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 <i>in vitro</i> mammalian cell micronucleus test (Mnvit) and the chromosome aberration (CA) test in human peripheral lymphocytes, and the <i>in vivo</i> homozygotization assay in <i>Aspergillus nidulans</i>, 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. <i>Aspergillus nidulans</i> 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.

苯达莫司汀（Bendamustine）是一种具备烷化活性的抗癌药物，被广泛应用于血液系统恶性肿瘤的临床治疗。由于氮芥家族烷化剂可诱导DNA损伤，且与继发性恶性肿瘤风险升高存在关联，本研究分别采用有丝分裂指数试验、体外（in vitro）哺乳动物细胞微核试验（Mnvit）、人外周淋巴细胞染色体畸变（CA）试验，以及体内（in vivo）构巢曲霉（Aspergillus nidulans）纯合化试验，评估苯达莫司汀的细胞毒性、致突变性与重组活性，该纯合化试验可检测体细胞重组引发的杂合性缺失（LOH）。
相较于阴性对照组，苯达莫司汀（6.0 μg/ml、9.0 μg/ml及12.0 μg/ml）可诱导微核频率呈现浓度依赖性的显著升高，同时使胞质分裂阻滞增殖指数（CBPI）显著降低。
在染色体畸变试验中，相较于阴性对照组，苯达莫司汀在三个受试浓度下均可显著提升结构畸变的发生频率。
经苯达莫司汀处理（6.0 μg/ml、12.0 μg/ml及24.0 μg/ml）后获得的构巢曲霉二倍体，经单倍体化后，其纯合化指数（HI）高于2.0，且与阴性对照组存在显著差异。
鉴于苯达莫司汀在所有受试浓度下均表现出遗传毒性，其中两个浓度对应于接受苯达莫司汀治疗的癌症患者的血浆峰浓度，本研究提供的数据可为确定该抗癌药物兼顾疗效与安全性的最优给药方案提供参考依据。