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Oncology-Basic Science: Therapy, Metrics & InterventionTherapy, Metrics & Intervention Posters |
1 Laboratory of Radiopharmacy, University Ghent, Ghent, Belgium; 2 Tumor Targeting Laboratory, Ludwig Institue for Cancer Research, Melbourne, Victoria, Australia
1409
Objectives: Previous animal studies have shown that radiolabeled monoclonal antibody (mAb) 14C5 is able to visualise human lung- and colon-carcinoma’s. Now we show that this IgG1 is also useful in the detection of human breast and pancreas tumours.
Methods: Saturation binding experiments were done with 125I-labeled mAb 14C5 using human pancreatic carcinoma cells (Capan-1), breast cancer cells (BT-20) and squamous cell carcinoma cells (Colo-16, negative control). Non-specific binding was determined in the presence of 167 nmol/L of unlabeled mAb 14C5. Biodistribution studies were done in athymic mice bearing Capan-1 or BT-20 tumours. Mice were injected in the tail vein with 2 µg 131I-labeled mAb 14C5 (specific activity: 2,05 µCi/µg). Groups of three were sacrificed at different time points post injection (p.i.), and tumour- and organ-uptake was determined. Planar scans were conducted with 123I-14C5 at different time intervals (20 µg/mouse, spec. act.: 30 µCi/µg).
Results: The dissociation constant (KD) of radiolabeled mAb 14C5 is 0,15 ± 0,02 nmol/l for BT-20 and 0,13 ± 0,02 nmol/l for Capan-1 cells. Tumour uptake was highest at 24 h p.i. for Capan-1 (8,20 ± 2,25 %ID/g) and 48 h p.i. for BT-20 (13,64 ± 5,64 %ID/g) tumours. Tumour-to-blood ratio’s were highest at 48 hours p.i. with 2,01 ± 0,65 and 2,52 ± 0,33 for the pancreatic and breast tumour model respectively. For both models, planar imaging was performed in triplicate. ROI’s were compared with contralateral flank values as a background at 48 hours p.i.: ratio’s of 1,88 ± 0,56 (Capan-1) and 2,69 ± 0,13 (BT-20) were obtained.
Conclusions: From these results we can conclude that radioiodinated mAb 14C5 is a promising diagnostic marker for breast and pancreatic cancer.
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