Yttrium 90 ((90)Y)
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 (90)Y
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 (90)Y
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). (90)Y
ibritumomab tiuxetan has substantial clinical benefits as a second-line
therapy, especially in patients with follicular NHL. The quality of disease remissions obtained when (90)Y
ibritumomab tiuxetan is administered after first relapse appears to be comparable with that observed with most
chemotherapy regimens in first-relapse patients.