Tyrosine kinase inhibitors (TKIs) targeting FLT3 have shown activity but when used alone have achieved limited success in clinical trials, suggesting the need for combination with other drugs. We investigated the combination of FLT3 TKIs (Gilteritinib or Sorafenib), with Venetoclax, a BCL-2 selective inhibitor (BCL-2i), on FLT3/ITD leukemia cells. The combination of a FLT3 TKI and a BCL-2i synergistically reduced cell proliferation and enhanced apoptosis/cell death in FLT3/ITD cell lines and primary AML samples. Venetoclax also re-sensitized FLT3 TKI-resistant cells to Gilteritinib or Sorafenib treatment, mediated through MAPK pathway inhibition. Gilteritinib treatment alone dissociated BIM from MCL-1 but increased the binding of BIM to BCL-2. Venetoclax treatment enhanced the binding of BIM to MCL-1 but dissociated BIM from BCL-2. Treatment with the drugs together resulted in dissociation of BIM from both BCL-2 and MCL-1, with an increased binding of BIM to the cell death mediator BAX, leading to increased apoptosis. These findings suggest that Venetoclax mitigates the unintended pro-survival effects of FLT3 TKI mainly through the dissociation of BIM and BCL-2 and also decreased BIM expression. This study provides evidence that the addition of BCL-2i enhances the effect of FLT3 TKI therapy in FLT3/ITD AML treatment.

靶向 FLT3 的酪氨酸激酶抑制剂 (TKI) 已显示出活性，但单独使用时在临床试验中取得的成功有限，这表明需要与其他药物联合使用。我们研究了 FLT3 TKI（Gilteritinib 或 Sorafenib）与 Venetoclax（一种 BCL-2 选择性抑制剂 (BCL-2i)）对 FLT3/ITD 白血病细胞的组合。FLT3 TKI 和 BCL-2i 的组合在 FLT3/ITD 细胞系和原发性 AML 样本中协同减少细胞增殖并增强细胞凋亡/细胞死亡。Venetoclax 还通过 MAPK 通路抑制介导使 FLT3 TKI 耐药细胞对 Gilteritinib 或 Sorafenib 治疗重新敏感。单独的 Gilteritinib 治疗使 BIM 与 MCL-1 分离，但增加了 BIM 与 BCL-2 的结合。Venetoclax 处理增强了 BIM 与 MCL-1 的结合，但使 BIM 与 BCL-2 分离。与药物一起治疗导致 BIM 从 BCL-2 和 MCL-1 解离，BIM 与细胞死亡介质 BAX 的结合增加，导致细胞凋亡增加。这些发现表明，Venetoclax 主要通过 BIM 和 BCL-2 的解离以及降低 BIM 表达来减轻 FLT3 TKI 的意外促生存作用。该研究提供的证据表明，添加 BCL-2i 可增强 FLT3 TKI 治疗在 FLT3/ITD AML 治疗中的效果。