A phase 2 trial of fludarabine and mitoxantrone chemotherapy followed by yttrium-90 ibritumomab tiuxetan for patients with previously untreated, indolent, nonfollicular, non-Hodgkin lymphoma

BACKGROUND. A prospective, single-arm, open-label, nonrandomized Phase 2 study of combined fludarabine and mitoxantrone (FM) plus radioimmunotherapy was conducted to evaluate efficacy and safety in patients with untreated, indolent, nonfollicular non-Hodgkin lymphoma (NHL). METHODS. Between February 2005 and June 2006, at their institute, the authors treated 26 eligible patients with previously untreated, indolent, nonfollicular NHL (10 marginal zone lymphomas, 8 lymphoplasmacytic lymphomas, and 8 small lymphocytic lymphomas) using a novel regimen that consisted of 6 cycles of FM chemotherapy followed 6 to 10 weeks later by yttrium-90 (90Y) ibritumomab tiuxetan. RESULTS. After FM chemotherapy, the overall response rate was 80.5% and included a 50% complete remission (CR) rate (13 patients) and a 30.5% partial remission (PR) rate (8 patients). Of the 20 patients (13 with CR and 7 with PR) who were evaluable (at least a PR with normal platelet counts and bone marrow infiltration <25%) for subsequent 90Y ibritumomab tiuxetan, 100% obtained a CR at the end of the entire treatment regimen. At a median follow-up of 20 months, the estimated 3-year progression-free survival rate was 89.5%, and the estimated 3-year overall survival rate was 100%. The 90Y ibritumomab tiuxetan toxicity included grade ≥3 hematologic toxicity in 16 of 20 patients; the most common grade ≥3 toxicities were neutropenia (11 patients) and thrombocytopenia (16 patients) (adverse events were graded according to the World Health Organization criteria for toxicity). Transfusions of erythrocytes and/or platelets were given to 5 patients. CONCLUSIONS. The current study established the feasibility, tolerability, and efficacy of the FM plus 90Y ibritumomab tiuxetan regimen for the treatment of patients with untreated, indolent, nonfollicular NHL.