Efficacy and Safety Of Bendamustine In Combination With Rituximab For Elderly Patients With Previously Untreated B-Cell Chronic Lymphocytic Leukemia. A Retrospective Multicenter Study

Chronic Lymphocytic Leukemia (B-CLL) is the most prevalent adult leukemia in western countries, with a median age of onset of 65 years. Front-line therapy for B-CLL young patients is chemo-immunotherapy with Fludarabine-Cyclophosphamide and Rituximab (FCR). However, many B-CLL patients are elderly and with comorbidities. FCR regimen can result in a significant myelosuppression and a high rate of early and late infections, suggesting that it may be too toxic and therefore unsuitable for this large subpopulation of patients. Data from the CLL 5 phase III trial of the German CLL study group (GCLLSG) comparing Fludarabine vs Chlorambucil (Chl) in patients older than 65 years showed no differences in overall survival and progression free survival (PFS) between Fludarabine and Chl. Recently, Bendamustine as single agent showed superiority in comparison to Chl in terms of overall response rate (ORR) and PFS, with a good safety profile. Later, the addition of Rituximab (RTX) to Bendamustine (Benda-R) was shown to be efficacious and safe in the same treatment-naïve setting. Insufficient data are available in patients older than 70 years regarding the efficacy and safety, nevertheless increased incidence of extra-hematological toxicity was noted in this subgroup. Here we report our multicentre retrospective study focusing on responses and toxicities rate in elderly patients with B-CLL.

We report data on 24 elderly patients with previously untreated B-CLL observed in 7 Italian Centers from November 2000 to June 2012. All patients were treated with a median of 6 cycles of Bendamustine (range, 3-6) at the median dose of 90 mg/m² (range, 70-90 mg/m²) for 2 consecutive days every 28 days plus RTX (375 mg/m² for the first course and 500 mg/m² for subsequent cycles every 28 days). The median number of RTX cycles was 6 (range, 3-6). The mean dose of RTX was 4500 mg (range, 1500-6200 mg). The primary end points were the ORR (complete response CR and partial response PR) and hematological-extrahematological toxicities rate.

Twenty male and four female with a median age of 72 years (range, 65-87 years) were included in the study. Only one patient was unfit with a CIRS score of 7. All patients had ECOG less than 2. Two B-CLL patients had A/I progressive stage according Binet and Rai, 10 patients had B/II and 12 patients had C/III or C/IV. The median lymphocytes count at diagnosis was 37.040/mmc (range, 2.200-140.000). FISH analysis was performed in 19/25 patients: 12 patients were classified as standard risk (normal karyotype, del13q14 or +12) and 7 patients as high risk (del11q and del17p). The analysis of the IgVH, available in 12 patients, showed 7 patients with somatic mutation and 5 patients with germ-line sequences. Only one patient was admitted to the hospital and one received reduced bendamustine dose for neutropenia. Fifteen patients received bendamustine at the dosage of 90 mg/m² while 9 were treated with 70 mg/m². The ORR rate was 87.5%: ten patients (41.7%) obtained a complete response and eleven patients (45.8%) obtained a partial response. Among biological features the presence of standard risk FISH karyotype showed a statistical significance in terms of better response to therapy (p= 0.013) and progression (p=0.034). Hematological toxicity was recorded in 7 patients (29%) (neutropenia grade III/IV), 5 of them required G-CSF. Extra-hematological toxicity grade I-III was noticed in 8 patients (3 skin reactions, 3 infusion related reactions, 2 nausea and vomiting). At the present only four patients showed a progressive disease with a PFS of 92% at 12 months. Only one unresponsive patient died from Richter disease 6 months after the end of therapy. When we stratified patients in two groups according to the age, we found that patients younger than 75 years (15 patients) showed a better response (p=0.004) and a delayed time to progression (p=0.027) in comparison to patients more than 75 years.

Retrospective data from this group of elderly B-CLL patients indicate Benda-R front-line provide a high response rate and a good safety profile. Also in a subgroup of very elderly patients (age > 75 years) the association of bendamustine 90 mg/m² and rituximab at standard dose is recommended because of a low rate of dose delay/reduction and acceptable hematological/extrahematological toxicities.