MA5

MA5 is a monoclonal antibody that specifically reacts with a breast tumor-associated antigen. It was investigated as an 111In-labelled agent for the imaging and localization of primary and metastatic breast cancer lesions. The antibody was chosen for its high reactivity with over 95% of primary and metastatic lesions, the presence of its recognized antigen on the cell surface in vivo, and its excellent localization properties in human breast tumor xenografts. Clinical studies involved administering the 111In-labelled antibody to patients to detect tumors larger than 3 cm in diameter, with observed uptake in the liver, spleen, and bone.