Radioimmunotherapy using I-131-labeled anti-CD22 monoclonal antibody (LL2)in patients with previously treated B-cell lymphomas

Experience in using rapidly internalizing antibodies, such as the anti-CD22 antibody, for radioimmunotherapy of B cell lymphomas is still limited. The present study was conducted to assess the efficacy and toxicity of a I-131 -labeled anti-CD22 monoclonal antibody (mAb), LL2, in patients with B-cell lymphomas failing first- or second-line chemotherapy. Eligible patients wer e required to have measurable disease, less than 25% B cells in unseparated bone marrow, and an uptake of Tc-99m-labeled LL2Fab' in at least one lymph oma lesion on immunoscintigram. Eight of nine patients examined with immuno scintigraphy were unequivocally found to have an uptake, and therapy with I -131-labeled anti-CD22 [1330 MBq/m(2) (36 mCi/m(2))] preceded by 20 mg of n aked anti-CD22 mAb was administered. Three patients achieved partial remiss ion (duration, 12, 3, and 2 months), and one patient with progressive lymph oma showed stable disease for 17 months. Four patients exhibited progressiv e disease. The toxicity was hematological. Patients with subnormal counts o f neutrophils or platelets before therapy seemed to be more at risk for hem atological side effects. Radioimmunotherapy in patients with B-cell lymphom as using I-131-Iabeled mouse anti-CD22 can induce objective remission in pa tients with aggressive as well as indolent lymphomas who have failed prior chemotherapy.