Use of Radioimmunotherapy in Stem Cell Transplantation and Posttransplantation: Focus on Yttrium 90 Ibritumomab Tiuxetan

Although autologous stem cell transplantation (ASCT) produces prolonged disease-free survival in many patients with non-Hodgkin's lymphoma (NHL), relapse remains the most common cause of treatment failure. Because of the potential benefit of adding targeted irradiation to conditioning regimens, clinical trials are testing the safety and efficacy of combining radioimmunotherapy with yttrium 90 ibritumomab tiuxetan or iodine 131 tositumomab and chemotherapy, either as replacement for total body irradiation or in addition to standard high-dose chemotherapy (HDC) regimens. Current strategies include using standard or escalated doses of radioimmunoconjugates with HDC before ASCT in patients with relapsed or refractory B-cell NHL. We reviewed the safety and efficacy of 90 Y ibritumomab tiuxetan as part of the conditioning regimen before ASCT. Preliminary data from phase 1 and 2 trials show that 90Y ibritumomab tiuxetan may be safely added to HDC preparative regimens for high-risk B-cell NHL. Additionally, comparisons of outcomes with radioimmunotherapy and ASCT with historical controls suggest that it may be more effective than conventional regimens. Results of 90Y ibritumomab tiuxetan alone posttransplantation in select patients who have relapsed after HDC and ASCT are also encouraging. Studies of 90Y ibritumomab tiuxetan in the setting of allogeneic stem cell transplantation appear promising as well.