Degrading therapeutically important kinases using small molecules

用小分子抑制剂靶向致癌激酶现在是一种经过充分验证的治疗肿瘤的范例。 癌症类型和大约25种针对靶点的药物，如ALK、EGFR、BCR-ABL、BTK、C-KIT、B- RAF和PDFGRβ现已在临床上常规使用。不幸的是，除了对BCR-ABL的长期反应外， 在慢性髓系白血病中，对其他抑制剂的耐药性通常在治疗后1-2年发展。 最初的成功回应。此外，一些肿瘤依赖于激酶的支架功能，而不是依赖于激酶的支架功能。 酶激酶活性，从而使抑制剂无效。例如，假激酶Her 3是一种 EGFR和Her 2的专性异二聚化配偶体，但其激酶活性不是必需的。这里我们 我建议探索一种全新的方法来废除激酶功能， 可以选择性地促进感兴趣的激酶靶的降解的分子。特别是要 利用最近描述的方法，涉及开发诱导 泛素化和随后的蛋白酶体降解的目标。我们将使用与 沙利度胺，它可以募集我们称为“选择性”的E3连接酶CUL 4-RBX 1-DDB 1-CRBN（CRL 4CRBN 降解剂“（也称为PROTAC或degronimid）。我们开发了一种强大的质谱仪- 基于蛋白质组学的方法，使我们能够确定哪些激酶更容易受到 通过这种策略，它已经确定了两个非常有效的认证目标， 降解：BTK和FLT 3。我们已经为FLT 3和BTK开发了出色的原型降能器， 进一步优化以获得能够在体内降解这些靶标的化合物。另外我们有 确定了治疗感兴趣的靶标，HER 3是假激酶（无催化活性），但作为 与EGFR和HER 2的关键二聚化伴侣，因此代表了靶向治疗的独特机会。 通过退化。这项拨款申请的目标是开发优化的小分子 BTK，FLT 3和HER 3的降解剂，并了解生物化学和结构基础 他们的行动机制。对这些激酶表现出依赖性的经过良好验证的细胞模型将是 用于研究激酶抑制和降解之间的细胞反应如何不同。

Targeting of oncogenic kinases with small molecule inhibitors is now a well validated paradigm for treatment of cancer types and approximately 25 drugs directed at targets such as ALK, EGFR, BCR-ABL, BTK, C-KIT, b- RAF and PDFGRβ are now in routine clinical use. Unfortunately, except for long-term responses to BCR-ABL inhibitors in Chronic Myeloid Leukemia, resistance to other inhibitors typically develops 1-2 years after an initially successful response. In addition, some tumors depend on the scaffolding function of a kinase and not on enzymatic kinase activity, thereby rendering inhibitors ineffective. For example the pseudokinase Her3 is an obligate heterodimerization partner with EGFR and Her2 but its kinase activity is not required. Here we propose to explore a fundamentally new approach to abrogating kinase function using small molecules that can selectively promote the degradation of kinase targets of interest. In particular, we will exploit a recently described approach involving the development of bivalent small molecules that induce ubiquitination and subsequent proteasomal degradation of targets of interest. We will use ligands related to thalidomide, which can recruit the E3 ligase CUL4-RBX1-DDB1-CRBN (CRL4CRBN) that we call `selective degraders' (also known as PROTACs or degronimids). We have developed a powerful mass spectrometry- based proteomics approach that has allowed us to determine which kinases are more susceptible to degradation by this strategy, which has identified two well credentialed targets that are very efficiently degraded: BTK and FLT3. We have developed excellent prototype degraders for FLT3 and BTK which will be further optimized to obtain compounds capable of degrading these targets in vivo. In addition, we have identified a target of therapeutic interest, HER3 that is a pseudokinase (catalytically inactive) but serves as a critical dimerization partner with EGFR and HER2 and therefore represents a unique opportunity for targeting through degradation. The goal of this grant application is to develop optimized small molecule degraders of BTK, FLT3 and HER3 and to understand the biochemical and structural underpinnings of their mechanism of action. Well validated cellular models that exhibit dependencies on these kinases, will be used to investigate how the cellular response differs between kinase inhibition and degradation.!