tiuxetan

Tiuxetan is a chelating agent used in nuclear medicine to enable targeted radiotherapy with monoclonal antibodies. It is best known as the chelator component of ibritumomab tiuxetan, sold under the brand name Zevalin. In this radiopharmaceutical, tiuxetan is covalently linked to the anti-CD20 monoclonal antibody rituximab, forming a conjugate capable of binding radiometals such as indium-111 for imaging and yttrium-90 for therapy.

Mechanism and applications: The ibritumomab tiuxetan conjugate allows radiolabeling with therapeutic or diagnostic metals. Indium-111 provides gamma emissions suitable for single-photon emission computed tomography (SPECT) imaging to verify biodistribution and targeting. Yttrium-90 is a beta emitter used for targeted radiotherapy, delivering cytotoxic radiation to CD20-positive B cells in certain non-Hodgkin lymphomas.

Clinical use: Tiuxetan-based radioimmunotherapy is primarily indicated for adult patients with CD20-positive B-cell non-Hodgkin lymphoma, such as relapsed or refractory follicular lymphoma, and is given as a treatment regimen that includes pre-dosing with rituximab to reduce circulating tumor burden before administration of the radiolabeled antibody.

Safety and logistics: Because of potential marrow suppression and radiation exposure, administration is restricted to specialized centers with appropriate radiation safety and monitoring capabilities. Common concerns include hematologic toxicity, infusion reactions, and the general risks associated with radiopharmaceuticals.

History: The development of tiuxetan as a radiolabeling chelator facilitated targeted radioimmunotherapy, with ibritumomab tiuxetan receiving regulatory approvals in the early 2000s in various regions.