首个类烷基化去乙酰化酶抑制剂分子替莫唑胺在胶质母细胞瘤的临床前模型中表现出抗肿瘤作用，并与放射治疗具有协同作用。

The first-in-class alkylating deacetylase inhibitor molecule tinostamustine shows antitumor effects and is synergistic with radiotherapy in preclinical models of glioblastoma.

机构信息

Laboratory of Radiobiology, Department of Applied Clinical Sciences and Biotechnologies, University of L'Aquila, L'Aquila, Italy.

Division of Radiotherapy, Department of Applied Clinical Sciences and Biotechnologies, University of L'Aquila, L'Aquila, Italy.

出版信息

J Hematol Oncol. 2018 Feb 27;11(1):32. doi: 10.1186/s13045-018-0576-6.

BACKGROUND

The use of alkylating agents such as temozolomide in association with radiotherapy (RT) is the therapeutic standard of glioblastoma (GBM). This regimen modestly prolongs overall survival, also if, in light of the still dismal prognosis, further improvements are desperately needed, especially in the patients with O6-methylguanine-DNA-methyltransferase (MGMT) unmethylated tumors, in which the benefit of standard treatment is less. Tinostamustine (EDO-S101) is a first-in-class alkylating deacetylase inhibitor (AK-DACi) molecule that fuses the DNA damaging effect of bendamustine with the fully functional pan-histone deacetylase (HDAC) inhibitor, vorinostat, in a completely new chemical entity.

METHODS

Tinostamustine has been tested in models of GBM by using 13 GBM cell lines and seven patient-derived GBM proliferating/stem cell lines in vitro. U87MG and U251MG (MGMT negative), as well as T98G (MGMT positive), were subcutaneously injected in nude mice, whereas luciferase positive U251MG cells and patient-derived GBM stem cell line (CSCs-5) were evaluated the orthotopic intra-brain in vivo experiments.

RESULTS

We demonstrated that tinostamustine possesses stronger antiproliferative and pro-apoptotic effects than those observed for vorinostat and bendamustine alone and similar to their combination and irrespective of MGMT expression. In addition, we observed a stronger radio-sensitization of single treatment and temozolomide used as control due to reduced expression and increased time of disappearance of γH2AX indicative of reduced signal and DNA repair. This was associated with higher caspase-3 activation and reduction of RT-mediated autophagy. In vivo, tinostamustine increased time-to-progression (TTP) and this was additive/synergistic to RT. Tinostamustine had significant therapeutic activity with suppression of tumor growth and prolongation of DFS (disease-free survival) and OS (overall survival) in orthotopic intra-brain models that was superior to bendamustine, RT and temozolomide and showing stronger radio sensitivity.

CONCLUSIONS

Our data suggest that tinostamustine deserves further investigation in patients with glioblastoma.

背景

替莫唑胺等烷化剂与放疗（RT）联合应用是胶质母细胞瘤（GBM）的治疗标准。尽管考虑到预后仍然不佳，仍迫切需要进一步改善，但这种方案仅能适度延长总生存期，尤其是在 O6-甲基鸟嘌呤-DNA-甲基转移酶（MGMT）未甲基化肿瘤患者中，标准治疗的获益较小。替莫唑胺（EDO-S101）是一种首创的烷化脱乙酰酶抑制剂（AK-DACi）分子，它将苯达莫司汀的 DNA 损伤作用与完全功能的组蛋白去乙酰化酶（HDAC）抑制剂伏立诺他融合在一个全新的化学实体中。

方法

替莫唑胺已在体外使用 13 种 GBM 细胞系和 7 种患者来源的 GBM 增殖/干细胞系的 GBM 模型中进行了测试。U87MG 和 U251MG（MGMT 阴性）以及 T98G（MGMT 阳性）被皮下注射到裸鼠中，而荧光素酶阳性 U251MG 细胞和患者来源的 GBM 干细胞系（CSCs-5）则在体内进行了原位实验。

结果

我们证明，替莫唑胺具有比单独使用伏立诺他和苯达莫司汀更强的抗增殖和促凋亡作用，并且与它们的组合相似，而与 MGMT 表达无关。此外，我们观察到由于 γH2AX 表达减少和消失时间延长，提示信号和 DNA 修复减少，单一治疗和用作对照的替莫唑胺的放射增敏作用更强。这与 caspase-3 激活增加和 RT 介导的自噬减少有关。在体内，替莫唑胺增加了无进展时间（TTP），并且与 RT 具有相加/协同作用。替莫唑胺在原位脑内模型中具有显著的治疗活性，可抑制肿瘤生长并延长无疾病生存期（DFS）和总生存期（OS），优于苯达莫司汀、RT 和替莫唑胺，并显示出更强的放射敏感性。