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Three-step tumor imaging with biotinylated monoclonal antibody, streptavidin and 111In-DTPA-biotin
Y Nakamoto1, T Saga, H Sakahara
1Department of Nuclear Medicine and Diagnostic Imaging, Graduate School of Medicine, Kyoto University, Japan. nakamoto@kuhp.kyoto-u.ac.jp
Abstract:
The purpose of this study was to test the three-step targeting of tumors in mice using biotinylated antibody, streptavidin and radiolabeled biotin. Nude mice bearing subcutaneous LS180 human colon cancer xenografts were intravenously administered with 200 microg of the biotinylated anti-Tn monoclonal antibody MLS128, and 2 days later they got intravenous injection of 50 microg of streptavidin. They were intravenously injected 1, 4 or 7 days later with 0.5 microg of 111In-diethylenetriamine pentaacetic acid (DTPA)-biotin. The tumor uptake, determined 2 h later, was 1.4, 0.5 and 0.6% injected dose/gram of tissue (ID/g), respectively, and the blood radioactivity was 1.0, 0.2 and 0.2% ID/g, respectively. When the interval between the streptavidin and radiolabeled biotin injections was prolonged from 1 day to 7 days, the tumor-to-blood ratio 2 h after injection of 111In-labeled biotin increased from 1.5 to 4.0. Clear tumor images were obtained as early as 2 h after injection of radiolabeled biotin. In conclusion, these preliminary data suggested that the three-step method using the streptavidin-biotin system would be applicable in an experimental mouse tumor model and provides images of tumors rapidly and clearly after injection of radiolabeled biotin.
Insights
This study shows a three-step tumor targeting method using biotinylated antibodies and streptavidin in mice. This technique successfully visualized tumors rapidly and clearly, demonstrating its potential for cancer imaging.
Area of Science:
- Oncology
- Immunology
- Radiochemistry
Background:
- Targeted cancer therapy and imaging require efficient delivery of agents to tumor sites.
- The streptavidin-biotin system offers high affinity for molecular targeting applications.
Purpose of the Study:
- To evaluate a three-step tumor targeting strategy in a mouse model.
- To assess the efficacy of using biotinylated antibodies, streptavidin, and radiolabeled biotin for tumor imaging.
Main Methods:
- Nude mice with LS180 human colon cancer xenografts were used.
- A sequential administration of biotinylated anti-Tn antibody (MLS128), streptavidin, and 111In-labeled biotin was performed.
- Tumor uptake and blood radioactivity were measured at various time points post-injection.
Main Results:
- Tumor uptake of 1.4% injected dose/gram (ID/g) was observed 2 hours after radiolabeled biotin injection.
- Increasing the interval between streptavidin and radiolabeled biotin enhanced the tumor-to-blood ratio from 1.5 to 4.0.
- Clear tumor images were obtained as early as 2 hours post-injection of the radiolabeled compound.
Conclusions:
- The three-step targeting method utilizing the streptavidin-biotin system is feasible in an experimental mouse tumor model.
- This approach enables rapid and clear visualization of tumors.
- Preliminary data suggest applicability for future cancer imaging strategies.