Src inhibition in Colorectal Cancer

描述（由申请人提供）：奥沙利铂是转移性结直肠癌治疗方案中的一种活性剂，但大多数患者要么对5-FU和奥沙利铂（FOLFOX）联合治疗无效，要么随后产生耐药性。可能导致奥沙利铂耐药的候选分子是蛋白酪氨酸激酶（Src），其活性在结直肠肿瘤进展期间增加，在转移性疾病中最高。我们的初步研究表明，奥沙利铂在体外和体内治疗后，Src在结肠癌细胞系中被激活。我们已经证明，siRNA抑制Src会增加对奥沙利铂的敏感性。同样，口服酪氨酸激酶抑制剂达沙替尼（dasatinib）对Src的药理学抑制在体外与奥沙利铂协同作用，并在原位小鼠模型中证明至少超加性地减少肿瘤大小。这些发现导致本提案需要验证以下假设：奥沙利铂治疗导致的Src激活是一种促进生存的机制，因此抑制Src将改善奥沙利铂在转移性结直肠癌中的细胞毒性。具体目的1是通过分子方法开发Src活性无法调节的结直肠肿瘤细胞系，确定在细胞培养和结直肠肝转移原位裸鼠模型中，组成型Src激活是否足以诱导奥沙利铂耐药。这些研究将使用转染Src的点突变，使Src具有组成性活性，从而允许评估奥沙利铂敏感性和达沙替尼治疗的后续影响。具体目的2是确定奥沙利铂治疗后肝转移患者肝转移中Src激活的频率，以证明这些临床前发现的临床相关性。特异性目的3旨在评估达沙替尼与FOLFOX +西妥昔单抗联合治疗转移性结直肠癌患者的安全性、初步疗效和药效学。这项由研究者发起的研究，包括广泛的相关研究，以证明Src和Src靶点在肿瘤中的抑制作用。特异性目标4在一项贝叶斯自适应随机、安慰剂对照的FOLFOX +西妥昔单抗+/-达沙替尼的II期研究中进一步评估了该方案的疗效，同时评估了Src抑制的生物标志物。成功的实施将提高目前转移性结直肠癌化疗的有效性，从而改善转移性结直肠癌人群的预后。

DESCRIPTION (provided by applicant): Oxaliplatin is an active agent in metastatic colorectal cancer regimens, but most patients either fail to respond to 5-FU and oxaliplatin (FOLFOX) combinations or subsequently develop resistance. A candidate molecule that might contribute to oxaliplatin resistance is the protein tyrosine kinase, Src, the activity of which is increased during colorectal tumor progression and highest in metastatic disease. Our preliminary studies demonstrate that Src is activated in colon cancer cell lines after oxaliplatin treatment in vitro and in vivo. We have shown that inhibition of Src by siRNA increases sensitivity to oxaliplatin. Likewise, pharmacologic inhibition of Src with dasatinib, an oral tyrosine kinase inhibitor, is synergistic with oxaliplatin in vitro and demonstrates at least supra-additive reductions in tumor size in an orthotopic murine model. These findings lead to the following hypothesis to be tested in this proposal: Src activation resulting from oxaliplatin treatment is a pro-survival mechanism and inhibition of Src will therefore improve oxaliplatin cytotoxicity in metastatic colorectal cancer. Specific aim 1 is to determine if constitutive Src activation is sufficient to induce oxaliplatin resistance in both cell cultures and an orthotopic nude mouse model of colorectal liver metastases by molecular approaches to develop colorectal tumor cell lines in which Src activity cannot be regulated. These studies will use transfected Src with a point mutation rendering Src constitutively active, thereby allowing evaluation of oxaliplatin sensitivity and the subsequent impact of dasatinib therapy. Specific aim 2 is to determine the frequency of Src activation in liver metastases after oxaliplatin treatment in colorectal patients undergoing liver metastasectomy in order to demonstrate the clinical relevance of these preclinical findings. Specific aim 3 is designed to evaluate the safety, preliminary efficacy, and pharmacodynamics of the combination of dasatinib and FOLFOX + cetuximab in patients with metastatic colorectal cancer. This investigator-initiated study, to which we have recently initiated accrual, includes extensive correlative studies to demonstrate inhibition of Src and Src targets in the tumor. Specific aim 4 further evaluates the efficacy of this regimen in a Bayesian adaptively randomized, placebo-controlled phase II study of FOLFOX + cetuximab +/- dasatinib, with concurrent evaluation of a biomarker of Src inhibition. Successful implementation will improve the effectiveness of current chemotherapies for metastatic colorectal cancer, resulting in improved outcomes for the metastatic colorectal cancer population.