99mTc-Radiolabeled Silica Nanocarriers for Targeted Detection and Treatment of HER2-Positive Breast Cancer

Paolo Rainone,1– 3 Antonella De Palma,4 Francesco Sudati,5 Valentina Roffia,4 Valentina Rigamonti,6 Lucia Salvioni,6 Miriam Colombo,6 Marilena Ripamonti,2 Antonello Enrico Spinelli,7 Davide Mazza,7 Pierluigi Mauri,4 Rosa Maria Moresco,1,2,7 Davide Prosperi,6 Sara Belloli2,7 1Department of Medicine and Surgery, University of Milano-Bicocca, Monza, 20900, Italy; 2Institute of Molecular Bioimaging and Physiology of CNR, Segrate, 20090, Italy; 3Doctorate School of Molecular and Translational Medicine, University of Milan, Milan, Italy; 4Institute of Biomedical Technologies of CNR, Segrate, 20090, Italy; 5PET and Nuclear Medicine Unit, San Raffaele Scientific Institute, Milan, 20132, Italy; 6NanoBioLab, Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, 20126, Italy; 7Experimental Imaging Center, San Raffaele Scientific Institute, Milan, 20132, ItalyCorrespondence: Sara BelloliInstitute of Molecular Bioimaging and Physiology of CNR, Via Fratelli Cervi 93, Segrate, 20090, ItalyTel +39 02 26433640Fax +39 02 26432717Email belloli.sara@hsr.itIntroduction: The overexpression of Human Epidermal Growth Factor Receptor 2 (HER2) is usually associated with aggressive and infiltrating breast cancer (BC) phenotype, and metastases. Functionalized silica-based nanocarriers (SiNPs) can be labeled for in vivo imaging applications and loaded with chemotherapy drugs, making possible the simultaneous noninvasive diagnosis and treatment (theranostic) for HER2-positive BC.Methods: Firstly, FITC-filled SiNPs, were engineered with two different amounts of Hc-TZ (trastuzumab half-chain) per single nanoparticle (1:2 and 1:8, SiNPs to Hc-TZ ratio), which was 99mTc-radiolabeled at histidine residues for ex vivo and in vivo biodistribution evaluations. Secondly, nanoparticles were loaded with DOX and their in vitro and ex vivo/in vivo delivery was assessed, in comparison with liposomal Doxorubicin (Caelyx). Finally, the treatment efficacy of DOX-SiNPs-TZ (1