The cytotoxic effects of bendamustine in combination with cytarabine in mantle cell lymphoma cell lines

Lymphocyte recovery after bendamustine therapy in patients with mantle cell lymphoma. Results of a retrospective analysis and prognostic impact in the CAR-T era

Bendamustine in combination with rituximab (BR) or with rituximab and cytarabine (R-BAC) is the standard first-line immunochemotherapy in mantle cell lymphoma (MCL) for elderly patients and patients ineligible for intensive regimens or autologous transplantation. As bendamustine causes prolonged lymphopenia and the literature lacks evidence of its persistence in patients with MCL, this retrospective analysis aims to estimate the lymphocyte recovery time, also in view of potential immunotherapy with CAR-T cells. Data were collected from 44 consecutive MCL patients who received bendamustine (BR or R-BAC) as first-line therapy at the Hematology Unit of Sapienza University Hospital between May 2011 and April 2022. Twenty patients (45%) were treated with R-BAC and 24 (55%) with BR. At baseline, the median lymphocyte count was 1795/µl (range: 370-11730/µL). One month after the end of therapy, it was 450/µl (range: 50-3300/µl) and 3 months after 768/µl (range: 260-1650/µl). After 6 and 9 months, we observed a gradual increase in median lymphocyte count of 900/µl (range: 370-2560/µl and 130-2770/µl, respectively). After 12 months median lymphocyte count was 1256/µl (range: 240-4140/µl). Median lymphocyte count at 1, 3, 6, and 9 months post-treatment was significantly lower than baseline but showed recovery by the 12 months. This finding is crucial for MCL patients considering CAR-T cell therapy, suggesting a minimum 9-month interval between bendamustine administration and leukapheresis.

Modified R-BAC plus BTK inhibitor regimen in newly diagnosed young patients with mantle cell lymphoma: a real-world retrospective study

To explore the optimal treatment for young patients with untreated mantle cell lymphoma (MCL), we compared the efficacy and safety of R-CHOP/R-DHAP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone/rituximab, dexamethasone, cytarabine and cisplatin) and R-BAP (rituximab, bendamustine, cytarabine, and prednisone) plus BTK (Bruton's tyrosine kinase) inhibitors in newly diagnosed patients. Eighty-three young patients (≤ 65 years old) with newly diagnosed MCL admitted to the First Affiliated Hospital of Zhengzhou University from January 1, 2014, to June 1, 2023, using R-CHOP/R-DHAP or R-BAP plus BTK inhibitor were assessed in this study. The median age at presentation was 60 (42-65) years in 83 patients, including 64 males and 19 females; 59 were treated with R-CHOP/R-DHAP regimen chemotherapy, and 24 were treated with R-BAP in combination with the BTK inhibitor regimen. The median follow-up was 17 months (2-86 months) in 83 patients, and the median PFS (progression-free survival) time was not reached. The CRR (complete response rate) of the R-BAP group was higher than that of the R-CHOP/R-DHAP group (87.5% vs. 54.2%, P = 0.005). The ORR (overall response rate) was not significantly different between the two groups (ORR: 91.7% vs. 84.7%, P = 0.497). The PFS (progression-free survival) of the R-BAP group was longer than that of the R-CHOP/R-DHAP group (P = 0.013), whereas OS was not significantly different between the two groups (P = 0.499). The most common adverse effect in both groups was hematotoxicity, with a higher incidence of grade 3-4 lymphopenia and grade 3-4 thrombocytopenia in the R-BAP group than in the R-CHOP/R-DHAP group (P = 0.015 and P = 0.039). Male sex (HR = 4.257, P = 0.013), LDH (lactate dehydrogenase) ≥ 245 U/L (HR = 3.221, P = 0.012), pleomorphic-blastoid (HR = 2.802, P = 0.043) and R-CHOP/R-DHAP regimen (HR = 7.704, P = 0.047) were independent risk factors for PFS. Ki67 ≥ 30% (HR = 8.539, P = 0.005) was an independent risk factor for OS. First-line treatment with R-BAP in combination with BTK inhibitor improved CRR and prolonged PFS in young patients with mantle cell lymphoma and adverse events were tolerable.

Long-term follow-up of rituximab plus bendamustine and cytarabine in older patients with newly diagnosed MCL

The combination of rituximab, bendamustine, and low-dose cytarabine (R-BAC) has been studied in a phase 2 prospective multicenter study from Fondazione Italiana Linfomi (RBAC500). In 57 previously untreated elderly patients with mantle cell lymphoma (MCL), R-BAC was associated with a complete remission rate of 91% and 2-year progression-free survival (PFS) of 81% (95% confidence interval [CI], 68-89). Here, we report the long-term survival outcomes, late toxicities, and results of minimal residual disease (MRD) evaluation. After a median follow-up of 86 months (range, 57-107 months), the median overall survival (OS) and PFS were not reached. The 7-year PFS and OS rates were 55% (95% CI, 41-67), and 63% (95% CI, 49-74), respectively. Patients who responded (n = 53) had a 7-year PFS of 59% (95% CI, 44-71), with no relapse or progression registered after the sixth year. In the multivariate analysis, blastoid/pleomorphic morphology was the strongest adverse predictive factor for PFS (P = .04). Patients with an end of treatment negative MRD had better, but not significant, outcomes for both PFS and OS than patients with MRD-positive (P = 0.148 and P = 0.162, respectively). There was no signal of late toxicity or an increase in secondary malignancies during the prolonged follow-up. In conclusion, R-BAC, which was not followed by maintenance therapy, showed sustained efficacy over time in older patients with MCL. Survival outcomes compare favorably with those of other immunochemotherapy regimens (with or without maintenance), including combinations of BTK inhibitors upfront. This study was registered with EudraCT as 2011-005739-23 and at www.clinicaltrials.gov as #NCT01662050.

Bendamustine: A review of pharmacology, clinical use and immunological effects (Review)

Bendamustine is an alkylating agent classified into the group of nitrogen mustard analogues, synthesized almost sixty years ago. It was registered in former East Germany in 1971 and approved by the US Food and Drug Administration in 2008 for treatment of chronic lymphocytic leukemia and indolent B-cell non-Hodgkin lymphoma. Considering its beneficial properties in the therapy of relapsed or refractory hematological malignancies, synergistic effects with other antineoplastic agents and increasing recent reports on its immunomodulatory effects, bendamustine has once again gained its justified attention. The uniqueness of bendamustine-mediated effects should be observed keeping in mind its distinctive structure with structural similarities to both alkylating agents and purine analogs. In the present review, the current knowledge on the use of bendamustine in oncology, its pharmacokinetics, mechanism of action and toxicity was summarized. In addition, its immune-modulating effects that have not been fully elucidated so far are emphasized, hoping to encourage further investigations of this unique drug.

High-Risk Mantle Cell Lymphoma in the Era of Novel Agents

PURPOSE OF REVIEW

Mantle cell lymphoma (MCL) is a heterogenous disease with a variety of morphologic and genetic features, some of which are associated with high risk disease. Here we critically analyze the current state of the understanding of MCL's biology and its implications in therapy, with a focus on chemotherapy-free and targeted therapy regimens.

RECENT FINDINGS

Mantle cell lymphoma (MCL) is a rare subtype of non-Hodgkin's lymphoma, defined by a hallmark chromosomal translocation t(11;14) which leads to constitutive expression of cyclin D1. Recent discoveries in the biology of MCL have identified a number of factors, including TP53 mutations and complex karyotype, that lead to unresponsiveness to traditional chemoimmunotherapy and poor outcomes. Bruton tyrosine kinase inhibitors, BH3-mimetics and other novel agents thwart survival of the neoplastic B-cells in a manner independent of high-risk mutations and have shown promising activity in relapsed/refractory MCL. These therapies are being investigated in the frontline setting, while optimal responses to chemotherapy-free regimens, particularly in high-risk disease, might require combination approaches. High-risk MCL does not respond well to chemoimmunotherapy. Targeted agents are highly active in the relapsed refractory setting and show promise in high-risk disease. Novel approaches may soon replace the current standard of care in both relapsed and frontline settings.

Mantle cell lymphoma

MCL is a well-characterized generally aggressive lymphoma with a poor prognosis. However, patients with a more indolent disease have been reported in whom the initiation of therapy can be delayed without any consequence for the survival. In 2017 the World Health Organization updated the classification of MCL describing two main subtypes with specific molecular characteristics and clinical features, classical and indolent leukaemic nonnodal MCL. Recent research results suggested an improving outcome of this neoplasm. The addition of rituximab to conventional chemotherapy has increased overall response rates, but it did not improve overall survival compared to chemotherapy alone. The use of intensive frontline therapies including rituximab and consolidation with autologous stem cell transplantation ameliorated response rate and prolonged progression-free survival in young fit patients, but any impact on survival remains to be proven. Furthermore, the optimal timing, cytoreductive regimen and conditioning regimen, and the clinical implications of achieving a disease remission even at molecular level remain to be elucidated. The development of targeted therapies as the consequence of better understanding of pathogenetic pathways in MCL might improve the outcome of conventional chemotherapy and spare the toxicity of intense therapy in most patients. Cases not eligible for intensive regimens, may be considered for less demanding therapies, such as the combination of rituximab either with CHOP or with purine analogues, or bendamustine. Allogeneic SCT can be an effective option for relapsed disease in patients who are fit enough and have a compatible donor. Maintenance rituximab may be considered after response to immunochemotherapy as the first-line strategy in a wide range of patients. Finally, since the optimal approach to the management of MCL is still evolving, it is critical that these patients are enrolled in clinical trials to identify the better treatment options.

Efficacy of R-BAC in relapsed, refractory mantle cell lymphoma post BTK inhibitor therapy

Patients with mantle cell lymphoma progressing on Bruton's tyrosine kinase inhibitor (BTKi) have very poor prognosis and there is currently no standard of care. In this retrospective cohort study, patients progressing on BTKi received R-BAC (rituximab, bendamustine, cytarabine). Overall response rate was 83% (complete response 60%) and 31% were bridged to allogeneic stem cell transplant (alloSCT). Median progression-free survival was 10.1 months (95% confidence interval (CI) 6·9-13·3) and median overall survival was 12·5 months (95% CI 11·0-14·0). In those consolidated with alloSCT only one patient relapsed. R-BAC demonstrates a high response rate in the post-BTKi setting and in transplant eligible patients is an effective bridge to alloSCT.

Bendamustine-EAM versus BEAM regimen in patients with mantle cell lymphoma undergoing autologous stem cell transplantation in the frontline setting: a multicenter retrospective study from Lymphoma Study Association (LYSA) centers

The combination of carmustine, etoposide, cytarabine, and melphalan (BEAM) as conditioning regimen prior to autologous stem-cell transplantation (ASCT) remains the standard of care for patients with mantle cell lymphoma (MCL) who are eligible for transplantation. The replacement of carmustine with bendamustine (BeEAM) was described as a promising alternative in non-Hodgkin lymphoma. The aim of this retrospective study was to compare the BeEAM with the BEAM regimen in MCL patients in the frontline setting. Sixty and 108 patients were included in the BeEAM and the BEAM groups, respectively. At 3 years, progression-free survival (PFS) was significantly higher in the BeEAM than in the BEAM group (84% [73-96] vs. 63% [51-79], p = 0.03). The overall survival was not statistically different between the two groups (p = 0.2). In multivariable analysis, BeEAM regimen remained associated with higher PFS (HR = 0.377, 95% CI, 0.146-0.970; p = 0.043). Subgroup analyses in patients treated with prior rituximab-aracytine induction alone showed that BeEAM improved the PFS compared with BEAM regimen (p = 0.04). Despite the high rate of acute renal failure KDIGO III (32%), treatment-related mortality was not increased with the BeEAM regimen. A prospective randomized trial will be necessary to confirm the beneficial effect of the BeEAM regimen in MCL patients undergoing ASCT.

High-dose Bendamustine-EAM followed by autologous stem cell rescue results in long-term remission rates in lymphoma patients, without renal toxicity

BACKGROUND

Autologous stem cell transplantation (ASCT) following BEAM (BCNU, etoposide, cytarabine, melphalan) conditioning is standard of care in relapsed low- and high-grade B-cell lymphoma (DLBCL) and other lymphoproliferative disorders, but BCNU is associated with interstitial pneumonia and an increased mortality. A less toxic regimen might improve the outcome of patients with lymphoma after transplantation.

OBJECTIVES

We investigated the role of bendamustine replacing BCNU in the BEAM regimen in patients with lymphoma undergoing ASCT.

PATIENTS/METHODS

The conditioning regimen BendaEAM consisted of bendamustine, cytarabine, etoposide, and melphalan and was used in patients with Hodgkin's disease (HD) and Non-Hodgkin lymphoma (NHL).

RESULTS

Forty-one patients with HD (n = 9) or NHL (n = 32) were consecutively treated with Benda-BEAM replacing BCNU. No pulmonary or renal toxicities occurred, and no patient died related to transplant. After a median follow-up of 55 months, CR rate was 56%, 18 patients (44%) showed progression after a median time of 7 months after transplantation (range: 2-29 months), and 11 patients (24%) have died, all due to lymphoma progression. The 1-, 2-, and 4-year PFS are 73.2%, 58.6%, and 55.6% and the 1-, 2-, and 4-year OS 85.4%, 78.0%, and 72.6%, respectively.

CONCLUSION

BendaEAM seems to be feasible with a promising response rate and acceptable toxicity.

The discovery and the development of bendamustine for the treatment of non-Hodgkin lymphoma

INTRODUCTION

Non-Hodgkin lymphoma (NHL) is a heterogeneous group of lymphoid malignancies. The treatment strategy for patients with NHL had remained unchanged until the advent of the era of molecular targeting agents. Although rituximab-containing chemotherapy has improved the response rates and survival of patients with B-cell NHL (B-NHL), several subtypes of B-NHL, especially indolent B-NHL and mantle cell lymphoma (MCL), remain incurable. Therefore, novel treatment modalities for B-NHL, especially for indolent B-NHL and MCL, are needed. Bendamustine is an old, but unique, multifunctional cytotoxic agent that exhibits structural similarity to alkylating agents and purine analogs. Areas covered: The basic aspects and preclinical development of bendamustine are summarized, followed by a discussion of the clinical development of bendamustine-based treatments for indolent B-NHL and MCL. Expert opinion: Bendamustine monotherapy or the use of bendamustine in combination with rituximab is highly effective against various types of hematological malignancies, especially relapsed or refractory indolent B-NHL, and exhibits an acceptable toxicity profile. Furthermore, bendamustine plus rituximab might be a promising treatment option for patients with untreated indolent B-NHL. Therefore, bendamustine has the potential to play an important role in the treatment of malignant lymphoma.

The combination effects of bendamustine with antimetabolites against childhood acute lymphoblastic leukemia cells

Bendamustine combined with other drugs is clinically efficacious for some adult lymphoid malignancies, but to date there are no reports of the use of such combinatorial approaches in pediatric patients. We investigated the in vitro activity of bendamustine combined with other antimetabolite drugs on B cell precursor acute lymphoblastic leukemia (BCP-ALL) cell lines established from pediatric patients with refractory or relapsed ALL. We also developed a mathematically drown improved isobologram method to assess the data objectively. Three BCP-ALL cell lines; YCUB-2, YCUB-5, and YCUB-6, were simultaneously exposed to various concentrations of bendamustine and cladribine, cytarabine, fludarabine, or clofarabine. Cell growth inhibition was determined using the WST-8 assay. Combinatorial effects were estimated using our improved isobologram method with IC80 (drug concentration corresponding to 80 % of maximum inhibition). Bendamustine alone inhibited ALL cell growth with mean IC80 values of 11.30-18.90 μg/ml. Combinations of bendamustine with other drugs produced the following effects: (1) cladribine; synergistic-to-additive on all cell lines; (2) cytarabine; synergistic-to-additive on YCUB-5 and YCUB-6, and synergistic-to-antagonistic on YCUB-2; (3) fludarabine; additive-to-antagonistic on YCUB-5, and synergistic-to-antagonistic on YCUB-2 and YCUB-6; (4) clofarabine; additive-to-antagonistic on all cell lines. Flow cytometric analysis also showed the combination effects of bendamustine and cladribine. Bendamustine/cladribine or bendamustine/cytarabine may thus represent a promising combination for salvage treatment in childhood ALL.

A phase 2 study of Rituximab-Bendamustine and Rituximab-Cytarabine for transplant-eligible patients with mantle cell lymphoma

Chemoimmunotherapy followed by autologous stem cell transplantation (ASCT) is a standard therapy for transplant-eligible patients with newly diagnosed mantle cell lymphoma (MCL). The achievement of complete remission (CR) and minimal residual disease (MRD) negativity are associated with better outcomes. We tested an induction regimen of rituximab/bendamustine followed by rituximab/high-dose cytarabine (RB/RC). This phase 2 study (NCT01661881) enrolled 23 transplant-eligible patients aged 42-69, of whom 70% were MCL international prognostic index low-risk. Patients received three cycles of RB followed by three cycles of RC. The primary endpoint of the trial was the rate of CR after six cycles of therapy, with a rate of 75% considered promising. 96% of patients achieved a CR/unconfirmed CR after treatment, meeting the primary objective. One patient progressed on study, one declined ASCT in CR, and the remaining 21 underwent successful stem cell collection and ASCT. After a median follow-up of 13 months, the progression-free survival rate was 96%. Among 15 MRD-evaluable patients who completed treatment, 93% achieved MRD negativity after RB/RC. In conclusion, RB/RC achieves very high CR and MRD negativity rates in transplant-eligible patients, with a favourable safety profile. RB/RC warrants further comparative studies, and may become a useful alternative to RCHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone)-based induction regimens in this patient population.

Determination and characterization of two degradant impurities in bendamustine hydrochloride drug product

Bendamustine hydrochloride is an alkylating antitumor agent with a good efficacy in the treatment of chronic lymphocytic leukemia (CLL) and B-cell non-Hodgkin's lymphoma (B-NHL). Under the stressed conditions, two degradant impurities in bendamustine hydrochloride drug product were detected by high-performance liquid chromatography. These two degradant impurities were isolated from preparative liquid chromatography, and were further characterized using Q-TOF/MS and nuclear magnetic resonance (NMR). Based on the MS and NMR spectral data, they were characterized as 4-[5-(2-chloro-ethylamino)-1-methyl-1H-benzoimidazol-2-yl] butyric acid hydrochloride (impurity-A) and 4-{5-[[2-(4-{5-[bis-(2-chloroethyl) amino]-1-methyl-1H-benzoimidazol-2-yl}-butyryloxy)-ethyl]-(2-chloroethyl)amino]-1-methyl-3a, 7a-dihydro-1H-benzoimidazol-2-yl} butyric acid hydrochloride (impurity-B). Isolation, structural elucidation of these two impurities by spectral data (Q-TOF/MS, (1)H NMR, (13)C NMR, D2O exchange NMR and two-dimensional NMR) and the probable formation mechanism of the impurities were discussed.

Downregulation of deoxycytidine kinase in cytarabine-resistant mantle cell lymphoma cells confers cross-resistance to nucleoside analogs gemcitabine, fludarabine and cladribine, but not to other classes of anti-lymphoma agents

BACKGROUND

Mantle cell lymphoma (MCL) is an aggressive type of B-cell non-Hodgkin lymphoma associated with poor prognosis. Implementation of high-dose cytarabine (araC) into induction therapy became standard-of-care for all newly diagnosed younger MCL patients. However, many patients relapse even after araC-based regimen. Molecular mechanisms responsible for araC resistance in MCL are unknown and optimal treatment strategy for relapsed/refractory MCL patients remains elusive.

METHODS

Five araC-resistant (R) clones were derived by long-term culture of five MCL cell lines (CTRL) with increasing doses of araC up to 50 microM. Illumina BeadChip and 2-DE proteomic analysis were used to identify gene and protein expression changes associated with araC resistance in MCL. In vitro cytotoxicity assays and experimental therapy of MCL xenografts in immunodeficient mice were used to analyze their relative responsiveness to a set of clinically used anti-MCL drugs. Primary MCL samples were obtained from patients at diagnosis and after failure of araC-based therapies.

RESULTS

Marked downregulation of deoxycytidine-kinase (DCK) mRNA and protein expression was identified as the single most important molecular event associated with araC-resistance in all tested MCL cell lines and in 50% primary MCL samples. All R clones were highly (20-1000x) cross-resistant to all tested nucleoside analogs including gemcitabine, fludarabine and cladribine. In vitro sensitivity of R clones to other classes of clinically used anti-MCL agents including genotoxic drugs (cisplatin, doxorubicin, bendamustine) and targeted agents (bortezomib, temsirolimus, rituximab) remained unaffected, or was even increased (ibrutinib). Experimental therapy of immunodeficient mice confirmed the anticipated loss of anti-tumor activity (as determined by overall survival) of the nucleoside analogs gemcitabine and fludarabine in mice transplanted with R clone compared to mice transplanted with CTRL cells, while the anti-tumor activity of cisplatin, temsirolimus, bortezomib, bendamustine, cyclophosphamide and rituximab remained comparable between the two cohorts.

CONCLUSIONS

Acquired resistance of MCL cells to araC is associated with downregulation of DCK, enzyme of the nucleotide salvage pathway responsible for the first phosphorylation (=activation) of most nucleoside analogs used in anti-cancer therapy. The data suggest that nucleoside analogs should not be used in the therapy of MCL patients, who relapse after failure of araC-based therapies.

Purine analog-like properties of bendamustine underlie rapid activation of DNA damage response and synergistic effects with pyrimidine analogues in lymphoid malignancies

Bendamustine has shown considerable clinical activity against indolent lymphoid malignancies as a single agent or in combination with rituximab, but combination with additional anti-cancer drugs may be required for refractory and/or relapsed cases as well as other intractable tumors. In this study, we attempted to determine suitable anti-cancer drugs to be combined with bendamustine for the treatment of mantle cell lymphoma, diffuse large B-cell lymphoma, aggressive lymphomas and multiple myeloma, all of which are relatively resistant to this drug, and investigated the mechanisms underlying synergism. Isobologram analysis revealed that bendamustine had synergistic effects with alkylating agents (4-hydroperoxy-cyclophosphamide, chlorambucil and melphalan) and pyrimidine analogues (cytosine arabinoside, gemcitabine and decitabine) in HBL-2, B104, Namalwa and U266 cell lines, which represent the above entities respectively. In cell cycle analysis, bendamustine induced late S-phase arrest, which was enhanced by 4-hydroperoxy-cyclophosphamide, and potentiated early S-phase arrest by cytosine arabinoside (Ara-C), followed by a robust increase in the size of sub-G1 fractions. Bendamustine was able to elicit DNA damage response and subsequent apoptosis faster and with shorter exposure than other alkylating agents due to rapid intracellular incorporation via equilibrative nucleoside transporters (ENTs). Furthermore, bendamustine increased the expression of ENT1 at both mRNA and protein levels and enhanced the uptake of Ara-C and subsequent increase in Ara-C triphosphate (Ara-CTP) in HBL-2 cells to an extent comparable with the purine analog fludarabine. These purine analog-like properties of bendamustine may underlie favorable combinations with other alkylators and pyrimidine analogues. Our findings may provide a theoretical basis for the development of more effective bendamustine-based combination therapies.

Management of relapsed/refractory mantle cell lymphoma: a review of current therapeutic strategies

Abstract Despite recent advances in therapeutic strategies, a large proportion of patients with mantle cell lymphoma (MCL) experience progression after first-line treatment. Several attempts have been made to assess the role of different therapies for the treatment of patients with relapsed/refractory mantle cell lymphoma; however, a consensus on the optimal therapeutic strategy for each individual patient has not been reached. Overall, clinical evidence from phase II studies shows that high-dose cytarabine containing regimens, stem cell transplant and different biological agents all have promising activity with acceptable safety profiles. Therefore, these therapies can represent suitable treatment options for patients with relapsed/refractory MCL. Among different biological agents, at present only temsirolimus has been tested in a phase III study. This review considers available evidence on the management of relapsed/refractory MCL as discussed during a consensus meeting on the current treatment strategies for MCL.

Combination of Rituximab, Bendamustine, and Cytarabine for Patients With Mantle-Cell Non-Hodgkin Lymphoma Ineligible for Intensive Regimens or Autologous Transplantation

Purpose

The combination of bendamustine (B) and rituximab (R) is efficacious, with favorable toxicity in mantle-cell lymphoma (MCL). In this phase II study, we combined cytarabine with R and B (R-BAC) in patients with MCL age ≥ 65 years who were previously untreated or relapsed or refractory (R/R) after one prior immunochemotherapy treatment.

Patients and Methods

In stage one, we established the maximum-tolerated dose (MTD) of cytarabine in R-BAC. In stage two, patients received R (375 mg/m2 intravenously [IV] on day 1), B (70 mg/m2 IV on days 2 and 3), and cytarabine (MTD IV on days 2 to 4) every 28 days for four to six cycles. The primary end point (overall response rate [ORR]) was evaluated by positron emission tomography. Secondary end points included safety, progression-free survival (PFS), response duration, and overall survival.

Results

Forty patients (median age, 70 years; 20 previously untreated patients) were enrolled; 93% had Ann Arbor stage III/IV disease; 49% had high Mantle Cell International Prognostic Index scores, with 15% blastoid histology. All R/R patients (35% refractory) had previously received R-containing regimens. The cytarabine MTD used in stage two was 800 mg/m2, and R-BAC was well tolerated, with an 85% treatment completion rate. The major toxicity was transient grades 3 to 4 thrombocytopenia (87% of patients); febrile neutropenia occurred in 12%. The ORR was 100% (95% complete response [CR]) for previously untreated and 80% (70% CR) for R/R patients. The 2-year PFS rate (± standard deviation) was 95% ± 5% for untreated and 70% ± 10% for R/R patients.

Conclusion

R-BAC is well tolerated and active against MCL.

The combination of rituximab, bendamustine, and cytarabine for heavily pretreated relapsed/refractory cytogenetically high-risk patients with chronic lymphocytic leukemia

Treatment of patients with B-cell chronic lymphocytic leukemia (CLL) relapsed/refractory (R/R) to conventional treatments is particularly challenging. The combination of bendamustine and cytarabine has demonstrated distinct and synergistic mechanisms of action in preclinical studies on cell lines and primary tumor cells of several B-cell lymphomas, including 17p deleted or TP53 mutated CLL. The efficacy of rituximab (375 mg/m(2) , Day 1), plus bendamustine (70 mg/m(2) , days 1-2), and cytarabine (800 mg/m(2) , Day 1-3; R-BAC), every 28 days for up to four courses, was evaluated in a pilot trial enrolling 13 patients with very selected high-risk R/R CLL. All patients (median age 60 years, range 53-74) had symptomatic Binet stage B or C active disease requiring treatment, were characterized by adverse cytogenetics (17p deletion, 11q deletion, or both), unmutated immunoglobulin heavy-chain variable region, and were heavily pretreated (1-5, median three previous lines). Overall, R-BAC was well tolerated with limited non-hematological toxicity. Major toxicities were transient Grade 3/4 neutropenia and thrombocytopenia in 84% and 85% of patients, respectively. Overall response rate (OR) was 84%, including complete and partial response in 38% and 46% of patients, respectively. Patients with 17p deletion had an OR of 78%. After a median follow-up of 17 months, median progression-free survival was 16 months while median overall survival (OS) was not reached (1-year OS: 75 ± 13%). R-BAC is an active regimen in R/R heavily pretreated high-risk patients with CLL, representing an option for the treatment of patients that are usually refractory to standard therapy.

Cytosine arabinoside potentiates the apoptotic effect of bendamustine on several B- and T-cell leukemia/lymphoma cells and cell lines

Bendamustine and cytosine arabinoside (ara-c) are commonly used cytotoxic agents with unique mechanisms of action. We have previously reported a striking additive cytotoxic effect of the consecutive combination of bendamustine and ara-c in mantle cell lymphoma (MCL) cell lines. In the present study, cell lines of follicular lymphoma (DOHH-2), chronic lymphocytic leukemia/lymphoma (EHEB), diffuse large B-cell lymphoma (SU-DHL-4), T-cell leukemia/lymphoma (JURKAT and KARPAS-299) and MCL (JEKO-1 and GRANTA-519) were exposed to the two single drugs or the drugs combined, given simultaneously and consecutively. Peripheral blood chronic lymphocytic leukemia (CLL) B-cells from five patients were also analyzed. Apoptosis, cell proliferation/metabolic activity and mitochondrial damage were evaluated. The combination index (CI) was used to assess synergy between the drugs. Bendamustine exhibited a relevant cytotoxic effect that was dose- and time-dependent, except for SU-DHL-4 and T-cell lymphoma cells. The addition of ara-c after bendamustine significantly potentiated the single-drug cytotoxic effect of bendamustine on all cell lines, including 17p - CLL B-cells, JURKAT and SU-DHL-4, the latter presenting the highest synergism (CI < 0.01). Bendamustine and ara-c are highly synergistic on T- and B-cell lymphoma cells and cell lines, similar to MCL, overcoming resistance to the single agents.