Rituximab plus Short-Duration Chemotherapy Followed by Yttrium-90 Ibritumomab Tiuxetan as First-Line Treatment for Patients with Follicular Non-Hodgkin Lymphoma: A Phase II Trial of the Sarah Cannon Oncology Research Consortium

Purpose: To evaluate the efficacy and safety of treatment with Yttrium-90 (Y-90) ibritumomab tiuxetan following completion of short-course rituximab/chemotherapy in patients with previously untreated follicular non-Hodgkin lymphoma. Patients and Methods: Forty-one patients with previously untreated follicular lymphoma received rituximab for 4 consecutive weeks, followed by 3 cycles of rituximab combined with either CHOP (cyclophosphamide/doxorubicin/vincristine/prednisone; 88%) or CVP (cyclophosphamide/vincristine/prednisone; 12%). To complete treatment, all patients received Y-90 ibritumomab tiuxetan 4-6 weeks after the final dose of chemotherapy. The primary efficacy endpoint was the clinical complete response (CR) rate after completion of therapy; all patients were followed for progression-free survival (PFS) and overall survival (OS). Results: After completion of short-course rituximab/chemotherapy, 95% had objective, responses, with a 30% clinical CR rate. The clinical CR rate increased to 72% following Y-90 ibritumomab tiuxetan. After a median follow-up of 67 months, the estimated 5-year PFS and OS rates are 64% and 96%, respectively. Reversible grade 3/4 neutropenia and thrombocytopenia occurred in 39% and 36% of the patients, respectively, following Y-90 ibritumomab tiuxetan; nonhematologic toxicity was uncommon. Conclusion: Y-90 ibritumomab tiuxetan was well tolerated after short-course rituximab/chemotherapy and resulted in a high CR rate and a long PFS. Definitive demonstration of improved efficacy versus rituximab/chemotherapy alone will require a randomized phase III trial.