Functionalized silica nanoparticles in the detection and treatment of Her2-positive breast cancer

Introduction: Nanobiotechnology can provide the development of nanoparticles for diagnosis/treatment of human cancer. Aim of this work was to validate a silica nanoparticles (SNP)-based system functionalized with anti-Her2 antibody fragment and loaded with radioactive/fluorescent probes for detection of aggressive breast cancer. Methods: SNPs carrying (ETZ-2) or not (ETZ-1, control) the Her2 antibody fragment were used in in vitro binding kinetic in Her2 positive (SKBR-3) and negative (MDA-MB-468) breast cancer cell lines. In parallel, the same SNPs were derivatized with nitril-triacetic acid and reacted with His-Tag, previously labelled with 99mTc-Tricarbonyl complex. Labelled SNPs were used for different experiments: in vitro uptake kinetic in SKBR-3 and MDA-MB-468 cells (20 min, 1h, 4h and 24h); ex vivo distribution in tumour and peripheral organs in animals implanted with MDA-MB-468 or SKBR-3 cells, at 4h from ETZ-2 injection. Afterwards, an additional experiment with ex vivo distribution and autoradiography at different time points (4h, 6h and 24h; n=4) were performed after the injection of labelled ETZ-1 and 2 SNPS on animals implanted with SKBR-3 cells. At the same times, in vitro uptake of both SNPs were measured by pre-treating SKBR-3 cells with 1 mg/ml of Trastuzumab. The uptake of labelled SNPs in cells was expressed as percentage of the total radioactivity counted, while in tumours and tissues was calculated as percentage of injected dose per gram of tissue (%ID/g). Tumour sample were also frozen in liquid N2 and sectioned for fluorescence microscopy. We have ongoing the evaluation of doxorubicin filled SNPs in comparison to liposomal doxorubicin (Caelix, 3 mg/kg in 40µl) to assess the efficacy of nanoparticles to targeting chemotherapy. The effect will be assessed by measuring tumoral features as volume and [18F]FDG and [11C]Choline uptake. Results: ETZ-2 specifically binds SKBR-3 cells in vitro, reaching a maximum uptake ratio of 2,1 on MDA-MB-468 cells after 4h. The same result was confirmed in tumours, after the biodistribution study and observation in fluorescence. Caelix treatment particularly affected SKBR-3 lesions growth, in which we observed a 12,4% decrease of [18F]FDG and a 14.3% increase of [11C]Choline uptake, compared to control. Comparison with filled doxorubicin NPSs are in progress. Conclusion: Preliminary results showed that 99mTc-ETZ-2 SNPs could be a useful system for Her2 positive breast cancer detection and treatment.