Production, Quality Control and Biodistribution Study of F(ab') Fragmant of Antibody PR8 Labeled with 99mTc for Diagnosis of Breast Carcinoma Bearing Mice

Immunoglobulin fragments offer a number of advantages for intratumor penetration over the intact antibodies. The goal of this study was to prepare F(ab') fragments from antibody PR8 and 99mTc labeling in order to produce a biological radiopharmaceutical for imaging of breast cancer in nuclear medicine. The antibody PR8 was digested with 5% (w/w) pepsin at different times to find the best time for a complete digestion. The prepared F(ab') fragments were purified by protein A column chromatography. The immunoreactivity of the complex assessed by radioimmunoassay was determined to be 65.% ± 5.. 99mTc radiolabeling of F(ab') fragment by using HYNIC as a chelator and tricine as a co-ligand resulted in a radiochemical purity of 70.%±5. after hr with a high stability. The complex was purified by the gel chromatography method to increase the radiochemical purity. Biodistribution and imaging studies in BALB/c mice with breast tumor xenograft demonstrated as a specific localization of the compound at the site of tumors h post injection with high sensitivity and minimum accumulation in non target organs. The results showed that F(ab') fragment of PR8 is a promising candidate for radioimmunoscintigraphy of the human breast carcinoma