Research Papers:

N-Acetylcysteine breaks resistance to trastuzumab caused by MUC4 overexpression in human HER2 positive BC-bearing nude mice monitored by 89Zr-Trastuzumab and 18F-FDG PET imaging

Zéna Wimana _, Geraldine Gebhart, Thomas Guiot, Bruno Vanderlinden, Denis Larsimont, Gilles Doumont, Gaetan Van Simaeys, Serge Goldman, Patrick Flamen and Ghanem Ghanem

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Oncotarget. 2017; 8:56185-56198. https://doi.org/10.18632/oncotarget.17015

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Zéna Wimana1,2, Geraldine Gebhart1, Thomas Guiot1, Bruno Vanderlinden1, Denis Larsimont3, Gilles Doumont4, Gaetan Van Simaeys4, Serge Goldman4, Patrick Flamen1 and Ghanem Ghanem1,2

1Nuclear Medicine Department, Institut Jules Bordet, Université Libre de Bruxelles, Brussels, Belgium

2Laboratory of Oncology and Experimental Surgery, Institut Jules Bordet, Université Libre de Bruxelles, Brussels, Belgium

3Pathology Department, Institut Jules Bordet, Université Libre de Bruxelles, Brussels, Belgium

4Center for Microscopy and Molecular Imaging (CMMI), Université Libre de Bruxelles, Brussels, Belgium

Correspondence to:

Zéna Wimana, email: [email protected]

Keywords: HER2, NAC, trastuzumab, resistance, immunoPET

Received: September 30, 2016     Accepted: March 30, 2017     Published: April 10, 2017


Trastuzumab remains an important drug in the management of human epidermal growth factor receptor 2 (HER2) overexpressing breast cancer (BC). Several studies reported resistance mechanisms to trastuzumab, including impaired HER2-accessibility caused by mucin 4 (MUC4). Previously, we demonstrated an increase of Zirconium-89-radiolabeled-trastuzumab (89Zr-Trastuzumab) accumulation when MUC4-overexpressing BC-cells were challenged with the mucolytic drug N-Acetylcysteine (NAC). Hereby, using the same approach we investigated whether tumor exposure to NAC would also enhance trastuzumab-efficacy.

Dual SKBr3 (HER2+/MUC4-, sensitive to trastuzumab) and JIMT1 (HER2+/MUC4+, resistant to trastuzumab) HER2-BC-bearing-xenografts were treated with trastuzumab and NAC. Treatment was monitored by molecular imaging evaluating HER2-accessibility/activity (89Zr-Trastuzumab HER2-immunoPET) and glucose metabolism (18F-FDG-PET/CT), as well as tumor volume and the expression of key proteins.

In the MUC4-positive JIMT1-tumors, the NAC-trastuzumab combination resulted in improved tumor-growth control compared to trastuzumab alone; with smaller tumor volume/weight, lower 18F-FDG uptake, lower %Ki67 and pAkt-expression. NAC reduced MUC4-expression, but did not affect HER2-expression or the trastuzumab-sensitivity of the MUC4-negative SKBr3-tumors.

These findings suggest that improving HER2-accessibility by reducing MUC4-masking with the mucolytic drug NAC, results in a higher anti-tumor effect of trastuzumab. This provides a rationale for the potential benefit of this approach to possibly treat a subset of HER2-positive BC overexpressing MUC4.

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