Oncology Discovery, AbbVie Inc., North Chicago, Illinois.
Genomics Research Center, AbbVie Inc., North Chicago, Illinois.
Clin Cancer Res. 2020 Jul 1;26(13):3371-3383. doi: 10.1158/1078-0432.CCR-19-1900. Epub 2020 Feb 13.
Patients with acute myeloid leukemia (AML) frequently do not respond to conventional therapies. Leukemic cell survival and treatment resistance have been attributed to the overexpression of B-cell lymphoma 2 (BCL-2) and aberrant DNA hypermethylation. In a phase Ib study in elderly patients with AML, combining the BCL-2 selective inhibitor venetoclax with hypomethylating agents 5-azacitidine (5-Aza) or decitabine resulted in 67% overall response rate; however, the underlying mechanism for this activity is unknown.
We studied the consequences of combining two therapeutic agents, venetoclax and 5-Aza, in AML preclinical models and primary patient samples. We measured expression changes in the integrated stress response (ISR) and the BCL-2 family by Western blot and qPCR. Subsequently, we engineered (NOXA)- and (PUMA)-deficient AML cell lines using CRISPR- methods to understand their respective roles in driving the venetoclax/5-Aza combinatorial activity.
In this study, we demonstrate that venetoclax and 5-Aza act synergistically to kill AML cells and display combinatorial antitumor activity . We uncover a novel nonepigenetic mechanism for 5-Aza-induced apoptosis in AML cells through transcriptional induction of the proapoptotic BH3-only protein NOXA. This induction occurred within hours of treatment and was mediated by the ISR pathway. NOXA was detected in complex with antiapoptotic proteins, suggesting that 5-Aza may be "priming" the AML cells for venetoclax-induced apoptosis. knockout confirmed its major role in driving venetoclax and 5-Aza synergy.
These data provide a novel nonepigenetic mechanism of action for 5-Aza and its combinatorial activity with venetoclax through the ISR-mediated induction of .
急性髓系白血病（AML）患者常对常规治疗无反应。白血病细胞的存活和治疗耐药性归因于 B 细胞淋巴瘤 2（BCL-2）的过表达和异常的 DNA 超甲基化。在一项针对老年 AML 患者的 Ib 期研究中，联合使用 BCL-2 选择性抑制剂 venetoclax 和低甲基化剂 5-氮杂胞苷（5-Aza）或地西他滨，总缓解率为 67%；然而，这种活性的潜在机制尚不清楚。
我们研究了联合两种治疗药物 venetoclax 和 5-Aza 在 AML 临床前模型和患者原代样本中的后果。我们通过 Western blot 和 qPCR 测量了整合应激反应（ISR）和 BCL-2 家族的表达变化。随后，我们使用 CRISPR 方法构建了 （NOXA）-和 （PUMA）-缺陷型 AML 细胞系，以了解它们在驱动 venetoclax/5-Aza 联合活性中的各自作用。
在这项研究中，我们证明 venetoclax 和 5-Aza 协同作用杀死 AML 细胞，并显示出组合抗肿瘤活性。我们揭示了 5-Aza 诱导 AML 细胞凋亡的一种新的非表观遗传机制，即通过促凋亡 BH3 仅蛋白 NOXA 的转录诱导。这种诱导发生在治疗后的数小时内，并由 ISR 途径介导。NOXA 与抗凋亡蛋白形成复合物，表明 5-Aza 可能“启动”AML 细胞对 venetoclax 诱导的凋亡。 基因敲除证实了其在驱动 venetoclax 和 5-Aza 协同作用中的主要作用。
这些数据为 5-Aza 及其通过 ISR 介导的 诱导的与 venetoclax 的组合活性提供了一种新的非表观遗传作用机制。
