Dual checkpoint blockade for the treatment of KRAS- or BRAF-driven neoplastic disease

KRAS是人类癌症中最常见的突变基因之一。由于直接靶向KRAS是困难的，因此提出了间接方法。这些方案已显示出良好的临床前活性，多项临床试验正在进行中，但临床可行性和有效性尚未得到证实。我们自己的初步数据显示，kras驱动的肿瘤通过Chk1和MK2对功能性细胞周期检查点信号表现出非癌基因依赖性。因此，我们的方法与之前治疗KRAS突变型癌症的大多数策略有很大不同，这些策略通常针对KRAS或其直接下游信号效应物之一，以消除其致癌潜力。然而，关于这种新型合成致命相互作用的许多问题仍未得到解答，目前还无法在临床中进一步验证。例如：其他检查点激酶，如ATM或Chk2是否同样适用于取消检查点的治疗方案？这个问题尤其重要，因为Chk1敲除小鼠显示出胚胎致命性，这可能表明长期使用Chk1抑制剂治疗可能受到毒性的限制。其他KRAS或braf驱动的恶性肿瘤，如结直肠癌，是否对Chk1-和mk2抑制剂表现出类似的敏感性？能否建立基于免疫组织化学的生物标志物来准确预测细胞周期检查点依赖性？为了解决这些问题并促进我们的新治疗方案的临床转化，我们在本应用中提出了三个具体目标：目标1：验证致癌KRAS和BRAF突变作为非癌基因对细胞周期检查点信号依赖的预测因素；目标2：评估Chk2-或atm -抑制剂是否与chk1 -抑制剂一样有效的联合伙伴；建立基于免疫组织化学的生物标志物来预测非癌基因对细胞周期检查点信号的依赖，这些目标专门验证以下假设：1)KRAS和BRAF是细胞周期检查点依赖的可推广预测因子，独立于癌症实体；2)ATM-和Chk2激酶抑制剂可以在细胞周期检查点取消方案中替代Chk1抑制剂；3)除了基于DNA测序的反应预测，可以建立基于免疫组织化学的评分系统，准确预测对细胞周期检查点废除治疗方案的反应。在相关的本地小鼠模型和人类材料中回答这些问题将为我们的假设的快速临床验证铺平道路。

KRAS is one of the most frequently mutated genes in human cancer. As direct targeting of KRAS is difficult, indirect approaches have been proposed. These regimens have shown promising preclinical activity and multiple clinical trials are underway, but the clinical feasibility and validity has yet to be demonstrated.Our own preliminary data show that KRAS-driven tumors display a non-oncogene addiction to functional cell cycle checkpoint signaling through Chk1 and MK2. Our approach thus substantially differs from most previous strategies, developed to treat KRAS-mutant cancers, which typically target KRAS or one of its direct downstream signaling effectors, in order to abolish its oncogenic potential. However, many questions regarding this novel synthetic lethal interaction remain unanswered and currently preclude further validation in the clinic. For instance: Are other checkpoint kinases, such as ATM or Chk2 equally good targets for checkpoint-abrogating therapeutic regimens? This question is particularly important, as Chk1 knockout mice display embryonic lethality, which might suggest that long-term treatment with Chk1 inhibitors might be limited by toxicity. Do other KRAS- or BRAF-driven malignancies, such as colorectal cancer display similar sensitivity against Chk1- and MK2-inhibitors? Could immuno-histochemistry-based biomarkers be established that allow an accurate prediction of cell cycle checkpoint dependence? To address these questions and to facilitate a clinical translation of our novel treatment regimen, we propose three specific aims in this application:Aim 1: Validate oncogenic KRAS and BRAF mutations as predictors for non-oncogene addiction to cell cycle checkpoint signalingAim 2: Assess whether Chk2- or ATM-inhibitors are equally effective combination partners as Chk1-inhibitorsAim 3: Establish immunohistochemistry-based biomarkers to predict non-oncogene addiction to cell cycle checkpoint signalingThese aims specifically test the hypothesis that 1) KRAS and BRAF are generalizable predictors of cell cycle checkpoint addiction, independent of the cancer entity, 2) ATM- and Chk2 kinase inhibitors can substitute Chk1 inhibitors in the cell cycle checkpoint-abrogation regimen and 3) that in addition to DNA sequencing-based response prediction, immunohistochemistry-based scoring systems can be established that accurately predict response to cell cycle checkpoint-abrogating therapeutic regimens. Answering these questions in relevant, autochthonous mouse models and human material will pave the way for a rapid clinical validation of our hypothesis.