A phase I study of bendamustine hydrochloride administered day 1+2 every 3 weeks in patients with solid tumours

Development and Validation of Stability Indicating RP-HPLC Method for the Estimation of Glycopyrrolate and Neostigmine in Bulk and Injection

A stability indicating RP-HPLC method is suggested for determination of Glycopyrrolate-Neostigmine (GLY/NEO) in bulk drugs and injection formulation. GLY/NEO were eluted from a Chromolith High Resolution RP-18e (100 mm×4.6 mm) with buffer solution (pH 3.0) as mobile phase A and a mixture of HPLC grade acetonitrile and water mixture (90:10) as mobile phase B. The gradient was optimized with a flowrate of 0.5 mL/min and wavelength of 222 nm. A complete analytical method validation was effectively carried out as per ICH Q2 (R1) guidelines. Recovery studies were performed at 50-150% level of working concentrations, and results were in the range of 99-101%. The linearity was detected in the range of LOQ to 200% of the specification limits i.e., 0.5% each for NEO and GLY, 0.01% for NEO Impurity B and 1.0% for rest of the impurities with respect to the test concentration of the respective components. For stability study, various stress conditions such as acid, base, oxidation and thermal as per ICH guidelines were studied. The high recovery and low relative standard deviation confirm the suitability of proposed method that can be employed for the routine analysis in bulk and pharmaceutical formulation.

Pharmacokinetics and safety of bendamustine in the BEABOVP regimen for the treatment of pediatric patients with Hodgkin lymphoma

PURPOSE

The Stanford V chemotherapy regimen has been used to treat Hodgkin lymphoma (HL) patients since 2002 with excellent cure rates; however, mechlorethamine is no longer available. Bendamustine, a drug structurally similar to alkylating agents and nitrogen mustard, is being substituted for mechlorethamine in combination therapy in a frontline trial for low- and intermediate-risk pediatric HL patients, forming a new backbone of BEABOVP (bendamustine, etoposide, doxorubicin, bleomycin, vincristine, vinblastine, and prednisone). This study evaluated the pharmacokinetics and tolerability of a 180 mg/m2 dose of bendamustine every 28 days to determine factors that may explain this variability.

METHODS

Bendamustine plasma concentrations were measured in 118 samples from 20 pediatric patients with low- and intermediate-risk HL who received a single-day dose of 180 mg/m2 of bendamustine. A pharmacokinetic model was fit to the data using nonlinear mixed-effects modeling.

RESULTS

Bendamustine concentration vs time demonstrated a trend toward decreasing clearance with increasing age (p = 0.074) and age explained 23% of the inter-individual variability in clearance. The median (range) AUC was 12,415 (8,539, 18,642) µg hr/L and the median (range) maximum concentration was 11,708 (8034, 15,741) µg/L. Bendamustine was well tolerated with no grade 3 toxicities resulting in treatment delays of more than 7 days.

CONCLUSIONS

A single-day dose of 180 mg/m2 of bendamustine every 28 days was safe and well tolerated in pediatric patients. While age accounted for 23% of inter-individual variability observed in bendamustine clearance, the differences did not affect the safety and tolerability of bendamustine in our patient population.

Reversible Cardiomyopathy after Rituximab Treatment in a Chronic Lymphocytic Leukemia Patient

INTRODUCTION

Rituximab is a monoclonal antibody that has shown efficacy in non-Hodgkin's lymphoma, chronic lymphocytic leukemia (CLL), both as a single agent and in combination with traditional chemotherapies.

CASE REPORT

Here, we present a case wherein a 56-year-old man developed dilated cardiomyopathy following one cycle of rituximab and bendamustine chemotherapy protocol used to treat chronic lymphocytic leukemia. On the fifth day the patient developed hypotensive shock followed closely by the development of cough after two days.

MANAGEMENT AND OUTCOME

The patient was started on carvedilol 3.125 mg, ramipril 2.5 mg, and torsemide 5 mg for treatment of cardiomyopathy. Blood transfusion was necessary for hypotensive shock. Antibiotic regimen was started for sepsis and progressive cough. The patient recovered fully from all the symptoms.

DISCUSSION

This case illustrates the potential for cardiomyopathy with rituximab, particularly in patients with chronic lymphocytic leukemia, and its proposed mechanisms and treatment. The expanding utility of rituximab impels us to increase monitoring and awareness of this serious cardiovascular adverse effect.

Dose-intensified bendamustine and melphalan (BenMel) conditioning before second autologous transplantation in myeloma patients

Consolidation in myeloma patients with high-dose melphalan chemotherapy (Mel HDCT) and autologous transplantation (ASCT) is standard of care since more than 2 decades. However, definite cure remains exceptional despite intensive treatment, and improving effectiveness of HDCT remains an unmet clinical need. Combining intensified bendamustine with melphalan may represent an option. We analyzed safety and efficacy of combining dose-intensified bendamustine (200 mg/m² on days -4/-3) with high-dose melphalan (100 mg/m² on days -2/-1) before a second (tandem) ASCT in adverse risk myeloma patients after Mel HDCT/ASCT1. Twelve patients received BenMel conditioning before ASCT2 because of high-risk cytogenetics and/or failure to achieve complete remission (CR) after Mel HDCT/ASCT1. Comparing Mel HDCT/ASCT1 and BenMel HDCT/ASCT2, we observed no differences in hematologic recovery and tolerance. Acute renal injury after BenMel conditioning occurred in 3 (25%) patients, but was reversible in all patients, and there were no treatment related deaths. Complete remission rates were increasing from 42% after Mel/ASCT1 to 75% after BenMel/ASCT2. PFS 1 year after ASCT2 was 67%, and OS was 83%. These data suggest that dose-intensified bendamustine with melphalan conditioning is safe and warrants a prospective randomized comparison to standard melphalan HDCT in myeloma patients.

Comparable safety profile of BeEAM (bendamustine, etoposide, cytarabine, melphalan) and BEAM (carmustine, etoposide, cytarabine, melphalan) as conditioning before autologous haematopoietic cell transplantation

Introduction

BEAM (carmustine, etoposide, cytarabine, melphalan) is the most frequently used high-dose chemotherapy regimen for patients with lymphoma referred for autologous haematopoietic cell transplantation (autoHCT). Recently, a novel conditioning protocol containing bendamustine instead of carmustine (BeEAM) has been proposed to potentially increase the efficacy.

Aim of the study

The aim of this study was to retrospectively compare the safety profile of BEAM and BeEAM based on single-centre experience.

Material and methods

A total of 237 consecutive patients with lymphoma treated with either BEAM (n = 174) or BeEAM (n = 63), between the years 2011 and 2016, were included in the analysis. Clinical characteristics of both groups were comparable. Patients with Hodgkin’s lymphoma (HL) constituted 49% of the BEAM group and 40% of the BeEAM group.

Results

Median time to neutrophil > 0.5 × 10⁹/l recovery was 10 days in both groups (p = 0.29), while median time to platelet > 50 × 10⁹/l recovery was 13 and 14 days after BEAM and BeEAM, respectively (p = 0.12). The toxicity profile was comparable except for arterial hypertension and severe hypokalaemia, which occurred more frequently after BeEAM compared to BEAM (p = 0.02 and p = 0.004, respectively). The rate of early mortality was 1.7% and 1.6%, respectively. The probabilities of the overall and progression-free survival were comparable for both groups (p = 0.73 and p = 0.55, respectively).

Conclusions

Administration of bendamustine instead of carmustine as part of conditioning does not affect the engraftment or the toxicity profile of the regimen. Therefore, BeEAM may be safely used in patients with lymphoma undergoing autoHCT. Its efficacy requires evaluation in prospective studies.

Bendamustine-based conditioning prior to autologous stem cell transplantation (ASCT): Results of a French multicenter study of 474 patients from LYmphoma Study Association (LYSA) centers

Carmustine shortage has led to an increase use of alternative conditioning regimens prior to autologous stem cell transplantation for the treatment of lymphoma, including Bendamustine-based (BeEAM). The aim of this study was to evaluate the safety of the BeEAM regimen in a large cohort of patients. A total of 474 patients with a median age of 56 years were analyzed. The majority of patients had diffuse large B-cell lymphoma (43.5%). Bendamustine was administered at a median dose of 197 mg/m² /day (50-250) on days-7 and -6. The observed grade 1-4 toxicities included mucositis (83.5%), gastroenteritis (53%), skin toxicity (34%), colitis (29%), liver toxicity (19%), pneumonitis (5%), and cardiac rhythm disorders (4%). Nonrelapse mortality (NRM) was reported in 3.3% of patients. Acute renal failure (ARF) was reported in 132 cases (27.9%) (G ≥2; 12.3%). Organ toxicities and death were more frequent in patients with post conditioning renal failure. In a multivariate analysis, pretransplant chronic renal failure, bendamustine dose >160 mg/m² and age were independent prognostic factors for ARF. Pretransplant chronic renal failure, hyperhydration volume, duration of hyperhydration, and etoposide dose were predictive factors of NRM. A simple, four-point scoring system can stratify patients by levels of risk for ARF and may allow for a reduction in the bendamustine dose to avoid toxicity. Drugs shortage may have dangerous consequences. Prospective, comparative studies are needed to confirm the toxicity/efficacy extents from this conditioning regimen compared to other types of high dose therapy.

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.

Bendamustine hydrochloride in patients with B-cell malignancies who have comorbidities - is there an optimal dose?

INTRODUCTION

The majority of patients with non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia (CLL) present with comorbidities. Many of them are poor candidates for intensive chemo-immunotherapy regimens, such as FCR (fludarabine, cyclophosphamide, rituximab). Still, most clinical trials aim to enroll 'fit' patients, who poorly represent the community oncology population. Areas covered: In the past decade, bendamustine hydrochloride, a cytotoxic agent with structural similarities to both alkylating agents and purine analogs, has received widespread use in therapy of NHL and CLL, and has demonstrated a relatively favorable toxicity profile. However, bendamustine has not been well studied in patients with hematologic malignancies who have comorbidities. Here we review the clinical data on use of bendamustine in older and unfit patients with NHL and CLL, and analyze whether there is an optimal dose of bendamustine in patients who have significant comorbidities, including renal dysfunction. Expert commentary: Reduced intensity regimens of bendamustine are effective in CLL patients with comorbidities and renal dysfunction. Even with the introduction of targeted therapies, bendamustine will likely continue to be an important therapeutic option in patients with comorbidities because of its tolerability, efficacy and cost.

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.

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.

Phase I/IIa study of sequential chemotherapy regimen of bendamustine/irinotecan followed by etoposide/carboplatin in untreated patients with extensive disease small cell lung cancer (EDSCLC)

PURPOSE

The sequence bendamustine (B) + Irinotecan (I) followed by etoposide (E) + carboplatin (C) was hypothesized to increase progression-free survival (PFS) and overall survival (OS) in untreated extensive-disease small cell lung cancer (EDSCLC) patients compared to historical controls by exploiting mitotic catastrophe. Absent expression of ERCC-1 and expression of topoisomerases were hypothesized to be predictive for PFS and OS.

METHODS

This was a phase I/IIa trial in 30 patients to determine the maximum tolerated dose (MTD) of B + I and the PFS of B + I E + C with secondary end points including overall response rate (ORR) and OS. Biomarkers measured by immunohistochemistry (IHC) obtained from diagnostic specimens were correlated with outcome.

RESULTS

The MTD of B + I was not reached. During treatment with B + I, there were two grade 5 toxicities from neutropenic sepsis and metabolic encephalopathy. Other toxicities included fatigue, nausea/vomiting, diarrhea, and weight loss. For the sequence, the PFS and OS were 6.0 months and 10 months, respectively. The ORR for B + I and the sequence were 82% and 83%, respectively. Topoisomerase-2 expression was predictive for TTP and OS, but absent ERCC-1 expression was not, contrary to our hypothesis.

CONCLUSIONS

B + I is an active regimen in EDSCLC. Toxicities included two grade 5 events but were otherwise manageable. The novel sequence B + I E + C increased PFS and OS compared to historical controls. Correlative studies are conflicting regarding the mechanism of action of this novel sequence.

Phase I study of bendamustine with concurrent whole brain radiation therapy in patients with brain metastases from solid tumors

A phase I study was conducted to evaluate the dose-limiting toxicities (DLTs) and to determine the maximum tolerated dose (MTD)/recommended phase II dose of bendamustine with concurrent whole brain radiation (WBR) in patients with brain metastases (BM) from solid tumors. Four doses of intravenous weekly bendamustine were administered with 3 weeks of WBR at three dose levels (60, 80, and 100 mg/m(2)) according to a standard 3 + 3 phase I design. A total of 12 patients with solid tumor BM were enrolled in the study (six with non-small cell lung cancer, four with melanoma, one with breast cancer, and one with neuroendocrine carcinoma). The first two dose levels had three patients each, and the third dose level had six total patients. Plasma pharmacokinetic studies of bendamustine demonstrated no significant differences from pharmacokinetic characteristics of bendamustine in other studies. No DLTs were noted at any dose levels, and no grade 4 toxicities occurred. The MTD of weekly bendamustine with concurrent WBR was 100 mg/m(2). The majority of trial patients died from progressive systemic disease rather than their brain disease. The combination of weekly bendamustine with concurrent WBR was acceptably tolerated. The efficacy of this combination may be evaluated in a phase II trial with stratification by histologies.

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.

Pharmacokinetics and excretion of 14C-bendamustine in patients with relapsed or refractory malignancy

BACKGROUND

Bendamustine is an alkylating agent with clinical activity against a variety of hematologic malignancies and solid tumors. To assess the roles of renal and hepatic drug elimination pathways in the excretion and metabolism of bendamustine, a mass balance study was performed in patients with relapsed or refractory malignancies.

METHODS

A single 60-minute intravenous dose of 120 mg/m(2), 80-95 μCi (14)C-bendamustine hydrochloride was administered to six patients, followed by collection of blood, urine, and fecal samples at specified time points up to day 8 or until the radioactivity of the 24-hour urine and fecal collections was below 1% of the administered dose (whichever was longer). Total radioactivity (TRA) was measured in all samples, and concentrations of unchanged bendamustine and its metabolites γ-hydroxy-bendamustine (M3), N-desmethyl-bendamustine (M4), and dihydroxy bendamustine (HP2) were determined in plasma and urine, using validated liquid chromatography-tandem mass spectrometry methods.

RESULTS

The mean recovery of TRA in excreta was 76% of the radiochemical dose. Approximately half of the administered dose was recovered in urine and a quarter in feces. Less than 5% of the administered dose was recovered in urine as unchanged bendamustine. Bendamustine clearance from plasma was rapid, with a half-life of ~40 minutes. Plasma concentrations of M3, M4, and HP2 were very low relative to bendamustine concentrations. Plasma levels of TRA were higher and more sustained as compared with plasma concentrations of bendamustine, M3, M4, and HP2, suggesting the presence of one or more longer-lived (14)C-bendamustine-derived compounds. Fatigue (50%) and vomiting (50%) were the most frequent treatment-related adverse events. A grade 3/4 absolute lymphocyte count decrease occurred in all patients at some point during the study.

CONCLUSION

Bendamustine is extensively metabolized, with subsequent excretion in both urine and feces. Accumulation of bendamustine is not anticipated in cancer patients with renal or hepatic impairment, because of the dose administration schedule and short half-life.

Development and validation of sensitive liquid chromatography/tandem mass spectrometry method for quantification of bendamustine in mouse brain tissue

A liquid chromatography-tandem mass spectrometry method for quantification of bendamustine in mouse brain tissue was developed and fully validated. Methanol was used to precipitate proteins in brain tissue. Bendamustine and internal standard (chlorambucil) were separated with reverse-phase chromatography on a C-18 column with a gradient of water and 95% methanol in 0.1% formic acid. Positive mode electrospray ionization was applied with selected reaction monitoring to achieve 5 ng/ml lower limits of quantitation in mouse brain tissue. The calibration curve for bendamustine in mouse brain was linear between 5 and 2000 ng/ml. The within- and between-batch accuracy and precision of the assay were within 15% at 10, 100 and 1000 ng/ml. The recovery and matrix effect of bendamustine in mouse brain tissue ranged from 41.1% to 51.6% and 107.4% to 110.3%, respectively. The validated method was then applied to quantitate bendamustine in an animal study. Results indicate the assay can be applied to evaluate bendamustine disposition in mouse brain tissue. This assay will be applied in the future to detect and quantify bendamustine in human brain tissue samples.

BeEAM (bendamustine, etoposide, cytarabine, melphalan) before autologous stem cell transplantation is safe and effective for resistant/relapsed lymphoma patients

We designed a phase 1-2 study to evaluate the safety and the efficacy of increasing doses of bendamustine (160 mg/m², 180 mg/m², and 200 mg/m² given on days -7 and -6) coupled with fixed doses of etoposide, cytarabine, and melphalan (BeEAM regimen) as the conditioning regimen to autologous stem cell transplantation for resistant/relapsed lymphoma patients. Forty-three patients (median age, 47 years) with non-Hodgkin (n = 28) or Hodgkin (n = 15) lymphoma were consecutively treated. Nine patients entered the phase 1 study; no patients experienced a dose-limiting toxicity. Thirty-four additional patients were then treated in the phase 2. A median number of 6 × 10⁶ CD34(+) cells/kg (range, 2.4-15.5) were reinfused. All patients engrafted, with a median time to absolute neutrophil count > 0.5 × 10⁹/L of 10 days. The 100-day transplantation-related mortality was 0%. After a median follow-up of 18 months, 35 of 43 patients (81%) are in complete remission, whereas 6 of 43 relapsed and 2 of 43 did not respond. Disease type (non-Hodgkin lymphomas vs Hodgkin disease) and disease status at transplantation (chemosensitive vs chemoresistant) significantly influenced DFS (P = .01; P = .007). Remarkably, 4 of 43 (9%) patients achieved the first complete remission after receiving the high-dose therapy with autologous stem cell transplantation. In conclusion, the new BeEAM regimen is safe and effective for heavily pretreated lymphoma patients. The study was registered at European Medicines Agency (EudraCT number 2008-002736-15).

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.

Phase I and pharmacokinetic study of bendamustine hydrochloride in relapsed or refractory indolent B-cell non-Hodgkin lymphoma and mantle cell lymphoma

Bendamustine is a cytotoxic agent with a novel mechanism of action. This phase I, dose-escalation study evaluated the safety, tolerability, efficacy, and pharmacokinetics of bendamustine in Japanese patients with relapsed/refractory indolent B-cell non-Hodgkin lymphoma (B-NHL) or mantle cell lymphoma (MCL) without major organ dysfunction. Bendamustine 90 or 120 mg/m(2) (dose escalation) was administered intravenously over 60 min on days 1 and 2 every 3 weeks for up to three cycles. Nine patients (eight indolent B-NHL and one MCL) received per-protocol treatment, three at 90 mg/m(2) and six at 120 mg/m(2) . No dose-limiting toxicities were observed; thus, the maximum-tolerated dose was not reached. Grade 3/4 hematologic toxicities were neutropenia (33%) and leukopenia (33%). Non-hematologic toxicities were grade 1/2 and included gastrointestinal events and fatigue. Peak plasma concentrations of bendamustine occurred near the end of infusion in both dose groups and were equivalent to therapeutic concentrations observed in vitro. Bendamustine was rapidly eliminated, with a mean elimination half-life (t(1/2) ) of 29 min. Plasma concentrations of active metabolites M3 and M4 were approximately 4 and <1% of the plasma concentration of the parent molecule, with t(1/2) of 42 and 33 min, respectively. Two unconfirmed complete responses and six partial responses were observed for an overall response rate (ORR) of 89%. The recommended dose for this schedule in phase II trials is 120 mg/m(2) . The acceptable safety profile and high ORR warrant further investigation of bendamustine in relapsed or refractory indolent B-NHL and MCL.

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 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.

Bendamustine pharmacokinetic profile and exposure-response relationships in patients with indolent non-Hodgkin's lymphoma

PURPOSE

The pharmacokinetic profiles of bendamustine and active metabolites were defined in patients with rituximab-refractory, relapsed indolent B-cell non-Hodgkin's lymphoma, and supported understanding of exposure-response relationships for efficacy and safety.

METHODS

Bendamustine was administered as a 60-min 120 mg/m(2) intravenous infusion on days 1 and 2 of six 21-day cycles. Pharmacokinetic models were developed, with covariate assessment. Correlations between bendamustine exposure and responder status or occurrence of neutropenia, thrombocytopenia, fatigue, nausea, and vomiting were examined.

RESULTS

Following a single dose of bendamustine HCl, concentrations declined in a triphasic manner, with rapid distribution, intermediate, and slow terminal phases. The intermediate t (1/2) (40 min) was considered the pharmacologically relevant (beta elimination) t (1/2) since the initial phases accounted for 99% of the AUC. Age, sex, mild/moderate renal, or mild liver impairment did not alter pharmacokinetics. Metabolite concentrations were low relative to parent. No correlation was observed between exposure and safety or efficacy measures because of the limited range of exposures after 120 mg/m(2) administration, except bendamustine C (max) was a significant (P value = 0.013) predictor of the probability of nausea in patients, most of whom were pretreated with antiemetics.

CONCLUSIONS

The BSA-based dosing regimen for bendamustine achieved the targeted exposure and was associated with a high incidence of therapeutic response. Given the short t (1/2) and low concentrations of bendamustine observed by 12 h after dosing, the single-dose profile for bendamustine described by these analyses is expected to be representative of the multiple-dose profile. The occurrence of nausea was significantly related to bendamustine exposure, with the probability of nausea increasing as bendamustine C (max) increases.

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.

Bendamustine in the treatment of chronic lymphocytic leukemia

Bendamustine is a cytotoxic agent that combines alkylating and antimetabolite effects. It has shown promising efficacy in a number of hematological cancers and, hence, is being investigated in patients with chronic lymphocytic leukemia (CLL), which is the most common form of adult leukemia in the Western world. Phase I/II trials with bendamustine as single-agent therapy in CLL have shown overall response rates of 56-93% and complete response rates of 7-29%. Preliminary data from a Phase III trial comparing bendamustine and chlorambucil (an agent widely used in the current treatment of CLL) have shown significantly higher response rates with bendamustine. Bendamustine has also shown activity in CLL when combined with mitoxantrone, rituximab or both. The principal toxicities associated with bendamustine are hematological, mainly leukopenia.

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, but not fludarabine, exhibits a low stem cell toxicity in vitro

PURPOSE

We investigated the in vitro toxicity of bendamustine and fludarabine to hematopoietic progenitors and stem cells from healthy donors.

METHODS

Clonogenic agar colony assays, non-clonogenic long-term liquid cultures (LTC) and apoptosis assays were used to assess the cytotoxicity of both the agents.

RESULTS

Total colony-forming units (CFU) were more sensitive to fludarabine than to bendamustine in agar colony assays (IC(50) 0.7 microM/L and 8.5 microM/L, respectively). Using the Bliss independence model and combining the two agents yielded additive inhibition of progenitors. Non-clonogenic assays, including LTC and an apoptosis assay detecting activated caspases showed that stem cells are characterized by low sensitivity to bendamustine. In contrast, fludarabine strongly inhibited the viability and growth of stem cells in LTC.

CONCLUSIONS

Our data show that bendamustine is characterized by lower in vitro toxicity to hematopoietic progenitors and stem cells than fludarabine and might thus be preferable in regimens prior to stem cells apheresis.