Development of Potent, Selective, Non-Myelotoxic FLT3 Inhibitors that Retain Efficacy Against Common Mechanisms of Resistance

项目总结/摘要 酪氨酸激酶的激活突变在人类骨髓恶性肿瘤中很常见。我们的长期目标是 通过基础和转化研究改善骨髓恶性肿瘤患者的预后。FLT 3是 在急性髓细胞白血病（AML）中最常见的突变基因。这笔赠款的目的是建立在 药物化学的最新进展推动了靶向治疗的界限， 告知激酶和疾病生物学，并推翻对靶和脱靶耐药的进化机制， 这些代理人。中心假设是，基础和翻译研究采用最先进的 研究耐药疾病的临床相关模型的分子工具将为新的治疗方法提供信息。 方法和推进我们对人类白血病生物学的理解。我们的理念是， BCR-ABL 1在慢性粒细胞白血病中的作用代表了一个范例，可以成功地应用于其他 骨髓恶性肿瘤以前，我们提供了令人信服的证据，证实激活的FLT 3作为治疗 靶向于人类AML。这项工作重新点燃了开发有效和选择性FLT 3激酶抑制剂的努力， 最大限度地减少FLT 3-ITD中赋予耐药的二级激酶结构域突变的脆弱性，并导致 gilteritinib最近获批然而，gilteritinib导致骨髓抑制，限制了其效用。我们 临床前工作提名激活RAS突变作为脱靶耐药的潜在介导物，我们的 最近对接受gilteritinib治疗的患者进行的转化研究证实，激活的RAS是主要的 对这种药物的获得性耐药机制。我们建议开发最好的FLT 3酪氨酸激酶 靶向耐药突变不受影响且无血液学毒性的TKI。我们 进一步提出研究，以确定和利用NRAS突变FLT 3-ITD阳性AML细胞中的漏洞。我们 具体的目的将测试以下假设：（目的1）有效的和选择性的FLT 3抑制剂将具有 足够治疗指数以使它们保持对常见的第二激酶结构域突变体的活性 并且将没有血液学毒性;（目的2）病理活化的FLT 3和NRAS的共存 将创造新的依赖性，可以利用治疗;和（目标3），结构研究和 化合物优化可以鉴定具有药物样性质的活性化合物。在结束这些 研究，我们将有一个更详细的了解化学支架，有效和选择性的目标 FLT 3，对含有共存FLT 3-ITD和NRAS突变的AML细胞的新认识， 在这种情况下的治疗弱点，以及新的治疗方法。这一贡献是重要的，因为它具有 快速影响临床研究和治疗结果的潜力。建议的研究是创新的 因为它提出了应用最先进的方法来系统地探测分子 AML耐药靶向治疗的基础，并将其与化学治疗的专业知识联合收割机结合起来， 结构生物学这项工作具有潜在的高度影响力，因为AML仍然与预后不良相关。

PROJECT SUMMARY/ABSTRACT Activating mutations in tyrosine kinase are common in human myeloid malignancies. Our long-term goal is to improve outcomes in patients with myeloid malignancies through basic and translational studies. FLT3 is the most commonly mutated gene in acute myeloid leukemia (AML). The objective of this grant is to build upon recent advances in medicinal chemistry that are pushing the boundaries of targeted therapeutics, to further inform kinase and disease biology, and to override evolving mechanisms of on- and off-target resistance to these agents. The central hypothesis is that basic and translational studies employing state-of-the-art molecular tools to interrogate clinically-relevant models of resistant disease will inform novel therapeutic approaches and advance our understanding of human leukemia biology. Our rationale is that pioneering work on BCR-ABL1 in chronic myeloid leukemia represents a paradigm that can successfully be applied to other myeloid malignancies. Previously, we provided compelling evidence validating activated FLT3 as a therapeutic target in human AML. This work rekindled efforts to develop potent and selective FLT3 kinase inhibitors that minimize vulnerabilities to resistance-conferring secondary kinase domain mutations in FLT3-ITD and led to the recent approval of gilteritinib. However, gilteritinib causes myelosuppression that limits its utility. Our preclinical work nominated activating RAS mutations as potential mediators of off-target resistance, and our recent translational studies of patients treated with gilteritinib have confirmed activated RAS as the dominant mechanism of acquired resistance to this drug. We propose to develop best-in-class FLT3 tyrosine kinase inhibitors (TKIs) that are impervious to on-target resistance mutations and devoid of hematologic toxicity. We further propose studies to identify and exploit vulnerabilities in NRAS-mutant FLT3-ITD-positive AML cells. Our specific aims will test the following hypotheses: (Aim 1) That potent and selective FLT3 inhibitors will have a sufficient therapeutic index to enable them to retain activity against common secondary kinase domain mutants and will be devoid of hematologic toxicity; (Aim 2) That coexistence of pathologically activated FLT3 and NRAS will create novel dependencies that can be exploited therapeutically; and (Aim 3) That structural studies and compound optimization can identify active compounds with drug-like properties. Upon conclusion of these studies, we will have a more detailed understanding of chemical scaffolds that potently and selectively target FLT3, novel understanding of AML cells that contain co-existent FLT3-ITD and NRAS mutations, insights into therapeutic vulnerabilities in this setting, and novel therapeutics. This contribution is significant since it has the potential to rapidly impact clinical investigation and therapeutic outcomes. The proposed research is innovative because it proposes application of state-of-the-art methodologies to systematically probe the molecular underpinnings of AML resistant to targeted therapeutics, and combine them with expertise in chemical structural biology. This work is potentially highly impactful as AML remains associated with a poor prognosis.