High anti-lymphoma activity of bendamustine/mitoxantrone/rituximab in rituximab pretreated relapsed or refractory indolent lymphomas and mantle cell lymphomas. A multicenter phase II study of the German Low Grade Lymphoma Study Group (GLSG)

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.

Mantle cell lymphoma: state-of-the-art management and future perspective

Mantle cell lymphoma (MCL) is a unique subtype of B-cell non-Hodgkin lymphomas (NHL) characterized in almost all cases by the chromosomal translocation t(11;14)(q13;q32) and nuclear cyclin D1 overexpression. Most patients present with advanced stage disease, often with extranodal dissemination, and typically pursue an aggressive clinical course. Recent improvement has been achieved by the successful introduction of monoclonal antibodies and dose-intensified approaches including autologous stem cell transplantation strategies. However, with the exception of allogeneic hematopoietic stem cell transplantation, current treatment approaches are not curative and the corresponding survival curve is characterized by a relatively steep and continuous decline, with a median survival of about 4 years and <15% long-term survivors. Despite its rarity, MCL is of particular clinical and scientific interest by providing a paradigm for neoplasms with dysregulated control of cell cycle machinery and impaired apoptotic pathways. Recently gained insights into underlying pathobiology unravel numerous promising molecular targeting strategies, however their introduction into clinical practice and current treatment algorithms remains a challenge. This article will provide relevant information for decision making in clinical practice and give a perspective on upcoming management strategies.

Bendamustine is effective therapy in patients with rituximab-refractory, indolent B-cell non-Hodgkin lymphoma: results from a Multicenter Study

BACKGROUND

Bendamustine hydrochloride is a novel alkylating agent. In this multicenter study, the authors evaluated the efficacy and toxicity of single-agent bendamustine in patients with rituximab-refractory, indolent B-cell lymphoma.

METHODS

Eligible patients (N = 100, ages 31-84 years) received bendamustine at a dose of 120 mg/m(2) by intravenous infusion on Days 1 and 2 every 21 days for 6 to 8 cycles. Histologies included follicular (62%), small lymphocytic (21%), and marginal zone (16%) lymphomas. Patients had received a median of 2 previous regimens (range, 0-6 previous regimens), and 36%were refractory to their most recent chemotherapy regimen. Primary endpoints included overall response rate (ORR) and duration of response (DOR). Secondary endpoints were safety and progression-free survival (PFS).

RESULTS

An ORR of 75% (a 14% complete response rate, a 3% unconfirmed complete response rate, and a 58% partial response rate) was observed. The median DOR was 9.2 months, and median PFS was 9.3 months. Six deaths were considered to be possibly treatment related. Grade 3 or 4 (determined using National Cancer Institute Common Toxicity Criteria [version 3.0.19]. reversible hematologic toxicities included neutropenia (61%), thrombocytopenia (25%), and anemia (10%). The most frequent nonhematologic adverse events (any grade) included nausea (77%), infection (69%), fatigue (64%), diarrhea (42%), vomiting (40%), pyrexia (36%), constipation (31%), and anorexia (24%).

CONCLUSIONS

Single-agent bendamustine produced a high rate of objective responses with acceptable toxicity in patients with recurrent, rituximab-refractory indolent B-cell lymphoma.

Bendamustine for the treatment of chronic lymphocytic leukemia and rituximab-refractory, indolent B-cell non-Hodgkin lymphoma

BACKGROUND

Bendamustine is a mechlorethamine derivative with a purine-like benzimidazole ring, which may enhance its clinical efficacy. Bendamustine was approved by the US Food and Drug Administration (FDA) for the treatment of chronic lymphocytic leukemia (CLL) in March 2008 and for the treatment of rituximab-refractory, indolent B-cell non-Hodgkin lymphoma (NHL) in October 2008.

OBJECTIVE

This article reviews the pharmacologic and pharmacodynamic properties of bendamustine, together with data on efficacy and toxicity from trials investigating the use of bendamustine for the treatment of various hematologic malignancies, including CLL, NHL, and multiple myeloma (MM).

METHODS

MEDLINE and International Pharmaceutical Abstracts (1970-April 15, 2009) were searched using the terms bendamustine, bendamustin, Treanda, Ribomustin, SDX-105, IMET-3393, and Cytostasan. References from relevant articles were also reviewed for additional sources and material. The databases of the American Society of Hematology (2004-2008) and the American Society of Clinical Oncology (1995-2008) were searched for relevant abstracts.

RESULTS

Bendamustine is a mechlorethamine derivative with structural similarity to chlorambucil and other drugs from the nitrogen mustard class, as well as a benzimidazole ring, which may act as an antagonist to purines and amino acids. It has good oral bioavailability but has been studied almost exclusively in the intravenous formulation. It undergoes extensive first-pass metabolism by cytochrome P450 1A2 to active metabolites gamma-hydroxy bendamustine and N-desmethyl-bendamustine, but clinical activity appears to be associated primarily with the parent compound. The t(1/2) of bendamustine is approximately 40 minutes. While bendamustine has 2 moieties with possible antitumor effect, it is unclear to what extent the benzimidazole ring enhances the efficacy of the drug. Numerous studies including in vitro assays have reported, however, that bendamustine has little cross-resistance with other alkylating agents and remains active even in extensively pretreated patients. FDA approval for use in CLL was based on findings from a randomized, open-label, Phase III study comparing bendamustine with chlorambucil as single-agent therapy in treatmentnaive patients with CLL (Binet stage B or C). Bendamustine was administered intravenously at a dose of 100 mg/m2 on days 1 and 2, while chlorambucil was administered orally at 0.8 mg/kg daily, both over 4-week cycles for up to 6 cycles. At interim analysis (the data used for FDA approval), bendamustine was associated with a greater overall response (68% vs 39%; P < 0.001), median progression-free survival (21.7 vs 9.3 months; P < 0.001) and median duration of remission (18.9 vs 6.1 months; P < 0.001) compared with chlorambucil. FDA approval for rituximabrefractory, indolent B-cell NHL followed a Phase III, open-label, single-arm study evaluating bendamustine monotherapy in patients who did not respond to rituximab or had progressive disease within 6 months of rituximab therapy. Bendamustine 120 mg/m(2) was administered intravenously on days 1 and 2 of a 21-day cycle for up to 8 cycles. At interim analysis, the overall response rate was 84%, including 29% complete response. The median progression-free survival was 9.7 months. The efficacy of bendamustine has also been reported in the treatment of MM in clinical studies, and bendamustine has been approved in Europe for treating MM, NHL, CLL, breast cancer, and Hodgkin lymphoma. Dose-limiting toxicity is primarily hematologic. Treatment-associated infections have been reported in some studies; however, nonhematologic adverse events have rarely been dose limiting. The most common nonhematologic adverse events include fatigue, nausea, xerostomia, and pyrexia.

CONCLUSIONS

Bendamustine is a mechlorethamine derivative with a purine-like benzimidazole ring, which may enhance its clinical efficacy. It has been approved in the United States for the treatment of CLL and rituximab-refractory, indolent B-cell NHL. It has been approved in Europe for use in other malignancies, and clinical studies have reported activity in MM.

The role of bendamustine in the treatment of indolent non-Hodgkin lymphoma

There is no consensus on recommendations for the treatment of relapsed and refractory indolent non-Hodgkin lymphoma (NHL). Bendamustine hydrochloride (bendamustine) has recently been approved for treatment of these patients. Bendamustine is a uniquely structured alkylating agent that lacks cross-resistance with other alkylators. This agent has a high degree of activity against a variety of tumor cell lines. Clinically, bendamustine has demonstrated activity against indolent NHL, chronic lymphocytic lymphoma, multiple myeloma and mantle cell lymphoma. Moreover, studies have validated its activity in patients with indolent NHL who are resistant to purine analogs and rituximab. The cytotoxic activity of bendamustine has been shown to be synergistic with rituximab in hematological malignancies. The incidence of alopecia is significantly less than with other alkylating agents. Myelosuppression is the major toxicity associated with bendamustine.

Rituximab retherapy in patients with relapsed aggressive B cell and mantle cell lymphoma

Neither effective salvage regimens nor the outcome and response to retherapy with rituximab containing chemotherapy have been defined for rituximab pre-treated patients with relapsing aggressive lymphoma. We report here a single-centre retrospective outcome analysis of second-line immunochemotherapy with rituximab. In 28 patients with relapsed or refractory diffuse large B cell lymphomas, first-line immunochemotherapy had induced objective responses in 18 patients. Nine of 28 patients responded to rituximab containing salvage therapy, leading to a median overall survival of 243 days after start of second immunochemotherapy. Long-term disease free survivors (1,260 and 949 days) were restricted to the group of twelve patients that had received allogeneic stem cell transplantation as consolidation therapy. In 21 patients with relapsed mantle cell lymphomas (MCL), 19 patients had reached remissions with first-line therapy. Of those, 16 patients experienced responses to salvage therapy with a median overall survival of 226 days. Noteworthy, none of patients with initial non-responding disease reached a remission with second immunochemotherapy. Seven patients with MCL stayed free from progression after high-dose therapy with autologous or allogeneic stem cell transplantation in two and five cases, respectively. In summary, responses to repeated immunotherapy with rituximab were observed in approximately one third and two thirds of initially responding patients with aggressive B cell lymphoma and mantle cell lymphoma, respectively, but not in primarily refractory disease. Lasting remissions were achieved only by high-dose chemotherapy with stem cell transplantation.

Bendamustine: Rebirth of an Old Drug

Bendamustine is a unique cytotoxic agent with structural similarities to alkylating agents and antimetabolites, but which is non–cross-resistant with alkylating agents and other drugs in vitro and in the clinic. Early clinical studies conducted in the German Democratic Republic more than 30 years ago suggested promising activity in indolent non-Hodgkin's lymphoma (NHL). Two North American trials reported responses in more than 70% of patients with chemotherapy- and rituximab-refractory disease, suggesting that bendamustine may be the most effective drug available for this patient population. Response rates of 90% to 92%, with complete remission in 55% to 60%, have been reported in patients with follicular and mantle-cell lymphoma with the combination of bendamustine and rituximab. Superiority over chlorambucil in previously untreated patients with chronic lymphocytic leukemia (CLL) led to its recent approval for this disease in the United States. Bendamustine is approved in Germany for the treatment of patients with indolent NHL, CLL, and multiple myeloma. Activity has also been noted in patients with breast cancer and small-cell lung cancer. Questions related to the optimization of bendamustine therapy, including dose and schedule, role relative to other available agents, and management of toxicities, are being investigated. However, the availability of bendamustine provides another effective treatment option for patients with lymphoid malignancies.

Bendamustine in the treatment of non-Hodgkin's lymphomas

PURPOSE

To review available data using bendamustine alone and in combination with other chemotherapeutic agents in treatment of patients with non-Hodgkin's lymphomas.

METHODS

Internet database searches and literature review.

RESULTS

Bendamustine was approved in March 2008 by the United States Food and Drug Administration for the treatment of patients with chronic lymphocytic leukemia. Many trials have been performed over the last decade using bendamustine not only as monotherapy, but also in combination with other agents including rituximab, vincristine, mitoxantrone, fludarabine, and other agents as therapy for patients with relapsed non-Hodgkin's lymphomas, and recently was approved for use in therapy of patients with relapsed indolent lymphomas considered refractory to rituximab therapy. As monotherapy, bendamustine induces good responses with only minor side effects. In combination with other agents, efficacy improves, especially when given in combination with rituximab. The drug has also been studied in combination with rituximab as initial therapy for indolent lymphomas, and has excellent activity with less toxicity than R-CHOP (rituximab - cyclophosphamide, hydroxydaunorubicin [Adriamycin], Oncovin [vincristine], and prednisone/prednisolone).

CONCLUSION

Overall, bendamustine has demonstrated promising results as therapy for non-Hodgkin's lymphomas and should be included in the armamentarium of agents used to treat relapsed indolent non-Hodgkin's lymphomas and may prove valuable as initial therapy for these diseases. Further studies are being conducted to demonstrate the efficacy of this drug in combination with other agents.

Therapy of mantle cell lymphoma: current standards and future strategies

Mantle cell lymphoma is characterized clinically by an aggressive clinical course and is relatively resistant to conventional chemotherapies. When in its advanced stages, currently available immunochemotherapy regimens remain noncurative despite high initial response rates. In contrast, consolidating high-dose therapy with autologous stem cell retransfusion significantly extends progression-free survival of young patients. Currently, allogenic bone marrow transplantation represents the only therapy with the potential for a curative approach, although associated with a high rate of complications. New concepts of therapy are urgently warranted, including new molecular approaches, such as bortezomib, thalidomide, lenalidomide, and temsirolimus.

Bendamustine is effective in p53-deficient B-cell neoplasms and requires oxidative stress and caspase-independent signaling

PURPOSE

Chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL) are two incurable B-cell lymphoid neoplasms characterized by distinct clinical presentation and evolution. Bendamustine hydrochloride is a multifunctional, alkylating agent with a purine-like ring system that exhibits activity in multiple cancer models, including CLL and MCL, but whose mechanism is only partially described. Our aim was to analyze the apoptotic pathways activated by bendamustine in CLL and MCL together with the relevance of p53 mutation in determining the response to this drug.

EXPERIMENTAL DESIGN

Thirteen CLL/MCL cell lines and primary tumor cells from 8 MCL and 25 CLL patients were cultured for up to 24 h with bendamustine followed by cytotoxic assays, flow cytometry, immunofluorescence, and Western blot analysis of p53 response pathway and apoptosis-related factors.

RESULTS

Bendamustine displayed cytotoxic activity on most CLL and MCL primary cells and cell lines irrespective of ZAP-70 expression and p53 status. Bendamustine was found to act synergistically with nucleoside analogues in both CLL and MCL, this combination being effective in p53 mutated cases resistant to standard chemotherapy. Bendamustine cytotoxicity was mediated by the generation of reactive oxygen species and triggering of the intrinsic apoptotic pathway involving up-regulation of PUMA and NOXA, conformational activation of BAX and BAK, and cytosolic release of caspase-related and caspase-unrelated mitochondrial apoptogenic proteins.

CONCLUSIONS

Our findings support the use of bendamustine as a therapeutic agent, alone or in combination, for CLL and MCL with p53 alterations and describe the molecular basis of its activity in these entities.

Low-dose, single-agent temsirolimus for relapsed mantle cell lymphoma: a phase 2 trial in the North Central Cancer Treatment Group

BACKGROUND

The objective of this study was to test a low dose of (25 mg weekly) of the mammalian target of rapamycin kinase inhibitor temsirolimus for patients with relapsed mantle cell lymphoma (MCL).

METHODS

Patients with relapsed or refractory MCL were eligible to receive temsirolimus 25 mg intravenously every week as a single agent. Patients who had a tumor response after 6 cycles were eligible to continue drug for a total of 12 cycles or 2 cycles after complete remission and then were observed without maintenance.

RESULTS

Of 29 enrolled patients, 28 were evaluable for toxicity, and 27 were evaluable for efficacy. The median age was 69 years (range, 51-85 years), 86% of patients had stage IV disease, and 71% had > or = 2 extranodal sites. Patients had received a median of 4 prior therapies (range, 1-9 prior therapies), and 50% were refractory to the last treatment. The overall confirmed response rate was 41% (11 of 27 patients; 90% confidence interval [CI], 22%-61%) with 1 complete response (3.7%) and 10 partial responses (37%). The median time to progression in all eligible patients was 6 months (95% CI, 3-11 months), and the median duration of response for the 11 responders was 6 months (range, 1-26 months). Hematologic toxicities were the most common, with 50% (14 of 28 patients) grade 3 and 4% (1 of 28 patients) grade 4 toxicities observed. Thrombocytopenia was the most frequent cause of dose reduction.

CONCLUSIONS

Single-agent temsirolimus at a dose of 25 mg weekly is an effective new agent for the treatment of MCL. The 25-mg dose level retained the antitumor activity of the 250-mg dose with less myelosuppression. Further studies of temsirolimus in combination with other active drugs for MCL and other lymphoid malignancies are warranted.

Bendamustine as a model for the activity of alkylating agents

Attempts to administer personalized standard cytotoxic chemotherapy based on individual patient characteristics have been disappointing. Alkylating agents are one of the oldest classes of anticancer medicine with a wide variety of molecular actions and thus the potential for broad utility. Bendamustine hydrochloride, a new addition to this class, was previously developed in the 1960s and has now been trialled in hematological malignancies and many solid tumor types as monotherapy or in combination with the known standard of care. It appears to occupy a particular role in resistant or refractory hematological disease and it was approved by the US FDA for the treatment of chronic lymphocytic leukemia in March 2008. Further trials will reveal whether it is likely to become incorporated into front-line regimens in non-Hodgkin's lymphoma and other malignancies.

Bendamustine; Levoleucovorin

The complexity of cancer chemotherapy requires that pharmacists be familiar with the complicated regimens and highly toxic agents used. This column reviews various issues related to preparation, dispensing, and administration of antineoplastic therapy and the agents, both commercially available and investigational, used to treat malignant diseases.

Bortezomib in mantle cell lymphoma

Mantle cell lymphoma (MCL) represents 6% of non-Hodgkin lymphomas, but is one of the most active fields of clinical investigation. Unfortunately, there is still no standard or curative therapy in MCL. Front-line therapy appears to benefit from intensification either through high-dose therapy with stem cell transplant consolidation or dose-intense chemotherapy with hyperfractionated cyclophosphamide, vincristine, adriamycin/doxorubicin and dexamethasone/rituximab. Most patients still relapse and a multitude of novel agents are currently being tested in this setting, including proteasome inhibitors with bortezomib (the first of its class and the first US FDA-approved drug for MCL), mTOR inhibitors, Bcl-2 inhibitors, antiangiogenesis agents and histone deacetylase inhibitors among others. An obvious effort is needed to enroll patients on clinical trials, the design of which might benefit from pharmacogenomics and a better understanding of MCL biology and its diversity.

Bendamustine in non-Hodgkin lymphoma: the double-agent that came from the Cold War

Bendamustine was first synthesized in the early 1960s at the Institute for Microbiology and Experimental Therapy in Jena, East Germany by Ozegowski and Krebs. The molecule, originally termed IMET 3393 (4-[5-(bis[2-chloroethyl]amino)-1-methyl-2-benzimidazolyl] butyric acid), was intended to be a "bi-functional" molecule with alkylator and antimetabolite properties. Extensive studies were conducted using this compound over a 20-year period in East Germany, and it became a highly used chemotherapeutic agent in the eastern block before the fall of the Iron Curtain. After its licensing in Europe in the mid 1990s, more than 18,000 patients were studied using this compound, principally in Germany. Over the past decade, significant interest has been generated as a result of ongoing studies that have demonstrated the unique antitumor properties of this compound as a single agent and in different combinations. This article provides a review of studies using bendamustine in the treatment of non-Hodgkin lymphomas.

NMDA receptor subunit NR2b: effects on LH release and GnRH gene expression in young and middle-aged female rats, with modulation by estradiol

BACKGROUND/AIMS

The loss of reproductive capacity during aging involves changes in the neural regulation of the hypothalamic gonadotropin-releasing hormone (GnRH) neurons controlling reproduction. This neuronal circuitry includes glutamate receptors on GnRH neurons. Previously, we reported an increase in the expression of the NR2b subunit protein of the NMDA receptor on GnRH neurons in middle-aged compared to young female rats. Here, we examined the functional implications of the NR2b subunit on the onset of reproductive aging, using an NR2b-specific antagonist ifenprodil.

METHODS

Young (3-5 months) and middle-aged (10-13 months) female rats were ovariectomized (OVX), 17beta-estradiol (E2) or vehicle (cholesterol) treated, and implanted with a jugular catheter. Serial blood sampling was undertaken every 10 min for 4 h, with ifenprodil (10 mg/kg) or vehicle injected (i.p.) after 1 h of baseline sampling. The pulsatile release of pituitary LH and levels of GnRH mRNA in hypothalamus were quantified as indices of the reproductive axis.

RESULTS

Our results showed effects of ifenprodil on both endpoints. In OVX rats given cholesterol, neither age nor ifenprodil had any effects on LH release. In E2-treated rats, aging was associated with significant decreases in pulsatile LH release. Additionally, ifenprodil stimulated parameters of pulsatile LH release in both young and middle-aged animals. Ifenprodil had few effects on GnRH mRNA; the only significant effect of ifenprodil was found in the middle-aged, cholesterol group.

CONCLUSION

Together, these findings support a role for the NR2b subunit of the NMDAR in GnRH/LH regulation. Because most of these effects were exhibited on pituitary LH release in the absence of a concomitant change in GnRH gene expression, it is likely that NMDA receptors containing the NR2b subunit play a role in GnRH-induced LH release, independent of de novo GnRH gene expression.