Toxicity of the alkylating agent bendamustin

Effects of chemotherapeutic agent bendamustine for non-hodgkin lymphoma on spermatogenesis in mice

Non-Hodgkin lymphoma (NHL) is one of the most common cancers affecting men of reproductive age. The high response rate of bendamustine as first-line treatment for NHL, coupled with young age of patients, makes elucidation of the impact of treatment on male reproduction important. Our aim was to determine the effects of bendamustine on male reproduction by animal model. Male mice were treated with bendamustine (40 mg/kg) through tail vein injection while cisplatin was given as a standard (3 mg/kg) through intraperitoneal injection. After 3 weeks, bendamustine induced weight loss and sperm morphology abnormalities were compared to the control. Additionally, sperm with folded tails were the most frequent abnormality in bendamustine-treated mice. But the mechanism of sperm abnormality induced by bendamustine remains to be elucidated. These results indicate bendamustine may affect spermatozoa of patients who have been treated for NHL.

Immunosuppressants and Male Reproduction

Prolonged use of immunosuppressant medications is occasionally seen in infertile men with chronic inflammatory conditions; autoimmune disorders; or an organ or hematopoietic stem cell transplant. Chronic inflammation impacts negatively on male reproductive endpoints, so immunosuppressant therapy can produce improvements. Corticosteroids have been used to treat antisperm antibodies and even as an empirical treatment for male infertility in general. Trials of these methods have provided mixed results on semen quality and fertility, with improvement, no change and negative effects reported by different investigators. In a substantial number of observational studies, patients on long-term therapy with prednisone for chronic inflammatory disease, testosterone levels were lower compared to untreated controls, though randomized controlled trials have not been conducted. Similarly decreases in testosterone have been reported in men receiving corticosteroids to minimize transplant rejection; however, most were treated with multiple immunosuppressive medications that may have contributed to this effect. A large number of trials of healthy men treated with corticosteroids have shown some disruption in reproductive hormone levels, but other studies reported no effect. Studies in monkeys, rats (at human equivalent dose), cattle, sheep, and horses have shown endocrine disruption, including low testosterone with dexamethasone treatment. Of the cytostatic immunosuppressives, which have high potential for cellular damage, cyclophosphamide has received the most attention, sometimes lowering sperm counts significantly. Methotrexate may decrease sperm numbers in humans and has significant negative impacts in rodents. Other chemotherapeutic drugs used as immunosuppressants are likely to impact negatively on male fertility endpoints, but few data have been collected. The TNF-α Inhibitors have also received little experimental attention. There is some evidence that the immunophilin modulators: cyclosporine, sirolimus, and everolimus cause endocrine disruption and semen quality impairment. As we review in this chapter, results in experimental species are concerning, and well-designed studies are lacking for the effects of these medications on reproductive endpoints in men.

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

The aim of the study was to determine the maximum tolerated dose (MTD), the dose limiting toxicity (DLT), and the pharmacokinetic profile (Pk) of bendamustine (BM) on a day 1 and 2 every 3 weeks schedule and to recommend a safe phase II dose for further testing. Patients with solid tumours beyond standard therapy were eligible. A 30-min intravenous infusion of BM was administered d1+d2 q 3 weeks. The starting dose was 120 mg m(-2) per day and dose increments of 20 mg m(-2) were used. Plasma and urine samples were analysed using validated high-performance liquid chromatography/fluorescence assays. Fifteen patients were enrolled. They received a median of two cycles (range 1-8). The MTD was reached at the fourth dose level. Thrombocytopaenia (grade 4) was dose limiting in two of three patients at 180 mg m(-2). One patient also experienced febrile neutropaenia. Lymphocytopaenia (grade 4) was present in every patient. Nonhaematologic toxicity including cardiac toxicity was not dose limiting with this schedule. Mean plasma Pk values of BM were tmax 35 min, t(1/2) 49.1 min, Vd 18.3 l m(-2), and clearance 265 ml min(-1) m(-2). The mean total amount of BM and its metabolites recovered in the first micturition was 8.3% (range 2.7-26%). The MTD of BM in the present dose schedule was 180 mg m(-2) on day 1+2. Thrombocytopaenia was dose limiting. The recommended dose for future phase II trials with this schedule is 160 mg m(-2) per day.

Alkylating benzamides with melanoma cytotoxicity: experimental chemotherapy in a mouse melanoma model

The in-vivo antineoplastic potential of the alkylating N-(2-dialkylaminoethyl)benzamides BZA1 and BZA2, novel melanoma targeted anticancer drugs, was evaluated in a mouse melanoma model with nude mice bearing subcutaneous SkMel28, B16 or WM266-4. The maximal tolerated dose (MTD) for the intraperitoneal application of both agents was found to be 24 mg/kg. Treatment was initiated with an intraperitoneal injection of 8 mg/kg of BZA1 or BZA2 on days 0, 2 and 4 in the case of B16 melanoma on days 0, 1 and 2 after the onset of the experiment, when the mean tumor diameter ranged within 4-6 mm. The experiment was terminated when the mean tumor diameter in the control group had reached a value of 12 mm. Tumor growth delay of these agents was compared with dacarbazine (3x250 mg/kg), chlorambucil (3x5 mg/kg) and an untreated control group. Significant tumor growth delay was observed under BZA1, BZA2 and dacarbazine treatment compared with the untreated control group in all three evaluated melanomas with insignificant differences among BZA1, BZA2 and dacarbazine. The insignificant effect of chlorambucil and the strong improvement on growth delay achieved with BZA1 and BZA2 demonstrated melanoma targeting characteristics of the N-(2-dialkylaminoethyl)benzamide structure element. Dacarbazine was more effective in the in-vivo antineoplastic assay compared with the in-vitro cytotoxicity studies, probably due to hepatic bioactivation. Similar side effect intensity of BZA2 and dacarbazine was observed, whereas BZA1 was more toxic. BZA2 might represent an alternative antimelanoma drug, especially in patients not responding to dacarbazine.

Weekly administration of bendamustine: a phase I study in patients with advanced progressive solid tumours

BACKGROUND

The cytotoxic agent bendamustine combines a purine-like benzimidazol and alkylating nitrogen mustard group. The clinically tolerated dose for single bolus bendamustine is 215 mg/m2, for fractionated therapy on four consecutive days 85 mg/m2. The maximum tolerated dose of a day 1 and 8 (q4w) 30 min infusion schedule was recently found to be 160 mg/m2, mouth dryness and fatigue were dose-limiting. Our current phase I trial was designed to define the recommended dose of a new weekly short infusion schedule.

PATIENTS AND METHODS

Patients with refractory malignant tumours qualified for the trial after written informed consent was obtained. Bendamustine was given as a 30-min i.v. infusion weekly for up to eight consecutive weeks.

RESULTS

Twelve patients (8 male, 4 female, median age 57.5 years, range 42-64) were enrolled in this trial. At the starting dose of 80 mg/m2, two patients had dose-limiting toxicity (fatigue grade 3, mouth dryness grade 3, fever grade 4 Common Toxicity Criteria). No dose-limiting events were observed in six patients treated at 60 mg/m2. An intermediate dose level of 70 mg/m2 was studied in three younger, less heavily pretreated patients, was well tolerated and not associated with dose-limiting events. Haematological toxicity was mild except for grade 3-4 lymphocytopenia, occurring in 11 of 12 patients. Bendamustine was found to induce long-lasting panlymphocytopenia with predominant B-cell cytotoxicity.

CONCLUSIONS

The maximum tolerated dose of weekly bendamustine given as a 30-min i.v. infusion is 80 mg/m2, mouth dryness, fatigue and fever are dose-limiting. The recommended dose for phase II trials is 60 mg/m2.