Phase II Study of Rituximab Plus Cyclophosphamide, Doxorubicin, Vincristine, and Prednisone Immunochemotherapy Followed by Yttrium-90-Ibritumomab Tiuxetan in Untreated Mantle-Cell Lymphoma: Eastern Cooperative Oncology Group Study E1499

Purpose To test the hypothesis that consolidation therapy with yttrium-90 (Y-90) -ibritumomab tiuxetan after brief initial therapy with four cycles of rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) in patients with previously untreated mantle-cell lymphoma would be a well-tolerated regimen that would improve outcomes compared with historical R-CHOP data. Patients and Methods Patients >= 18 years old with histologically confirmed mantle-cell lymphoma expressing CD20 and cyclin D1 who had not received any previous therapy and had an Eastern Cooperative Oncology Group performance status of 0 to 2 and adequate organ function were eligible. The study enrolled and treated 57 patients, of whom 56 patients were eligible. Fifty-two patients (50 eligible patients) received 90Y-ibritumomab tiuxetan. The study design required 52 eligible patients to detect a 50% improvement in the median time to treatment failure (TTF) compared with that reported for six cycles of R-CHOP. Results With 56 analyzed patients (median age, 60 years; men, 73%), the overall response rate was 82% (55% complete response/complete response-unconfirmed). With a median follow-up of 72 months, the median TTF was 34.2 months. The median overall survival (OS) has not been reached, with an estimated 5-year OS of 73% (79% for patients <= age 65 years v 62% for patients > age 65 years; P = .08 [log-rank test]). There were no unexpected toxicities. Conclusion R-CHOP given for four cycles followed by Y-90-ibritumomab tiuxetan compared favorably with historical results with six cycles of R-CHOP in patients with previously untreated mantle-cell lymphoma. This regimen was well tolerated and should be applicable to most patients with this disease. J Clin Oncol 30: 3119-3126. (C) 2012 by American Society of Clinical Oncology