Bendamustine Improves Clinical Outcome in Chronic Lymphocytic Leukemia (CLL) According to Different Clinical and Biological Prognostic Factors
Authors: Del Poeta Giovanni , Del Principe Maria Ilaria , Ragusa Dario , Bulian Pietro , Buccisano Francesco , Rossi Francesca Maria , Perrotti Alessio Pio , Maurillo Luca , de Fabritiis Paolo , Gattei Valter , Amadori Sergio 
Published: October 2019

Abstract
Bendamustine has been demonstrated to be effective for the treatment of CLL, either alone compared with chlorambucil (Knauf et al, JCO 2009 and BJH 2012) or in combination with monoclonal antibodies such as rituximab both in second or more lines (Fischer et al, JCO 2011) and in first line treatment (Fischer et al, JCO 2012). However, the relationship between its activity with clinical and biological prognosticators has been addressed only in few studies. For this purpose, we evaluated the efficacy and safety of bendamustine, in a real-life contest, on 56 patients, median age 66 years (41-80), median number of previous regimens 1 (0-3, 32% previously untreated). Bendamustine was given for a median number of 6 cycles (70-90 mg/m2), in 82% of cases with rituximab at conventional doses. Overall (ORR) and complete response (CRR) rates were 73% and 44.6%, respectively. Obviously, CRR was higher (83.3%) for 18 patients treated in first line. A significant correlation was found between lower ORR and lymphocyte doubling time <12 months (OR 4.30; P=0.019), thus suggesting that a high proliferation rate may confer a reduced response to bendamustine. As already previously reported, there was a relationship between ORR and number of prior treatments in univariate analysis (OR 0.23; P=0.0055). Interestingly, there was also a significant correlation between lower ORR and the higher expression (>30%) of alpha-4 integrin CD49d (OR 13.0; P=0.018), an important marker of bad prognosis in CLL (Bulian et al, JCO 2014). On the other hand, no significant correlations were found between ORR and CD38, ZAP-70 or IGHV mutational status. Similarly, no significant correlations were noted between ORR and FISH cytogenetics, excluding del(17)p, or NOTCH1 mutations, thus confirming the independence of response to bendamustine from some well-known important biologic prognostic factors. In fact, multivariate analysis confirmed a significant relationship only between ORR and TP53/del(17)p (OR 0.020; P=0.0015) and concomitant rituximab (OR 0.019; P=0.0074). The estimated 1-year OS and PFS were 57% and 86%, respectively. Side effects included grade 3-4 neutropenia, infections, thrombocytopenia and anemia which occurred in 21%, 12%, 12% and 5% of patients, respectively. Grade 3-4 non-hematologic toxicity, including infusion-related reactions, heart or kidney or liver failure were found almost exclusively in elderly patients treated with bendamustine after two or more lines of therapy (12.5%). In multivariate analisys of OS, calculated from the end of treatment with bendamustine, only response to bendamustine (P=0.008) was confirmed to be an independent prognostic factor, while both the number of previous therapies and the concomitant use of rituximab demonstrated no statistical significance. These our results confirm both the activity and safety of bendamustine, particularly in combination with rituximab, also in the setting of elderly patients, often affected by two or three comorbidities. Noteworthy, this effectiveness appears to be present also in patients with unfavorable clinical and biological features, excluding del(17)p or TP53 mutations, in which the employment either of modern oral BCR inhibitors or of BH3 mimetics anti-Bcl-2 will be definitely active, also in combination with the same bendamustine.

Disclosures
No relevant conflicts of interest to declare.