90Y-ibritumomab tiuxetan therapy in allogeneic transplantation in B-cell lymphoma with extensive marrow involvement and chronic lymphocytic leukemia

Abstract

Biodistribution data to-date using 111In- ibritumomab tiuxetan has been initially obtained in patients with <25% lymphomatous bone marrow involvement and adequate hematopoietic synthetic function. In this article we present the results of an analysis of the biodistribution data obtained from a cohort of patients with extensive bone marrow involvement, baseline cytopenias, and chronic lymphocytic leukemia (CLL). Thirty nine patients with diagnosis of B-cell lymphoma or CLL expressing the CD20 antigen, who had failed at least one prior regimen, and had evidence of persistent disease were included in this analysis, however only 38 of these completed the treatment. Semiquantitative analysis of the biodistribution was performed using regions of interest (ROI) over the liver, lungs, kidneys, spleen and sacrum. The observed interpatient variability including higher liver uptake in 4 patients is discussed. No severe solid organs toxicity was observed at the maximum administered activity of 1184 MBq (32 mCi) 90Yibritumomab tiuxetan. After accounting for differences in marrow involvement, patients with CLL exhibit comparable biodistributions to those with B-NHL. We found that the estimated sacral marrow uptake on 48 hour images in patients with bone marrow involvement may be an indicator of bone marrow involvement. There was no correlation between tumor visualization and response to treatment. These data suggest that the imaging step is not critical when the administered activity is below 1184 MBq (32 mCi). However our analysis confirms that the semiquantitative imaging data can be used to identify patients at risk for liver toxicity when higher doses of 90Y- ibritumomab tiuxetan are used. Patients with CLL can have excellent targeting of disease by 111Inibritumomab tiuxetan, indicating potential efficacy in this patient population.