Tiuxetan (MX-DTPA) is the isothiocyanatobenzyl derivative of diethylenetriaminepentaacetic acid (DTPA). It is a second-generation chelator. It was developed to increase stability of the chelate without compromising antibody specificity, altering metabolism of antibody conjugates, or allowing measurable elution of 90Y. A comparison of the MX-DTPA derivative with other chelates containing DTPA or its cyclic anhydride derivative demonstrated that the MX-DTPA derivative yielded conjugates with increased tumor-to-nontumor ratios, and resulted in greater in vivo retention of 90Y. Whole-body autoradiography revealed substantially greater uptake of 90Y in the skeleton when MX-DTPA was used as the chelator. Ibritumomab tiuxetan is a CD20 antigen inhibitor used for the treatment of Non-Hodgkin's lymphoma. The Ibritumomab antibody targets the CD20 antigen. The antibody is covalently bound to the chelator-linker tiuxetan (MX-DTPA), which tightly chelates the isotope 90Y.