Summary
90Y-ibritumomab-tiuxetan ( 90 YIT) was used as a first-line therapy for patients with early-stage follicular lymphoma (FL) or marginal zone B-cell lymphoma (MZL). Thirty-one patients were treated, with an overall 3-month response rate of 100% (68% complete response, 29% unconfirmed complete response and 3% partial response). At a median follow-up of 56 months, ten patients (32%) had disease relapse or progression. The progression-free rates at 3 and 5 years were lower in males, patients with FL, stage II diseaseand non-bulky disease, although they did not reach statistical significance. Grade 3-4 neutropenia, thrombocytopenia and anaemia were 61%, 35%, and 3%, respectively.
90YIT was well tolerated, including in those patients over 60 years old, and achieved high response rates in patients with earlystage low-grade B-cell lymphomas. Bulky disease did not adversely affect tumour response.Keywords: zevalin, myelosuppression, radiation, follicular, marginal zone.Low-grade B-cell lymphomas include the histological types of follicular lymphoma (FL), marginal zone lymphoma (MZL), splenic MZL and lymphoplasmacytic lymphoma. Because these lymphomas are clinically unaggressive and progress slowly, the optimal treatment for stage I-II low-grade B-cell lymphomas has not yet been determined and they are unlikely to be included in clinical trials. Frontline targeted therapy with the antibody rituximab produces an overall response rate of 72%, with a 36% complete remission rate, in patients with advanced-stage grade I FL (Witzig et al, 2005). Adding rituximab to chemotherapy has consistently enhanced response rates (Marcus et al, 2008). However, the availability of numerous therapies for early-stage low-grade B-cell lymphomas and a lack of adherence to one single treatment plan make the best treatment recommendations unclear.The mouse anti-cluster of differentiation (CD) 20 antibody, which targets the same epitope as rituximab, has been conjugated with the radioisotope complex yttrium-90-ibritumomab tiuxetan ( 90 YIT), which has shown clinical benefit in lymphoma therapy. An initial randomized clinical trial with patients with relapsed FL, including transformed lymphoma, showed response rates of 80% in the 90 YIT group and 56% in the rituximab group; the complete response (CR) rates were 30% and 16%, respectively (Witzig et al, 2002). The second type of radiotherapy, YIT as consolidation therapy after various frontline chemotherapies for FL was shown to increase the PFS rate at 8 years from 32% to 48% (Morschhauser et al, 2013).Although the benefits of 90 YIT as treatment for advancedstage FL in the frontline and relapse settings are well documented, little data exist that document whether individuals with early-stage low-grade B-cell lymphomas benefit from 90 YIT therapy.