Targeting AML Mitochondria by Ceramide

总结 该提案的长期目标是开发一种基于机制的治疗药物，用于治疗 人类急性髓性白血病（AML），这是美国最致命的癌症之一。尽管 尽管在治疗方面取得了一些进展，但AML的生存率在几十年来并没有显著提高，只有极少数例外 对于特定的子类。虽然FLT 3、IDH和Bcl-2抑制剂的靶向治疗增加了反应， 虽然死亡率很高，但存活期仅延长了几个月。因此，新的和创新的治疗 需要药物来改善AML患者的生存结果。鞘脂神经酰胺，一种新兴的 肿瘤抑制脂质，介导响应各种应激刺激的抗增殖信号传导事件， 包括酪氨酸激酶抑制剂（TKI）。我们已发表和未发表的数据表明， C18-神经酰胺在AML的病理生理、进展和耐药中可能起着重要作用。这些数据 还揭示了通过分子和药理学工具重建C18-神经酰胺导致 抑制AML生长，并帮助克服耐药性。由于药物的挑战， 传统的外源性短链神经酰胺，我们已经开发了新的线粒体靶向吡啶- C18-神经酰胺（Pyr-Cer）类似物，诱导癌细胞线粒体自噬和肿瘤抑制。这些Pyr-Cer 类似物表现出增加的水溶性、细胞膜渗透性和癌细胞选择性线粒体膜通透性。 与不带电的常规神经酰胺相比，Pyr-Cer类似物药物，如LCL 461（专利 I类）或LCL 768（II类），在离域π电子系统中含有正电荷。这将导致 药物优先定位于癌细胞/组织中高度带负电荷的线粒体中， 瓦尔堡效应。Pyr-Cer在线粒体中的积累通过诱导细胞凋亡导致癌细胞死亡。 线粒体自噬通过减少细胞能量产生和减少其他重要大分子的合成， 例如核苷酸。Pyr-Cer对线粒体自噬诱导的这种作用在癌细胞被激活时进一步增加。 暴露于一般ROS/RNS诱导剂亚硒酸钠，导致Drp 1激活和线粒体分裂。 因此，我们已经产生了与亚硒酸钠缀合的新的（II类）Pyr-Cer类似物药物，命名为 SoSe-C18-Pyr-Cer（LCL 768），其选择性地在AML中原位诱导线粒体自噬依赖性细胞死亡，并在AML中诱导线粒体自噬依赖性细胞死亡。 vivo.基于这些数据，我们的目标是开发LCL 768作为治疗AML的抗癌药物。在 在这些可行性研究中，我们将：1）阐明Pyr-Cer药物靶向AML线粒体的机制 2）测定LCL 768的生物活性、毒性、药代动力学和抗AML活性 in vivo.我们将确定可能的脱靶效应、最大耐受剂量（MTD）， 在各种模型中，LCL 768的药代动力学/药效学特征和抗AML作用。这些包括 药物敏感性与耐药性AML异种移植物、AML PDX和原发性AML原始细胞。第一阶段可行性 这项研究将有助于LCL 768的第二阶段应用的商业开发。

SUMMARY This proposal's long-term objective is to develop a mechanism-based therapeutic drug for the treatment of human acute myeloid leukemias (AML), which are among the deadliest cancers in the United States. Despite some advances in treatment, survival for AML has not improved significantly in decades, with rare exceptions for specific subclasses. While targeted therapies with FLT3, IDH, and Bcl-2 inhibitors have increased response rates significantly, survival has been extended only by several months. Thus, novel and innovative therapeutic drugs are needed to improve the survival outcomes of AML patients. The sphingolipid ceramide, an emerging tumor suppressor lipid, mediates anti-proliferative signaling events in response to various stress stimuli, including tyrosine kinase inhibitors (TKIs). Our published and unpublished data suggest that decreased levels of C18-ceramide might be critical in the pathophysiology, progression and drug-resistance of AML. These data also revealed that reconstitution of C18-ceramide by molecular and pharmacologic tools results in the suppression of AML growth, and help overcome drug resistance. Because of pharmacologic challenges of the conventional exogenous short-chain ceramides, we have developed novel mitochondrial targeted pyridinium- C18-ceramide (Pyr-Cer) analogs that induce cancer cell mitophagy and tumor suppression. These Pyr-Cer analogs exhibit increased water solubility, cell-membrane permeability, and cancer cell-selective mitochondrial uptake, compared to uncharged conventional ceramides. Pyr-Cer analog drugs, such as LCL461 (patented Class I) or LCL768 (Class II), contain a positive charge at a delocalized pi-electron system. This then results in preferential localization of the drug into highly negatively charged mitochondria in cancer cells/tissues due to the Warburg effect. The accumulation of Pyr-Cer in mitochondria results in cancer cell death via induction of mitophagy by reducing cellular energy generation and decreasing the synthesis of other vital macromolecules, such as nucleotides. This effect of Pyr-Cer on mitophagy induction is further increased when cancer cells are exposed to general ROS/RNS inducer sodium selenite that causes Drp1 activation and mitochondrial fission. Thus, we have generated a new (Class II) Pyr-Cer analog drugs conjugated with sodium selenite, named as SoSe-C18-Pyr-Cer (LCL768), which selectively induced mitophagy-dependent cell death in AML in situ and in vivo. Based on these data, our goal is to develop LCL768 as an anti-cancer drug for the treatment of AML. In these feasibility studies, we will: 1) Validate the mechanism by which Pyr-Cer drugs target AML mitochondria by mitophagy in vitro; and 2) Determine bioactivity, toxicity, pharmacokinetics and anti-AML activity of LCL768 in vivo. We will determine the possible off-target effects, maximum tolerated dose (MTD), pharmacokinetic/pharmacodynamic profiles and anti-AML effects of LCL768 in various models. These include drug sensitive versus resistant AML xenografts, AML PDXs, and primary AML blasts. This Phase I feasibility study will help the commercial development of LCL768 for a Phase II application.