Development of novel inhibitors targeting oncogenic signaling in TKI-resistant gastrointestinal stromal tumors

胃肠道间质瘤（GIST）是最常见的肉瘤，其特征在于激活KIT和PDGFRA受体酪氨酸激酶的突变。在成功的靶向治疗后，绝大多数患者最终产生耐药性并死于疾病。继发性耐药突变的基因组异质性阻碍了有效和持久挽救治疗的开发。目前，没有可用的药物（临床或实验）针对这种广谱耐药。在第一个资助期，我们一方面特别筛选抑制D816突变的化合物，另一方面我们合理设计了具有17号和13号外显子组合活性的化合物。最近，我们已经将这些化合物进一步修饰成共价KIT抑制剂的第一组先导物，这是一种尚未开发的靶向KIT的策略。我们进一步开发了一种新型的AKT共价变构抑制剂（CAI），其在我们的GIST模型中显示出高效力，作为靶向致癌信号传导的补充策略。我们通过五篇高影响力的出版物和上述CAIs的专利申请强调了这一合作的持续成功。扩大我们最初的筛选方法，我们引入了一个相当大的化合物库（n = 35，000），并改进了我们的工作流程，现在使我们能够显着提高吞吐量。我们已经扩大了我们的GIST模型的设备，例如通过开发第一个携带关键KITV 654 A二级突变的GIST-T1亚系以及第一个TKI耐药PDGFRAD 842 V细胞系。对于第二个资助期，我们计划通过三重策略来解决临床上对GIST致癌信号的新型强效抑制剂的需求。因此，我们将1。在体外和体内进一步完善和表征我们的新型共价KIT抑制剂。2.确定我们的新型AKT抑制剂（borussertib）在体内的疗效和治疗窗口。3.应用我们新的广泛的化合物库来鉴定针对KITV 654 A的特异性抑制剂，其不阻断VEGFR以及针对PDGFRA G680 R/D842 V双突变体和G652 E/V658 A/D842 V三突变体GIST。这一资助期将使我们能够实现一组新型化合物向高级临床前开发的过渡。因此，结合我们在药物开发和疾病特异性验证方面的资源和互补专业知识，将使我们能够发现特定的抑制剂，以满足罕见癌症患者尚未满足的医疗需求。

Gastrointestinal stromal tumors (GIST) are the most common sarcomas and characterized by activating mutations of the KIT and PDGFRA receptor tyrosine kinases. Following successful targeted therapy, the vast majority of patients eventually develop resistance and die of the disease. Genomic heterogeneity of secondary resistance mutations hampers the development of effective and long-lasting salvage therapies. Currently, no available drug (clinical or experimental) targets this broad spectrum of resistance.In the first funding period, we have on the one hand screened particularly for compounds inhibiting D816 mutations while on the other hand we rationally designed compounds with combined exon 17 and 13 activity. Most recently we have further modified these compounds into a first set of leads for covalent KIT-inhibitors, a yet unexploited strategy to target KIT. We have further developed a novel covalent allosteric inhibitor (CAI) of AKT displaying high potency in our GIST models as a complementing strategy to target oncogenic signaling. We underlined the ongoing success of this cooperation by five high impact publications and the patent application for said CAIs.Expanding our initial screening approach we have introduced a considerably larger compound library (n = 35,000) and refined our workflow now enabling us to dramatically increase throughput. We have broadened our armamentarium of GIST models for example by developing the first GIST-T1 subline harboring the critical KITV654A secondary mutation as well as the first TKI-resistant PDGFRAD842V cell line. For the second funding period, we plan to tackle the clinically dictated need for novel potent inhibitors of GIST oncogenic signaling by a threefold strategy. Thus, we will 1. Further refine and characterize our novel covalent KIT-inhibitors in vitro and in vivo. 2. Determine the efficacy and therapeutic window of our novel AKT-inhibitor (borussertib) in vivo. 3. Apply our new extensive compound library to identify specific inhibitors against KITV654A not blocking VEGFR as well as against PDGFRA G680R/D842V double and G652E/V658A/D842V triple mutant GIST. This funding period will enable us to realize the transition of a novel set of compounds into advanced preclinical development. Combining our resources and complementary expertise in drug development and disease-specific validation will thus enable us to discover specific inhibitors addressing the yet unmet medical needs of patients with a rare cancer.