Bendamustine Plus Rituximab Versus CHOP Plus Rituximab in the First-Line-Treatment of Patients with Follicular, Indolent and Mantle Cell Lymphomas: Results of a Randomized Phase III Study of the Study Group Indolent Lymphomas (StiL)

Background: Promising results have been observed in our previous phase-II study evaluating the combination of Bendamustine plus Rituximab (B-R) in patients with relapsed/refractory indolent or mantle cell lymphomas. An overall response rate (ORR) of 90%, including a 60% rate of complete remissions (CR) was documented. Objective: In October 2003, we initiated a multicenter randomized phase-III study to compare efficacy and safety of the combination B-R versus CHOP plus Rituximab (CHOP-R) as first-line therapy for follicular, indolent and mantle cell lymphomas.

Methods: Patients (pts) were randomized to receive Rituximab 375 mg/qm (day 1) plus either Bendamustine 90 mg/qm (days 1+2) every 28 days or the standard CHOP regimen every 21 days for a maximum of 6 cycles. The primary endpoint was event-free survival (EFS). The trial was calculated to power the study to demonstrate a non-inferior EFS associated with B-R treatment, as defined by a difference in EFS between the two regimes of less than 10% after 3 years. An event was defined by a response less than a partial response, disease progression, relapse, or death from any cause. The study is closed according to the planned recruitment schedule.

Results: 546 patients have been randomized. For this second interim analysis, 437 patients are evaluable for response (B-R: n=221; CHOP-R: n=212). Median patient age is 64 years. Histologies are equally distributed between arms: follicular 52%, mantle cell 20%, and other indolent lymphomas 28% in both treatment groups, each. The ORR for pts treated with B-R was similar to that associated with CHOP-R (94% vs 93%, respectively). CR was also similar at 41% for B-R compared to 33% for CHOP-R. The median follow-up time for both groups is 28 months. Thus far, 50 deaths have been observed (B-R: 25; CHOP-R: 25). Progressive or relapsed disease has been documented during the follow-up period: 58 in pts treated with B-R and 75 in the CHOP-R group. The median EFS for B-R is not yet reached, the median EFS for CHOP-R is 39 months with no statistical significant difference for the EFS between both groups. The B-R regimen appears to have a better toxicity profile, as evidenced by a lower rate of total alopecia (0% with B-R vs. 89% CHOP-R) and a lower number of infectious complications (number of patients with infections of any grade were 56 (25%) in the B-R group vs. 78 (37%) in CHOP-R group). Correlating, the CHOP-R regimen was more hematotoxic: WHO grade 3/4 leukocytopenia was reported in 36% CHOP-R treated pts compared with 19% in pts treated with B-R, while in the CHOP-R group more frequently G-CSF was used.

Conclusions: In this second interim analysis, the combination of Bendamustine plus Rituximab appears to be non-inferior to the standard CHOP-R while showing a better tolerability profile. Further updated results will be presented at this time.