90Y-Ibritumomab tiuxetan (Zevalin®) is an IgG1 kappa-monoclonal murine antibody directed against the CD20 antigen radiolabeled with Yttrium-90. It was the first radioimmunotherapy drug approved by the FDA in February 2002 to treat cancer. EU approval was obtained in January 2004.

111In-Ibritumomab tiuxetan was developed as the Imaging agent able to select the potential positive responders to the therapeutic agent. The Imaging step was mandatory as a consequence of the absence of Imaging potential for 90Y. Over time it could be demonstrated that for the targeted population this first Imaging step was not useful and by 2011 the drug was authorized to be used without this Imaging step before treatment. This was however the first example of a real Radiotheranostics.

90Y-Ibritumomab tiuxetan is indicated for the treatment of relapsed or refractory, low-grade or follicular B-cell non-Hodgkin’s lymphoma (NHL) and the treatment of previously untreated follicular NHL in patients who achieve a partial or complete response to first-line chemotherapy.

Several phase III trials have been initiated to expand the indication such as diffuse large B-cell lymphoma (DLBCL) or relapsed DLBCL in patients who have received Autologous stem cell transplantation (ASCT).

RIT with 90Y-Ibritumomab tiuxetan achieved 65 to 80% overall response rate and more than 20% complete response in relapse or refractory NHL patients.

Target/Mechanism: CD20

Carrier/Ligand: Ibritumomab

Radiation Type: beta electrons (β-)