Safety and efficacy of (90) yttrium-ibritumomab-tiuxetan for untreated follicular lymphoma patients. An Italian cooperative study.

(90) Yttrium ((90) Y)-Ibritumomab-Tiuxetan combines the targeting advantage of a monoclonal antibody with the radiosensitivity of Follicular Lymphoma (FL). Previous studies showed that 90Y-IT is safe and effective in relapsed/refractory indolent FL, irrespective of prior treatment with rituximab. This multicentre trial aimed to evaluate the safety and the efficacy of "upfront" single-agent ((90) Y)-Ibritumomab-Tiuxetan in advanced-stage FL. The primary objective was the incidence of responses in terms of complete (CR) and partial remission (PR). Fifty patients with stage II "bulky", III or IV FL received a single treatment course with ((90) Y)-Ibritumomab-Tiuxetan as initial therapy. The median age was 60 years. Bone marrow involvement (<25\%) was observed in 24 patients (48\%) and 7 (14\%) had an elevated lactate dehydrogenase level. The overall response (ORR) and CR rates were 94\% and 86\%, respectively with a median follow-up of 38·8 months. The median progression-free survival (PFS) was not reached, whereas the 3-year estimated PFS and overall survival (OS) rate was 63·4\% and 90\%, respectively. Grade 3/4 neutropenia and thrombocytopenia occurred in 30\% and 26\% of patients respectively; none experienced grade 3/4 non-haematological toxicity. No cases of secondary haematological malignancies were observed. ((90) Y)-Ibritumomab-Tiuxetan was demonstrated to be highly effective and safe as first-line treatment for advanced-stage FL.