A novel therapy for pancreatic neuroendocrine tumors

胰腺神经内分泌肿瘤（PNTH）的发病率在过去两年中有所增加， 几十年局限性PNIPs的主要治疗方法是手术切除，但目前尚无有效的治疗方法。 晚期不可切除或转移性疾病患者的治疗。无进展生存率为 FDA批准的药物依维莫司的最佳治疗时间为11个月，而安慰剂为4.6个月。然而，在这方面， 大多数患者产生耐药性，我们对耐药性的认识存在空白。 PNIPs的耐药机制。MEN 1（44%）、DAXX/ATRX（43%）、mTOR（15%）中的频繁突变 途径基因和Von Hippel Lindau病（VHL）以及其他几种遗传性疾病， 观察到在Pennsylvania。VHL的丧失与增强的肿瘤有氧糖酵解（瓦尔堡效应）有关。在 在这种情况下，癌细胞更严重地依赖于烟酰胺腺嘌呤二核苷酸（NAD）库，这是一个关键的 辅因子的氧化还原反应的代谢途径的癌细胞与高有氧糖酵解。就这样- 对NAD的依赖性可以在NAD补救途径内提供可行的治疗途径。我们 在PNET细胞系和患者来源的组织中的初步研究证实了VHL调节的NAD的活化 生物合成限速酶烟酰胺磷酸核糖基转移酶（NAMPT），以及过氧化氢酶。 mTOR启动子p21激活激酶4（PAK 4）的表达。PAK 4蛋白凭借其 已显示接合多个配体来调节包括PNET在内的信号传导途径的所有组成部分 抵抗分子值得注意的是，PAK 4-NAMPT双重RNAi抑制PNET细胞系的增殖。的 CRISPR/Cas9验证的PAK 4-NAMPT双重抑制剂KPT-9274（I期药物）显示出抗肿瘤活性， 体外，在PNET异种移植物中，并可协同增强依维莫司的细胞毒性。的分子分析 联合治疗显示已知的依维莫司抗性启动子抑制ATP的下调 和NAD。正常细胞可以利用烟酸磷酸核糖基转移酶（NAPRT 1，一种在正常细胞中通常不存在的酶）。 肿瘤由于启动子甲基化）通过烟酸产生NAD。因此，烟酸共- 治疗可以允许KPT-9274剂量递增而对正常组织没有过度毒性。我们假设 靶向PAK 4-NAMPT信号传导可能成为PNET的广泛和临床可行的治疗策略。 目的1：分析PNET患者组织中的PAK 4和NAMPT畸变。目的2：证明PAK 4的作用- PNET治疗耐药的NAMPT。目的3：证明PAK 4-NAMPT双重免疫抑制剂的临床前体内功效 PNET异种移植物中的抑制剂，并在来自正在进行的 一期试验。临床影响：我们的研究将增强对PAK信号传导的基本理解， PNET生存中的NAD代谢。这项工作还将揭示理想的患者人群， 最佳治疗缓解的NAPRT状态。我们的临床前研究将导致开发一种新的 为治疗耐药性和目前无法治愈的PNS患者量身定制的治疗方案。

The incidence of the pancreatic neuroendocrine tumor (PNETs) has increased over the past two decades. The principal treatment for localized PNETs is surgical resection; however, there is no effective therapy for patients with advanced unresectable or metastatic disease. The progression-free survival rate is at the best 11 months with FDA approved agent Everolimus compared to 4.6 months with the placebo. However, the majority of the patients develop drug resistance and there is a void in our understanding of the mechanisms of resistance in PNETs. Frequent mutations in MEN1 (44%), DAXX/ATRX (43%), mTOR (15%) pathway genes and Von Hippel Lindau disease (VHL) alongside several other hereditary disorders are observed in PNETs. Loss of VHL has been linked to enhanced tumor aerobic glycolysis (Warburg effect). In this scenario, cancer cells rely more heavily on Nicotinamide Adenine Dinucleotide (NAD) pool that is a crucial co-factor in the redox reactions of metabolic pathways of cancer cells with high aerobic glycolysis. This over- dependence on NAD may provide actionable therapeutic avenues within the NAD salvage pathway. Our preliminary studies in PNET cell lines and patient derived tissue demonstrate activation of VHL regulated NAD biosynthesis rate-limiting enzyme Nicotinamide Phosphoribosyltransferase (NAMPT) alongside the over- expression of the mTOR promoter p21 activated kinase 4 (PAK4). PAK4 protein by virtue of its ability to engage multiple ligands has been shown to regulate a repertoire of signaling pathways including PNET resistance molecules. Significantly, PAK4-NAMPT dual RNAi suppressed proliferation in PNET cell lines. The CRISPR/Cas9 validated PAK4-NAMPT dual inhibitor KPT-9274 (a Phase I drug) shows antitumor activity in vitro, in PNET xenograft and could synergistically enhance the cytotoxicity of Everolimus. Molecular analysis of combination treatment showed down-regulation of known Everolimus resistance promoter suppression of ATP and NAD. Normal cells can utilize Nicotinate phosphoribosyltransferase (NAPRT1, an enzyme often absent in tumors due to promoter methylation) to generate NAD through nicotinic acid. Therefore, nicotinic acid co- treatment can allow KPT-9274 dose escalation without undue toxicity to normal tissue. We hypothesize that targeting of PAK4-NAMPT signaling could become a broad and clinically viable therapeutic strategy for PNET. Aim1: Profile the PAK4 and NAMPT aberrations in PNET patient tissue. Aim 2: Demonstrate the role of PAK4- NAMPT in PNET therapy resistance. Aim 3: Demonstrate the preclinical in vivo efficacy of PAK4-NAMPT dual inhibitors in PNET xenograft and define a biomarker of therapeutic response in biopsies from an ongoing Phase I trial. Clinical impact: Our studies will enhance the fundamental understanding of PAK signaling and NAD metabolism in PNET subsistence. This work will also uncover the ideal patient population based on their NAPRT status for best treatment response. Our preclinical studies will lead to the development of a novel tailored regimen for therapy-resistant and by far incurable PNETs.