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 August 1, 2016; First 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 1

Surface expression of HER2 and IL13Rα2 in primary GBM and the GBM cell line U373 and loss of target antigen in CAR T cell–treated xenografts.

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Surface expression of HER2 and IL13Rα2 in primary GBM and the GBM cell l...
(A) Single-cell suspensions of primary GBM excision samples and U373 were costained for HER2 and IL13Rα2, and more than 100,000 events were analyzed by flow cytometry. Shown are representative dot plots of 3 experiments. UPN, unique patient number. (B) Analysis of U373 xenografts recurring after CAR T cell therapy targeting HER2 and IL13Rα2 using coimmunofluorescence for HER2 and IL13Rα2. Original magnification, ×100. Scale bar – 20 µm. (C) Quantification of staining for HER2 and IL13Rα2 of the data shown in B. Cells were counted in 5 high-power fields (hpfs) per sample. Individual values per hpf and average (bar) are shown. A single-step Tukey’s range test was used for multiple comparisons. *P < 0.05, **P < 0.005.