S.

Duke University
Durham, United States
LS

Luis Sanchez-Perez, PhD

Duke
Durham, United States
John H. Sampson, M.D., Ph.D.

The Preston Robert Tisch Brain Tumor Center, Duke University Medical Center
Durham, United States

Introduction: Chimeric antigen receptor (CAR) T cells specific for the glioblastoma (GBM)-specific epidermal growth factor receptor variant III (EGFRvIII; CARvIII) have successfully treated tumors homogeneously expressing EGFRvIII when combined with lymphodepletion, however this is not recapitulated clinically. We generated an “armored” CARvIII which constitutively secretes IL-12, a stimulatory cytokine that enhances T cell persistence and function, that is capable of treating orthotopic heterogeneous GBM in immune competent mice.

Methods: C57Bl/6 mice were intracranially (IC) implanted with 5 x 10⁵ of either homogenous (CT2AvIII) or heterogeneous (1:1 CT2AvIII and CT2A parental) tumor cells. Mice were treated with 2 x 10⁶ CARvIII or IL-12 CARvIII seven days post tumor implant and monitored for survival. TCRα^-/-, CD8^-/- and C57Bl/6 mice were IC implanted with homogeneous or heterogeneous tumors and treated 7 days post implant with intracranial IL-12 CARvIII therapy to assess the role of endogenous T cells. T cells within the tumor microenvironment were characterized by flow cytometry days 8, 14, and 17 post tumor implantation.

Results: IL-12 CARvIII cells were successfully generated, secreted IL-12, and were cytotoxic against EGFRvIII-expressing tumor cells in vitro. IL-12 CARvIII therapy was curative in homogenous CT2AvIII tumors (p < 0.0001) and conferred a long-term survival in 50% of mice with heterogeneous CT2AvIII:CT2A parental tumors in vivo (p < 0.0001). Furthermore, IL-12 CARvIII therapy successfully eradicated the homogeneous CT2AvIII tumors in TCRα^-/- and CD8^-/- mice but failed to produce any efficacy against the heterogeneous CT2AvIII:CT2A parental tumors (p=0.0002). Endogenous T cells in IL-12 CARvIII treated mice were found to be more migratory, and interestingly more exhausted than in CARvIII treated mice.

Conclusions: Our findings show that IL-12 CARvIII can effectively eradicate IC homogenous tumors without lymphodepletion. Surprisingly, IL12 CARvIII therapy also treated IC heterogeneous glioma. Heterogeneous tumor clearance required an endogenous CD8 T cell response.