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Open Access

TEM8 specific T cells target the tumor cells and tumor-associated vasculature in triple negative breast cancer

  • Tiara Byrd1,
  • Kristen Fousek1,
  • Antonella Pignata1,
  • Amanda Wakefield1,
  • Brad St Croix2,
  • Bradley S Fletcher3,
  • Meenakshi Hegde1 and
  • Nabil Ahmed1
Journal for ImmunoTherapy of Cancer20142(Suppl 3):P7

https://doi.org/10.1186/2051-1426-2-S3-P7

Published: 6 November 2014

Keywords

Triple Negative Breast CancerChimeric Antigen ReceptorTriple Negative Breast Cancer CellSingle Chain Variable Fragment51Cr Release Assay

Background

Tumor endothelium marker 8 (TEM8) was discovered by St Croix, et. al. as one of nine gene products preferentially upregulated in the tumor-associated vs. normal endothelium [1]. Interestingly, TEM8 has also been identified as a tumor restricted antigen in triple negative breast cancers (TNBC) [2, 3]; a clinical entity associated with a particularly poor prognosis. Being null for HER2, estrogen and progesterone receptors, targeted therapies for TNBC are quite limited.

Purpose

To use T cells expressing TEM8-specific chimeric antigen receptors (CAR) as a novel approach to target both TNBC cells and their tumor-associated vasculature.

Methods/ results

We used in silico design to construct a novel TEM8-specific CAR molecule. The antigen recognition exodomain consisted of a single chain variable fragment based on the TEM8-specific monoclonal antibody, SB5. The signaling endodomain consisted of the costimulatory molecule CD28 and CD3-zeta chain. The encoding DNA was codon optimized, synthesized and then sequence verified. We used a retroviral transduction system to express the TEM8 CAR transgene on HEK 293T, then on primary T cells. Approximately 70% of primary human T cells expressed the TEM8 CAR, as detected by flow cytometry. The expression of TEM8 was characterized using flow cytometry and western blot on a battery of TNBC lines, TEM8 transduced (modest and high expressers) cell lines as well as TEM8 negative cell lines. TEM8 CAR T cells recognized and killed TEM8 positive target cells in an antigen-dependent fashion in 51Cr release assays and secreted immunostimulatory cytokines upon encounter of TEM8 positive cells. There was no reactivity against TEM8 negative cell lines. No cytotoxicity or cytokine release was exhibited by T cells expressing an irrelevant (CD19 specific) CAR or non-transduced T cells from the same blood donor. We are currently testing this strategy in a vascularized orthotopic breast cancer murine model.

Conclusion

TEM8 specific CAR T cells could serve as a tumor and vascular-targeted immunotherapeutic modality for triple-negative breast cancer.

Authors’ Affiliations

(1)
Baylor College of Medicine, Houston, USA
(2)
National Cancer Institute, Frederick, USA
(3)
University of Florida, Gainesville, USA

References

  1. St Croix B, Rago C, Velculescu V, Traverso G, Romans KE, Montgomery E, Lal A, Riggins GJ, Lengauer C, Vogelstein B, Kinzler KW: Genes expressed in human tumor endothelium. Science. 2000, 289 (5482): 1197-202. 10.1126/science.289.5482.1197.View ArticlePubMedGoogle Scholar
  2. Gutwein LG, Al-Quran SZ, Fernando S, Fletcher BS, Copeland EM, Grobmyer SR: Tumor endothelial marker 8 expression in triple-negative breast cancer. Anticancer Res. 2011, 31 (10): 3417-22.PubMedGoogle Scholar
  3. Opoku-Darko M, Yuen C, Gratton K, Sampson E, Bathe OF: Tumor endothelial marker overexpression in breast cancer cells enhances tumor growth and metastasis. Cancer Invest. 2011, 29 (10): 676-82. 10.3109/07357907.2011.626474.View ArticlePubMedGoogle Scholar

Copyright

© Byrd et al.; licensee BioMed Central Ltd. 2014

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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