Objectives: The SP90, identified by phage display, is a 12-amino-acid small peptide specifically binds to breast cancer cells. The aim of this study was to investigate the biodistribution evaluation of 188Re-liposome-SP90 in 4T1-1uc2 breast cancer solid tumor model via intravenously administrated route.
Methods: Female BALB/c mice were subcutaneously inoculated with 2 x 106 4T1-luc2 cells. At 12 days after tumor inoculation, the tumor-bearing mice were intravenously injected via tail vein with 3.7 MBq/100 μL of 188Re-liposome-SP90. Biodistribution was performed at 1, 4, 24 and 48 h after injection of 188Re-liposome-SP90. They were sacrificed at the desired time points by CO2 asphyxiation. Data are expressed as the percentage injected dose per gram of tissue (%ID/g).
Results: After intravenous administration of 188Re-liposome-SP90, radioactivity in tumors progressively accumulated from 1 h to 24 h, and reached a maximum level of 6.29 ± 1.23 %ID/g at 24 h. The tumor/muscle ratio reached a maximum level of 15.89 at 24 h. Radioactivity in the spleen reached a maximum level of 7.15 ± 0.30 %ID/g at 4 h and then gradually decreased. Radioactivity in the liver reached a maximum level of 16.74 ± 0.93 %ID/g at 4 h and gradually decreased with time. Radioactivity in the bile reached a maximum level of 19.64 ± 2.79 %ID/g at 1 h. Radioactivity in the kidney and lung was maintained at relatively higher levels before 4 h and gradually decreased with time. Low levels of radioactivity distribution were found in the skin, organs of the central nervous system and musculoskeletal system.
Conclusions: The biodistribution result demonstrated obvious tumor localization and concentration of liposome-SP90 therapeutics loaded with 188Re. Therefore, intravenous administration of 188Re-liposome-SP90 could provide a potential therapeutic strategy for breast cancer in oncology applications.