Fang Nie,1 Lin Li,2 Yingying Bai,1 Jian Yang1,3 

1Department of Radiology, Nurturing Center of Jiangsu Province for State Laboratory of AI Imaging & Interventional Radiology, State Key Laboratory of Digital Medical Engineering, Zhongda Hospital, Medical School, Southeast University, Nanjing, People’s Republic of China; 2Department of Radiology, Jiangsu Province Hospital of Chinese Medicine, Nanjing, People’s Republic of China; 3Department of Physiology, Nurturing Center of Jiangsu Province for State Laboratory of AI Imaging & Interventional Radiology, State Key Laboratory of Digital Medical Engineering, Zhongda Hospital, Medical School, Southeast University, Nanjing, People’s Republic of China

Correspondence: Jian Yang, Email jianyang0514@126.com

Objective: Imaging early-stage brain metastases from triple-negative breast cancer (TNBC) is challenging due to the blood–brain barrier (BBB). To address this issue, we developed Den-Angio-GE11, a nanoprobe engineered to traverse the BBB and selectively target metastatic cells.
Methods: A TNBC brain metastasis model was established in mice through intracardiac injection of MDA-MB-231 brain-seeking cells (MDA-MB-231-BR). Metastatic lesions were longitudinally monitored using T2-weighted magnetic resonance imaging (MRI) and confirmed through contrast-enhanced MRI with Gadolinium-DTPA (Gd-DTPA). The Den-Angio-GE11 nanoprobe was synthesized on a polyamidoamine (PAMAM)-G5 dendrimer platform, incorporating Angiopep-2 and GE11 peptides for BBB traversal and metastatic cell targeting. Dual-modal imaging capability was achieved by conjugating Gd-DTPA for MRI and NIR783 for near-infrared fluorescence (NIRF) imaging.
Results: Den-Angio-GE11 demonstrated significantly enhanced affinity to EGFR compared to controls, as confirmed by immunofluorescence staining and flow cytometry assays. Brain metastases appeared on T2-weighted MRI three weeks post-injection of MDA-MB-231BR cells and maintained uncompromised BBB function for another one or two weeks, as demonstrated by a lack of enhancement in Gd-DTPA-enhanced MRI. Compared to control nanoparticles, Den-Angio-GE11 remarkably enhanced T1 and NIRF signals of lesions after administration. Histological analysis confirmed Den-Angio-GE11 targeting brain metastatic cells. For lesions in extreme-early stage (undetectable by T2-weighted imaging), NIRF imaging post-Den-Angio-GE11 administration successfully indicated potential lesions. Fluorescence imaging analyses further verified Den-Angio-GE11 targeted sporadically metastatic cells in the brain parenchyma.
Conclusion: Early brain metastases of TNBC can be detected by Den-Angio-GE11 through T1-weighted MRI or NIRF imaging.

Keywords: breast cancer brain metastases, early imaging, EGFR, angiopep-2