Tandem CAR T cells targeting HER2 and IL13Rα2 mitigate tumor antigen escape
Meenakshi Hegde, … , Jordan S. Orange, Nabil Ahmed
Meenakshi Hegde, … , Jordan S. Orange, Nabil Ahmed
Published July 18, 2016
Citation Information: J Clin Invest. 2016;126(8):3036-3052. https://doi.org/10.1172/JCI83416.
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Research Article Oncology

Tandem CAR T cells targeting HER2 and IL13Rα2 mitigate tumor antigen escape

Abstract

In preclinical models of glioblastoma, antigen escape variants can lead to tumor recurrence after treatment with CAR T cells that are redirected to single tumor antigens. Given the heterogeneous expression of antigens on glioblastomas, we hypothesized that a bispecific CAR molecule would mitigate antigen escape and improve the antitumor activity of T cells. Here, we created a CAR that joins a HER2-binding scFv and an IL13Rα2-binding IL-13 mutein to make a tandem CAR exodomain (TanCAR) and a CD28.ζ endodomain. We determined that patient TanCAR T cells showed distinct binding to HER2 or IL13Rα2 and had the capability to lyse autologous glioblastoma. TanCAR T cells exhibited activation dynamics that were comparable to those of single CAR T cells upon encounter of HER2 or IL13Rα2. We observed that TanCARs engaged HER2 and IL13Rα2 simultaneously by inducing HER2-IL13Rα2 heterodimers, which promoted superadditive T cell activation when both antigens were encountered concurrently. TanCAR T cell activity was more sustained but not more exhaustible than that of T cells that coexpressed a HER2 CAR and an IL13Rα2 CAR, T cells with a unispecific CAR, or a pooled product. In a murine glioblastoma model, TanCAR T cells mitigated antigen escape, displayed enhanced antitumor efficacy, and improved animal survival. Thus, TanCAR T cells show therapeutic potential to improve glioblastoma control by coengaging HER2 and IL13Rα2 in an augmented, bivalent immune synapse that enhances T cell functionality and reduces antigen escape.

Authors

Meenakshi Hegde, Malini Mukherjee, Zakaria Grada, Antonella Pignata, Daniel Landi, Shoba A. Navai, Amanda Wakefield, Kristen Fousek, Kevin Bielamowicz, Kevin K.H. Chow, Vita S. Brawley, Tiara T. Byrd, Simone Krebs, Stephen Gottschalk, Winfried S. Wels, Matthew L. Baker, Gianpietro Dotti, Maksim Mamonkin, Malcolm K. Brenner, Jordan S. Orange, Nabil Ahmed

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Figure 4

Dynamics of activation of TanCAR T cells upon encounter of a density gradient of HER2 and IL13Rα2.

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Dynamics of activation of TanCAR T cells upon encounter of a density gra...
The activation dynamics of TanCAR T cells, biCAR T cells, HER2 CAR T cells, and IL13Rα2 CAR T cells was studied by seeding of the cells onto polypropylene surface-bound HER2 (range 0–2.0 μg/ml), IL13Rα2 (range 0–20 μg/ml), an irrelevant target (GD2.scFv anti-idiotype, 5 µg/ml), and OKT3 (1 µg/ml). Cytokine analysis (IFN-γ and IL-2) of the culture supernatant using ELISA was performed after 24 hours. Shown are representative data from 3 independent experiments done in triplicates. The titration included 10 antigen concentrations on each axis. Two-tailed t test was used to compare TanCAR cytokine values with those for each single-specificity CAR and biCAR T cells. Significant results are reported in Results. Nonspecific positive control OKT3 induced both IFN-γ (5.5 ng/ml) and IL-2 (2.0 ng/ml) release by TanCAR T cells while there was no cytokine production with GD2 anti-idiotype.