Project 3 - Novel Therapies for Spliceosomal-Mutant MDS.

项目摘要 目前治疗骨髓增生异常综合征(MDS)和急性髓系白血病(AML)的方法并不令人满意。 我们和其他人发现，前mRNA剪接复合体的组件在 MDS和AML患者并诱导RNA剪接改变。它的小分子调节剂 我们的合作者和其他人已经开发出了复合体(即剪接调节器)。我们最近 报道了突变剪接因子的表达或剪接与剪接的药物干扰 调节剂增加了R环的丰度，R环是含有DNA：RNA杂交物和 置换了单链DNA。R环触发依赖于ATR的DNA损伤检查点响应 调节R环的分解，以保护细胞免受基因组不稳定和细胞死亡的影响。我们的预赛 临床前数据表明，剪接体突变细胞比野生型细胞对ATR抑制更敏感。 我们假设剪接因子突变会产生对ATR抑制(ATRI)的易感性，这可能是 单独使用或与剪接结合使用时用于开发新的治疗策略 调节剂药物。我们将在髓系患者ATRI的II期临床试验中验证这一假说。 并使用定义明确的体外和体内模型。在具体目标1中，我们将进行第二阶段 ATR抑制治疗复发/难治性MDS和慢性粒单核细胞白血病(CMML)的试验 确定对这种新疗法的敏感性和耐药性的分子基础。我们预测患有这种疾病的患者 与没有剪接的患者相比，剪接体突变对ATRI的应答率更高 因子突变。相关研究将评估药效学终点并检查其作用机制 药物敏感性和耐药性，如果发生的话。在具体目标2中，我们将联合测试ATRI的疗效 在剪接体-突变型MDS模型中使用剪接调节器。初步证据表明，暴露于 表达造血细胞的剪接因子突变体与剪接体小分子调节剂的关系 加剧R环的形成，增加细胞对ATRI的敏感性。我们将使用基因定义的 体外和体内暴露于多种剪接体调节剂的细胞和小鼠模型 与ATRI相结合。最后，我们将进行全基因组CRISPR/Cas9筛查，以确定基因和 可使剪接体突变细胞对ATRI的细胞毒作用敏感的途径可能被追寻 在未来的临床试验中。这个项目通过在人类中进行第一次实验来解决孢子翻译的终点问题 ATRI治疗髓系恶性肿瘤的临床试验。我们将识别符合以下条件的遗传生物标志物 预测ATRI的反应，并建立提名联合治疗所需的临床前数据 这可以用来开发第一个新的：治疗MDS和AML的药物的新组合 剪接因子突变。

Project Summary Current therapies for myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) are unsatisfactory. We and others discovered that components of the pre-mRNA splicing complex are recurrently mutated in patients with MDS and AML and induce alterations in RNA splicing. Small molecule modulators of this complex (i.e., splicing modulators) have been developed by our collaborators and others. We recently reported that expression of mutant splicing factors or pharmacologic perturbation of splicing with splicing modulators increase the abundance of R loops, which are structures containing DNA:RNA hybrids and displaced single-strand DNA. R loops trigger an ATR-dependent DNA damage checkpoint response that mediates resolution of the R loop to protect cells from genomic instability and cell death. Our preliminary preclinical data suggest that spliceosome mutant cells are more sensitive to ATR inhibition than wild-type cells. We hypothesize that splicing factor mutations create a vulnerability to ATR inhibition (ATRi) that can be exploited for the development of novel therapeutic strategies when used alone or in combination with splicing modulator drugs. We will test this hypothesis in a phase II clinical trial of an ATRi in patients with myeloid malignancies and using well-defined in vitro and in vivo models. In Specific Aim 1, we will conduct a phase II trial of ATR inhibition in relapsed/refractory MDS and chronic myelomonocytic leukemia (CMML) and determine the molecular basis of sensitivity and resistance to this novel therapy. We predict that patients with spliceosome mutations will have an increased response rate to ATRi compared to patients without a splicing factor mutation. Correlative studies will assess pharmacodynamic endpoints and examine the mechanisms of drug sensitivity and resistance, if it occurs. In Specific Aim 2, we will test the efficacy of ATRi in combination with splicing modulators in models of spliceosome-mutant MDS. Preliminary evidence suggests that exposure of splicing factor mutant expressing hematopoietic cells to small molecule modulators of the spliceosome exacerbates R loop formation and increases sensitivity of cells to ATRi. We will use genetically-defined cellular and mouse models exposed in vitro and in vivo to a variety of spliceosome modulators alone or in combination with ATRi. Finally, we will perform a genome-wide CRISPR/Cas9 screen to identify genes and pathways that could sensitize spliceosome-mutant cells to the cytotoxic effects of ATRi that could be pursued in future clinical trials. This project addresses SPORE translational endpoints by conducting a first in human clinical trial of an ATRi in patients with myeloid malignancies. We will identify genetic biomarkers that are predictive of response to ATRi and establish the preclinical data necessary to nominate combination therapies that could be used to develop the first novel:novel combination of drugs for the treatment of MDS and AML with splicing factor mutations.