Preclinical Testing of PI3K Inhibitors for Vestibular Schwannomas

摘要 Merlin(NF2)抑癌基因突变导致良性肿瘤疾病-神经纤维瘤病型 2(NF2)。这种疾病易导致双侧前庭神经鞘瘤(VS) 进行性听力损失，可导致危及生命的脑干压迫。因为手术切除了一个 VS通常会导致耳聋、面瘫和失衡，因此有必要开发药物疗法来减缓或 防止VS生长，保护神经功能。我们已经致力于建立一种体外和体内的药物 筛选平台，以确定新的化合物以及FDA批准的药物 为VS疗法开发/再利用。为了这个目标，我们创造了缺乏梅林的老鼠和人类 并在384井高通量和高含量分析中优化了它们的使用，以便 使用机器人平台筛选大型化合物/药物库。这种方法鉴定了几种磷脂酰肌醇- 与野生型相比选择性降低Merlin缺陷小鼠存活率的3-激酶(PI3K)抑制剂 具有纳米分子IG50的雪旺细胞。这一初步发现在人类Merlin缺陷的雪旺细胞中得到证实 多个PI3K、双PI3K/mTOR和PI3K/HDAC抑制剂系列。因为PI3K在细胞中起着关键作用 增殖、存活和侵袭，目前有15种不同的PI3K抑制剂在不同的临床试验中 血癌和实体瘤。第一个PI3K类抑制剂(Idelalisib)于2014年被批准用于白血病。 在这项建议中，我们通过对PI3K途径抑制剂进行系统的体外筛选来推进我们的发现 在活体内。这项建议的目的是：1)描述PI3K途径抑制剂的库，以了解其在降低 人Merlin缺陷雪旺细胞系和原代人VS细胞的活性；2)检测 先进的PI3K抑制剂在新型大鼠异种移植中减缓移植物扩张并保护听力和平衡 模型，以及3)进行表型、基因组和转录组分析以揭示分子特征和 细胞和移植物对抑制剂的适应性变化。我们希望获得必要的临床前数据，以 支持PI3K抑制剂在NF2相关性VS患者中的潜在应用。

ABSTRACT Mutations in the merlin (NF2) tumor suppressor gene cause the benign tumor disorder, Neurofibromatosis type 2 (NF2). This disorder predisposes individuals to develop bilateral vestibular schwannomas (VS) that cause progressive hearing loss and can cause life-threatening brainstem compression. Because surgical removal of a VS often causes deafness, facial paralysis, and imbalance, there is a need to develop drug therapies to slow or prevent VS growth and preserve nerve function. We have worked to establish an in vitro and in vivo drug screening platform to identify novel compounds as well as FDA-approved drugs that can be developed/repurposed for VS therapies. Toward this goal, we have created mouse and human merlin-deficient Schwann cell lines and optimized their use in 384-well high-throughput and high-content assays in order to screen large compound/drug libraries using robotic platforms. This approach identified several phosphoinositide- 3 kinase (PI3K) inhibitors that selectively reduce viability of mouse merlin-deficient compared to wild-type Schwann cells with nanomolar IG50. This initial finding was confirmed in human merlin-deficient Schwann cell lines for multiple PI3K, dual PI3K/mTOR and PI3K/HDAC inhibitors. Because PI3K plays a critical role in cell proliferation, survival, and invasion, there are currently 15 different PI3K inhibitors in clinical trials for various blood cancers and solid tumors. The first in class PI3K inhibitor (idelalisib) was approved in 2014 for leukemia. In this proposal, we advance our findings by conducting a systematic screen of PI3K pathway inhibitors in vitro and in vivo. The aims of this proposal are to: 1) profile a library of PI3K pathway inhibitors for efficacy in reducing viability of human merlin-deficient Schwann cell lines and primary human VS cells; 2) test efficacy of the advanced PI3K inhibitors to slow graft expansion and preserve hearing and balance in a novel rat xenograft model, and 3) conduct phenotypic, kinome, and transcriptome analysis to reveal the molecular signatures and adaptive changes of the cells and grafts to the inhibitors. We expect to obtain the necessary pre-clinical data to support the potential use of PI3K inhibitors in patients with NF2-associated VS.