Definition

An immunoconjugate of the monoclonal antibody ibritumomab conjugated with the linker-chelator tiuxetan, a high affinity, conformationally restricted chelation site for radioisotopes. When bound to indium In 111 or yttrium Y 90, ibritumomab tiuxetan, targeting the CD20 antigen on B cell surfaces, specifically delivers a potentially cytotoxic dose of radiation to B lymphocytes. Ibritumomab is a murine IgG1 kappa monoclonal antibody directed against the CD20 antigen, which is found on the surface of normal and malignant B lymphocytes.