Inhibiting PLEKHA7 for mutant KRAS therapy

抑制 PLEKHA7 用于突变 KRAS 治疗

• 批准号: 8777034
• 负责人: Lynn Kirkpatrick
• 金额: $ 22.5万
• 依托单位: PHUSIS THERAPEUTICS, INC.
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-15 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8777034
• 关键词: Adopted; Affinity; Automobile Driving; Binding; Businesses; Cancer Cell Growth; Cancer Patient; Cell Proliferation; Cell membrane; Cells; Crystallization; Development; Diagnosis; Disease; Docking; Event; Goals; Growth; Guanosine Triphosphate Phosphohydrolases; HRAS gene; Hand; Homology Modeling; Human; KRAS2 gene; Lead; Lipids; MEKs; Malignant Neoplasms; Medical; Membrane Proteins; Modeling; Molecular; Monomeric GTP-Binding Proteins; Mutate; Mutation; Neoplasm Metastasis; New Agents; Oncogenic; PH Domain; Patients; Pharmaceutical Preparations; Phase; Phosphatidylinositols; Pilot Projects; Play; Point Mutation; Positioning Attribute; Property; Proteins; Roentgen Rays; Role; Scaffolding Protein; Signal Pathway; Signal Transduction; Site; Small Business Innovation Research Grant; Stream; Structure; Testing; Therapeutic; Time; base; cancer cell; cancer therapy; cancer type; cell growth; design; effective therapy; experience; functional genomics; genetic regulatory protein; in vivo; inhibitor/antagonist; mutant; novel strategies; pre-clinical; protein folding; public health relevance; ras Proteins; screening; small molecule; therapy resistant; tumor; tumor growth

DESCRIPTION (provided by applicant): Oncogenic KRAS is found in 25% of patient tumors across many cancer types. Despite extensive effort since its discovery over 30 years ago there is still no effective treatment for KRAS tumors. An estimated 350,000 patients in the US in 2013 will be diagnosed with mutated KRAS in their tumor, and many will die of their disease. Mutated KRAS plays a critical role in driving tumor growth and resistance to therapy. Its effects are so powerful that it overrides the activity of many of the new molecularly targeted signaling drugs being developed for cancer. Thus, finding new agents that inhibit the effects of mutated KRAS is one of the most important unmet medical needs in cancer today. Mutated KRAS as a target also presents an untapped business opportunity because of the large number of patients that could benefit from an effective inhibitor, used alone or in combination with molecularly targeted therapies from which the patients are currently excluded. PHusis Therapeutics has adopted a new paradigm for attacking KRAS tumors through inhibition of critical KRas associated regulatory proteins as surrogate targets for inhibiting KRas signaling activity and cell growth. Using functional genomic screening PHusis has identified PLEKHA7, a protein associated with the mutated KRas signaling nanocluster, as a top hit and has shown that PLEKHA7 is absolutely necessary for the growth and down-stream signaling activity of mutated KRas in cancer cells. Remarkably inhibiting PLEKHA7 is without effect on wild type KAS cancer cell growth. PHusis has validated PLEKHA7 as an essential mutated KRas regulator protein using extensive molecular, cellular and in vivo studies. The PLEKHA7 protein has a unique 3D fold, the pleckstrin homology (PH) domain that binds to phosphoinositide lipids thus positioning host proteins at specific sites in the cell membrane. The mechanism, we propose for PLEKHA7 is that its PH domain is necessary to correctly position the mutated KRas signaling nanocluster at sites in the plasma membrane where it drives cancer cell growth and invasion. PHusis Therapeutics has extensive experience developing PH domain inhibitors and has been able to show that the PH domain of PLEKHA7 is a druggable entity, and has developed proof of principle low micromolar selective small molecule leads using computational docking and a homology model of the PLEKHA7 PH domain. PHusis now has in hand a 1.4-Angstrom X-ray crystal structure of the PLEKHA7 PH domain and will use it to design proprietary, higher affinity inhibitors of PLEKHA7 that selectively block the growth of mutant KRAS cancer cells. Thus, the hypothesis upon which the studies are based is "There is no effective therapy for oncogenic KRAS tumors. PLEKHA7, acting through its PH domain, is necessary for mutant KRas but not wild type KRas, signaling, cell proliferation and tumor growth. PLEKHA7 has a unique druggable PH domain that is required for PLEKHA7's facilitation of mutant KRas signaling providing a window of opportunity to develop small molecules inhibitors as potential agents for the treatment of KRas tumors". Thus the objectives of the Phase I SBIR study are: 1) to use the newly developed X-ray crystal structure of the PLEKHA7 PH domain to design more potent, selective and drug-like small molecule inhibitors and confirm their binding by co-crystallization studies; 2) to test the ability of the agents to selectively inhibit mutated KRAS signaling and cell growth; an 3) to conduct a proof of principle in vivo pilot study of the most active compound as an inhibitor of a mutant KRas tumor growth.

描述（由申请人提供）：在许多癌症类型中，25%的患者肿瘤中发现致癌KRAS。尽管自30多年前被发现以来已经付出了巨大的努力，但KRAS肿瘤仍然没有有效的治疗方法。据估计，2013年美国将有35万名患者被诊断出肿瘤中存在KRAS突变，其中许多人将死于这种疾病。突变的KRAS在驱动肿瘤生长和对治疗的抵抗中起着关键作用。它的作用是如此强大，以至于它超越了许多正在开发的针对癌症的新型分子靶向信号药物的活性。因此，寻找抑制突变KRAS影响的新药物是当今癌症领域最重要的未满足的医疗需求之一。突变的KRAS作为靶标也提供了一个未开发的商业机会，因为大量患者可以从有效的抑制剂中获益，单独使用或与分子靶向治疗联合使用，而这些患者目前被排除在外。PHusis Therapeutics采用了一种新的模式，通过抑制关键的KRAS相关调节蛋白作为抑制KRAS信号活性和细胞生长的替代靶点来攻击KRAS肿瘤。通过功能基因组筛选，PHusis发现了与突变KRas信号纳米簇相关的蛋白PLEKHA7，并表明PLEKHA7对于突变KRas在癌细胞中的生长和下游信号活性是绝对必要的。明显抑制PLEKHA7对野生型KAS癌细胞生长无影响。PHusis通过广泛的分子、细胞和体内研究证实PLEKHA7是一种重要的突变KRas调节蛋白。PLEKHA7蛋白具有独特的3D折叠，即与磷酸肌醇脂结合的pleckstrin同源（PH）结构域，从而将宿主蛋白定位在细胞膜的特定位置。我们提出PLEKHA7的机制是，它的PH结构域对于将突变的KRas信号纳米簇正确定位在质膜上驱动癌细胞生长和侵袭的位点是必要的。PHusis Therapeutics在开发PH结构域抑制剂方面拥有丰富的经验，并且已经能够证明PLEKHA7的PH结构域是一个可药物实体，并且已经通过计算对接和PLEKHA7 PH结构域的同源模型开发了低微摩尔选择性小分子先导物的原理证明。PHusis现在已经掌握了PLEKHA7 PH结构域的1.4埃x射线晶体结构，并将利用它来设计专利的、高亲和力的PLEKHA7抑制剂，选择性地阻断突变KRAS癌细胞的生长。因此，这些研究所基于的假设是“对于致癌的KRAS肿瘤没有有效的治疗方法”。PLEKHA7通过其PH结构域起作用，是突变型KRas而非野生型KRas、信号传导、细胞增殖和肿瘤生长所必需的。PLEKHA7具有独特的可药物性PH结构域，这是PLEKHA7促进突变KRas信号传导所必需的，这为开发小分子抑制剂作为治疗KRas肿瘤的潜在药物提供了机会。”因此，I期SBIR研究的目标是：1)利用新开发的PLEKHA7 PH结构域的x射线晶体结构来设计更有效的、选择性的和类似药物的小分子抑制剂，并通过共结晶研究确认它们的结合；2）