High overall and complete response rates can be achieved with six to eight cycles of R-CHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone) in patients with mantle cell lymphoma (MCL), but median response duration is only 18 to 24 months.
Given the high activity of radioimmunotherapy (RIT) in patients with relapsed MCL (J Clin Oncol 2009; 27:5213), investigators conducted a multicenter phase II trial to test the efficacy and safety of four cycles of R-CHOP plus yttrium-90 (90Y)–ibritumomab tiuxetan RIT consolidation in patients with previously untreated MCL.
Of 56 treatment-naive adults (median age, 60; 73% men; 91% with stage III–IV disease; 48% with extranodal involvement), 52 received four cycles of R-CHOP followed by a single dose of standard 90Y-RIT. The overall response rate was 82%, and response improved to complete or partial remission in 22 patients after 90Y-RIT. At a median follow-up of 72 months, the median time to treatment failure was 34.2 months; median overall survival (OS) had not been reached. The estimated 5-year OS rate trended higher for patients aged 65 versus those >65 (79% vs. 62%; P=0.08). Toxicities were as expected with R-CHOP and were primarily transient neutropenia and thrombocytopenia for 90Y-RIT.
Comment: Given the typically short duration of progression-free survival after immunochemotherapy in MCL patients, postinduction strategies are under study to improve outcomes. In younger patients, high-dose chemotherapy and autologous stem-cell transplantation are often utilized, whereas older or infirm patients might benefit from maintenance rituximab (JW Oncol Hematol Aug 21 2012). The present study confirms 90Y-RIT as an active agent that increases response rate and duration following abbreviated induction cycles, although without an established survival benefit as yet. Confirmatory studies will be important, as will optimizing patient selection for 90Y-RIT versus alternative postinduction regimens.