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In vitro cytotoxicity of 211At-labeled trastuzumab in human breast cancer cell lines: effect of specific activity and HER2 receptor heterogeneity on survival fraction.

Publication ,  Journal Article
Akabani, G; Carlin, S; Welsh, P; Zalutsky, MR
Published in: Nucl Med Biol
April 2006

INTRODUCTION: Radioimmunotherapy with anti-HER2 monoclonal antibodies (mAbs) such as trastuzumab is a promising strategy for treating HER2-positive breast and ovarian carcinoma patients. The objective of this study was to determine the cytotoxic effectiveness of trastuzumab labeled with the 7.2-h half-life alpha-particle emitter 211At. METHODS: Experiments were performed on SKBr-3, BT-474 and the transfected MCF7/HER2-18 human breast carcinoma cell lines. Intrinsic radiosensitivity was determined after exposure to external beam irradiation. The cytotoxicity of 211At-labeled trastuzumab was measured by clonogenic assays. The distribution of HER2 receptor expression on the cell lines was measured using fluorescence-activated cell sorting. A pharmacokinetic (PK)/microdosimetric model was established to assess the effects of specific activity (SA), HER2 receptor expression and absorbed dose on survival fraction (SF). RESULTS: With external beam irradiation, the 2-Gy SF for BT-474, SKBr-3 and MCF7/HER2-18 cells was 0.78, 0.53 and 0.64 Gy, respectively. Heterogeneous HER2 expression was observed, with a subpopulation of cells lacking measurable receptor (14.5%, SKBr-3; 0.34%, MCF-7/HER2; 1.73%, BT-474). When plotted as a function of activity concentration, SF curves were biphasic and inversely proportional to SA; however, when the model was applied and absorbed doses calculated, the SF curve was monoexponential independent of SA. Thus, the PK model was able to demonstrate the effects of competition between cold and labeled mAb. These studies showed that the relative biological effectiveness of 211At-labeled trastuzaumab was about 10 times higher than that of external beam therapy. CONCLUSION: These in vitro studies showed that 211At-labeled trastuzumab mAb is an effective cytotoxic agent for the treatment of HER2-positive tumor cells. The SA of the labeled mAb and the homogeneity of HER2 receptor expression are important variables influencing the efficiency of cell killing.

Duke Scholars

Published In

Nucl Med Biol

DOI

ISSN

0969-8051

Publication Date

April 2006

Volume

33

Issue

3

Start / End Page

333 / 347

Location

United States

Related Subject Headings

  • Tumor Cells, Cultured
  • Trastuzumab
  • Receptor, erbB-2
  • Receptor, ErbB-2
  • Nuclear Medicine & Medical Imaging
  • In Vitro Techniques
  • Immunoconjugates
  • Humans
  • Colony-Forming Units Assay
  • Cell Survival
 

Citation

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MLA
NLM
Akabani, G., Carlin, S., Welsh, P., & Zalutsky, M. R. (2006). In vitro cytotoxicity of 211At-labeled trastuzumab in human breast cancer cell lines: effect of specific activity and HER2 receptor heterogeneity on survival fraction. Nucl Med Biol, 33(3), 333–347. https://doi.org/10.1016/j.nucmedbio.2005.12.006
Akabani, Gamal, Sean Carlin, Phil Welsh, and Michael R. Zalutsky. “In vitro cytotoxicity of 211At-labeled trastuzumab in human breast cancer cell lines: effect of specific activity and HER2 receptor heterogeneity on survival fraction.Nucl Med Biol 33, no. 3 (April 2006): 333–47. https://doi.org/10.1016/j.nucmedbio.2005.12.006.
Akabani, Gamal, et al. “In vitro cytotoxicity of 211At-labeled trastuzumab in human breast cancer cell lines: effect of specific activity and HER2 receptor heterogeneity on survival fraction.Nucl Med Biol, vol. 33, no. 3, Apr. 2006, pp. 333–47. Pubmed, doi:10.1016/j.nucmedbio.2005.12.006.
Journal cover image

Published In

Nucl Med Biol

DOI

ISSN

0969-8051

Publication Date

April 2006

Volume

33

Issue

3

Start / End Page

333 / 347

Location

United States

Related Subject Headings

  • Tumor Cells, Cultured
  • Trastuzumab
  • Receptor, erbB-2
  • Receptor, ErbB-2
  • Nuclear Medicine & Medical Imaging
  • In Vitro Techniques
  • Immunoconjugates
  • Humans
  • Colony-Forming Units Assay
  • Cell Survival