Radiation dosimetry results and safety correlations from 90Y-ibritumomab tiuxetan radioimmunotherapy for relapsed or refractory non-Hodgkin’s lymphoma: combined data from 4 clinical trials

Ibritumomab tiuxetan is an anti-CD20 murine IgG1 monoclo-nal antibody (ibritumomab) conjugated to the linker-chelator tiuxetan, which securely chelates 111In for imaging or dosimetry and 90Y for radioimmunotherapy (RIT). Dosimetry and pharma-cokinetic data from 4 clinical trials of 90Y-ibritumomab tiuxetan RIT for relapsed or refractory B-cell non-Hodgkin’s lymphoma (NHL) were combined and assessed for correlations with toxic-ity data. Methods: Data from 179 patients were available for analysis. Common eligibility criteria included 25 % bone mar-row involvement by NHL, no prior myeloablative therapy, and no prior RIT. The baseline platelet count was required to be 100,000 cells/mm3 for the reduced 90Y-ibritumomab tiuxetan administered dose (7.4–11 MBq/kg [0.2–0.3 mCi/kg]) or 150,000 cells/mm3 for the standard 90Y-ibritumomab tiuxetan administered dose (15 MBq/kg [0.4 mCi/kg]). Patients wer