Targeting PLK1 in RAS mutant chronic myelomonocytic leukemia

项目摘要 慢性粒单核细胞白血病（CMML）是一种侵袭性血液系统恶性肿瘤，预后不良。 对CMML集中的合理衍生疗法存在未满足的需求。CMML可以分为 “增殖性”（pCMML）和“发育异常”亚型，其中pCMML具有高频率的RAS途径 突变，并且与<18个月的中位生存期相关。我们已经证明，在pCMML中， 突变型NRAS是一种真正的致癌驱动因子，RAS途径突变与一种独特的 在有丝分裂检查点激酶如PLK 1中富集的基因表达谱。PLK 1是其中的顶级 蛋白质编码基因在RAS突变体CMML中上调，并且考虑到先前的RNAi研究已经显示， RAS突变细胞对PLK 1抑制的敏感性增加，以及PLK 1与 RAF 1在有丝分裂纺锤体中的作用，以及临床级PLK 1抑制剂在AML试验中的持续使用，我们 选择PLK 1作为RAS突变pCMML的治疗靶点。我们发现RAS的敏感性差异 使用体外（祖细胞集落测定）和体内模型（患者- 衍生的异种移植物），并显示出与低甲基化剂（HMA）的潜在协同作用。我们现建议 一项开创性的1期临床试验，测试Onvansertib的安全性和初步疗效，Onvansertib是一种新型口服PLK 1 复发性/难治性pCMML患者中的抑制剂，使用创新的BOIN（贝叶斯最优区间） 设计试验患者的样本将用于评估药代动力学、靶向疗效和应答 与PLK 1和KMT 2A（RAS PLK 1轴的调节因子）表达水平相关。我们还将利用我们的大 CMML生物储存库（n=177个RAS突变样本）开发体外和体内模型以评估突变， 应答和耐药的转录组学和表观遗传学预测因子;特别是个体RAS的影响 途径突变和共同发生的TET 2和ASXL 1突变，这两种最常见的反应定义了 CMML突变对Onvansertib应答的影响。根据我们的初步数据，我们的中心假设是， PLK 1抑制是RAS突变型pCMML的有效治疗策略，其反应受以下因素的影响： 明确的突变谱和表观遗传特征。我们将首先执行一个阶段来解决这个假设 1项临床试验测试了Onvansertib（一种口服选择性PLK 1抑制剂）在以下患者中的安全性和靶向疗效： pCMML（AIM 1）。其次，我们将确定单个RAS通路突变的体外影响， 相关的CMML转录组学和表观遗传学特征对Onvansertib应答的影响（AIM 2）。最后我们将 评估ASXL 1/TET 2突变对RAS患者对Onvansertib和Onvansertib + HMA的应答的影响- 途径突变CMML异种移植物（AIM 3）。如果成功的话，这项研究将提供第一个靶向治疗， RAS突变型髓系肿瘤，为血液学中的个性化治疗奠定基础 恶性肿瘤

PROJECT SUMMARY Chronic myelomonocytic leukemia (CMML) is an aggressive hematological malignancy with dismal outcomes. There is an unmet need for CMML focused rationally derived therapies. CMML can be divided into “proliferative” (pCMML) and “dysplastic” subtypes, with pCMML having a high frequency of RAS pathway mutations and being associated with a median survival of <18 months. We have shown that in pCMML, mutant NRAS is a bona fide oncogenic driver and that RAS pathway mutations are associated with a unique gene expression profile enriched in mitotic check point kinases such as PLK1. PLK1 was among the top protein coding genes upregulated in RAS mutant CMML and given that prior RNAi studies had shown increased sensitivity of RAS mutant cells to PLK1 inhibition and the fact that PLK1 physically interacts with RAF1 at the mitotic spindles, as well as the ongoing use of clinical grade PLK1 inhibitors in AML trials, we selected PLK1 as a therapeutic target in RAS mutant pCMML. We showed differential sensitivity of RAS mutant pCMML cells to PLK1 inhibition using in vitro (progenitor colony assays) and in vivo models (patient- derived xenografts) and demonstrated potential synergy with hypomethylating agents (HMA). We now propose a seminal Phase 1 clinical trial testing the safety and preliminary efficacy of Onvansertib, a novel, oral, PLK1 inhibitor in patients with relapsed/refractory pCMML, using an innovative BOIN (Bayesian Optimal Interval) design. Samples from trial patients will be used to assess pharmacokinetics, targeting efficacy and response correlations with PLK1 and KMT2A (regulator of RAS PLK1 axis) expression levels. We will also use our large CMML biorepository (n=177 RAS mutant samples) to develop in vitro and in vivo models to assess mutational, transcriptomic and epigenetic predictors of response and resistance; specifically the impact of individual RAS pathway mutations and cooccurring TET2 and ASXL1 mutations, the two most common response defining mutations in CMML, on Onvansertib responses. Based on our preliminary data, it is our central hypothesis that PLK1 inhibition is an effective treatment strategy in RAS mutant pCMML, with responses being influenced by defined mutational profiles and epigenetic features. We will address this hypothesis by first performing a Phase 1 clinical trial testing the safety and targeting efficacy of Onvansertib, an oral selective PLK1 inhibitor, in pCMML (AIM 1). Second, we will determine the in vitro impact of individual RAS pathway mutations and associated CMML transcriptomic and epigenetic profiles on Onvansertib responses (AIM 2). Finally, we will assess the impact of ASXL1/TET2 mutations on response to Onvansertib and Onvansertib plus HMA in RAS- pathway mutant CMML xenografts (AIM 3). If successful, this research will provide the first targeted therapy for RAS mutant myeloid neoplasms, setting the stage for personalized therapeutics in hematological malignancies.