Bendamustine Plus Rituximab Versus Fludarabine Plus Rituximab In Patients with Relapsed Follicular, Indolent and Mantle Cell Lymphomas – Final Results of the Randomized Phase III Study NHL 2–2003 on Behalf of the StiL (Study Group Indolent Lymphomas, Germany)

Promising results have been observed in two phase II studies evaluating the combination of bendamustine plus rituximab (B-R) in patients (pts) with relapsed/refractory follicular, other indolent or mantle cell lymphomas (MCL) (Rummel et al. JCO 2005; Robinson et al. JCO 2008). Fludarabine plus rituximab (F-R) is an established treatment option in this setting. Therefore, we initiated in 2003 a multicenter, randomized phase III study to compare the efficacy and safety of B-R versus F-R for pts with relapsed follicular (FL), indolent or MCL.

219 pts with relapsed FL, indolent or MCL in need of treatment were randomized to rituximab 375 mg/m² (day 1) plus either bendamustine 90 mg/m² (days 1+2) or fludarabine 25 mg/m² (days 1–3) q 28 days for a maximum of 6 cycles. Prophylactic use of antibiotics or granulocyte-colony stimulating factor (G-CSF) was not generally recommended; however in cases of severe granulocytopenia, G-CSF use was permitted. The primary endpoint was progression-free survival (PFS). The protocol was amended in 2006 to allow rituximab maintenance therapy (rituximab 375 mg/m² q 3 months for up to 2 years) in both arms, following regulatory approvals in this setting.

11 pts were not evaluable due to protocol violations, and were not followed further. A total of 208 pts were evaluable for the final analysis (109 B-R; 99 F-R). There were no significant differences between arms for patient characteristics, including age, stage, LDH, International Prognostic Index (IPI), follicular IPI (FLIPI), bone marrow infiltration and extranodal involvement. Most pts had stage IV (71.6% B-R; 60.6% F-R) or stage III disease (21.1% B-R and 25.3% F-R, respectively). Median patient age was 68 yrs (range 38–87). Patients had received a median of 1 prior therapy (range 1–7). Histological subtypes were distributed equally between the B-R and F-R arms: follicular 45.9 % and 47.5%, respectively; immunocytoma 11.9% and 11.1%; MCL 20.2% and 21.2%; other indolent lymphomas 23% and 20.2%. A median number of 6 cycles were given in both treatment arms, with 75.2% of B-R pts and 53.4% of F-R pts receiving 6 cycles, respectively. At the time of this analysis (June 2010), the median observation time was 33 months. Median PFS was significantly prolonged with B-R compared with F-R (30 vs 11 months; hazard ratio [HR] 0.51, 95 % confidence interval [CI] 0.34–0.67; p<0.0001). The overall response rate was significantly higher with B-R than with F-R (83.5 vs 52.5%, respectively; p< 0.0001). The CR rate with B-R was also significantly higher than that with F-R (38.5 vs 16.2%; p=0.0004). Overall survival did not differ significantly between arms, with 42 and 46 deaths documented in the B-R and F-R arms, respectively.

There were no significant differences in the rates of alopecia, stomatitis, erythema, allergic reactions, peripheral neuropathy or infectious episodes between groups. Hematologic toxicities were also similar between arms: 8.9% grade 3/4 neutropenia with B-R vs 9.1% with F-R; 11.8% grade 3/4 leukocytopenia with B-R vs 12.4% with F-R. The overall incidence of serious adverse events was similar for the B-R and F-R groups (17.4 and 22.2%, respectively).

An unplanned subanalysis showed that rituximab maintenance therapy significantly prolonged overall survival (HR 0.21, 95% CI 0.22–0.67; p=0.0008) and PFS (HR 0.27, 95% CI 0.27–0.59; p< 0.0001) in the small group of 40 pts who received this treatment (23 B-R, 17 F-R), compared with those who did not. Although the numbers are too small in this non-randomized comparison to draw some validated conclusions, these results appear to confirm the favorable role of rituximab maintenance.

These data confirm the efficacy of B-R in pts with relapsed FL, indolent or MCL, and, in this setting, demonstrate a superior PFS benefit for this regimen in comparison with F-R.

No relevant conflicts of interest to declare.