Enhanced cytotoxicity against solid tumors by bispecific antibody-armed CD19 CAR T cells: a proof-of-concept study



Although adoptive cell therapy with chimeric antigen receptor (CAR)-engineered T cells has shown durable clinical efficacy in patients with CD19+ B cell malignancies, the application of this approach to solid tumors is challenging. The goal of this proof-of-concept study was to investigate whether loading of CD19-CAR T cells (CART19) with anti-HER2 or anti-EGFR bispecific antibodies (BiAb) will target HER2+/EGFR+ CD19 targets and signal the intracellular domain of CAR without engaging antigen-specific CD19 ScFv of CAR T cells.


We used CART19 armed with anti-CD3 (OKT3) × anti-HER2 BiAb (HER2Bi) or anti-CD3 (OKT3) × anti-EGFR BiAb (EGFRBi) to evaluate the cytotoxicity directed at HER2 or EGFR expressing cancer cell lines compared with unarmed CART19 measured by short-term 51Cr release assay and long-term real-time cell analysis using xCelligence. We also determined the differences in exhaustion or effector phenotypes and cytokine profiles during the short- and long-term cytotoxicity assays.


Specific cytotoxicity was exhibited by CART19 armed with HER2Bi or EGFRBi against multiple tumor cell lines. Armed CART19 and armed activated T cells (ATC) showed comparable specific cytotoxicity that ranged between 10 and 90% against breast, pancreatic, ovarian, prostate, and lung cancer cell lines at 10:1 E/T ratio. Serial killing (repeated killing) by HER2Bi-armed CART19 ranged between 80 and 100% at 10:1 E/T ratio against MCF-7 cells up to 19 days (up to 4th round of repeated killing) measured by a real-time cell analysis without CART19 becoming exhausted.


HER2Bi- or EGFRBi-armed CART19 exhibited specific cytotoxicity against multiple HER2+/EGFR+/CD19 tumor targets in overnight and long-term serial killing assays. CART19 showed improved survival and were resistant to exhaustion after prolonged repeated exposure to tumor cells.

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The data presented in this manuscript are original and have not been published elsewhere except in the form of abstracts and poster presentations at symposia and meetings.


This study was primarily supported by funding from in part by R01 CA 182526, P30CA022453 (Microscopy, Imaging, and Cytometry Resources Core) and startup funds from the University of Virginia Cancer Center.

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LGL and CHJ conceived the idea. AT, LGL, CHJ and JS designed the study, performed statistical analysis, and wrote the manuscript. AT, JS and DLS performed the experiments and participated in the data analysis. All authors read and approved the final manuscript.

Corresponding authors

Correspondence to Archana Thakur or Lawrence G. Lum.

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Conflict of interest

LGL is co-founder of Transtarget Inc. and serves on the SAB for Rapa Therapeutics, CHJ is a co-founder of Tmunity Therapeutics, Inc. and AT is co-founder of Nova Immune Platform LLC, JS and DLS have no conflict of interest.

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Thakur, A., Scholler, J., Schalk, D.L. et al. Enhanced cytotoxicity against solid tumors by bispecific antibody-armed CD19 CAR T cells: a proof-of-concept study. J Cancer Res Clin Oncol 146, 2007–2016 (2020). https://doi.org/10.1007/s00432-020-03260-4

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  • Pancreatic cancer
  • Breast cancer
  • CAR T cells
  • Bispecific antibody
  • Th1 cytokines