Treatment with yttrium 90 ibritumomab tiuxetan at early relapse is safe and effective in patients with previously treated B-cell non-Hodgkin's lymphoma

Yttrium 90 (Y-90) ibritumomab tiuxetan ( Zevalin), a radiolabeled monoclonal antibody against the CD20 antigen, is indicated for the treatment of patients with relapsed or refractory low-grade, follicular, or transformed B-cell non-Hodgkin's lymphoma (NHL), including patients with rituximab-refractory follicular NHL. Data on 211 patients treated in four clinical trials were analysed to compare the efficacy and safety of Y-90 ibritumomab tiuxetan when it was used after the first relapse of NHL and when it was used after two or more prior therapies. Sixty-three patients (30%) were treated with Y-90 ibritumomab tiuxetan after their first relapse and 148 (70%) after two or more prior therapies. Demographics, disease characteristics and the frequency of adverse events were similar in all groups, with the exception of a higher rate of marrow involvement in first-relapse patients than in patients with two or more prior therapies (57% vs. 39%; P<0.05). The complete response rate [ confirmed (CR) and unconfirmed (Cru)] was higher in first-relapse patients (49% vs. 28%; P<0.01), and the median time to progression (TTP) was longer (12.6 vs. 7.9 months; P<0.05). In patients with follicular NHL, the differences were even more pronounced (CR/CRu: 51% vs. 28%; P<0.01; TTP: 15.4 vs. 9.2 months; P<0.05). Y-90 ibritumomab tiuxetan has substantial clinical benefits as a second-line therapy, especially in patients with follicular NHL. The quality of disease remissions obtained when Y-90 ibritumomab tiuxetan is administered after first relapse appears to be comparable with that observed with most chemotherapy regimens in first-relapse patients.