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

项目摘要/摘要 酪氨酸激酶的激活突变在人类髓系恶性肿瘤中很常见。我们的长期目标是 通过基础研究和翻译研究改善髓系恶性肿瘤患者的预后。Flt3是 急性髓系白血病(AML)最常见的突变基因。这笔赠款的目标是在 药物化学的最新进展正在推动靶向治疗的边界，以进一步 告知激酶和疾病生物学，并推翻靶上和靶外抗性的进化机制 这些特工。中心假设是基础研究和翻译研究使用了最先进的技术 询问临床相关耐药疾病模型的分子工具将提供新的治疗方法 方法，并促进我们对人类白血病生物学的理解。我们的理论基础是开创性的工作 慢性粒细胞白血病bcr-abl1基因的研究 髓系恶性肿瘤。此前，我们提供了令人信服的证据，证实激活的Flt3是一种治疗方法 人类急性髓细胞白血病的靶点。这项工作重新点燃了开发有效和选择性的Flt3激酶抑制剂的努力 最大限度地减少对Flt3-ITD中导致抗药性的二级激酶结构域突变的易感性，并导致 吉特利替尼最近的批准。然而，吉特利替尼会导致骨髓抑制，从而限制了其用途。我们的 临床前工作提名激活RAS突变作为靶外耐药的潜在媒介，而我们的 最近对服用吉特利替尼的患者进行的翻译研究证实，激活的RAS是主要的 对这种药物产生获得性耐药的机制。我们建议开发同类最好的Flt3酪氨酸激酶 抑制物(TKI)，不受靶标耐药突变的影响，没有血液毒性。我们 进一步提出识别和利用NRAS突变的Flt3-ITD阳性AML细胞中的脆弱性的研究。我们的 特定的AIMS将检验以下假设：(AIMS 1)有效和选择性的Flt3抑制剂将具有 足够的治疗指数，使它们能够保持对常见次级激酶结构域突变体的活性 将不会有血液毒性；(目标2)病理激活的Flt3和NRAS共存 将产生新的依赖关系，可用于治疗；以及(目标3)结构研究和 化合物优化可以识别具有类药物性质的活性化合物。在得出这些结论之后 通过研究，我们将对有效和选择性靶向的化学支架有更详细的了解 对包含共存的Flt3-ITD和NRAS突变的AML细胞的新理解，对 在这种情况下的治疗脆弱性，以及新的治疗方法。这一贡献意义重大，因为它具有 有可能迅速影响临床研究和治疗结果。建议的研究具有创新性。 因为它提出了应用最先进的方法学来系统地探索分子 急性髓系白血病耐药靶向治疗的基础，并与化学专业知识相结合 结构生物学。这项工作可能具有很高的影响力，因为AML仍然与预后不良有关。

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.