Maximal MYC control using dual PI-3K/BRD4 (kinase/epigenetic) inhibitors

描述(由申请人提供)：抑制关键的癌症促进转录因子MYC的需求尚未得到满足。MYC(cMYC和MYCN)作用于许多细胞受体复合体和信号转导通路的下游，激活驱动癌细胞生长和增殖的基因。到目前为止，MYC的小分子抑制剂一直难以捉摸。一种创新的方法是通过使用PI-3激酶(PI-3K)抑制剂促进MYC的降解，并使用溴结构域蛋白BRD4的抑制剂阻止产生MYC的基因的转录来间接地降低MYC的活性。虽然小分子抑制剂或PI-3K和BRD4单独用于癌症临床试验，但没有一种药物通过FDA的批准。尽管联合治疗在癌症中很常见，但每个增加的联合治疗都有一个尚未满足的需求，即抑制多个靶点以最大限度地提高疗效。这变得不可行，因为当结合昂贵的靶向治疗时，成本过高，此外还阻碍了对这种复杂药物组合的早期临床评估。在探索一种新型的PI-3K抑制剂支架--基于色酮衍生物的硫代吡喃酮(TP)支架时，我们发现这些化合物也能有效地抑制BRD4(初步结果)。色酮骨架对这两个靶标的抑制作用是共同的，因此提供了现在探索新发现的BRD4活性的机会，同时保持强大的PI-3K活性(总体目标)。整合PI-3K和BRD4的抑制，用一个分子最大限度地抑制MYC活性，将填补上述所有未满足的需求。本提案将通过实现以下目标来评估这一方法，为第二阶段的工作奠定基础，将预期的双重抑制剂先导化合物(S)优化为临床候选化合物：目标(任务)#1.确定TP化合物对BRD4抑制的结构活性关系(SAR)。方法：合成30个茶多酚类化合物，测定它们的BRD4和PI-3K抑制谱。目标(任务)#2.为设计化合物的电子对接开发预测性计算BRD4模型。方法：改变BRD4模型的分子匹配参数，直到TP数据集的对接预测与实际的BRD4分析结合结果相关联，创建一个经过验证的对接模型。目的(任务)#3.确定BRD4/PI-3K双重抑制对MYC的影响和治疗指数。方法：确定MYC的表达和活性水平，并比较单一BRD4或PI-3K与双重BRD4/PI-3K抑制条件下对癌细胞株和正常细胞株的毒性。这项研究的贡献在于它提供了一种有效的机制来阻断导致癌症的MYC活性，而且将具有重大意义，因为它将允许对依赖MYC的癌症，如CLL、髓母细胞瘤和神经母细胞瘤进行强化的联合治疗。这种方法是创新的，因为它使用一种化合物的两种正交机制攻击一个关键的癌症靶点，并挑战了在没有FDA批准的治疗方法的领域的癌症研究中普遍存在的一种忽视成本的疗效限制心态。

DESCRIPTION (provided by applicant): There is an unmet need to inhibit the key cancer promoting transcription factor MYC. MYC (both cMYC and MYCN) acts downstream of many cell receptor complexes and signal transduction pathways to activate genes that drive cancer cell growth and proliferation. To date, small molecule inhibitors of MYC have been elusive. An innovative approach would be to indirectly orthogonally diminish the activity of MYC by enhancing its degradation using PI-3 kinase (PI-3K) inhibitors combined with blocking transcription of the gene producing MYC using inhibitors of the bromodomain protein BRD4. While small molecule inhibitors or PI-3K and BRD4 are individually used in cancer clinical trials, none has made it through development to FDA approval. Although combination treatments are common in cancer, there is an unmet need for every increasing combinations to inhibit multiple targets to maximize efficacy. This becomes unfeasible due to prohibitive costs when combining expensive targeted therapies in addition to being a barrier to early clinical evaluation of such complex combinations of drugs. While exploring a novel PI-3K inhibitor scaffold, thienopyranone (TP) scaffold based on a chromone derivative we discovered that these compounds also can potently inhibit BRD4 (preliminary results). The chromone backbone is common to the inhibition of BOTH targets thus providing the opportunity to now explore the newly found BRD4 activity while maintaining potent PI-3K activity (overall objective). Consolidating the inhibition of PI-3K AND BRD4 to maximally inhibit MYC activity with one molecule would fill all the unmet needs stated above. This proposal will evaluate this approach by achieving the following aims setting the stage for phase II efforts to optimize the expected dual inhibitor lead compound(s) to a clinical candidate: Aim (Task) #1. Determine structure activity relationship (SAR) for TP compounds for BRD4 inhibition. Approach: Synthesize 30 TP compounds and determine their BRD4 and PI-3K inhibition profiles. Aim (Task) #2. Develop predictive computational BRD4 model for the in silico docking of designed compounds. Approach: Vary the molecular in silico fit parameters of the BRD4 model until docking predictions of a TP dataset correlates with actual BRD4 assay binding results creating a validated docking model. Aim (Task) #3. Determine effects on MYC and therapeutic index for dual BRD4/PI-3K inhibition. Approach: Determine MYC expression and activity levels and compare toxicity towards cancer cell lines versus normal cell lines when exposed to single BRD4 or PI-3K versus dual BRD4/PI-3K inhibition conditions. The contribution of this research is it provides an effective mechanism to block MYC activity that drives cancer and will be significant because it will allow enhanced combination treatments of MYC dependent cancers, such as CLL, medulloblastoma, and neuroblastoma. This approach is innovative because it attacks a key cancer target using two orthogonal mechanisms with a single compound and it challenges the cost-ignoring efficacy-limiting mentality of one-drug one-target prevalent in cancer research in an area with no FDA approved treatments.