Identifying molecular markers that predict relapse after therapy discontinuation inchronic myeloid leukemia.

伊马替尼（IM）的开发彻底改变了慢性粒细胞白血病（CML）的临床结局 以及靶向Bcr-abl癌基因的新一代酪氨酸激酶抑制剂（TKI）。目前，约55%的患者 新诊断的CML患者对TKI治疗（MMR）达到主要分子反应，17%的患者完全缓解。 分子反应（CMR）。由于CML患者存活多年，因此有兴趣确定那些 可以停止治疗。这种兴趣是鼓励30%的发生率的副作用，在长期 TKI治疗和长期TKI治疗对患者和医疗保健系统的巨大成本。不幸的是， 在几项临床试验中，约60%的持续性MMR/CMR受试者在TKI停药后复发。给定 复发后TKI重新诱导的有利率结果，尝试停止治疗是治疗的一部分， 美国国家综合癌症网络（NCCN）针对长期CMR患者的指南。 这些中止研究表明一些白血病干细胞（LSC）持续缓解。持久性 LSC不具有BCRABL融合基因的突变或重复，如在明显的TKI抗性中所见，但 提供易于获得此类突变或导致胚变危象（BC）的细胞库。电流 临床工具在预测TKI停药后复发与持续缓解的可能性方面不准确。 我们建立了一个小鼠骨髓移植模型，以确定与 TKI成功停药。在该模型中，Bcr-abl转导的同基因骨髓的原代受者 (in慢性期; CP）为次级受体的供体。二次受体接受TKI+其他治疗 试剂，并且具有MMR的小鼠是三级受体的供体。第三次接受者被随访， 治疗我们发现，接受IM诱导的MMR小鼠骨髓移植的受者， 与来自处理供体的Bcr-abl+细胞数或Bcr-abl转录本拷贝/细胞无关。 在以往的研究中，我们发现Fas和Gsk 3 β抑制剂Fap 1表达增加有助于Fas CML-LSC中的抗性和β连环蛋白/存活素活性。我们发现，加入Fap 1抑制剂或 生存素与IM治疗预防Bcr-abl+骨髓受体的复发。重要的是，没有第三接收者 来自IM + Fap 1或存活素抑制剂处理的小鼠的骨髓在24周的观察期间复发（相当于 15+人类年）。我们发现在小鼠骨髓中Bcr-abl转录本拷贝/GFP+细胞增加了50倍， IM与IM + Fap 1或生存素抑制剂治疗。这反映了这些人骨髓群体的差异。 小鼠在用TKI +生存素抑制剂治疗的小鼠骨髓的转录组分析中，我们发现， 参与先天性免疫应答，NOD样信号传导， 细胞因子的产生和核糖核酸酶活性的调节。 我们假设，确定与复发相关的途径将允许选择CML 受试者能够安全地停止治疗。这些途径可能是合理的治疗靶点，以允许更多的 受试者停止治疗或重新获得MMR。我们将通过两个目标来调查这一点; 目的1：确定与接受治疗的CMR-CML患者复发相关的分子标志物 停止尝试。将根据NCCN指南停止TKI治疗。临床试验将与 复发受试者骨髓中的分子标志物与持续的无治疗缓解。 目的2：确定在小鼠CML模型中TKI停药后易复发的特征。 我们将研究TKI停药后易复发的分子机制， 异种移植或鼠骨髓移植。在临床前研究中，将针对涉及的途径。 在这些研究中，我们采用临床前小鼠模型研究TKI停药。结果将 翻译为人类CML受试者的研究提供信息。其目标是确定与复发相关的途径 作为预后指标和潜在的未来治疗靶点。

Clinical outcomes in chronic myeloid leukemia (CML) were revolutionized by development of imatinib (IM) and later generation tyrosine kinase inhibitors (TKIs) that target the Bcr-abl oncogene. Currently, ~55% patients with newly diagnosed CML achieve a major molecular response to TKI treatment (MMR) and 17% a complete molecular response (CMR). Because CML patients survive many years, there is interest in identifying those who can discontinue treatment. This interest is encouraged by the 30% incidence of side effects in during long term TKI therapy and the substantial costs of chronic TKI treatment to patients and healthcare systems. Unfortunately, ~60% of subjects with sustained MMR/CMR relapsed after TKI discontinuation in several clinical trials. Given favorable rates results of TKI re-induction with after relapse, a therapy discontinuation attempt is a part of the National Comprehensive Cancer Network (NCCN) guidelines for patients with prolonged CMR. These discontinuation studies suggest some leukemia stem cells (LSCs) persist in remission. Persistent LSCs do not have mutation or duplication of the BCRABL fusion gene, as is seen with overt TKI resistance, but provide a reservoir of cells susceptible to acquiring such mutations, or those leading to blast crisis (BC). Current clinical tools are inaccurate in predicting the likelihood of relapse vs sustained remission post TKI discontinuation. We developed a murine bone marrow transplantation model to define characteristics associated with successful TKI discontinuation. In this model, primary recipients of Bcr-abl transduced syngeneic bone marrow (in chronic phase; CP) were donors to secondary recipients. Secondary recipients were treated with TKIs + other agents, and mice with an MMR were donors for tertiary recipients. Tertiary recipients were followed without treatment. We found a 64% relapse rate in recipients of bone marrow from mice with IM-induced MMR that did not correlate with number of Bcr-abl+ cells from the treated donors or Bcr-abl transcript copies/cell. In prior studies, we found increased expression of Fap1 (a Fas and Gsk3β inhibitor) contributed to Fas resistance and βcatenin/survivin activity in CML-LSCs. We found that the addition of an inhibitor of Fap1 or survivin to IM treatment prevented relapse in Bcr-abl+ bone marrow recipients. Importantly, no tertiary recipients of bone marrow from IM + Fap1 or survivin inhibitor treated mice relapsed over 24 wks of observation (equivalent to 15+ human years). We found a 50x increase Bcr-abl transcript copies/GFP+ cell in the bone marrow of mice treated with IM vs IM + Fap1 or survivin inhibitor. This reflected differences in bone marrow populations in these mice. In transcriptome analysis of bone marrow from mice treated with TKI + a survivin inhibitor, we identified differences in pathways involved in positive regulation of the innate immune response, NOD-like signaling, cytokine production, and regulation of ribonuclease activity. We hypothesize that identifying pathways which are associated with relapse will permit selection of CML subjects able to safely discontinue treatment. Such pathways may be rationale therapeutic targets to permit more subjects to discontinue treatment, or regain an MMR. We will investigate this through two Aims; Aim 1: Identify molecular markers associated with relapse in CMR-CML patients undergoing a therapy discontinuation attempt. TKI treatment will be discontinued per NCCN guidelines. A clinical trial will correlate molecular markers in the subject’s bone marrow with relapse vs sustained therapy free remission. Aim 2: Define characteristics that predispose to relapse after TKI discontinuation in a murine CML model. We will investigate molecular mechanisms predisposing to relapse after TKI discontinuation in patient derived xenografts or murine bone marrow transplants. Implicated pathways will be targeted in pre-clinical studies. In these studies, we employ a pre-clinical murine model to study TKI discontinuation. Results will be translated to inform studies in human CML subjects. The goal is to identify pathways associated with relapse after TKI discontinuation as prognostic indicators and potential future therapeutic targets.