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

Abstract

Purpose: To test the hypothesis that consolidation therapy with yttrium-90 ((90)Y) -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 (90)Y-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 (90)Y-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.

Fig 1.

For the 56 eligible patients enrolled onto the trial, (A) time to treatment failure and (C) overall survival are shown. For these 56 patients, (B) time to treatment failure and (D) overall survival by patients ≤ 65 years old versus patients older than age 65 years at enrollment onto the trial are shown.

Fig 2.

(A) Time to treatment failure and (B) overall survival for the 50 eligible patients who received radioimmunotherapy (RIT).