A procedure for radiolabeling monoclonal antibody, CAMA3C8, specific for polymorphic epithelial mucin with 188Re is described. CAMA3C8 was reduced (by reacting) with 1:10 diluted mercaptoethanol for 30 minutes at room temperature and purified over Sephadex G-25 column using phosphate buffer saline as an eluant. Purified fractions (at 1 mg/mL concentration) were pooled together and stored at −20°C. Reduced CAMA3C8 (0.5mg/mL) was reacted with 0.5 mL of ReO4-(~74 MBq) in saline at pH 5 in the presence of stannous chloride (5 mg), sodium oxalate (20 mg) and ascorbic acid (lOmg). The labeling yield was determined by Sephadex G 25 gel and thin layer chromatography. 188Re-CAMA3C8 was formed in > 95% yields. The radiolabeled antibody was stable when stored at room temperature for a period of 48 h. Cell uptake studies were carried out with MCF 7 cell line in DMEM tissue culture media for 2h at 37°C. Immunoreactivity of the labeled antibody was retained to the extent of 95% as determined by Lidmo's plot. Palpable tumor was raised in Balb/c mice by injecting MCF-7 cell line by the air pouch technique. Biodistribution studies in tumor bearing mice revealed ~1% uptake/g of tumor at 48 h p.i. with the excretion of activity through renal pathway.
Radioimmunotherapy, tumor targeting, monoclonal antibody, breast cancer, rhenium-188
