Fludarabine and Mitoxantrone Followed by Yttrium-90 Ibritumumab Tiuxetan in Untreated Patients with Follicular Lymphoma. Long Term Efficacy and Toxicity Results of the FLUMIZ Trial.

Abstract 1604

We previously reported the results of a multicenter non-randomized phase II trial of fludarabine and mitoxantrone plus radioimmunotherapy (RIT) [FLUMIZ (Fludarabine, Mitoxantrone, Zevalin) trial], demonstrating that this combination was safe and very effective in untreated patients with follicular non-Hodgkin lymphoma. We are now providing long term efficacy and toxicity results of this combination strategy.

Sixty-one patients with stage III and IV untreated follicular lymphoma were enrolled between June 2004 and April 2006, at 13 Italian institutions. Briefly, treatment schedule was the following: oral fludarabine 40 mg/m² on days 1–3, intravenous mitoxantrone 10 mg/m² on day 1 every 28 days for six cycles, followed by one course of yttrium-90 (⁹⁰Y)-labelled ibritumumab tiuxetan (Zevalin), which consisted in two weekly infusions of Rituximab 250 mg/m² followed by a weight based dose of ⁹⁰Y-ibritumumab tiuxetan. Primary endpoints at the time of the first analysis were complete response and hematological toxic effects, secondary endpoints were overall survival (OS) and progression free survival (PFS). Fifty-seven patients were treated with RIT after the completion of six courses of fludarabine and mitoxantrone (FN) regimen. Four patients were excluded because of disease progression (n=1) and bone marrow infiltration > 25% (n=3) at the end of the FN regimen. Median follow up at the time of the last analysis was 52 months (range 24–75). Five-year PFS was estimated to be 68%, 5-year OS was estimated to be 93.0%. Noteworthy, late hematological side effects such as myelodisplastic syndromes or acute myeloid leukemias have not been observed so far. All patients had a complete hematological recovery after the completion of the sequential treatment. 16 patients relapsed during the follow-up period and 4 patients died due to disease progression. 22 patients (38%) are in first complete remission after more than 4 years of follow-up. All relapsed patients underwent second line chemotherapy and high dose chemotherapy with stem cell rescue was performed in 4 patients.

These results confirm the long term efficacy and safety of 6 cycles of fludarabine and mitoxantrone followed by consolidation with ⁹⁰Y-ibritumumab tiuxetan: the 5-year PFS and OS compare favourably with the results of chemoimmunotherapy alone in untreated follicular lymphoma, with no increased incidence of secondary hematologic malignancie