Targeting gain-of-function p53 and BCL-2 for small cell lung cancer treatment

项目概要/摘要 通过一个独特的基因组学和药物筛选平台，约800个实体瘤细胞系，我们发现了一个子集， 的SCLC细胞系对维奈托克（一种FDA批准的BCL-2抑制剂）过敏。这些敏感的SCLC BCL-2的高表达。基于这些数据，一项在SCLC中进行的维奈托克I/II期临床试验 患者已在VCU设计（NCT 04543916）。最近有人提出，SCLC可以分为 基于关键转录因子表达的四种亚型：SCLC-A（ASCL 1阳性）、SCLC-N （NeuroD 1阳性）、SCLC-P（POU 2F 3阳性）和SCLC-Y（YAP 1阳性）。其中，SCLC-A和 SCLC-P占SCLC的近80%，经常表达高水平的BCL-2。我们注意到BCL-2 我们检测的高度和维奈托克敏感的细胞系都属于SCLC-A。然而，我们发现， SCLC-A和SCLC-P中BCL-2高表达，但对维奈托克耐药。此外，其中大部分 SCLC细胞系具有TP 53错义突变，其产生单个氨基酸改变。这些变种人不 不仅失去野生型p53肿瘤抑制功能，而且还获得新的促癌活性[ 函数（GOF）]。已经表明GOF p53表达与化疗和放射抗性相关， 各种癌症。此外，最近一项对GOF p53基因敲入小细胞肺癌小鼠模型的研究表明， 功能丧失活性可减弱化疗功效。基于这些观察，我们假设， GOF p53赋予维奈托克抗性，同时抑制BCL-2和GOF p53诱导 在SCLC-A和SCLC-P亚组中的协同抗癌活性。我们的初步数据支持这一假设： (1)GOF p53的下调增加了仅BH 3促凋亡BIM的表达，并对 venetoclax在SCLC-P细胞中;（2）通过HSP 90抑制剂ganetespib靶向GOF p53，增加BIM表达 并且在SCLC-P和SCLC-A细胞中对维奈托克敏感。虽然目前有许多组合 对于维奈托克的研究提出，同时靶向BCL-2和GOF p53的概念是创新的， 联合应用维奈托克和HSP 90抑制剂有望成为治疗SCLC的有效方法。在这 建议，我们将确定这种组合在体外的作用机制和这种组合的功效。 使用细胞系异种移植物和患者来源的异种移植物的SCLC-A和SCLC-P亚型亚组的组合 (PDX)模型目的1探讨维奈托克和甘尼替匹诱导细胞死亡的机制 在体外SCLC细胞系中的组合。目的2将确定维奈托克和甘尼替匹联合用药的疗效 在SCLC小鼠模型中的治疗。由于venetoclax是FDA批准的，HSP 90抑制剂正在 在包括SCLC在内的临床试验中进行了调查，成功完成拟议项目将导致 在VCU Massey癌症中心和Holmes Hunter VA医疗中心进行临床试验。

Project Summary/Abstract Through a unique genomics and drug screening platform with ~800 solid tumor cell lines, we have found a subset of SCLC cell lines are hypersensitive to venetoclax, an FDA-approved inhibitor of BCL-2. These sensitive SCLCs have invariably high BCL-2 expression. Based on this data, a phase I/II clinical trial with venetoclax in SCLC patients has been designed at VCU (NCT04543916). It has been recently proposed that SCLC can be classified in four subtypes based on the expression of key transcription factors: SCLC-A (ASCL1 positive), SCLC-N (NeuroD1 positive), SCLC-P (POU2F3 positive), and SCLC-Y (YAP1 positive). Among them, SCLC-A and SCLC-P, which make up almost 80% of SCLC, frequently express high levels of BCL-2. We noticed that BCL-2 high and venetoclax-sensitive cell lines that we examined all belong to SCLC-A. However, we found that a subset of SCLC-A and SCLC-P showed high BCL-2 expression but were venetoclax-resistant. In addition, most of these SCLC cell lines have TP53 missense mutations, which make a single amino acid change. These mutants not only lose wild-type p53 tumor suppressor functions, but also acquire novel cancer-promoting activities [gain-of- function (GOF)]. It has been shown that GOF p53 expression is associated with chemo- and radio-resistance in a variety of cancers. Furthermore, a recent study with GOF p53 knock-in mouse models of SCLC suggests gain- of-function activity can attenuate chemotherapeutic efficacy. Based on these observations, we hypothesize that GOF p53 confers venetoclax-resistance and that simultaneous inhibition of BCL-2 and GOF p53 induces synergistic anticancer activity in a subset of SCLC-A and SCLC-P. Our preliminary data support this hypothesis: (1) Down-regulation of GOF p53 increases the expression of a BH3-only pro-apoptotic BIM and sensitizes to venetoclax in SCLC-P cells; (2) targeting GOF p53 by the HSP90 inhibitor, ganetespib, increases BIM expression and sensitizes to venetoclax in SCLC-P and SCLC-A cells. Although currently there are many combination studies for venetoclax proposed, the concept of simultaneous targeting of BCL-2 and GOF p53 is innovative and the combination of venetoclax and HSP90 inhibitors would be promising approach for SCLC treatment. In this proposal, we will determine the mechanism of action of this combination in vitro and the efficacy of this combination in a subset of SCLC-A and SCLC-P subtypes using cell line xenograft and patient-derived xenograft (PDX) models. Aim 1 will determine the mechanisms of cell death induced by venetoclax and ganetespib combination in SCLC cell lines in vitro. Aim 2 will define the efficacy of venetoclax and ganetespib combination treatment in mouse models of SCLC. Since venetoclax is FDA-approved and HSP90 inhibitors are being investigated in clinical trials including SCLC, the successful completion of the proposed project will lead to developing clinical trials at VCU Massey Cancer Center and Holmes Hunter VA Medical Center.