Potentiating targeted drugs in breast cancer via transcription-regulating kinases

摘要 目前的乳腺癌治疗主要基于靶向治疗。特别是激素治疗的目标 雌激素受体（ER）阳性癌症，而过表达HER 2的癌症用 不同类型的HER 2靶向药物。后者包括单克隆抗体、小分子抑制剂或其组合。 与细胞毒性药物缀合的HER 2抗体。乳腺癌治疗中使用的其他靶向药物作用于 CDK4/6、mTOR、EGFR、HDAC或PARP。不幸的是，许多患者对靶向治疗没有反应， 先有反应，然后产生抗药性。新的“可药物化”的致癌介质的鉴定 目前的乳腺癌药物靶点的作用可能会在癌症治疗中产生临床改善， 对靶向治疗有抵抗力。基本上所有信号传导途径的共同终点 由癌症药物靶点介导的是对调节肿瘤生长、存活和转移的基因转录的影响。 转移在转录空间中最可靶向的蛋白质是转录调节激酶 属于细胞周期蛋白依赖性激酶（CDK）家族，CDK 7、CDK 8/19和CDK 9。这些激酶的抑制剂 正在进行临床前和临床开发。我们假设转录调节抑制剂 激酶将与用于治疗乳腺癌的靶向药物协同作用， 与转录调节激酶抑制剂的联合应用可以克服或防止耐药性的发展， 靶向药物。我们已经确定了几种靶向乳腺癌药物的协同组合， 转录调节激酶抑制剂，最值得注意的是CDK 8/19抑制剂与ER-和 HER 2靶向药物和CDK 7抑制剂与EGFR靶向药物。在项目的剩余时间里， 我们将表征所发现的组合中最有效的组合，即HER 2和 CDK 8/19抑制剂。在目标1下，HER 2抑制剂拉帕替尼和一种抗HER 2抗体之间的组合的功效被评估。 CDK 8/19抑制剂将使用拉帕替尼敏感性和耐药性HER 2- 阳性乳腺癌细胞。目的2是研究拉帕替尼与 CDK 8/19抑制剂。该目的的实验计划基于RNA-Seq分析的结果， 确定了这种协同作用的候选下游介质。这些候选基因的表达受到调控 通过转录因子，其磷酸化依赖于CDK 8/19和HER 2。目标3是 开发抗HER 2单克隆抗体和强效CDK 8/19抑制剂之间的偶联物，并检测 该结合物相对于未结合药物的体外功效。这个项目的成功将为 本发明提供了通过以下新组合提高乳腺癌靶向治疗的功效的方法： 目前的靶向药物与转录调节激酶抑制剂。未来的基础和转化研究 HER 2和CDK 8/19靶向药物的联合作用可能对治疗产生深远影响 转移性HER 2阳性乳腺癌对HER 2靶向药物耐药。

ABSTRACT Current breast cancer therapy is largely based on targeted therapeutics. In particular, hormonal therapy targets the estrogen receptor (ER) in ER-positive cancers, whereas cancers that overexpress HER2 are treated with different types of HER2-targeted drugs. The latter include monoclonal antibodies, small molecule inhibitors, or HER2-antibodies conjugated to a cytotoxic drug. Other targeted drugs used in breast cancer therapy act on CDK4/6, mTOR, EGFR, HDAC or PARP. Unfortunately, many patients do not respond to targeted therapies or respond initially and then develop resistance. Identification of new “druggable” mediators of the oncogenic effects of the current breast cancer drug targets could yield clinical improvements in the treatment of cancers resistant to targeted therapy. The common endpoint of essentially all the signal transduction pathways mediated by cancer drug targets is an effect on transcription of genes that regulate tumor growth, survival and metastasis. The most targetable proteins in the transcription space are transcription-regulating kinases belonging to the cyclin-dependent kinase (CDK) family, CDK7, CDK8/19 and CDK9. Inhibitors of these kinases are undergoing preclinical and clinical development. We hypothesize that inhibitors of transcription-regulating kinases will synergize with targeted drugs used to treat breast cancer, and that combinations of targeted drugs with transcription-regulating kinase inhibitors may overcome or prevent the development of resistance to targeted drugs. We have identified several synergistic combinations of targeted breast cancer drugs and transcription-regulating kinase inhibitors, most notably the combinations of CDK8/19 inhibitors with ER- and HER2-targeting drugs and CDK7 inhibitors with EGFR-targeting drugs. In the remaining period of the project, we will characterize the most potent of the discovered combinations, namely a combination of HER2 and CDK8/19 inhibitors. Under Aim 1, the efficacy of a combination between HER2 inhibitor lapatinib and a CDK8/19 inhibitor will be tested in vivo, using xenograft models of lapatinib-sensitive and resistant HER2- positive breast cancer cells. Aim 2 is to investigate the mechanism of the synergy between lapatinib and CDK8/19 inhibitors. The experimental plan for this Aim is based on the results of RNA-Seq analysis that identified candidate downstream mediators of this synergy. Expression of these candidate genes is regulated by transcription factors, phosphorylation of which is dependent on both CDK8/19 and HER2. Aim 3 is to develop a conjugate between an anti-HER2 monoclonal antibody and a potent CDK8/19 inhibitor and to test the in vitro efficacy of this conjugate, relative to the unconjugated agents. The success of this project will pave the way towards improving the efficacy of targeted therapy in breast cancer through novel combinations of the current targeted drugs with transcription-regulating kinase inhibitors. Future basic and translational research on the combinatorial effects of HER2- and CDK8/19-targeted drugs may have a profound impact on the treatment of metastatic HER2-positive breast cancers that are resistant to HER2-targeted drugs.