Metabolism and mechanisms of action of bendamustine: rationales for combination therapies

Bendamustine in the treatment of patients with indolent non-Hodgkin lymphoma refractory or relapse to rituximab treatment: An open-label, single-agent, multicenter study in China

BACKGROUND

The optimal treatment strategy for refractory or relapse (R/R) indolent non-Hodgkin lymphoma (iNHL) has not been fully identified. This study aims to investigate the efficacy and tolerance of bendamustine hydrochloride developed in native Chinese corporation in the treatment of patients with R/R iNHL.

METHODS

A total of 101 patients from 19 centers were enrolled in this study from July 2016 to February 2019. Bendamustine hydrochloride (120 mg/m² ) was given on days 1 and 2 of each 21-day treatment cycle for six planned cycles or up to eight cycles if tolerated. Parameters of efficacy and safety were analyzed.

RESULTS

The median age of the patients was 53.44 (range, 24.4-74.6) years old. A total of 56 (55.44%) patients completed at least six treatment cycles, and the relative dose intensity was 93.78%. The overall response rate was 72.28%, and the median duration of response was 15.84 months (95% confidence interval [CI], 13.77-27.48 months). Median progression-free survival was 16.52 months (95% CI, 14.72-23.41 months), and the median overall survival was not reached. Grade 3 or 4 hematologic toxicities included neutropenia (77.22%), thrombocytopenia (29.70%), and anemia (15.84%). The most frequent nonhematologic adverse events (any grade) included nausea, vomiting, fatigue, fever, decreased appetite, and weight loss. Seven patients died during the trial, and four cases may be related to the investigational drug.

CONCLUSIONS

This study reveals that bendamustine hydrochloride is a feasible treatment option for the indolent B-cell non-Hodgkin lymphoma patient who has not remitted or relapsed after treatment with rituximab. All adverse events were predictable and manageable.

Post-Transplantation Cyclophosphamide Uniquely Restrains Alloreactive CD4+ T-Cell Proliferation and Differentiation After Murine MHC-Haploidentical Hematopoietic Cell Transplantation

Post-transplantation cyclophosphamide (PTCy) reduces the incidence and severity of graft-versus-host disease (GVHD), thereby improving the safety and accessibility of allogeneic hematopoietic cell transplantation (HCT). We have shown that PTCy works by inducing functional impairment and suppression of alloreactive T cells. We also have identified that reduced proliferation of alloreactive CD4⁺ T cells at day +7 and preferential recovery of CD4⁺CD25⁺Foxp3⁺ regulatory T cells (T_regs) at day +21 are potential biomarkers associated with optimal PTCy dosing and timing in our B6C3F1→B6D2F1 MHC-haploidentical murine HCT model. To understand whether the effects of PTCy are unique and also to understand better the biology of GVHD prevention by PTCy, here we tested the relative impact of cyclophosphamide compared with five other optimally dosed chemotherapeutics (methotrexate, bendamustine, paclitaxel, vincristine, and cytarabine) that vary in mechanisms of action and drug resistance. Only cyclophosphamide, methotrexate, and cytarabine were effective in preventing fatal GVHD, but cyclophosphamide was superior in ameliorating both clinical and histopathological GVHD. Flow cytometric analyses of blood and spleens revealed that these three chemotherapeutics were distinct in constraining conventional T-cell numerical recovery and facilitating preferential T_reg recovery at day +21. However, cyclophosphamide was unique in consistently reducing proliferation and expression of the activation marker CD25 by alloreactive CD4⁺Foxp3^- conventional T cells at day +7. Furthermore, cyclophosphamide restrained the differentiation of alloreactive CD4⁺Foxp3^- conventional T cells at both days +7 and +21, whereas methotrexate and cytarabine only restrained differentiation at day +7. No chemotherapeutic selectively eliminated alloreactive T cells. These data suggest that constrained alloreactive CD4⁺Foxp3^- conventional T-cell numerical recovery and associated preferential CD4⁺CD25⁺Foxp3⁺ T_reg reconstitution at day +21 may be potential biomarkers of effective GVHD prevention. Additionally, these results reveal that PTCy uniquely restrains alloreactive CD4⁺Foxp3^- conventional T-cell proliferation and differentiation, which may explain the superior effects of PTCy in preventing GVHD. Further study is needed to determine whether these findings also hold true in clinical HCT.

Brentuximab vedotin in association with bendamustine in refractory or multiple relapsed Hodgkin lymphoma. A retrospective real-world study

OBJECTIVE AND METHODS

In order to assess the efficacy of brentuximab vedotin (Bv) in combination with bendamustine (B) in multiple relapsed or refractory (RR) classic Hodgkin lymphoma (cHL), medical records of 47 patients treated with BvB in second relapse or beyond were reviewed.

RESULTS

The median number of previous treatments was 2 (1-4). Bv was given at 1.8 mg/kg on day 1 and bendamustine at 90 mg/m² on days 1 and 2 of a 21-day cycle. The median number of BvB cycles was 4 (2-7), and all patients were evaluable for efficacy. The CR and OR rates were 49% and 79%, respectively; 67% of responding patients and 2 in stable disease proceeded to a SCT procedure. After a median follow-up of 19 months (5-47), median PFS was 18 months (95%CI: 23-29), and the 2-year OS was 72%. Significantly longer PFS and OS were observed in patients attaining a major clinical response to treatment and in those who received consolidation with SCT. Fifteen (32%) patients experienced severe (G > 2) toxicity. The main toxicities were neutropenia (23%), gastrointestinal (10%), peripheral sensory neuropathy (11%), and infection (4%).

CONCLUSION

Our real-world results suggest that BvB is an effective third-line rescue and bridge-to-transplant regimen for RR-cHL patients.

Nitrogen Mustards as Anticancer Chemotherapies: Historic Perspective, Current Developments and Future Trends

Nitrogen mustards, a family of DNA alkylating agents, marked the start of cancer pharmacotherapy. While traditionally characterized by their dose-limiting toxic effects, nitrogen mustards have been the subject of intense research efforts, which have led to safer and more effective agents. Even though the alkylating prodrug mustards were first developed decades ago, active research on ways to improve their selectivity and cytotoxic efficacy is a currently active topic of research. This review addresses the historical development of the nitrogen mustards, outlining their mechanism of action, and discussing the improvements on their therapeutic profile made through rational structure modifications. A special emphasis is made on discussing the nitrogen mustard prodrug category, with Cyclophosphamide (CPA) serving as the main highlight. Selected insights on the latest developments on nitrogen mustards are then provided, limiting such information to agents that preserve the original nitrogen mustard mechanism as their primary mode of action. Additionally, future trends that might follow in the quest to optimize these invaluable chemotherapeutic medications are succinctly suggested.

Novel Therapies and Approaches to Relapsed/Refractory HL Beyond Chemotherapy

Although Hodgkin lymphoma (HL) is highly curable with first-line therapy, relapses occur in approximately 10–20% of patients with early stage disease and 30–40% of patients with advanced stage disease. The standard approach for relapsed or refractory disease is salvage therapy, followed by consolidation with high dose therapy and autologous stem cell transplant (ASCT). Patients who achieve a complete response to salvage therapy prior to ASCT have better outcomes, thus recent studies have focused on incorporating newer agents in this setting. Major challenges in the management of relapsed patients remain how to choose and sequence the many salvage therapies that are currently available and how to best incorporate novel agents in the current treatment paradigms. In this article, we will summarize the most recent advances in the management of patients with recurrent HL and will mainly focus on the role of new agents approved and under investigation. Aside from brentuximab vedotin and checkpoint inhibitors, other novel agents and therapies are showing promising early results. However, at least with some of the newest targeted strategies, it is important to recognize that we are facing new challenges in terms of toxicities, which require very close monitoring and education of both the patient and treating physician.

Assessment of bendamustine-induced genotoxicity in eukaryotic cells

Bendamustine, an anticancer drug with alkylating properties, is widely used to treat hematological malignancies. Since the nitrogen mustard family alkylators induce DNA damages and have been associated with an elevated risk of second malignancy, current study evaluates the cytotoxic, mutagenic, and recombinogenic effects of bendamustine by using, respectively the mitotic index assay, the in vitro mammalian cell micronucleus test (Mnvit) and the chromosome aberration (CA) test in human peripheral lymphocytes, and the in vivo homozygotization assay in Aspergillus nidulans, which detects the loss of heterozygosity (LOH) due to somatic recombination. Bendamustine (6.0 µg/ml, 9.0 µg/ml, and 12.0 µg/ml) induced a statistically significant concentration-related increase in the frequencies of micronuclei and a significant reduction in the cytokinesis block proliferation index (CBPI) rates when compared to negative control. In the CA test, bendamustine significantly increased the frequencies of structural aberrations at the three tested concentrations when compared to the negative control. Aspergillus nidulans diploids, obtained after bendamustine treatment (6.0 µg/ml, 12.0 µg/ml, and 24.0 µg/ml), produced, after haploidization, homozygotization index (HI) rates higher than 2.0 and significantly different from the negative control. Since bendamustine showed genotoxic effects in all tested concentrations, two of them corresponding to the peak plasma concentrations observed in cancer patients treated with bendamustine, data provided in the current research work may be useful to identify the most appropriate dosage regimen to achieve the efficacy and safety of this anticancer medication.

A phase I-II trial of fludarabine, bendamustine and rituximab (FBR) in previously treated patients with CLL

Chemoimmunotherapy regimens have been the standard first-line therapy for patients with chronic lymphocytic leukemia (CLL). For young, fit patients the standard of care is combination of fludarabine, cyclophosphamide, and rituximab (FCR). Based on the preclinical work demonstrating that bendamustine combined with fludarabine resulted in increased DNA damage, we designed a phase I-II clinical trial with fludarabine, bendamustine, and rituximab (FBR) for patients with relapsed/refractory CLL. Treatment consisted of fludarabine 20 mg/m² daily x 3 days and rituximab 375-500 mg/m² x 1 day. Phase I included bendamustine at increasing doses of 20, 30, 40, or 50 mg/m² daily x 3 days; phase II was with FR, and B at the selected dose. DNA damage response (H2AX phosphorylation) was evaluated in a subset of patients. Fifty-one patients were enrolled. The median age was 62 years; median number of prior therapies was 2; 40% had del(11q); and 41 patients had received prior FCR-based therapies. Hematologic toxicity was more common in =40 mg/m² dose cohorts. Maximum tolerated dose (MTD) was not identified. Bendamustine-elicited H2AX phosphorylation was not dose-dependent, but markedly increased after fludarabine. We identified bendamustine 30 mg/m² as the safe dose for phase II. The overall response rate (ORR) was 67% with 36% complete response (CR) / CR with incomplete count recovery (CRi). Younger patients (<65 years) had significantly higher ORR (81% vs. 50%; p=0.038). The median progression-free survival was 19 months, and the median overall survival was 52.5 months. FBR is an effective and tolerable CIT regimen for patients with relapsed CLL.

Idelalisib and bendamustine combination is synergistic and increases DNA damage response in chronic lymphocytic leukemia cells

Idelalisib is a targeted agent that potently inhibits PI3Kδ which is exclusively expressed in hematological cells. Bendamustine is a well-tolerated cytotoxic alkylating agent which has been extensively used for treatment of chronic lymphocytic leukemia (CLL). Both these agents are FDA-approved for CLL. To increase the potency of idelalisib and bendamustine, we tested their combination in primary CLL lymphocytes. While each compound alone produced a moderate response, combination at several concentrations resulted in synergistic cytotoxicity. Idelalisib enhanced the bendamustine-mediated DNA damage/repair response, indicated by the phosphorylation of ATM, Chk2, and p53. Each drug alone activated γH2AX but combination treatment further increased the expression of this DNA damage marker. Compared with the control, idelalisib treatment decreased global RNA synthesis, resulting in a decline of early-response and short-lived MCL1 transcripts. In concert, there was a decline in total Mcl-1 protein in CLL lymphocytes. Isogenic mouse embryonic fibroblasts lacking MCL1 had higher sensitivity to bendamustine alone or in combination compared to MCL1 proficient cells. Collectively, these data indicate that bendamustine and idelalisib combination therapy should be investigated for treating patients with CLL.

Bendamustine and its role in the treatment of unfit patients with chronic lymphocytic leukaemia: a perspective review

With a median age of 72 years at first diagnosis, chronic lymphocytic leukaemia (CLL) is a disease of the elderly. At this age, many patients cannot bear an intensive chemoimmunotherapy like fludarabine, cyclophosphamide and rituximab (FCR), and therapeutic decisions are commonly complicated by a high burden of accompanying comorbidities. Clinical trials, on the other hand, are mostly designed to include a far healthier and younger trial population, with a median age in most studies well below 70 years, leading to an insufficient reflection of clinical reality. With the introduction of new targeted therapies, treatment of CLL is currently undergoing a profound change. New compounds like ibrutinib or idelalisib have enlarged the therapeutic options in treating CLL. However, so far, these oral medications imply continuous intake by the patient, which will at some point lead to the issue of adherence in most patients. In addition, long-term experiences are largely missing. In this setting, one of the oldest chemoactive substances remains a viable option for many CLL patients and their treating physicians: bendamustine, a nitrogen-mustard derivative, has proven to be a safe and efficient agent for treatment of CLL in the first- and second-line setting. In particular, there is some evidence that the substance is relatively well tolerated in elderly and unfit patients. In this review, we summarize the current data on bendamustine in the treatment of elderly and unfit patients with CLL and aim to provide a concise analysis and outlook on the current and future role of this substance in the era of new targeted agents.

OptoGluNAM4.1, a Photoswitchable Allosteric Antagonist for Real-Time Control of mGlu4 Receptor Activity

OptoGluNAM4.1, a negative allosteric modulator (NAM) of metabotropic glutamate receptor 4 (mGlu4) contains a reactive group that covalently binds to the receptor and a blue-light-activated, fast-relaxing azobenzene group that allows reversible receptor activity photocontrol in vitro and in vivo. OptoGluNAM4.1 induces light-dependent behavior in zebrafish and reverses the activity of the mGlu4 agonist LSP4-2022 in a mice model of chronic pain, defining a photopharmacological tool to better elucidate the physiological roles of the mGlu4 receptor in the nervous system.

Determination of Bendamustine in Human Plasma and Urine by LC-FL Methods: Application in a Drug Monitoring

Simple and sensitive liquid chromatography (LC) methods with fluorescence (FL) detection for the determination of bendamustine (BM) in human plasma and urine were developed and validated. The procedure of BM extraction from a plasma sample involved solid-phase extraction with a C18 SPE column, while liquid–liquid extraction with dichloromethane was applied for a urine sample. In both methods, cinoxacin was used as the internal standard. Chromatographic separations were performed on a Synergi Max-RP column, while FL detector was set at the excitation wavelength of 328 nm and the emission wavelength of 420 nm. The LC-FL methods were validated for accuracy, precision, selectivity, linearity, recovery, and stability. The detection limits for BM were 0.5 and 2.5 ng mL⁻¹ in plasma and urine, respectively. The intra-day and inter-day precisions were less than 9.86 %, while the accuracies were higher than 92.63 and 94.29 % for BM in plasma and urine, respectively. The proposed LC-FL methods were sensitive, robust, and specific, allowing reliable drug quantification in plasma and urine samples. The methodologies were successfully applied to monitoring of BM in a child with cancer treated with BM.

Pt(iv) derivatives of cisplatin and oxaliplatin with phenylbutyrate axial ligands are potent cytotoxic agents that act by several mechanisms of action

The Pt(iv) derivative of cisplatin, ctc-[Pt(NH₃)₂(PhB)₂Cl₂], is a p53 independent very potent cytotoxic agent that kills cancer cells by triggering various cellular pathways.

Our study demonstrates that Pt(iv) derivative of cisplatin, with two axial PhB ligands, ctc-[Pt(NH₃)₂(PhB)₂Cl₂], is a very potent cytotoxic agent against many different human cancer cell lines and is up to 100 fold more potent than cisplatin, and significantly more potent than the Pt(iv) derivatives of cisplatin with either two hydroxido, two acetato or two valproato ligands. The high potency of this compound (and some others) is due to several factors including enhanced internalization, probably driven by “synergistic accumulation” of both the Pt moiety and the phenylbutyrate, that correlates with enhanced DNA binding and cytotoxicity. ctc-[Pt(NH₃)₂(PhB)₂Cl₂] inhibits 60–70% HDAC activity in cancer cells, at levels below the IC₅₀ values of PhB, suggesting synergism between Pt and PhB. Mechanistically, ctc-[Pt(NH₃)₂(PhB)₂Cl₂] induces activation of caspases (3 and 9) triggering apoptotic signaling via the mitochondrial pathway. Data also suggest that the antiproliferative effect of ctc-[Pt(NH₃)₂(PhB)₂Cl₂] may not depend of p53. Pt(iv) derivatives of cisplatin with either two axial PhB or valproate ligands are more potent than their oxaliplatin analogs. ctc-[Pt(NH₃)₂(PhB)₂Cl₂] is significantly more potent than its valproate analog ctc-[Pt(NH₃)₂(VPA)₂Cl₂]. These compounds combine multiple effects such as efficient uptake of both Pt and PhB with DNA binding, HDAC inhibition and activation of caspases to effectively kill cancer cells.

Clinical Options in Relapsed or Refractory Hodgkin Lymphoma: An Updated Review

Hodgkin lymphoma (HL) is a potentially curable lymphoma, and modern therapy is expected to successfully cure more than 80% of the patients. Second-line salvage high-dose chemotherapy and autologous stem cell transplantation (auto-SCT) have an established role in the management of refractory and relapsed HL, leading to long-lasting responses in approximately 50% of relapsed patients and a minority of refractory patients. Patients progressing after intensive treatments, such as auto-SCT, have a very poor outcome. Allogeneic SCT represents the only strategy with a curative potential for these patients; however, its role is controversial. Based on recent knowledge of HL pathology, biology, and immunology, antibody-drug conjugates targeting CD30, small molecule inhibitors of cell signaling, and antibodies that inhibit immune checkpoints are currently explored. This review will discuss the clinical results regarding auto-SCT and allo-SCT as well as the current role of emerging new treatment strategies.

Optimal use of bendamustine in hematologic disorders: Treatment recommendations from an international consensus panel - an update

Bendamustine has achieved widespread international regulatory approval and is a standard agent for the treatment for chronic lymphocytic leukemia (CLL), indolent non-Hodgkin lymphoma and multiple myeloma. Since approval, the number of indications for bendamustine has expanded to include aggressive non-Hodgkin lymphoma and Hodgkin lymphoma and novel targeted therapies, based on new bendamustine regimens/combinations, are being developed against CLL and lymphomas. In 2010, an international panel of bendamustine experts met and published a set of recommendations on the safe and effective use of bendamustine in patients suffering from hematologic disorders. In 2014, this panel met again to update these recommendations since the clarification of issues including optimal dosing and management of bendamustine-related toxicities. The aim of this report is to communicate the latest consensus on the use of bendamustine, permitting the expansion of its safe and effective administration, particularly in new combination therapies.

Bendamustine in multiple myeloma

The advent of high-dose melphalan with autologous stem-cell transplantation (ASCT), the availability of novel agents such as thalidomide, lenalidomide (immunomodulatory drugs or IMiDs) and bortezomib (proteasome inhibitor) and improvements in supportive care have allowed to increase overall survival in multiple myeloma (MM) patients; nevertheless, MM remains an incurable pathology. For this reason, newer agents are required for continued disease control. Bendamustine is an old drug rediscovered in the last decade. In fact, its unique mechanism of action with structural similarities to both alkylating agents and antimetabolities, but which is not cross-resistant to alkylating agents, has reawakened interest in the use of this drug in the treatment of MM. Studies have proven the safety and efficacy of bendamustine administered alone or in combination with new drugs in both upfront and relapse/refractory settings of MM patients, including those with renal impairment. Moreover, bendamustine has been successfully used as conditioning for autologous stem-cell transplantation. Finally, the use of bendamustine does not compromise peripheral blood stem-cell collection. This drug is generally well tolerated, with the majority of adverse events being due to myelosuppression. Non-haematological adverse events are infrequent and usually mild.

Establishment of paclitaxel-resistant breast cancer cell line and nude mice models, and underlying multidrug resistance mechanisms in vitro and in vivo

BACKGROUND

Breast cancer is a common malignant tumor which affects health of women and multidrug resistance (MDR) is one of the main factors leading to failure of chemotherapy. This study was conducted to establish paclitaxel-resistant breast cancer cell line and nude mice models to explore underlying mechanisms of MDR.

METHODS

The breast cancer drug-sensitive cell line MCF-7 (MCF-7/S) was exposed in stepwise escalating paclitaxel (TAX) to induce a resistant cell line MCF-7/TAX. Cell sensitivity to drugs and growth curves were measured by MTT assay. Changes of cell morphology and ultrastructure were examined by optical and electron microscopy. The cell cycle distribution was determined by flow cytometry. Furthermore, expression of proteins related to breast cancer occurrence and MDR was tested by immunocytochemistry. In Vivo, nude mice were injected with MCF-7/S and MCF-7/TAX cells and weights and tumor sizes were observed after paclitaxel treatment. In addition, proteins involved breast cancer and MDR were detected by immunohistochemistry.

RESULTS

Compared to MCF-7/S, MCF-7/TAX cells had a higher resistance to paclitaxel, cross-resistance and prolonged doubling time. Moreover, MCF-7/TAX showed obvious alterations of ultrastructure. Estrogen receptor (ER) expression was low in drug resistant cells and tumors while expression of human epidermal growth factor receptor 2 (HER2) and Ki-67 was up-regulated. P-glycoprotein (P-gp), lung resistance-related protein (LRP) and glutathione-S-transferase-π (GST-π) involved in the MDR phenotype of resistant cells and tumors were all overexpressed.

CONCLUSION

The underlying MDR mechanism of breast cancer may involve increased expression of P-gp, LRP and GST-π.

Bendamustine and prednisone in combination with bortezomib (BPV) in the treatment of patients with newly diagnosed/untreated multiple myeloma

INTRODUCTION

Bortezomib is a proteasome inhibitor that has shown important clinical efficacy either as a single agent or in combination in patients with multiple myeloma (MM). In the present protocol, bortezomib was combined with bendamustine and prednisone, in order to assess the efficacy and safety of this combination therapy in patients with newly diagnosed/untreated MM.

METHODS

Between June 2006 and October 2013, 49 patients with newly diagnosed/untreated MM were treated with bendamustine 60 mg/m(2) on days 1 and 2, bortezomib 1.3 mg/m(2) on days 1, 4, 8 and 11, and prednisone 100 mg on days 1, 2, 4, 8 and 11 bendamustine, prednisone and bortezomib (BPV) once every 21 days. Patients were divided into three groups: group A (n = 19) consisted of patients with normal renal function or mild dysfunction (eGFR ≥ 60 ml/min), group B (n = 15) patients with moderate or severe renal dysfunction (eGFR 15-59 ml/min) and group C (n = 15) patients with renal failure/dialysis (eGFR <15 ml/min).

RESULTS

A median number of two (range 1-5) BPV treatment cycles were given to the patients. The majority of the patients (n = 40, 82 %) responded after at least one cycle of BPV therapy with five stringent complete responses (CRs), nine near complete responses, 12 very good partial responses and 14 partial responses. Five patients had MR, three stable and one progressive disease. After a median observation time of 13 months, progression-free survival (PFS) and overall survival (OS) at 12 months were 92 and 94 %, respectively, for patients with normal renal function or mild renal dysfunction (group A) and 83 and 93 %, respectively, for patients with moderate or severe renal dysfunction (group B). Outcome for these patients was slightly better but not statistically significantly better than that for patients with renal failure/dialysis (group C), who had a PFS, and OS of 66 % (p = 0.08) and 73 % (p = 0.05), respectively. These results indicate that this BPV combination is feasible, effective and well tolerated in patients with newly diagnosed MM and normal or impaired renal function.

Bendamustine-based therapy as first-line treatment for non-Hodgkin lymphoma

Recently, bendamustine has become an important agent in the treatment for patients with lymphoid malignancies. Although the drug has received approval for second-line therapy in indolent lymphoma, a growing body of evidence suggests its efficacy and safety in first-line use. The results of randomised and observational studies with bendamustine as front-line therapy in non-Hodgkin lymphoma (NHL) with emphasis on efficacy and toxicity are presented. Furthermore, completed and ongoing clinical trials evaluating upfront bendamustine effectiveness in combination with other agents are discussed. The review refers mainly to indolent lymphoma, mantle cell lymphoma and aggressive lymphoma, as the most commonly diagnosed NHL types. Finally, we elaborated on the safety profile of bendamustine and the perspectives of using the drug as a first-line therapy.

Evaluation of bendamustine in combination with fludarabine in primary chronic lymphocytic leukemia cells

The fludarabine and cyclophosphamide couplet has become the backbone of the chronic lymphocytic leukemia (CLL) standard of care. Although this is an effective treatment, it results in untoward toxicity. Bendamustine is a newly approved and better-tolerated alkylating agent. We hypothesized that similar to cyclophosphamide, bendamustine-induced DNA damage will be inhibited by fludarabine, resulting in increased cytotoxicity. To test this hypothesis and the role of the stromal microenvironment in this process, we treated CLL lymphocytes in vitro with each drug alone and in combination. Simultaneous or prior addition of fludarabine to bendamustine resulted in maximum cytotoxicity assayed by 3,3'-dihexyloxacarbocyanine iodine negativity, annexin positivity, and poly (adenosine 5'-diphosphate-ribose) polymerase cleavage. Cytotoxicity elicited by combination of both agents was similar in these malignant B cells cultured either in suspension or on marrow stroma cells. Cell death was associated with DNA damage response, which was determined by phosphorylation of H2AX and unscheduled DNA synthesis. H2AX activation was maximum with the drug combination, and unscheduled DNA synthesis induced by bendamustine was blocked by fludarabine. In parallel, ATM, Chk2, and p53 were phosphorylated and PUMA was induced. Cell death was caspase independent; however, caspases did decrease levels of Mcl-1 survival protein. These data provide a rationale for combining fludarabine with bendamustine for patients with CLL.

A Canadian perspective on the safe administration of bendamustine and the prevention and management of adverse events

Although bendamustine has been used to treat lymphoproliferative disorders for decades, it has only recently been approved for use in Canada. Thus, Canadian recommendations on the administration of bendamustine and the management of common adverse events (aes) are needed. This article highlights effective management and assessment strategies recommended by Canadian nurses and pharmacists for the most common aes arising from the use of bendamustine in patients with chronic lymphocytic leukemia and indolent non-Hodgkin lymphoma. Those strategies include administering bendamustine over 60 minutes instead of 30 minutes, administering pre-medications to control infusion-related reactions and nausea, hydrating patients to minimize fatigue, and using free-flowing saline at the closest port to prevent phlebitis.

An old drug with a new future: bendamustine in multiple myeloma

INTRODUCTION

Bendamustine is a unique bifunctional alkylating agent with promising activity in multiple myeloma (MM). It is currently licensed in Europe for use as frontline treatment with prednisolone for patients with MM who are unsuitable for transplantation and who are contraindicated for thalidomide and bortezomib therapy.

AREAS COVERED

Studies evaluating the safety and efficacy of bendamustine administered alone or in combination in both the upfront and relapse settings of MM patients, including those with renal insufficiency, were reviewed. The use of bendamustine as conditioning for autologous stem-cell transplantation and the possibility of stem-cell mobilization after bendamustine therapy are discussed.

EXPERT OPINION

Bendamustine seems to be efficacious either in monotherapy or in combination with other drugs in previously treated or untreated patients. This is due to its unique mechanism of action including its ability to activate apoptosis and inhibit mitotic checkpoints, making it potentially more effective than other alkylating agents. Moreover, it has an acceptable toxicity profile and is suitable for patients with renal impairment. Finally, this drug does not seem to compromise the possibility of achieving a stem-cell mobilization. Nonetheless, data from Phase III studies demonstrating its effectiveness in terms of overall survival are not yet available.

New drugs and targeted treatments in Hodgkin's lymphoma

New drugs are being developed in recent years that may change the handling of relapsed and refractory Hodgkin's lymphoma patients. Brentuximab vedotin treatment has already been approved by the FDA; and other drugs are promising, such as histone deacetylase inhibitors, bendamustine, lenalidomide and m-TOR inhibitors.

Phase II study of bendamustine in relapsed and refractory Hodgkin lymphoma

PURPOSE

Limited data exist regarding the activity of bendamustine in Hodgkin lymphoma (HL). This phase II study evaluated the efficacy of bendamustine in relapsed and refractory HL.

PATIENTS AND METHODS

Patients with relapsed and refractory HL who were ineligible for autologous stem-cell transplantation (ASCT), or for whom this treatment failed, received bendamustine 120 mg/m(2) as a 30-minute infusion on days 1 and 2 every 28 days with growth factor support. The primary end point was overall response rate (ORR). A secondary end point was referral rate to allogeneic stem-cell transplantation (alloSCT) for patients deemed eligible for alloSCT at the time of enrollment.

RESULTS

Of the 36 patients enrolled, 34 were evaluable for response. Patients had received a median of four prior treatments, and 75% had relapsed after ASCT. The ORR by intent-to-treat analysis was 53%, including 12 complete responses (33%) and seven partial responses (19%). The response rate among evaluable patients was 56%. Responses were seen in patients with prior refractory disease, prior ASCT, and prior alloSCT; however, no responses were seen in patients who relapsed within 3 months of ASCT. The median response duration was 5 months. Five patients (20% of those eligible) proceeded to alloSCT after treatment with bendamustine. Grade ≥ 3 adverse events were infrequent and most commonly included thrombocytopenia (20%), anemia (14%), and infection (14%).

CONCLUSION

This study confirms the efficacy of bendamustine in heavily pretreated patients with HL. These results support current and future studies evaluating bendamustine combinations in relapsed and refractory HL.

Bendamustine for treatment of chronic lymphocytic leukemia

INTRODUCTION

Chronic lymphocytic leukemia (CLL) often has an extended disease course. With a median age at diagnosis of 72 years, newer treatment options with less toxicity than standard nucleoside analogue-based regimens are needed. Historically, few therapy options are available once CLL has become refractory to nucleoside analogues. Bendamustine has emerged as a feasible therapy for older and less fit CLL patients, with clinical efficacy in previously untreated and refractory CLL.

AREAS COVERED

This paper reviews several of the pivotal clinical trials that established the clinical activity of bendamustine in previously untreated and relapsed/refractory CLL. The toxicity profile of bendamustine, primarily myelosuppression and infections, is reviewed and compared across different CLL populations. A review of the clinical data focuses on potential explanations for differences in response rates and duration of remission reported across studies and how this may impact the development of therapies for CLL.

EXPERT OPINION

Bendamustine is a valuable new agent for the management of CLL. Ongoing clinical trials are comparing bendamustine with standard CLL regimens in untreated disease, and investigating bendamustine combinations with novel targeted therapies and monoclonal antibodies. These studies will help to define the optimal role for bendamustine in CLL management.

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.

Investigation of bendamustine HCL in a phase 2 study in women with resistant ovarian cancer

We investigated the safety and efficacy of 90 mg/m(2) bendamustine HCL, administered intravenously on days 1 and 2 every 28 days in 10 women with platinum and taxane resistant epithelial ovarian cancer. There were no objective tumor responses observed; 2 patients had stable disease. Plasma samples collected at pre-treatment and end of cycle one were analyzed for changes in circulating total cytokeratin 18 and caspase cleaved cytokeratin 18 as exploratory early biomarkers of bendamustine-induced tumor cell death. All patients had measureable levels of both total and cleaved caspase 3 cytokeratin 18, but no relationship with response was possible due to the lack of clinical benefit in treated patients. Due to the high incidence of adverse events and absence of objective responses, only ten patients were treated as predefined by the Simon Two-Stage Design in the protocol. Overall, the regimen was not well tolerated and was associated with fatigue and a greater number of gastrointestinal side effects as compared to previously reported experiences in different patient populations. However, our study subjects did experience less bone marrow suppression. The lack of tolerability could reflect the degree of tumor burden within the peritoneal cavity as well as the high number of prior regimens (median of 5) received by the patients participating in this study.

Multicenter Phase II Study with Weekly Bendamustine and Paclitaxel as First- or Later-Line Therapy in Patients with Metastatic Breast Cancer: RiTa II Trial

The combination of bendamustine (B) and paclitaxel (P) as anthracycline-free treatment option in patients with advanced breast cancer has been evaluated in the previous RiTa I trial. The regimen of weekly B 70 mg/m(2) and P 90 mg/m(2) with a pause every 4th week was established as an effective regimen with low toxicity. The aim of the present RiTa II study was to investigate the potential of BP as anthracycline-free combination therapy. The primary objective was to determine the progression-free survival (PFS); secondary endpoints were safety, tolerability, overall response rate (ORR) and overall survival (OS). 26 patients were available, 15 received BP as first-line, 11 as beyond first-line treatment. 27% patients had triple-negative breast cancer (TNBC). Median PFS and OS were 7.3 months (95% confidence interval (CI): 5.5-10.9) and 14.9 months (95% CI: 9.9-22.9), respectively. The 1-year PFS rate was 20.3% and the 1-year OS rate 71.2%. The ORR was 42.3%, including 4 complete and 7 partial remissions. TNBC patients reached an ORR of 71.4%. Anthracycline-pretreated patients showed an ORR of 43.8%, confirming bendamustine's lack of cross-resistance to anthracycline agents. BP represents a favorable option with moderate toxicity in pretreated metastatic breast cancer and offers a possibility for application in anthracycline-pretreated and TNBC patients.

Neovascular niche for human myeloma cells in immunodeficient mouse bone

The interaction with bone marrow (BM) plays a crucial role in pathophysiological features of multiple myeloma (MM), including cell proliferation, chemoresistance, and bone lesion progression. To characterize the MM-BM interactions, we utilized an in vivo experimental model for human MM in which a GFP-expressing human MM cell line is transplanted into NOG mice (the NOG-hMM model). Transplanted MM cells preferentially engrafted at the metaphyseal region of the BM endosteum and formed a complex with osteoblasts and osteoclasts. A subpopulation of MM cells expressed VE-cadherin after transplantation and formed endothelial-like structures in the BM. CD138⁺ myeloma cells in the BM were reduced by p53-dependent apoptosis following administration of the nitrogen mustard derivative bendamustine to mice in the NOG-hMM model. Bendamustine maintained the osteoblast lining on the bone surface and protected extracellular matrix structures. Furthermore, bendamustine suppressed the growth of osteoclasts and mesenchymal cells in the NOG-hMM model. Since VE-cadherin⁺ MM cells were chemoresistant, hypoxic, and HIF-2α-positive compared to the VE-cadherin⁻ population, VE-cadherin induction might depend on the oxygenation status. The NOG-hMM model described here is a useful system to analyze the dynamics of MM pathophysiology, interactions of MM cells with other cellular compartments, and the utility of novel anti-MM therapies.

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

Bendamustine is clinically useful in mantle-cell lymphoma (MCL). Its favorable toxicity profile in-vivo favors its combination with other cytotoxic drugs. Cytarabine is a key drug in the treatment of younger patients with MCL. The current study investigated the in-vitro cytotoxic effect of bendamustine and cytarabine, alone or combined, on two MCL cell lines representing the classic and blastoid variant of the lymphoma subtype (JEKO-1 and GRANTA-519). Cell lines were exposed to each drug alone, or simultaneously and consecutively to both drugs, for different time schedules. Apoptosis was measured by flow cytometry. Mitochondrial damage, cell proliferation/metabolic activity, and cell cycle analysis were also assessed. The synergistic, additive, or antagonistic effects of the drugs were calculated with the combination index (CI) method. Bendamustine and cytarabine alone exhibited relevant cytotoxic activity on both cell lines. Both drugs induced cell cycle arrest in S phase. Drug combinations were associated with significantly higher cytotoxic effects than each drug alone. Among the combination schedules, the consecutive incubation of bendamustine followed by cytarabine was associated with the lower CI, being 10-100-fold lower than with simultaneous incubations. The cytotoxic effect of the consecutive combination was prominent on both cell lines, indicating a very strong and highly significant synergy in inducing apoptosis. Similar results were obtained measuring mitochondrial damage or the decline of the metabolic activity in all cell lines. The strong synergistic effect of bendamustine and cytarabine on MCL cells provides a rationale for developing schedules combining these agents in the treatment of MCL.

Bendamustine: rescue of an effective antineoplastic agent from the mid-twentieth century

Although the alkylating agent bendamustine was developed in Germany in the mid-twentieth century, it has only recently come to the forefront in the rest of the world as an effective chemotherapeutic agent for the treatment of several hematologic malignancies. Based on the activity demonstrated in single-arm and randomized trials, this nitrogen mustard is approved by the US Food and Drug Administration (FDA) for the treatment of chronic lymphocytic leukemia and rituximab-refractory indolent non-Hodgkin lymphoma. The unique structural and mechanistic features of bendamustine differentiate it from other alkylating agents, providing increased stability and potency in DNA cross linking and subsequent cytotoxicity. Due to its unusual development, few studies have closely examined the mechanisms of action for this nitrogen mustard and many unanswered questions remain. Additionally, phase I and pharmacokinetic studies are limited, although increased understanding of the clinical pharmacology of bendamustine led to development of dosing recommendations by international experts based on the available data. The clinical activity of bendamustine as a single agent and in combination with other chemotherapeutic and immunotherapeutic drugs, coupled with its potential lack of cross-resistance with many other chemotherapy agents, make bendamustine an attractive therapy for patients with newly diagnosed and refractory hematologic malignancies. This review will discuss the development of bendamustine, its structural and pharmacologic characteristics, and current data regarding the optimal dosing of this agent in specific clinical settings.

Mechanism of action: the unique pattern of bendamustine-induced cytotoxicity

Bendamustine has demonstrated substantial efficacy in the treatment of hematologic malignancies and continues to distinguish itself from other alkylating agents with regard to its activity in tumor cells. The mechanistic and clinical differences associated with bendamustine may be directly related to its unique structural features. Although the precise mechanisms of action are still poorly understood, bendamustine is associated with extensive and durable DNA damage. The increased potency of bendamustine may be due to secondary mechanisms such as inhibition of mitotic checkpoints, inefficient DNA repair, and initiation of p53-dependent DNA-damage stress response, all of which lead to mitotic catastrophe and apoptosis. It has also been hypothesized that the presence of a benzimidazole ring in addition to the nitrogen mustard group may influence the way bendamustine interacts with DNA and/or confer antimetabolite properties. Further elucidation of the mechanisms of action for bendamustine and the signaling pathways involved in the response to bendamustine-induced DNA damage is essential to maximize its therapeutic potential, identify biomarkers for response, and understand the potential for synergy with other agents involved in DNA damage and inhibition of DNA repair. This review will discuss the current understanding and hypotheses regarding bendamustine mechanisms of action and suggest future investigations that would shed light on the many unanswered questions.

Bendamustine: safety and efficacy in the management of indolent non-hodgkins lymphoma

Bendamustine (Treanda, Ribomustin) was recently approved by the US Food and Drug Administration (FDA) for treatment of patients with rituximab refractory indolent lymphoma and is expected to turn into a frontline therapy option for indolent lymphoma. This compound with amphoteric properties was designed in the former Germany Democratic Republic in 1960s and re-discovered in 1990s with multiple successive well-designed studies. Bendamustine possesses a unique mechanism of action with potential antimetabolite properties, and only partial cross-resistance with other alkylators. Used in combination with rituximab in vitro, bendamustine shows synergistic effects against various leukemia and lymphoma cell lines. In clinical studies, bendamustine plus rituximab is highly effective in patients with relapsed-refractory indolent lymphoma, inducing remissions in 90% or more and a median progression-free survival of 23-24 months. The optimal dosing and schedule of bendamustine administration is largely undecided and varies among studies. Results of ongoing trials and dose-finding studies will help to further help ascertain the optimal place of bendamustine in the management of indolent NHL.

Bendamustine: a review of its use in the management of indolent non-Hodgkin's lymphoma and mantle cell lymphoma

Bendamustine (bendamustine hydrochloride) is an alkylating agent indicated in several countries for the treatment of indolent non-Hodgkin's lymphoma (NHL) and mantle cell lymphoma (MCL). While the precise mechanism of action of bendamustine is as yet unknown, it has limited cross resistance to other alkylating agents and appears to exert its antineoplastic effects via a different mechanism to that of other alkylating agents. Bendamustine monotherapy was effective in treatment-refractory (including rituximab-refractory) indolent NHL or MCL. Moreover, bendamustine-based combination treatment was at least as effective as cyclophosphamide-based treatment, and bendamustine plus rituximab was at least as effective as cyclophosphamide, doxorubicin, vincristine plus prednisone (CHOP) plus rituximab, as first-line therapy in patients with indolent NHL or MCL. Treatment-refractory disease also appeared to respond favourably to bendamustine-containing combination treatment. In general, bendamustine was associated with a high overall response rate and a durable response. The most common adverse events associated with bendamustine were haematological or gastrointestinal in nature, and most were of mild to moderate severity. Regimens that included bendamustine were also associated with a very low rate of alopecia compared with regimens that included other antineoplastic drugs. In conclusion, bendamustine is a unique alkylating agent, which in clinical trials has demonstrated consistent efficacy and acceptable tolerability in patients with indolent NHL or MCL. It may be a particularly useful treatment option in patients with rituximab-refractory disease, but has also demonstrated efficacy as part of a first-line combination treatment. While further research is necessary to firmly establish the best place for bendamustine in the management of indolent NHL and MCL, it is a valuable addition to the pool of available treatments for these diseases.

Bendamustine: a new treatment option for chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a slow-growing hematologic malignancy and the most common type of leukemia in the western world. The lifetime risk for developing CLL is 1 in 216 men and women. Unfortunately, CLL is considered incurable with the chemotherapeutic agents available today. Bendamustine is a new agent that was recently added to the available regimens for the treatment of CLL. It was also recently approved for the treatment of non-Hodgkin's lymphoma. Its mechanism of action is unknown, but it contains an alkylating group similar to that of other bifunctional alkylating agents such as chlorambucil, and it also contains a benzimidazole central ring thought to exhibit antipurine-like properties. The United States Food and Drug Administration approved bendamustine based on results from an international phase III study of CLL in which bendamustine was compared with chlorambucil in treatment-naïve patients. Ongoing clinical trials are assessing the utility of bendamustine in combination with other agents for the treatment of CLL, as well as for other malignancies.

Bendamustine: something old, something new

BACKGROUND

Bendamustine (Treanda, Ribomustin) is a water-soluble, bifunctional chemotherapeutic agent that also has potential antimetabolite properties and only partial cross-resistance with other alkylators. Designed in 1963 and re-discovered in 1990s, this drug's unique mechanism of action and favorable side-effect profile promise a major role in the management of lymphoproliferative disorders. Bendamustine has been designated as an orphan drug in the United States, conferring prolonged market exclusivity.

OBJECTIVE

This article provides a comprehensive review of the data on efficacy and toxicity from trials investigating the use of bendamustine for the treatment of lymphoproliferative neoplasms. The pharmacology, pharmacokinetics, and pre-clinical studies with bendamustine are also reviewed.

METHODS

MEDLINE and Pubmed databases (1970-2010) were searched using the terms bendamustine, bendamustin, Treanda, Ribomustin, SDX-105, IMET-3393, and Cytostasan. All relevant articles were reviewed and references screened for additional articles. The databases of the American Society of Hematology (2004-2009) and the American Society of Clinical Oncology (1995-2009) were also searched for relevant abstracts.

RESULTS

Bendamustine induces a remission in more than three-fourths of patients with rituximab-refractory indolent B cell non-Hodgkin lymphoma (NHL). Combined with rituximab in vitro, bendamustine shows synergistic effects against various leukemia and lymphoma cell lines. Clinical trials supporting these results show that bendamustine plus rituximab is highly effective in patients with relapsed-refractory indolent lymphoma, inducing remissions in 90% or more and a median progression-free survival of 23-24 months. Bendamustine has been reasonably well tolerated in clinical trials with low propensity to induce alopecia.

CONCLUSIONS

Combination of bendamustine and rituximab has the potential to become a new standard first-line treatment option for patients with FL, MCL, and indolent lymphomas. Results of ongoing trials will help to further elucidate the optimal role of bendamustine in indolent NHL.

Bendamustine in patients with relapsed or refractory multiple myeloma

Objective

In patients with multiple myeloma, bendamustine monotherapy is effective as 1^st and 2^nd line therapy. However, data for patients with advanced multiple myeloma is rare.

Methods

In this retrospective analysis we have identified 39 patients with relapsed or refractory multiple myeloma by means of case research, who have been treated at our institution with bendamustine as salvage therapy. After in median 2 lines of prior therapy (range:1-5) patients received in median 3 (range: 1-10) cycles of bendamustine. Bendamustine dosage was 80-150 mg on day 1+2 of a monthly cycle. Bendamustine was administered as monotherapy in 39% of patients, whereas 61% received concomitant steroids.

Results

Toxicity was mild to moderate. Response rates were as follows: 3% vgPR, 33% PR, 18% MR, 26% SD and 20% PD. The median event-free and overall survival were 7 and 17 months, respectively.

Conclusions

In conclusion, in patients with advanced multiple myeloma bendamustine is effective and associated with mild toxicity. Therefore, the role of bendamustine in patients with multiple myeloma should be investigated in further clinical trials.