Radioiodination, purification, and evaluation of antihuman tumor-derived immunoglobulin G light chain monoclonal antibody in tumor-bearing nude mice

We report the synthesis and biological evaluation of ¹³¹I-labeled antihuman tumor-derived immunoglobulin G (IgG) light chain monoclonal antibody (4E9) ([¹³¹I]I-4E9) as a promising probe for tumor imaging. [¹³¹I]I-4E9 was synthesized in radiochemical yield of 89.9 ± 4.7% with radiochemical purity of more than 99%. [¹³¹I]I-4E9 showed high stability in normal saline and human serum. In cell uptake studies, [¹³¹I]I-4E9 exhibited favorable binding affinity and high specificity in HeLa MR cells. In biodistribution studies, [¹³¹I]I-4E9 showed high tumor uptake, high tumor/non-tumor ratios, and specific binding in BALB/c nu/nu mice bearing human HeLa MR xenografts. Single-photon emission computerized tomography (SPECT) imaging of [¹³¹I]I-4E9 in the HeLa MR xenograft model demonstrated clear visualization of tumor after 48 h and confirmed specific binding in tumor. These findings suggest that [¹³¹I]I-4E9 possesses favorable biological characteristics and warrants further investigation as a prospective probe for imaging and treatment of cancers.